GPRS (General Packet Radio Service) is a packet-based mobile data service available to users of GSM and IS-136 mobile phones. It allows improved and simplified wireless access to packet data networks. The key components of a GPRS network include the SGSN (Serving GPRS Support Node) which tracks user locations and performs security functions, and the GGSN (Gateway GPRS Support Node) which acts as an interface to external networks. A PDP (Packet Data Protocol) context must be activated to establish a logical link between a mobile device and the SGSN to transfer data packets between the device and GGSN via tunneling protocols. Common applications of GPRS include email, internet access,

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GPRS
NISHI BHANU PRATAP SINGH
ELECTRONICS AND COMMUNICATION
ENGINEERING
GALGOTIAS COLLEGE OF ENGINEERING
&
TECHNOLOGY,
GREATER NOIDA

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General Overview
► GPRS stands for General Packet Radio System. GPRS provides
packet radio access for mobile GSM and TDMA users.
► The GPRS specifications are written by the European
Telecommunications Standard Institute (ETSI), the European
counterpart of the American National Standard Institute (ANSI).
► GPRS is a Mobile Data Service available to users of GSM and IS-
136 mobile phones.
► GPRS is packet-switched and multiple users share the same
transmission channel for transmitting the data.

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 GPRS is important as a migration step toward third-gen
eration (3G) networks and allows network operators to i
mplement an IP-based core architecture .
 GPRS is a new bearer service for GSM that greatly impr
oves and simplifies wireless access to packet data net
works.
 Networks based on the Internet Protocol and X.25 netw
orks are also supported in the current versions of GPRS
.

4. GPRS Overview 4GPRS Overview 4
Basic GSM System Architecture
BTS
BTS
BTS
BTS
BTS
BTS
BSC
BSC
MSC
HLR VLR AUC
OMC
PSTN
ISDN
CSPDN
PSPDN
MS
MS
Um
Abis
A
TE

5. GPRS Overview 5
Basic GPRS System Architecture
BTS BSC
SGSN
MSC/VLR HLR
IP
X.25
MS
MS
BSS
Um
TE
GGSN
PCU
BTS BSC PCU
Gs Gr
GnGb

6. GPRS Overview 6GPRS Overview 6
GPRS Transmission Plane
MS
Relay
Network
Service
GTP
Application
IP / X.25
SNDCP
LLC
RLC
MAC
GSM RF
SNDCP
LLC
BSSGP
L1bis
RLC
MAC
GSM RF
BSSGP
L1bis
Relay
L2
L1
IP
L2
L1
IP
GTP
IP / X.25
Um Gb Gn
Gi
MS BSS SGSN GGSN
Network
Service
UDP /
TCP
UDP /
TCP
MS
Gb Gn
SGSN GGSNBTS BSC PCU

7. GPRS Overview 7GPRS Overview 7
GPRS Logical Channel
Downlink
& Uplink
Downlink Uplink
Downlink
Downlink
Downlink
Logical Channel
Signaling Channels
Packet
Traffic Channel
Packet
Broadcast Control Channel
Packet
Common Control Channel
PDTCH
PACCH
PBCCH PRACH
PPCH
PAGCH
PNCH
Traffic Channels

8. GPRS Overview 8
Basic GPRS System Architecture
 SGSN : The Serving GPRS Support Node (SGSN)
– Same hierarchical level as the MSC
– Serves attached mobiles
– keeps track of the individual MSs' location and performs
security functions and access control.
– Connected to the BSS with Frame Relay(in future, ATM)
– Data/packet Counting(for charging)

9. GPRS Overview 9
Basic GPRS System Architecture
 GGSN : The Gateway GPRS Support Node
– Interworking with external packet-switched networks
– Connected with SGSNs via an IP-based GPRS backbone
network.
– The HLR is enhanced with GPRS subscriber information
– Enhanced MSC/VLR : co-ordination of GPRS and non-
GPRS services (paging , LA)
 PCU : Packet Control Unit
– Packet Segmentation
– Radio Channel Allocation
– QoS measurements

10. GPRS Overview 10
GPRS Attach/Dettach
 Establishes a logical link between the MS and the
SGSN
 Performed when a mobile indicates its presence to
the network, for the purpose of using the services
provided by the network
 Dependent upon the class of the mobile
– IMSI attach for GSM circuit switched(CS) services
– GPRS attach
– Combined IMSI/GPRS attach

11. GPRS Overview 11
PDP Context Activation
 PDP Context
– Contains mapping and routing information btw. MS & GGSN
– Activation
 Allocation of PDP Address
 Access point name(APN)
 Quality of service required(QoS)
– Priority (for packet transfer)
– Reliability (of connection, I.e. loss of data)
– Delay (within the network)
– Throughput (data/time)

12. GPRS Overview 12
GPRS Mobile States
GPRS
Attach
GPRS
Dettach
Ready timer expiry
or
Force to Standby
PDU Transmission
Idle
Ready
Standby

13. GPRS Overview 13
GPRS Mobile Class
 Modes of operation
Either GPRS or GSM
services
Both GPRS and GSM
services
Both GPRS and GSM
services
Attached to
Alternate use onlyClass C
Only operate one set of
services at a timeClass B
Simultaneous
attach • monitor • traffic
Class A
SupportMode

14. GPRS Overview 14
GPRS Operation
1. GPRS Attach
2. PDP Activation
Encapsulation & Tunneling
PDNs
GPRS Attach
makes the MS known in
the corresponding GGSN
PDP Activation
establishes a logical link
between MS and SGSN
Encapsulation & Tunneling
data Packets are equipped with
GPRS-specific protocol information
and transferred between MS and GGSN
3. Data Transfer
Gb Gn
SGSN GGSNBTS BSC PCU

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Applications
► Communications: E-mail, fax, unified messaging and intranet/Inter
net access etc.
► Value-added services: Information services and games etc.
► E-commerce: Retail, ticket purchasing, banking and financial tradi
ng etc.
► Location-based applications: Navigation, traffic conditions, airline/
rail schedules and location finder etc.
► Vertical applications: Freight delivery, fleet management and sales-
force automation.
► Advertising: Advertising may be location sensitive. For example, a
user entering a mall can receive advertisements specific to the stor
es in that mall.

16. GPRS Overview 16
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