7/30/2019 LCPCH

1/2

Golden Bridge Technology (GBT) invented theCommon Packet Channel (CPCH) technology and

holds a number of CPCH patents and patentapplications worldwide.GBT's CPCH technology is designed for transfer ofmedium-size packet data, the most common size forapplications such as M-commerce, unified messaging,video clips, video monitoring, chatting, pictures andfile transfer. The deployment of CPCH maximizes thenumber of users sharing the network resources. CPCHis broadly considered to be the 3rd Generation GPRSequivalent of the UMTS standard.A pioneer in the wireless industry, GBT fullyunderstood the importance of packet-switched

technology in the ITUs quest to create a globalwireless 3G standard. As early as 1996, GBT begancollaboration with AT&T Labs on the development ofa packet-switched W-CDMA technology solution.GBTs packet based technology was incorporatedinto "WP-CDMA" (Wideband Packet-CDMA)proposal and submitted to the ITU in January 1999.

The committee responsible for WP-CDMA waschaired by AT&T Labs and Nokia. Besides GBT,AT&T Labs and Nokia, Ericsson, Hughes Network,OKI, Lucent, IDC, Bell South, among others, werepart of this committee.

Subsequently, GBT introduced its packet basedtechnology, now known as the CPCH, into the ThirdGeneration Partnership Project (3GPP) forum, wherestandard organizations around the world cooperateto produce globally applicable TechnicalSpecifications for a 3rd Generation (3G) MobileSystem. GBTs CPCH was evaluated, accepted andincorporated into the 1999 release of the IMT2000W-CDMA specification.

DESCRIPTION

The Common Packet Channel (CPCH) 3G's GPRS

-CPC

BENEFITS

Elaborate analysis and simulations1 have shownthat deployment of CPCH in association with theFACH provides the following advantages over

that of DCH:

a 21-fold increase in spectrum efficiency in theuplink

a 3.3-fold increase in spectrum efficiency inthe downlink

an increase in the hardware resourceutilization by a factor of 16

CPCH also offers an 8-fold increase in throughputand spectral efficiency as compared to that ofRACH.

The use of the CPCH/ FACH packet switchedmethod provides a much higher throughput andspectral utilization efficiency as compared toother existing packet methods within UMTS. Thiswill greatly reduce infrastructure cost andmaximize profitability.

CPCH offers the best and the most cost efficientimplementation of the 3GPP W-CDMA standardfor packet data transfer.

Simulation results are subject to changing assumptions. Forthe most recent description, please refer to joint paper(footnote 1).

1Joint Paper: Kourosh Parsa, Golden Bridge TechnologyInc., Saeed Ghassemzadeh, AT&T Labs, SaiedKazeminejad, SBC Technology Resources, "SystemEngineering of Data Services in UMTS W-CDMA System",IST Mobile Communications Summit, Galway, Ireland, 1-4October 2000

GOLDEN BRIDGE TECHNOLOGYGOLDEN BRIDGE TECHNOLOGY

7/30/2019 LCPCH

2/2

Corporate: 185 Route 36, West Long Branch, New Jersey 07764 T: +732 870 8088 F: +732 870 9008 www.gbtwireless.com

The Following Graphs are Illustrative Comparisons of the CPCH/FACH and the DCH/DSCH Operation

There are currently two modes of operations for packet data transport in the 3GPP W-CDMA: packet mode and circuitmode. In the packet mode, the downlink transport channels include use of the Forward Access Channel (FACH). Theuplink transport channels for packet mode are Random Access Channel (RACH) and the Common Packet Channel(CPCH). In the circuit mode, DCH is used to transfer packet data in both directions. The Downlink Shared Channel(DSCH) can be used in either mode.

UPLINK COMPARISON:

Use of DCHinUplink Impairs Downlink Capacity

Downlink

Uplink

Downlink

Uplink

DCH:CPCHOverhead ratio =20 :1 Downlink Overhead Uplink Overhead

DCH METHOD

CPCH METHOD

DOWNLINK COMPARISON:

Use of DSCHinUplink Impairs Downlink Capacity

Downlink

DCH/DSCH:CPCH/FACHOverhead ratio =20 :1

DCH/DSCH DOWNLINK

CPCH/ FACH DOWNLINK

Downlink Overhead

Downlink

DOWNLINK COMPARISON:

Multiple Users Scenario Compounds DSCHOverhead

DSCH

DCH1DCH2

DCH3

DCH4

FACH

DCH:CPCHOverhead ratio =20 :1 Downlink Overhead

DCH/DSCH SOLUTION

CPCH SOLUTION

CALCULATION:CPCH/FACHSupports 4 Times More Users ThanDCH/ DSCH

www.gbtwireless.com

Assumptions:

Inactivity timer =Ti secOverhead=(Ti+0.06)*16 kb/ s =16* Ti Kbits (drop 0.06)Ti =1 sec (currently considered from1 to 3 sec)DSCH Data /DSCH Overhead =3,840/ (1*16,000) =1/ 4

For Ti = 1 sec,

(FACH/ CPCH Users) / (DSCH/ DCH Users)

= (DSCH/DCH Data + DSCH/DCH Overhead) / (FACH/CPCH Data + FACH/CPCH Overhead)

= (3,840+16,000) / (3,840+960)

= 19,840/ 4,800

4 / 1

Inactivity Timer Ti =0 secFACH Overhead =0.06*16 kb/ s =960 bitsFACH Data / FACH Overhead =3,840 / 960=4 / 1

Data Rate = 64 kb/ s Packet Duration = 60 msec

Packet Duration = 60 msec Data = 60 msec * 64 kb/ s = 3,840 bits

DCH CONTROL CHANNELFACH

RACH DCH CONTROL CHANNEL

DATA

60ms1-3 sec Inactivity Time

DATA

DATA

FACH

DATA

DSCH

60ms1-3 sec Inactivity Time

DCH CONTROL CHANNEL

1

1 2 3 4 5 1 2 3 4 . . .

2

3

4

DCH CONTROL CHANNEL

DCH CONTROL CHANNEL

DCH CONTROL CHANNEL

DCH CONTROL CHANNEL

FACH

1 2 3 4 5 1 2 3 4 . . .

DCH/ DSCH CPCH/ FACH