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General Packet Radio ServiceGeneral Packet Radio Service
(GPRS)(GPRS)
A new Dimension to WirelessA new Dimension to Wireless
CommunicationCommunication
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Contents of PresentationContents of Presentation
GPRS and its Features GPRS Network Architecture
GPRS Protocol Architecture
GPRS Backbone Network
GPRS interworking with External Network Call routing in GPRS
Session Management in GPRS
Location Management in GPRS Mobility Management in GPRS
Logical Channels of GPRS
GPRS Applications
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Constraints with existingConstraints with existing
networknetwork
Data Rates too slow about 9.6 kbps
Connection setup time too long Inefficient resource utilization for bursty
traffic
Proves expensive for bursty traffic
utilization No efficient method for packet transfers
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Comparison of GSM &Comparison of GSM &
GPRSGPRSGSM GPRS
Data Rates 9.6 Kbps 14.4 to 115.2
Kbps
ModulationTechnique GMSK GMSK
Billing Duration of
connection
Amount of
data
transferredType of
Connection
Circuit Switched
Technology
Packet -
Switched
Technology
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GPRS in INDIAGPRS in INDIA
BPL Mobile
Bharti Cellular
Hutchison MaxHutchison Essar
Idea Cellular
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What is GPRS ?What is GPRS ?
General Packet Radio Service (GPRS) is a
new bearer service for GSM that greatly
improves and simplifies wireless access to
packet data networks
GPRS applies packet radio principal to
transfer user data packets in an efficient way
b/w MS & external packet data network
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Benefits of GPRSBenefits of GPRS New Data Services
High Speed (Data Rate 14.4 115 kbps)
Efficient use of radio bandwith (Statistical
Multiplexing)
Circuit switching & Packet Switching can be
used in parallel Constant connectivity
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Statistical MultiplexingStatistical Multiplexing
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Salient Features of GPRSSalient Features of GPRS
Important step on the path to 3G
Standardized by ETSI
GPRS is an overlay network over the GSM
Provides Data Packet delivery service Support for leading internet communication
protocols
Billing based on volume of data transferred
Utilizes existing GSM authentication andprivacy procedures.
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High Data RateHigh Data Rate
GPRS uses radio channel i.e. 200 kHz wide
Radio channel carries digital data stream of271 kbps
This rate is divided into 8 time slots eachcarrying 34 kbps per time slot
Data rate 14 kbps per time slot achieved after
corrections GPRS can combine upto 8 time slots giving
data rate of 114 kbps
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GPRS ServicesGPRS Services
Offers end-to-end packet switched data transfer
Bearer Services
PTP - Point-To-Point service (CLNS mode)
PTM - Point-To-Multipoint service(CONS Mode) PTM-M Multicast service
PTM-G Group call service
Supplementary Services
SMSShort Message Service
CFU Call Forwarding Unconditional
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GPRS Services (Contd.)GPRS Services (Contd.)
CFNRc Call Forwarding on mobile subscriber
not reachable
CUG Closed User Group
Tele action, access to data bases
Quality of Service
GPRS allows defining QoS profiles
Service precedence, reliability,delay,throughput
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GPRS TerminalsGPRS Terminals
Class A
MS supports simultaneous operation ofGPRS and GSM services
Class B
MS able to register with the n/w for bothGPRS & GSM services simultaneously.It can only use one of the two servicesat a given time.
Class C
- MS can attach for either GPRS or GSMservices
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GPRS Network ElementsGPRS Network Elements
GPRS Architecture is same as GSM except fewhardware modifications.
Two new nodes introduced for packet data Serving GPRS Support Node (SGSN)
handles all packet data for the appropriate geographicarea
monitors GPRS users
handles security and access control
may be regarded as the packet switched equivalent ofthe circuit-switched MSC
Gateway GPRS Support Node (GGSN) internetworking functionality
routes incoming data to correct SGSN
translates between different protocols and formats
Details of data services added to HLR
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Architecture of a GSMArchitecture of a GSM
NetworkNetwork
SD
Mo
ie Statio
BTS
MS /
VLR
SIMME
BS
Base Station
Subsystem
GMS
Network Subsystem
AUEIR HLR
Other Networks
Note: Inter es have been omitted forclarity purposes.
+
PSTN
PLMN
Internet
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Integrating GPRSIntegrating GPRS
SD
Mobie Station
BTS
MSC
BSC
Base Station
Subsystem
MSC
Network Subsystem
AUC
OtherNetworks
ote: Interfaces have been omitted for clarity purposes.
GGSNSGSN
SIM ME
+
PSTN
PLMN
Internet
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GPRS SYSTEM ARCHITECTURE
BSC
SGSN
MS
BTS
BTS
Other
GPRS
PLMN
GGSN
PDN
Gb
Gd
Gp
Gn
Gf
Gs
Gc
GGSN
EIRHLR+GPRS
Register
MSC LR
D
SMS-GMSCSMS-INMSC
Gi
Gr
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InterfacesInterfaces
Gb Connects BSC with SGSN
Gn SGSN SGSN/GGSN (in the samenetwork)
Gp SGSN GGSN (in different networks)
Gf For equipment querying at registeringtime
Gi Connects PLMN with external PacketData Networks (PDNs)
Gr To exchange User profile betweenHLR & SGSN
Gs To exchange Database betweenSGSN & MSC
Gd Interface between SMS & GPRS
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SGSNSGSN Serving GPRSServing GPRS
Support NodeSupport Node Delivers data packets to mobile stations &
vice-versa
Detect and Register new GPRS MS in its
serving area
Packet Routing, Transfer & MobilityManagement
Authentication, Maintaining user profiles
Its location register stores location info. &
user profiles
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GGSNGGSN Gateway GPRSGateway GPRS
Support NodeSupport Node Interfaces GPRS backbone network & externalpacket data networks
Converts the GPRS packets from SGSN to the
PDP format Converts PDP addresses change to GSM
addresses of the destination user
Stores the current SGSN address and profile of
the user in its location register
Performs authentication
Many-to- many relations among SGSNs & GGSNs
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GPRS RegisterGPRS Register
GPRS Register is integrated with GSM-HLR.
Maintains the GPRS subscriber data and
Routing information.
Stores current SGSN address
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GPRS Backbone NetworkGPRS Backbone Network
GSNs are connected through IP based backbone Two Backbones:
Intra PLMN backbone networks that connectsGSNs of the same PLMN & are private IPnetworks
Inter PLMN backbone networks that connectsGSNs of the different PLMN. Roaming agreementis necessary
GPRS Tunneling protocol (GTP)
PLMN- Inter PLMN interconnect are called Bordergateways (performs security functions to protectIntra- PLMN backbone against unauthorized usersand attacks).
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GPRS BACKBONE NETWORK
inter-PLMN
GPRS backbone
External Packet
Data Network (PDN)
intra-PLMN
GPRS backbone
intra-PLMN
GPRS backbone
PLMN1
PLMN2
SGSN
SGSNSGSN
GGSNGGSN
Border
gatewayBorder
gateway
Gp
Gn
Gi
Gn
Gn
BTS BTS
BSC
BSC
Host
Router LAN
MS
Gi
Gn
Gn
Gp
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Protocol StackProtocol Stack
GSM RF
SNDCP
IP / X.25
Application
Um GnGb
MAC
RLC
LLC
IP / X.25
GTP
L1
L2
LLC
GSM RF
Frame
RelayMAC
RLC BSSGP
L1bis
BSSGP
Frame
Relay
LLC
SNDCP GTP
L1bis L1
L2
IP
MS BSS (PCU) SGSN GGSN Gi
IP
UDP/
TCP
UDP/
TCP
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SNDCPSNDCP -- Sub Network DependentSub Network Dependent
Convergence ProtocolConvergence Protocol
Used to transfer data packets between SGSNand MS
Multiplexing of several connections ofnetwork layer onto one logical connection ofunderlying LLC layer
Compression and decompression of userdata and header information
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Data Link layerData Link layer Divided into two sub layers :
LLC layer (between MS-SGSN)
RLC/MAC (between MS-BSS)
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LLCLLC--Logical Link ControlLogical Link Control Establishes highly reliable logical link
between MS & its assigned SGSN
Works either in acknowledged or
unacknowledged modes
Data confidentiality is ensured by ciphering
functions
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RLC/MAC LayerRLC/MAC Layer Radio Link Control(RLC)
Establish a reliable link between MS & BSS Segmentation and reassembly of LLC frames
into RLC data blocks
Medium Access Control(MAC) Controls access attempts of an MS on radio
channels shared by several MSs
Employs algos. for contention resolution,multiuser multiplexing on PDTCH
Both ack and unack. Modes of operation aresupported in RLC/MAC layer
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Physical LayerPhysical Layer
Divided into two sub layers :
Physical Link Layer (PLL)
Physical RF Layer (RFL)
PLL Provides a physical channel betweenMS and BSS
Channel coding, interleaving, detection
of physical link congestion
RFL - Operates below PLL
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BSSGPBSSGP--(BSS GPRS(BSS GPRS
Application Protocol)Application Protocol)
Delivers routing & Quality of Servicerelated information between BSS and
SGSN
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GTPGTP GPRS TunnelingGPRS Tunneling
ProtocolProtocol GTP tunnels user data packets and related
signaling information between GSNs
Signaling is used to create, modify and deletetunnels
Defined both at Gn and Gp interface
Below GTP, TCP or UDP are employed totransport the GTP Packets within backbone
network
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Inter working with IPInter working with IP
networksnetworks GPRS n/w can be interconnected with an IP-
based packet data network
GPRS supports both IPv4 and IPv6 GPRS n/w looks like IP sub network and
GGSN looks like a IP router
DHCP, DNS servers are installed
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GPRSGPRS Internet ConnectionInternet Connection
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CALL ROUTINGCALL ROUTING
DATA CALL ORGINATING
DATA CALL TERMINATING
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DATA CALL ROUTING
inter-PLMN
GPRS backbone
External Packet
data network(PDN)
Intra-PLMN
GPRS backbone
intra-PLMN
GPRS backbone
PLMN1
PLMN2
SGSN
SGSNSGSN
GGSNGGSN
Border
gatewayBorder
gateway
Gp
Gn
Gi
Gn
Gn
BTS BTS
BSCBSC
Host
Router LAN
MS
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SESSION MANAGEMENT INSESSION MANAGEMENT INGPRSGPRS
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Attachment & DetachmentAttachment & Detachment
ProcedureProcedure
GPRS attach- User is registered in SGSN, after authentication
check from HLR
- SGSN assigns P-TMSI to MS
GPRS detach- Disconnection of MS from GPRS network is called
GPRS detach- It can be initiated by MS or by network(SGSN or
HLR)
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Session ManagementSession Management
Mobile Station applies for PDP address
For each session PDP context is created & itcontains
PDP type
PDP addressed assigned to MS
Address of GGSN that servers access pointto PDN
With active PDP context MS able to send or
receive data packetsAllocation of PDP address can be static or
dynamic
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PDP Context ActivationPDP Context Activation
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LOCATION MANAGEMENTLOCATION MANAGEMENT
IN GPRSIN GPRS
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State Model of GPRS MSState Model of GPRS MS
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Location ManagementLocation Management
Mobile station can be in 1 of the 3 statesdepending on traffic amount
Idle : MS is not using GPRS service
Ready : Performing GPRS Attach,
MS gets into READY State
Standby : When MS does not send anypackets for longer period of time,
Ready timer Expires
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Routing Area UpdateRouting Area Update
GSM Location Area(LA) is divided into
several Routing Areas(RA)
RA consists of several cells
SGSN is informed when MS moves to a newRA
MS sends a Routing Area Update Request
to its assigned SGSN
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Types of Routing AreaTypes of Routing Area
UpdateUpdate
Intra SGSN Routing Area Update
Inter SGSN Routing Area Update
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Routing Area UpdateRouting Area Update
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Mobility ManagementMobility ManagementConsists of two levels:
Micro mobility management :
- Tracks the current RA or cell of MS
- It is performed by SGSN
Macro mobility management :
- Keep tracks of MSs current SGSN
- Stores it in HLR, VLR, and GGSN
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Channels in GPRSChannels in GPRS
Logical ChannelTraffic Channels
Signaling Channels (Control Channels)
Physical Channels
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Logical ChannelsLogical Channels
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Packet Data Channel(PDCH)Packet Data Channel(PDCH)
Physical Channel for GPRS Traffic
PDCH are taken from all channels available
in the cell Depending on current traffic load and priority
of service, the physical channel are allocatedto either GPRS or GSM services.
Physical channels not currently used by GSMcan be allocated as PDCH to increase theQOS for GPRS
M ltif St t fM ltif St t f
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Multiframe Structure ofMultiframe Structure of
PDCHPDCH
Four consecutive TDMA frame formsone block - B0 B11TwoTDMA frames for transmissionof PTCCH - T
Two Idle frames - X
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BillingBilling
GGSN
MSC
PSTN
BSC
SGSNGPRS
Network
Charging Gateway
Mediation
MSC
Billing
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Applications of GPRSApplications of GPRS
Web browsing
Corporate & Internet Email
Vehicle Positioning
Remote LAN Access
Home Automation
Document Sharing/Collaborative
working
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THANKTHANK YOUYOU