technical guide for wcdma lac planning(v1.1) zte
TRANSCRIPT
Internal Use Only
Technical Guide for WCDMA LAC Planning
Version v10
Release 2007-11-6 Implementation 2007-11-6
Released by Network Planning amp Optimization Dept ZTE Corp
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
Internal Use Only
Modification Record
File NoDrafter
ModifierMajor Points Modified
Update
DateVersion
Reason for
modification
1 WANG Feng 2007-3-6 V10 Guide
establishment
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
Contents
1 OVERVIEW1
2 PAGING PRINCIPLE PAGING CHANNEL PARAMETER AND SYSTEM
PARAMETER1
21 PAGING PRINCIPLE1
22 PAGING CHANNEL PARAMETER1
23 SYSTEM PARAMETER2
3 PAGING CAPACITY CALCULATION2
31 PCH CAPACITY CALCULATION2
311 Channel Number Confirmation2
312 GOS Confirmation2
313 Channel Capacity Calculation3
32 EACH UErsquoS PAGING TRAFFIC CALCULATION ON BUSY HOUR3
321 CS Traffic Model3
33 CALCULATION OF THE MAXIMUM SUBSCRIBER NUMBER THAT EACH LAC
SUPPORTS5
4 LAC DIVISION PRINCIPLE6
5 FEASIBILITY ANALYSIS OF WCDMA AND GSM CO-USE LAC7
51 WCDMA PAGING CAPACITY CALCULATION7
52 GSM PAGING CAPACITY CALCULATION7
53 ADVANTAGE AND DISADVANTAGE OF WCDMA AND GSM CO-USE LAC AS WELL AS
SUGGESTIONS8
6 LIBYA LAC DIVISION CASE9
Internal Use Only
1 Overview
The guide introduces WCDMA paging channel capacity calculation from which deduces the
maximum number of sectors that can be supported by each LAC with different traffic model as
well as general suggestions for LAC division the guide provides instructions for LAC planning on
the phase of WCDMA radio network planning
The guide includes paging principle paging capacity calculation and LAC division principle
2 Paging Principle Paging Channel Parameter and System
Parameter
21 Paging Principle
LAC is an abbreviation for Location Area Code a parameter represents UE paging location
When a UE is paged CN will send paging request through RNC to all NodeB that use the
corresponding LAC One LAC may be used by tens or hundreds of cells so the number of paging
message sent to RNC may be astonishing NodeB has to send paging request through limited PCH
to UE therefore too many NodeB that use one same LAC may cause NodeB paging overload
even signaling congestion and paging message drop But if too less NodeB use one same LAC
then there will be many boundaries of areas with different LAC that make it easy for UE on these
boundaries to update location frequently among areas with different LAC if UE is moving to an
area with different LAC and carrying out location update when a paging message is sent then UE
canrsquot receive the paging message sent to the area with the original LAC during the location update
period and therefore UE canrsquot be connected
22 Paging Channel Parameter
In 3G network paging happens in PCCH Logical channel PCCH is mapped to transmission
channel PCH and transmission channel PCH is mapped to physical channel SCCPCH so paging is
transmitted in physical channel SCCPCH
Related PCCH parameters are defined in Criterion 34108 Two modes 240bit10ms and
80bit10ms are transmitted in PCCH We usually use the mode 240bit10ms According to the
definition in the protocol the length of IMSI-GSM-MAP is 60bits with further consideration of
selection bits and paging reason bits one PCCH frame can carry 3 IMSI The length of TMSI-
GSM-MAP or PTMSI-GSM-MAP is 32bits therefore one 10ms PCCH frame comprises at most 5
TMSI paging or PTMSI paging
Paging channel of each cell includes one of the following combinations
1048727 3 IMSI paging
1048727 2 IMSI paging+ at most 2 TMSI paging
1048727 1 IMSI paging + at most 4 TMSI paging
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
1
Internal Use Only
1048727 At most 5 TMSI paging
The maximum paging number in one Paging Type1 Record is 8 ( refer to 25331
maxpage1) therefore when it is IMSI paging the maximum paging capacity of each paging
channel of each cell is Min(38)=3 when it is TMSI paging the maximum paging capacity of each
paging channel of each cell is Min(58)=5
23 System Parameter
The present system parameter default settings are
Paging period is 640ms
Radio paging repeats 4 times
CN paging is resent once total sending times is twice
CN paging resending interval is 3 seconds
Paging total congestion rate is set as 02
3 Paging Capacity Calculation
31 PCH Capacity Calculation
311 Channel Number Confirmation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5 Take the worst situation into account we define sub-channel number of each
PCCH is 3 which can be adjusted dynamically
312 GOS Confirmation
For improving paging success rate RNC uses multi-retransmission therefore the
corresponding relationship between call loss of multi-retransmission and call loss of single
retransmission needs to be calculated Presently systemrsquos RNC retransmission times are 4
Suppose that the call completion ratio first time is x1 call loss is s1 then x1=1-s1
Suppose that the call completion ratio second time is x2 call loss is s2 then x1=1-s2
Suppose that the call completion ratio third time is x3 call loss is s3 then x1=1-s3
Suppose that the call completion ratio forth time is x4 call loss is s4 then x1=1-s4
Then the call incompletion probability in these 4 times is
(1- x1)(1-x2)(1-x3)(1-x4) = s1s2s3s4
Suppose that call loss ratios each time are the same then
GoS single call lose = Power (actual call loss in RNC multi-retransmission 1RNC
retransmission times)
Here Power means multiplied by itself a certain number of times or extraction of a root
It is given that the actual RNC multi-retransmission call loss rate is 02 so GoS single call
lose = (0002)14=0211474
Notice the proper actual RNC multi-retransmission call loss rate needs to be discussed
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
2
Internal Use Only
313 Channel Capacity Calculation
Erlang B formula requires average call loss of GoS in multi-paging because RNC repeat
multi-transmission and paging ratio is independent here we can regard that the average call loss of
GoS in multi-paging is equal to single call loss of GoS
Channel number (equivalent sub-channel number) and congestion rate are given we can
calculate PCH traffic according to Erlang B formula which is shown as follows
Here is average received call times in unit period of time is average call
duration which is the traffic
Actual Erlang B formula calculation is according to recursive algorithm
B(0rho)=1
B(Serversrho)=(rhoB(Servers -1rho) Servers)(1+rhoB(Servers -1rho) Servers)
Servers = Number of telephone lines
Intensity rho= Arrival rate of calls Completion rate of calls
Arrival rate = the number of calls arriving per hour
Completion rate = the number of calls completed per hour
We already know paging congestion rate is 0211474 when all uses IMSI paging sub-
channel number is 3 when all uses TMSI paging sub-channel number is 5 Input those into
Erlang B formula we can calculate paging traffic that PCH supports
IMSI paging paging traffic =200633(erl)
TMSI paging paging traffic =413931(erl)
32 Each UErsquos Paging Traffic Calculation on Busy Hour
321 CS Traffic Model
CS domain uses traditional call model represented by traffic on busy hour mainly includes
the following parameters
BHCA(A)Busy Hour Call Attempts
Holding Time(B)Each callrsquos duration unit s
Then single subscriberrsquos average traffic on busy hour =AtimesB3600(Erl)CS traffic model refers to voice service model in ZXWR Radio Performance Indicator
Technical Guide V40 which is shown in the following table Table 3-1 Traffic Density of Voice Service
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic(Erl)
Traffic density(Erlkm2)
Initial phase
Dense urban
1200 100 1200 003 36
Mean urban 300 100 300 0013 39
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
3
Internal Use Only
Developing phase
Dense urban
3600 100 3600 004 144
Mean urban 900 100 900 0018 162
Stable phase
Dense urban
7500 100 7500 0045 3375
Mean urban 1950 100 1950 002 39
Table 3-2 Traffic Density of Visual Telephone
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic (mErl)
Traffic density(mErlkm2)
Initial phase
Dense urban
1200 5 60 075 45
Mean urban 300 2 6 035 21
Developing phase
Dense urban
3600 8 288 15 432
Mean urban 900 5 45 07 315
Stable phase
Dense urban
7500 10 750 34 2550
Mean urban 1950 8 156 15 234
Paging traffic calculation on busy hour requires call times and call duration that converted by
traffic on busy hour in traditional traffic model CS122K call duration is set as 72 seconds
CS64K call duration is set as 60 seconds and then converted traffic model is shown in the
following table Table 3-3 CS Traffic Model after Conversion
Area
CS122K voice traffic CS64K visual telephone service
BHCA Call Duration(s) BHCA Call Duration(s)
Initial phaseDense urban 15 72 0045 60
Mean urban 065 72 0021 60
Developing phase
Dense urban 2 72 009 60
Mean urban 09 72 0042 60
Stable phase
Dense urban 225 72 0204 60
Mean urban 1 72 009 60
Notice BHCA and Call Duration need to be filled according to the actual situation of
countries and operators As to each subscriberrsquos traffic on busy hour in traditional CS traffic
model different BHCA will dramatically vary subscriber number that each LAC supports
BHCA in traffic model is counted bilaterally including MOC and MTC Therefore when
counting paging BHCA paging times shall be the half of call attempts which is shown in the
following table
Table 3-4 Paging BHCA Model
AreaCS122K paging
BHCA(timeshour)
CS64K paging BHCA(timeshour
)
CS domain paging BHCA(timeshou
r)
Initial phase
Dense urban 075 00225 07725
Mean urban 0325 00105 03355
Developing phase
Dense urban 1 0045 1045
Mean urban 045 0021 0471
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
4
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
Modification Record
File NoDrafter
ModifierMajor Points Modified
Update
DateVersion
Reason for
modification
1 WANG Feng 2007-3-6 V10 Guide
establishment
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
Contents
1 OVERVIEW1
2 PAGING PRINCIPLE PAGING CHANNEL PARAMETER AND SYSTEM
PARAMETER1
21 PAGING PRINCIPLE1
22 PAGING CHANNEL PARAMETER1
23 SYSTEM PARAMETER2
3 PAGING CAPACITY CALCULATION2
31 PCH CAPACITY CALCULATION2
311 Channel Number Confirmation2
312 GOS Confirmation2
313 Channel Capacity Calculation3
32 EACH UErsquoS PAGING TRAFFIC CALCULATION ON BUSY HOUR3
321 CS Traffic Model3
33 CALCULATION OF THE MAXIMUM SUBSCRIBER NUMBER THAT EACH LAC
SUPPORTS5
4 LAC DIVISION PRINCIPLE6
5 FEASIBILITY ANALYSIS OF WCDMA AND GSM CO-USE LAC7
51 WCDMA PAGING CAPACITY CALCULATION7
52 GSM PAGING CAPACITY CALCULATION7
53 ADVANTAGE AND DISADVANTAGE OF WCDMA AND GSM CO-USE LAC AS WELL AS
SUGGESTIONS8
6 LIBYA LAC DIVISION CASE9
Internal Use Only
1 Overview
The guide introduces WCDMA paging channel capacity calculation from which deduces the
maximum number of sectors that can be supported by each LAC with different traffic model as
well as general suggestions for LAC division the guide provides instructions for LAC planning on
the phase of WCDMA radio network planning
The guide includes paging principle paging capacity calculation and LAC division principle
2 Paging Principle Paging Channel Parameter and System
Parameter
21 Paging Principle
LAC is an abbreviation for Location Area Code a parameter represents UE paging location
When a UE is paged CN will send paging request through RNC to all NodeB that use the
corresponding LAC One LAC may be used by tens or hundreds of cells so the number of paging
message sent to RNC may be astonishing NodeB has to send paging request through limited PCH
to UE therefore too many NodeB that use one same LAC may cause NodeB paging overload
even signaling congestion and paging message drop But if too less NodeB use one same LAC
then there will be many boundaries of areas with different LAC that make it easy for UE on these
boundaries to update location frequently among areas with different LAC if UE is moving to an
area with different LAC and carrying out location update when a paging message is sent then UE
canrsquot receive the paging message sent to the area with the original LAC during the location update
period and therefore UE canrsquot be connected
22 Paging Channel Parameter
In 3G network paging happens in PCCH Logical channel PCCH is mapped to transmission
channel PCH and transmission channel PCH is mapped to physical channel SCCPCH so paging is
transmitted in physical channel SCCPCH
Related PCCH parameters are defined in Criterion 34108 Two modes 240bit10ms and
80bit10ms are transmitted in PCCH We usually use the mode 240bit10ms According to the
definition in the protocol the length of IMSI-GSM-MAP is 60bits with further consideration of
selection bits and paging reason bits one PCCH frame can carry 3 IMSI The length of TMSI-
GSM-MAP or PTMSI-GSM-MAP is 32bits therefore one 10ms PCCH frame comprises at most 5
TMSI paging or PTMSI paging
Paging channel of each cell includes one of the following combinations
1048727 3 IMSI paging
1048727 2 IMSI paging+ at most 2 TMSI paging
1048727 1 IMSI paging + at most 4 TMSI paging
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
1
Internal Use Only
1048727 At most 5 TMSI paging
The maximum paging number in one Paging Type1 Record is 8 ( refer to 25331
maxpage1) therefore when it is IMSI paging the maximum paging capacity of each paging
channel of each cell is Min(38)=3 when it is TMSI paging the maximum paging capacity of each
paging channel of each cell is Min(58)=5
23 System Parameter
The present system parameter default settings are
Paging period is 640ms
Radio paging repeats 4 times
CN paging is resent once total sending times is twice
CN paging resending interval is 3 seconds
Paging total congestion rate is set as 02
3 Paging Capacity Calculation
31 PCH Capacity Calculation
311 Channel Number Confirmation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5 Take the worst situation into account we define sub-channel number of each
PCCH is 3 which can be adjusted dynamically
312 GOS Confirmation
For improving paging success rate RNC uses multi-retransmission therefore the
corresponding relationship between call loss of multi-retransmission and call loss of single
retransmission needs to be calculated Presently systemrsquos RNC retransmission times are 4
Suppose that the call completion ratio first time is x1 call loss is s1 then x1=1-s1
Suppose that the call completion ratio second time is x2 call loss is s2 then x1=1-s2
Suppose that the call completion ratio third time is x3 call loss is s3 then x1=1-s3
Suppose that the call completion ratio forth time is x4 call loss is s4 then x1=1-s4
Then the call incompletion probability in these 4 times is
(1- x1)(1-x2)(1-x3)(1-x4) = s1s2s3s4
Suppose that call loss ratios each time are the same then
GoS single call lose = Power (actual call loss in RNC multi-retransmission 1RNC
retransmission times)
Here Power means multiplied by itself a certain number of times or extraction of a root
It is given that the actual RNC multi-retransmission call loss rate is 02 so GoS single call
lose = (0002)14=0211474
Notice the proper actual RNC multi-retransmission call loss rate needs to be discussed
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
2
Internal Use Only
313 Channel Capacity Calculation
Erlang B formula requires average call loss of GoS in multi-paging because RNC repeat
multi-transmission and paging ratio is independent here we can regard that the average call loss of
GoS in multi-paging is equal to single call loss of GoS
Channel number (equivalent sub-channel number) and congestion rate are given we can
calculate PCH traffic according to Erlang B formula which is shown as follows
Here is average received call times in unit period of time is average call
duration which is the traffic
Actual Erlang B formula calculation is according to recursive algorithm
B(0rho)=1
B(Serversrho)=(rhoB(Servers -1rho) Servers)(1+rhoB(Servers -1rho) Servers)
Servers = Number of telephone lines
Intensity rho= Arrival rate of calls Completion rate of calls
Arrival rate = the number of calls arriving per hour
Completion rate = the number of calls completed per hour
We already know paging congestion rate is 0211474 when all uses IMSI paging sub-
channel number is 3 when all uses TMSI paging sub-channel number is 5 Input those into
Erlang B formula we can calculate paging traffic that PCH supports
IMSI paging paging traffic =200633(erl)
TMSI paging paging traffic =413931(erl)
32 Each UErsquos Paging Traffic Calculation on Busy Hour
321 CS Traffic Model
CS domain uses traditional call model represented by traffic on busy hour mainly includes
the following parameters
BHCA(A)Busy Hour Call Attempts
Holding Time(B)Each callrsquos duration unit s
Then single subscriberrsquos average traffic on busy hour =AtimesB3600(Erl)CS traffic model refers to voice service model in ZXWR Radio Performance Indicator
Technical Guide V40 which is shown in the following table Table 3-1 Traffic Density of Voice Service
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic(Erl)
Traffic density(Erlkm2)
Initial phase
Dense urban
1200 100 1200 003 36
Mean urban 300 100 300 0013 39
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
3
Internal Use Only
Developing phase
Dense urban
3600 100 3600 004 144
Mean urban 900 100 900 0018 162
Stable phase
Dense urban
7500 100 7500 0045 3375
Mean urban 1950 100 1950 002 39
Table 3-2 Traffic Density of Visual Telephone
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic (mErl)
Traffic density(mErlkm2)
Initial phase
Dense urban
1200 5 60 075 45
Mean urban 300 2 6 035 21
Developing phase
Dense urban
3600 8 288 15 432
Mean urban 900 5 45 07 315
Stable phase
Dense urban
7500 10 750 34 2550
Mean urban 1950 8 156 15 234
Paging traffic calculation on busy hour requires call times and call duration that converted by
traffic on busy hour in traditional traffic model CS122K call duration is set as 72 seconds
CS64K call duration is set as 60 seconds and then converted traffic model is shown in the
following table Table 3-3 CS Traffic Model after Conversion
Area
CS122K voice traffic CS64K visual telephone service
BHCA Call Duration(s) BHCA Call Duration(s)
Initial phaseDense urban 15 72 0045 60
Mean urban 065 72 0021 60
Developing phase
Dense urban 2 72 009 60
Mean urban 09 72 0042 60
Stable phase
Dense urban 225 72 0204 60
Mean urban 1 72 009 60
Notice BHCA and Call Duration need to be filled according to the actual situation of
countries and operators As to each subscriberrsquos traffic on busy hour in traditional CS traffic
model different BHCA will dramatically vary subscriber number that each LAC supports
BHCA in traffic model is counted bilaterally including MOC and MTC Therefore when
counting paging BHCA paging times shall be the half of call attempts which is shown in the
following table
Table 3-4 Paging BHCA Model
AreaCS122K paging
BHCA(timeshour)
CS64K paging BHCA(timeshour
)
CS domain paging BHCA(timeshou
r)
Initial phase
Dense urban 075 00225 07725
Mean urban 0325 00105 03355
Developing phase
Dense urban 1 0045 1045
Mean urban 045 0021 0471
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
4
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Contents
1 OVERVIEW1
2 PAGING PRINCIPLE PAGING CHANNEL PARAMETER AND SYSTEM
PARAMETER1
21 PAGING PRINCIPLE1
22 PAGING CHANNEL PARAMETER1
23 SYSTEM PARAMETER2
3 PAGING CAPACITY CALCULATION2
31 PCH CAPACITY CALCULATION2
311 Channel Number Confirmation2
312 GOS Confirmation2
313 Channel Capacity Calculation3
32 EACH UErsquoS PAGING TRAFFIC CALCULATION ON BUSY HOUR3
321 CS Traffic Model3
33 CALCULATION OF THE MAXIMUM SUBSCRIBER NUMBER THAT EACH LAC
SUPPORTS5
4 LAC DIVISION PRINCIPLE6
5 FEASIBILITY ANALYSIS OF WCDMA AND GSM CO-USE LAC7
51 WCDMA PAGING CAPACITY CALCULATION7
52 GSM PAGING CAPACITY CALCULATION7
53 ADVANTAGE AND DISADVANTAGE OF WCDMA AND GSM CO-USE LAC AS WELL AS
SUGGESTIONS8
6 LIBYA LAC DIVISION CASE9
Internal Use Only
1 Overview
The guide introduces WCDMA paging channel capacity calculation from which deduces the
maximum number of sectors that can be supported by each LAC with different traffic model as
well as general suggestions for LAC division the guide provides instructions for LAC planning on
the phase of WCDMA radio network planning
The guide includes paging principle paging capacity calculation and LAC division principle
2 Paging Principle Paging Channel Parameter and System
Parameter
21 Paging Principle
LAC is an abbreviation for Location Area Code a parameter represents UE paging location
When a UE is paged CN will send paging request through RNC to all NodeB that use the
corresponding LAC One LAC may be used by tens or hundreds of cells so the number of paging
message sent to RNC may be astonishing NodeB has to send paging request through limited PCH
to UE therefore too many NodeB that use one same LAC may cause NodeB paging overload
even signaling congestion and paging message drop But if too less NodeB use one same LAC
then there will be many boundaries of areas with different LAC that make it easy for UE on these
boundaries to update location frequently among areas with different LAC if UE is moving to an
area with different LAC and carrying out location update when a paging message is sent then UE
canrsquot receive the paging message sent to the area with the original LAC during the location update
period and therefore UE canrsquot be connected
22 Paging Channel Parameter
In 3G network paging happens in PCCH Logical channel PCCH is mapped to transmission
channel PCH and transmission channel PCH is mapped to physical channel SCCPCH so paging is
transmitted in physical channel SCCPCH
Related PCCH parameters are defined in Criterion 34108 Two modes 240bit10ms and
80bit10ms are transmitted in PCCH We usually use the mode 240bit10ms According to the
definition in the protocol the length of IMSI-GSM-MAP is 60bits with further consideration of
selection bits and paging reason bits one PCCH frame can carry 3 IMSI The length of TMSI-
GSM-MAP or PTMSI-GSM-MAP is 32bits therefore one 10ms PCCH frame comprises at most 5
TMSI paging or PTMSI paging
Paging channel of each cell includes one of the following combinations
1048727 3 IMSI paging
1048727 2 IMSI paging+ at most 2 TMSI paging
1048727 1 IMSI paging + at most 4 TMSI paging
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
1
Internal Use Only
1048727 At most 5 TMSI paging
The maximum paging number in one Paging Type1 Record is 8 ( refer to 25331
maxpage1) therefore when it is IMSI paging the maximum paging capacity of each paging
channel of each cell is Min(38)=3 when it is TMSI paging the maximum paging capacity of each
paging channel of each cell is Min(58)=5
23 System Parameter
The present system parameter default settings are
Paging period is 640ms
Radio paging repeats 4 times
CN paging is resent once total sending times is twice
CN paging resending interval is 3 seconds
Paging total congestion rate is set as 02
3 Paging Capacity Calculation
31 PCH Capacity Calculation
311 Channel Number Confirmation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5 Take the worst situation into account we define sub-channel number of each
PCCH is 3 which can be adjusted dynamically
312 GOS Confirmation
For improving paging success rate RNC uses multi-retransmission therefore the
corresponding relationship between call loss of multi-retransmission and call loss of single
retransmission needs to be calculated Presently systemrsquos RNC retransmission times are 4
Suppose that the call completion ratio first time is x1 call loss is s1 then x1=1-s1
Suppose that the call completion ratio second time is x2 call loss is s2 then x1=1-s2
Suppose that the call completion ratio third time is x3 call loss is s3 then x1=1-s3
Suppose that the call completion ratio forth time is x4 call loss is s4 then x1=1-s4
Then the call incompletion probability in these 4 times is
(1- x1)(1-x2)(1-x3)(1-x4) = s1s2s3s4
Suppose that call loss ratios each time are the same then
GoS single call lose = Power (actual call loss in RNC multi-retransmission 1RNC
retransmission times)
Here Power means multiplied by itself a certain number of times or extraction of a root
It is given that the actual RNC multi-retransmission call loss rate is 02 so GoS single call
lose = (0002)14=0211474
Notice the proper actual RNC multi-retransmission call loss rate needs to be discussed
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
2
Internal Use Only
313 Channel Capacity Calculation
Erlang B formula requires average call loss of GoS in multi-paging because RNC repeat
multi-transmission and paging ratio is independent here we can regard that the average call loss of
GoS in multi-paging is equal to single call loss of GoS
Channel number (equivalent sub-channel number) and congestion rate are given we can
calculate PCH traffic according to Erlang B formula which is shown as follows
Here is average received call times in unit period of time is average call
duration which is the traffic
Actual Erlang B formula calculation is according to recursive algorithm
B(0rho)=1
B(Serversrho)=(rhoB(Servers -1rho) Servers)(1+rhoB(Servers -1rho) Servers)
Servers = Number of telephone lines
Intensity rho= Arrival rate of calls Completion rate of calls
Arrival rate = the number of calls arriving per hour
Completion rate = the number of calls completed per hour
We already know paging congestion rate is 0211474 when all uses IMSI paging sub-
channel number is 3 when all uses TMSI paging sub-channel number is 5 Input those into
Erlang B formula we can calculate paging traffic that PCH supports
IMSI paging paging traffic =200633(erl)
TMSI paging paging traffic =413931(erl)
32 Each UErsquos Paging Traffic Calculation on Busy Hour
321 CS Traffic Model
CS domain uses traditional call model represented by traffic on busy hour mainly includes
the following parameters
BHCA(A)Busy Hour Call Attempts
Holding Time(B)Each callrsquos duration unit s
Then single subscriberrsquos average traffic on busy hour =AtimesB3600(Erl)CS traffic model refers to voice service model in ZXWR Radio Performance Indicator
Technical Guide V40 which is shown in the following table Table 3-1 Traffic Density of Voice Service
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic(Erl)
Traffic density(Erlkm2)
Initial phase
Dense urban
1200 100 1200 003 36
Mean urban 300 100 300 0013 39
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
3
Internal Use Only
Developing phase
Dense urban
3600 100 3600 004 144
Mean urban 900 100 900 0018 162
Stable phase
Dense urban
7500 100 7500 0045 3375
Mean urban 1950 100 1950 002 39
Table 3-2 Traffic Density of Visual Telephone
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic (mErl)
Traffic density(mErlkm2)
Initial phase
Dense urban
1200 5 60 075 45
Mean urban 300 2 6 035 21
Developing phase
Dense urban
3600 8 288 15 432
Mean urban 900 5 45 07 315
Stable phase
Dense urban
7500 10 750 34 2550
Mean urban 1950 8 156 15 234
Paging traffic calculation on busy hour requires call times and call duration that converted by
traffic on busy hour in traditional traffic model CS122K call duration is set as 72 seconds
CS64K call duration is set as 60 seconds and then converted traffic model is shown in the
following table Table 3-3 CS Traffic Model after Conversion
Area
CS122K voice traffic CS64K visual telephone service
BHCA Call Duration(s) BHCA Call Duration(s)
Initial phaseDense urban 15 72 0045 60
Mean urban 065 72 0021 60
Developing phase
Dense urban 2 72 009 60
Mean urban 09 72 0042 60
Stable phase
Dense urban 225 72 0204 60
Mean urban 1 72 009 60
Notice BHCA and Call Duration need to be filled according to the actual situation of
countries and operators As to each subscriberrsquos traffic on busy hour in traditional CS traffic
model different BHCA will dramatically vary subscriber number that each LAC supports
BHCA in traffic model is counted bilaterally including MOC and MTC Therefore when
counting paging BHCA paging times shall be the half of call attempts which is shown in the
following table
Table 3-4 Paging BHCA Model
AreaCS122K paging
BHCA(timeshour)
CS64K paging BHCA(timeshour
)
CS domain paging BHCA(timeshou
r)
Initial phase
Dense urban 075 00225 07725
Mean urban 0325 00105 03355
Developing phase
Dense urban 1 0045 1045
Mean urban 045 0021 0471
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
4
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
1 Overview
The guide introduces WCDMA paging channel capacity calculation from which deduces the
maximum number of sectors that can be supported by each LAC with different traffic model as
well as general suggestions for LAC division the guide provides instructions for LAC planning on
the phase of WCDMA radio network planning
The guide includes paging principle paging capacity calculation and LAC division principle
2 Paging Principle Paging Channel Parameter and System
Parameter
21 Paging Principle
LAC is an abbreviation for Location Area Code a parameter represents UE paging location
When a UE is paged CN will send paging request through RNC to all NodeB that use the
corresponding LAC One LAC may be used by tens or hundreds of cells so the number of paging
message sent to RNC may be astonishing NodeB has to send paging request through limited PCH
to UE therefore too many NodeB that use one same LAC may cause NodeB paging overload
even signaling congestion and paging message drop But if too less NodeB use one same LAC
then there will be many boundaries of areas with different LAC that make it easy for UE on these
boundaries to update location frequently among areas with different LAC if UE is moving to an
area with different LAC and carrying out location update when a paging message is sent then UE
canrsquot receive the paging message sent to the area with the original LAC during the location update
period and therefore UE canrsquot be connected
22 Paging Channel Parameter
In 3G network paging happens in PCCH Logical channel PCCH is mapped to transmission
channel PCH and transmission channel PCH is mapped to physical channel SCCPCH so paging is
transmitted in physical channel SCCPCH
Related PCCH parameters are defined in Criterion 34108 Two modes 240bit10ms and
80bit10ms are transmitted in PCCH We usually use the mode 240bit10ms According to the
definition in the protocol the length of IMSI-GSM-MAP is 60bits with further consideration of
selection bits and paging reason bits one PCCH frame can carry 3 IMSI The length of TMSI-
GSM-MAP or PTMSI-GSM-MAP is 32bits therefore one 10ms PCCH frame comprises at most 5
TMSI paging or PTMSI paging
Paging channel of each cell includes one of the following combinations
1048727 3 IMSI paging
1048727 2 IMSI paging+ at most 2 TMSI paging
1048727 1 IMSI paging + at most 4 TMSI paging
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
1
Internal Use Only
1048727 At most 5 TMSI paging
The maximum paging number in one Paging Type1 Record is 8 ( refer to 25331
maxpage1) therefore when it is IMSI paging the maximum paging capacity of each paging
channel of each cell is Min(38)=3 when it is TMSI paging the maximum paging capacity of each
paging channel of each cell is Min(58)=5
23 System Parameter
The present system parameter default settings are
Paging period is 640ms
Radio paging repeats 4 times
CN paging is resent once total sending times is twice
CN paging resending interval is 3 seconds
Paging total congestion rate is set as 02
3 Paging Capacity Calculation
31 PCH Capacity Calculation
311 Channel Number Confirmation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5 Take the worst situation into account we define sub-channel number of each
PCCH is 3 which can be adjusted dynamically
312 GOS Confirmation
For improving paging success rate RNC uses multi-retransmission therefore the
corresponding relationship between call loss of multi-retransmission and call loss of single
retransmission needs to be calculated Presently systemrsquos RNC retransmission times are 4
Suppose that the call completion ratio first time is x1 call loss is s1 then x1=1-s1
Suppose that the call completion ratio second time is x2 call loss is s2 then x1=1-s2
Suppose that the call completion ratio third time is x3 call loss is s3 then x1=1-s3
Suppose that the call completion ratio forth time is x4 call loss is s4 then x1=1-s4
Then the call incompletion probability in these 4 times is
(1- x1)(1-x2)(1-x3)(1-x4) = s1s2s3s4
Suppose that call loss ratios each time are the same then
GoS single call lose = Power (actual call loss in RNC multi-retransmission 1RNC
retransmission times)
Here Power means multiplied by itself a certain number of times or extraction of a root
It is given that the actual RNC multi-retransmission call loss rate is 02 so GoS single call
lose = (0002)14=0211474
Notice the proper actual RNC multi-retransmission call loss rate needs to be discussed
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
2
Internal Use Only
313 Channel Capacity Calculation
Erlang B formula requires average call loss of GoS in multi-paging because RNC repeat
multi-transmission and paging ratio is independent here we can regard that the average call loss of
GoS in multi-paging is equal to single call loss of GoS
Channel number (equivalent sub-channel number) and congestion rate are given we can
calculate PCH traffic according to Erlang B formula which is shown as follows
Here is average received call times in unit period of time is average call
duration which is the traffic
Actual Erlang B formula calculation is according to recursive algorithm
B(0rho)=1
B(Serversrho)=(rhoB(Servers -1rho) Servers)(1+rhoB(Servers -1rho) Servers)
Servers = Number of telephone lines
Intensity rho= Arrival rate of calls Completion rate of calls
Arrival rate = the number of calls arriving per hour
Completion rate = the number of calls completed per hour
We already know paging congestion rate is 0211474 when all uses IMSI paging sub-
channel number is 3 when all uses TMSI paging sub-channel number is 5 Input those into
Erlang B formula we can calculate paging traffic that PCH supports
IMSI paging paging traffic =200633(erl)
TMSI paging paging traffic =413931(erl)
32 Each UErsquos Paging Traffic Calculation on Busy Hour
321 CS Traffic Model
CS domain uses traditional call model represented by traffic on busy hour mainly includes
the following parameters
BHCA(A)Busy Hour Call Attempts
Holding Time(B)Each callrsquos duration unit s
Then single subscriberrsquos average traffic on busy hour =AtimesB3600(Erl)CS traffic model refers to voice service model in ZXWR Radio Performance Indicator
Technical Guide V40 which is shown in the following table Table 3-1 Traffic Density of Voice Service
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic(Erl)
Traffic density(Erlkm2)
Initial phase
Dense urban
1200 100 1200 003 36
Mean urban 300 100 300 0013 39
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
3
Internal Use Only
Developing phase
Dense urban
3600 100 3600 004 144
Mean urban 900 100 900 0018 162
Stable phase
Dense urban
7500 100 7500 0045 3375
Mean urban 1950 100 1950 002 39
Table 3-2 Traffic Density of Visual Telephone
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic (mErl)
Traffic density(mErlkm2)
Initial phase
Dense urban
1200 5 60 075 45
Mean urban 300 2 6 035 21
Developing phase
Dense urban
3600 8 288 15 432
Mean urban 900 5 45 07 315
Stable phase
Dense urban
7500 10 750 34 2550
Mean urban 1950 8 156 15 234
Paging traffic calculation on busy hour requires call times and call duration that converted by
traffic on busy hour in traditional traffic model CS122K call duration is set as 72 seconds
CS64K call duration is set as 60 seconds and then converted traffic model is shown in the
following table Table 3-3 CS Traffic Model after Conversion
Area
CS122K voice traffic CS64K visual telephone service
BHCA Call Duration(s) BHCA Call Duration(s)
Initial phaseDense urban 15 72 0045 60
Mean urban 065 72 0021 60
Developing phase
Dense urban 2 72 009 60
Mean urban 09 72 0042 60
Stable phase
Dense urban 225 72 0204 60
Mean urban 1 72 009 60
Notice BHCA and Call Duration need to be filled according to the actual situation of
countries and operators As to each subscriberrsquos traffic on busy hour in traditional CS traffic
model different BHCA will dramatically vary subscriber number that each LAC supports
BHCA in traffic model is counted bilaterally including MOC and MTC Therefore when
counting paging BHCA paging times shall be the half of call attempts which is shown in the
following table
Table 3-4 Paging BHCA Model
AreaCS122K paging
BHCA(timeshour)
CS64K paging BHCA(timeshour
)
CS domain paging BHCA(timeshou
r)
Initial phase
Dense urban 075 00225 07725
Mean urban 0325 00105 03355
Developing phase
Dense urban 1 0045 1045
Mean urban 045 0021 0471
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
4
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
1048727 At most 5 TMSI paging
The maximum paging number in one Paging Type1 Record is 8 ( refer to 25331
maxpage1) therefore when it is IMSI paging the maximum paging capacity of each paging
channel of each cell is Min(38)=3 when it is TMSI paging the maximum paging capacity of each
paging channel of each cell is Min(58)=5
23 System Parameter
The present system parameter default settings are
Paging period is 640ms
Radio paging repeats 4 times
CN paging is resent once total sending times is twice
CN paging resending interval is 3 seconds
Paging total congestion rate is set as 02
3 Paging Capacity Calculation
31 PCH Capacity Calculation
311 Channel Number Confirmation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5 Take the worst situation into account we define sub-channel number of each
PCCH is 3 which can be adjusted dynamically
312 GOS Confirmation
For improving paging success rate RNC uses multi-retransmission therefore the
corresponding relationship between call loss of multi-retransmission and call loss of single
retransmission needs to be calculated Presently systemrsquos RNC retransmission times are 4
Suppose that the call completion ratio first time is x1 call loss is s1 then x1=1-s1
Suppose that the call completion ratio second time is x2 call loss is s2 then x1=1-s2
Suppose that the call completion ratio third time is x3 call loss is s3 then x1=1-s3
Suppose that the call completion ratio forth time is x4 call loss is s4 then x1=1-s4
Then the call incompletion probability in these 4 times is
(1- x1)(1-x2)(1-x3)(1-x4) = s1s2s3s4
Suppose that call loss ratios each time are the same then
GoS single call lose = Power (actual call loss in RNC multi-retransmission 1RNC
retransmission times)
Here Power means multiplied by itself a certain number of times or extraction of a root
It is given that the actual RNC multi-retransmission call loss rate is 02 so GoS single call
lose = (0002)14=0211474
Notice the proper actual RNC multi-retransmission call loss rate needs to be discussed
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
2
Internal Use Only
313 Channel Capacity Calculation
Erlang B formula requires average call loss of GoS in multi-paging because RNC repeat
multi-transmission and paging ratio is independent here we can regard that the average call loss of
GoS in multi-paging is equal to single call loss of GoS
Channel number (equivalent sub-channel number) and congestion rate are given we can
calculate PCH traffic according to Erlang B formula which is shown as follows
Here is average received call times in unit period of time is average call
duration which is the traffic
Actual Erlang B formula calculation is according to recursive algorithm
B(0rho)=1
B(Serversrho)=(rhoB(Servers -1rho) Servers)(1+rhoB(Servers -1rho) Servers)
Servers = Number of telephone lines
Intensity rho= Arrival rate of calls Completion rate of calls
Arrival rate = the number of calls arriving per hour
Completion rate = the number of calls completed per hour
We already know paging congestion rate is 0211474 when all uses IMSI paging sub-
channel number is 3 when all uses TMSI paging sub-channel number is 5 Input those into
Erlang B formula we can calculate paging traffic that PCH supports
IMSI paging paging traffic =200633(erl)
TMSI paging paging traffic =413931(erl)
32 Each UErsquos Paging Traffic Calculation on Busy Hour
321 CS Traffic Model
CS domain uses traditional call model represented by traffic on busy hour mainly includes
the following parameters
BHCA(A)Busy Hour Call Attempts
Holding Time(B)Each callrsquos duration unit s
Then single subscriberrsquos average traffic on busy hour =AtimesB3600(Erl)CS traffic model refers to voice service model in ZXWR Radio Performance Indicator
Technical Guide V40 which is shown in the following table Table 3-1 Traffic Density of Voice Service
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic(Erl)
Traffic density(Erlkm2)
Initial phase
Dense urban
1200 100 1200 003 36
Mean urban 300 100 300 0013 39
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
3
Internal Use Only
Developing phase
Dense urban
3600 100 3600 004 144
Mean urban 900 100 900 0018 162
Stable phase
Dense urban
7500 100 7500 0045 3375
Mean urban 1950 100 1950 002 39
Table 3-2 Traffic Density of Visual Telephone
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic (mErl)
Traffic density(mErlkm2)
Initial phase
Dense urban
1200 5 60 075 45
Mean urban 300 2 6 035 21
Developing phase
Dense urban
3600 8 288 15 432
Mean urban 900 5 45 07 315
Stable phase
Dense urban
7500 10 750 34 2550
Mean urban 1950 8 156 15 234
Paging traffic calculation on busy hour requires call times and call duration that converted by
traffic on busy hour in traditional traffic model CS122K call duration is set as 72 seconds
CS64K call duration is set as 60 seconds and then converted traffic model is shown in the
following table Table 3-3 CS Traffic Model after Conversion
Area
CS122K voice traffic CS64K visual telephone service
BHCA Call Duration(s) BHCA Call Duration(s)
Initial phaseDense urban 15 72 0045 60
Mean urban 065 72 0021 60
Developing phase
Dense urban 2 72 009 60
Mean urban 09 72 0042 60
Stable phase
Dense urban 225 72 0204 60
Mean urban 1 72 009 60
Notice BHCA and Call Duration need to be filled according to the actual situation of
countries and operators As to each subscriberrsquos traffic on busy hour in traditional CS traffic
model different BHCA will dramatically vary subscriber number that each LAC supports
BHCA in traffic model is counted bilaterally including MOC and MTC Therefore when
counting paging BHCA paging times shall be the half of call attempts which is shown in the
following table
Table 3-4 Paging BHCA Model
AreaCS122K paging
BHCA(timeshour)
CS64K paging BHCA(timeshour
)
CS domain paging BHCA(timeshou
r)
Initial phase
Dense urban 075 00225 07725
Mean urban 0325 00105 03355
Developing phase
Dense urban 1 0045 1045
Mean urban 045 0021 0471
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
4
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
313 Channel Capacity Calculation
Erlang B formula requires average call loss of GoS in multi-paging because RNC repeat
multi-transmission and paging ratio is independent here we can regard that the average call loss of
GoS in multi-paging is equal to single call loss of GoS
Channel number (equivalent sub-channel number) and congestion rate are given we can
calculate PCH traffic according to Erlang B formula which is shown as follows
Here is average received call times in unit period of time is average call
duration which is the traffic
Actual Erlang B formula calculation is according to recursive algorithm
B(0rho)=1
B(Serversrho)=(rhoB(Servers -1rho) Servers)(1+rhoB(Servers -1rho) Servers)
Servers = Number of telephone lines
Intensity rho= Arrival rate of calls Completion rate of calls
Arrival rate = the number of calls arriving per hour
Completion rate = the number of calls completed per hour
We already know paging congestion rate is 0211474 when all uses IMSI paging sub-
channel number is 3 when all uses TMSI paging sub-channel number is 5 Input those into
Erlang B formula we can calculate paging traffic that PCH supports
IMSI paging paging traffic =200633(erl)
TMSI paging paging traffic =413931(erl)
32 Each UErsquos Paging Traffic Calculation on Busy Hour
321 CS Traffic Model
CS domain uses traditional call model represented by traffic on busy hour mainly includes
the following parameters
BHCA(A)Busy Hour Call Attempts
Holding Time(B)Each callrsquos duration unit s
Then single subscriberrsquos average traffic on busy hour =AtimesB3600(Erl)CS traffic model refers to voice service model in ZXWR Radio Performance Indicator
Technical Guide V40 which is shown in the following table Table 3-1 Traffic Density of Voice Service
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic(Erl)
Traffic density(Erlkm2)
Initial phase
Dense urban
1200 100 1200 003 36
Mean urban 300 100 300 0013 39
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
3
Internal Use Only
Developing phase
Dense urban
3600 100 3600 004 144
Mean urban 900 100 900 0018 162
Stable phase
Dense urban
7500 100 7500 0045 3375
Mean urban 1950 100 1950 002 39
Table 3-2 Traffic Density of Visual Telephone
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic (mErl)
Traffic density(mErlkm2)
Initial phase
Dense urban
1200 5 60 075 45
Mean urban 300 2 6 035 21
Developing phase
Dense urban
3600 8 288 15 432
Mean urban 900 5 45 07 315
Stable phase
Dense urban
7500 10 750 34 2550
Mean urban 1950 8 156 15 234
Paging traffic calculation on busy hour requires call times and call duration that converted by
traffic on busy hour in traditional traffic model CS122K call duration is set as 72 seconds
CS64K call duration is set as 60 seconds and then converted traffic model is shown in the
following table Table 3-3 CS Traffic Model after Conversion
Area
CS122K voice traffic CS64K visual telephone service
BHCA Call Duration(s) BHCA Call Duration(s)
Initial phaseDense urban 15 72 0045 60
Mean urban 065 72 0021 60
Developing phase
Dense urban 2 72 009 60
Mean urban 09 72 0042 60
Stable phase
Dense urban 225 72 0204 60
Mean urban 1 72 009 60
Notice BHCA and Call Duration need to be filled according to the actual situation of
countries and operators As to each subscriberrsquos traffic on busy hour in traditional CS traffic
model different BHCA will dramatically vary subscriber number that each LAC supports
BHCA in traffic model is counted bilaterally including MOC and MTC Therefore when
counting paging BHCA paging times shall be the half of call attempts which is shown in the
following table
Table 3-4 Paging BHCA Model
AreaCS122K paging
BHCA(timeshour)
CS64K paging BHCA(timeshour
)
CS domain paging BHCA(timeshou
r)
Initial phase
Dense urban 075 00225 07725
Mean urban 0325 00105 03355
Developing phase
Dense urban 1 0045 1045
Mean urban 045 0021 0471
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
4
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
Developing phase
Dense urban
3600 100 3600 004 144
Mean urban 900 100 900 0018 162
Stable phase
Dense urban
7500 100 7500 0045 3375
Mean urban 1950 100 1950 002 39
Table 3-2 Traffic Density of Visual Telephone
Area3G UE density
Activated UE
proportion on busy
hour
Activated UE density
on busy hour
Single UErsquos traffic (mErl)
Traffic density(mErlkm2)
Initial phase
Dense urban
1200 5 60 075 45
Mean urban 300 2 6 035 21
Developing phase
Dense urban
3600 8 288 15 432
Mean urban 900 5 45 07 315
Stable phase
Dense urban
7500 10 750 34 2550
Mean urban 1950 8 156 15 234
Paging traffic calculation on busy hour requires call times and call duration that converted by
traffic on busy hour in traditional traffic model CS122K call duration is set as 72 seconds
CS64K call duration is set as 60 seconds and then converted traffic model is shown in the
following table Table 3-3 CS Traffic Model after Conversion
Area
CS122K voice traffic CS64K visual telephone service
BHCA Call Duration(s) BHCA Call Duration(s)
Initial phaseDense urban 15 72 0045 60
Mean urban 065 72 0021 60
Developing phase
Dense urban 2 72 009 60
Mean urban 09 72 0042 60
Stable phase
Dense urban 225 72 0204 60
Mean urban 1 72 009 60
Notice BHCA and Call Duration need to be filled according to the actual situation of
countries and operators As to each subscriberrsquos traffic on busy hour in traditional CS traffic
model different BHCA will dramatically vary subscriber number that each LAC supports
BHCA in traffic model is counted bilaterally including MOC and MTC Therefore when
counting paging BHCA paging times shall be the half of call attempts which is shown in the
following table
Table 3-4 Paging BHCA Model
AreaCS122K paging
BHCA(timeshour)
CS64K paging BHCA(timeshour
)
CS domain paging BHCA(timeshou
r)
Initial phase
Dense urban 075 00225 07725
Mean urban 0325 00105 03355
Developing phase
Dense urban 1 0045 1045
Mean urban 045 0021 0471
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
4
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
Stable phase
Dense urban 1125 0102 1227
Mean urban 05 0045 0545
Paging traffic in RNC once paging can be calculated through paging BHCA model which is
equal to BHCA x paging duration (10ms one frame of PCCH)
Now ZTE RNC radio paging retransmission times is set as 4 RNC retransmission times is
set as 2 CN paging interval between two paging is 3 seconds CN twice paging proportion is 25
RNC transmits each paging for four times therefore each subscriberrsquos paging traffic is equal
to the sum of all paging traffic in the four paging initiated by RNC as well as two paging traffic
initiated by CN But the proportion of CN twice paging is not 100 so the paging traffic of CN
twice paging is lower which is the true situation in actual network Each subscriberrsquos CS paging
traffic on busy hour = (the first paging traffic initiated by RNC + the second paging traffic
initiated by RNC + the third paging traffic initiated by RNC + the forth paging traffic initiated by
RNC)(1+ the proportion of CN twice paging) The calculation result is shown in the following
table
Table 3-5 Each Subscriberrsquos CS Paging Traffic on Busy Hour
AreaThe first paging traffic
initiated by RNC(Erl)
The second paging traffic initiated by
CN(Erl)
Each Subscriberrsquos CS Paging Traffic
on Busy Hour(Erl)
Initial phase
Dense urban 214583E-06 536458E-07 911979E-06
Mean urban 931944E-07 232986E-07 396076E-06
Developing phase
Dense urban 290278E-06 725694E-07 123368E-05
Mean urban 130833E-06 327083E-07 556042E-06
Stable phase
Dense urban 340833E-06 852083E-07 144854E-05
Mean urban 151389E-06 378472E-07 643403E-06
33 Calculation of the Maximum Subscriber Number that Each LAC Supports
When network is configured with one PCH which is the common configuration in most
actual networks and RNC retransmission congestion rate is 02 if we use IMSI paging paging
traffic that PCH supports =200633(erl) if we use TMSI paging paging traffic that PCH supports
=413931(erl) Therefore the subscriber number that each LAC supports = paging traffic that
PCH supportseach subscriberrsquos paging traffic on busy hour As to IMSI paging and TMSI paging
the subscriber number that each LAC supports is shown in the following table
Table 3-6 Maximum Subscriber Number that Each LAC Supports
Area
CS domain paging traffic of each
subscriber on busy hour (Erl)
Subscriber number that each LAC
supports in IMSI paging
Subscriber number that each LAC
supports in TMSI paging
Initial phase
Dense urban 912E-06 220000 454000
Mean urban 396E-06 507000 1050000
Developing phase
Dense urban 123E-05 163000 336000
Mean urban 556E-06 361000 744000
Stable Dense urban 145E-05 139000 286000
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
5
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
phase Mean urban 643E-06 312000 643000
4 LAC Division Principle
1) In LAC division the upper limit of LAC is determined by paging capacity of each cell
lower limit of LAC is determined by LAC update frequency If LAC is too large paging
times in the network will be increased dramatically even congestion will occur and
network paging success rate will be decreased If LAC is too small LAC update will be too
frequent and network signaling load will be increased Therefore these two factors need to
be considered in LAC division and LAC shall be divided properly according to actual
network situation
2) LACs of areas with different traffic characteristics vary Generally LAC of dense urban lt
LAC of mean urban lt LAC of suburb lt LAC of rural
3) Geographic characteristic and UE distribution shall be taken into account in LAC boundary
selection for decreasing LAC update frequency Generally LAC boundary is located in
areas that have lesser subscribers or lower handover probability
4) Try to avoid LAC boundary locating in areas that have group subscriber or VIP clients
5) Impact from load increase shall be considered in LAC division
6) NodeBs that use multi-carriers shall belong to one same LAC
7) NodeBs coverage shall be continuous in one same LAC
8) In principle LAC setting methods of 2G and 3G system are generally the same therefore
3G LAC planning can refer to 2G LAC planning Firstly calculate paging capacity in radio
interfaces according to paging process and channel characteristic secondly figure out
traffic that one LAC can support according to traffic model and finally set LAC according
to actual or estimated traffic in the network
9) RNC capacity in 3G network is generally larger than BSC capacity in 2G network thus the
number of RNC is smaller than that of BSC and one LAC will not step across BSC
therefore existing network LAC configuration and BSC traffic situation shall be taken into
account while planning 3G network LAC 3G LAC can be the combination of the existing
network LACs according to traffic balance principle 3G LAC boundary shall be better the
same with the boundary of the outer layer of combined 2G LACs
5 Feasibility Analysis of WCDMA and GSM co-use LAC
This section offers calculation of paging capacity without consideration of factors such as
paging congestion rate RNC multi-paging times and CN second paging but brief comparison of
ideal paging capacity of WCDMA and GSM system so as to analyze whether co-using LAC is
feasible as well as what advantages and disadvantages it may introduce
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
6
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
51 WCDMA Paging Capacity Calculation
3 IMSI coding paging messages or 5 TMSI coding paging messages can be put in 1X240
PCH FP transmission therefore the maximum number of paging message that can be put in each
FP is defined as 5
WCDMA maximum paging capacity per second the whole network uses TMSI paging one
10ms PCCHPCH frame includes 5 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 500 paging messages
WCDMA minimum paging capacity per second the whole network uses IMSI paging one
10ms PCCHPCH frame includes 3 paging messages 100 PCCHPCH frames can be transmitted
on one PCH each second totally 300 paging messages
52 GSM Paging Capacity Calculation
According to GSM criterion as to Combined BCCHSDCCH cell each 235ms multi-frame
transmits 3 paging groups but as to Non-Combined BCCHSDCCH cell each 235ms multi-frame
transmits 9 paging groups BTS broadcasts paging request through paging group The following is
probable configuration in one paging request
2 IMSIs
1 IMSI and 2 TMSIs
4 TMSIs
Suppose all paging groups are used by PCH (extreme situation)
In IMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 2 paging
messages therefore 42532=25 paging messages are sent each second
In IMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 2 paging
messages therefore 42592=76 paging messages are sent each second
In TMSI paging as to Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 3 paging groups each paging group has 4 paging
messages therefore 42534=51 paging messages are sent each second
In TMSI paging as to Non-Combined BCCHSDCCH cell each PCH each second transmits
10235=425 multi-frames each multi-frame has 9 paging groups each paging group has 4 paging
messages therefore 42594=153 paging messages are sent each second
In different combination paging capacity comparison of WCDMA and GSM system is
shown in the following table
WCDMA GSM(Combined BCCH SDCCH cell)
GSM(Non-Combined BCCH SDCCH cell)
IMSI 300 25 76
TMSI 500 51 153From the upper table we can see that in the situation of general parameter configuration
WCDMA paging capacity is obviously stronger than that of GSM therefore traffic that WCDMA
each LAC supports is much higher than that of GSM
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
7
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
1)Advantage of GSM900 GSM1800 and WCDMA co-use LAC
When WCDMA and GSM are co-constructed especially when most WCDMA sites co-site
with GSM sites WCDMA uses the same LAC planning with that of GSM for speeding up data
configuration in network commissioning that facilitates fast commissioning of commercialized
WCDMA network
After long-term optimization GSM LAC planning project is mature and LAC division is
reasonable It accelerates LAC optimization process and decrease LAC optimization pressure if
WCDMA network uses the same LAC planning with that of GSM network
GSM LAC division reflects existing networkrsquos traffic distribution and paging load WCDMA
network is generally constructed after GSM network construction then unreasonable LAC
division caused by inexact traffic estimation will be decreased if WCDMA uses the same LAC
planning with that of GSM network
2)Disadvantage of GSM900 GSM1800 and WCDMA co-use LAC
WCDMA paging capacity is stronger than that of GSM so WCDMA paging capacity cannot
be used fully when WCDMA uses the same LAC planning with that of GSM network
Too small WCDMA LAC will cause frequent LAC update and heave signaling load UE on
the boundary may even not receive paging
Subscriber location and operation of WCDMA and GSM network may not the same so
GSM LAC planning may not comply with characteristic of WCDMA service statistic
3)Suggestions for LAC division when GSM900 GSM1800 co-exist with WCDMA
WCDMA LAC division can be operated separately from reference to GSM LAC division
which includes
WCDMA LAC boundary location refers to that of GSM GSM LAC boundaries are usually
on cells with low traffic and less handover times WCDMA LAC is larger than that of GSM but
WCDMA LAC boundary selection can refer to that of GSM completely One important reason to
take GSM LAC boundary as a reference is that WCDMA traffic is low in the initial phase and its
traffic distribution has no statistic meaning
The WCDMA LAC division refers to GSM LAC paging load statistics try to balance each
LACrsquos paging load GSM network is mature and GSM subscriber number increases slowly so it
will be more accurate in balancing WCDMA LAC paging load according to GSM existing
network traffic statistics
6 Libya LAC Division Case
There are totally 260 sites in the phase one and phase two Libya Tripoli network and they
belong to 7 LACs RNC10 has 2 LACs RNC1 has 5 LACs It is hard to avoid areas with high
traffic becoming LAC boundary due to too many LACs which will surly impact call performance
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
8
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
DT KPI is regulated in Libya acceptance including Call Setup Success Rate which will inevitably
be impacted by too many LACs
As to commercialized network stability is the primary demand Therefore we use this
project while combining LAC Sites controlled by RNC1 are classified into 2 LACs sites
controlled by RNC10 are classified into 1 LAC so the original 7 LACs now turn out to be the
present 3 LACs and then LAC update requests decrease dramatically The project is shown in the
following figure
Figure 1 LAC Combination Illustration
We use concentric circles mode to re-plan LAC LAC1080 and LAC1090 of RNC10 are
combined as one LAC LAC1010 LAC1020 and LAC1030 of RNC1 are combined as one LAC
LAC1050 and LAC1070 are combined as one LAC
In order to validate whether the maximum paging times of combined LAC exceeds
equipment capacity in OMCR LMT choose a cell randomly in each LAC to test and calculate
each LACrsquos maximum paging times on busy hour after combination so as to observe each LACrsquos
paging load The maximum paging times of RNC10 after combination on busy hour is 18+16=34
per second average paging times is 575+398=973 RNC1 has 2 LACs after combination the
total maximum paging times of LAC1010 LAC1020 and LAC1030 on busy hour is
165+21+19=565 per second average paging times is 514+517+584=1615 the total maximum
paging times of LAC1050 and LAC1070 after combination on busy hour is 165+14=305 per
second while average paging times is 504+379=883 System maximally supports 100 times
paging per second therefore after combination peak value of each LACrsquos paging channel
utilization ratio are separately 34 565 and 305 While average paging channel utilization
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
9
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-
Internal Use Only
ratio are separately 973 1615 and 883
NoticeHere is a problem The sum of the maximum paging times of each LAC is larger
than the actual maximum paging times because it is impossible that all LACsrsquo paging times reach
their peak values at the same time the total maximum paging times is just estimation
Now the number of active subscriber in VLR in Libya is only around 30000 after RNC1
combination one of its LACrsquos paging utilization ratio is over 50 paging load is obviously too
large The RampD Dept has not provided a reasonable explanation or solution for the situation
therefore the combination project is temporarily suspended in the field
The PCH paging times calculation in the table is according to Section 624 in 25435-700
Protocol Two consecutive PCH frames carry paging indication information and paging message
separately and the two compose a complete paging message Related description in the protocol is
as follows
The PCH DATA FRAME includes the paging indication information and paging messages [FDD -
To page one User Equipment two consecutive PCH DATA FRAMEs with consecutive CFN
numbers are transmitted the first frame contains the Paging Indication Information and the second
contains the Paging Message] [TDD ndash To page one User Equipment one or more PCH DATA
FRAMEs are transmitted]
This document contains proprietary information of ZTE Corporation and is not to be disclosed or used except in accordance with applicable agreements
10
- 1 Overview
- 2 Paging Principle Paging Channel Parameter and System Parameter
-
- 21 Paging Principle
- 22 Paging Channel Parameter
- 23 System Parameter
-
- 3 Paging Capacity Calculation
-
- 31 PCH Capacity Calculation
-
- 311 Channel Number Confirmation
- 312 GOS Confirmation
- 313 Channel Capacity Calculation
-
- 32 Each UErsquos Paging Traffic Calculation on Busy Hour
-
- 321 CS Traffic Model
-
- 33 Calculation of the Maximum Subscriber Number that Each LAC Supports
-
- 4 LAC Division Principle
- 5 Feasibility Analysis of WCDMA and GSM co-use LAC
-
- 51 WCDMA Paging Capacity Calculation
- 52 GSM Paging Capacity Calculation
- 53 Advantage and Disadvantage of WCDMA and GSM co-use LAC as well as Suggestions
-
- 6 Libya LAC Division Case
-