1. Mobile Communication Division
GPRS Overview
Kwak Min Seok
Samsung Electronics
R & D 3Group
Mobile Communication Division
GPRS Overview

2. Contents GPRS overview GPRS System Arcitecture Overview
Features
Applications
GPRS System Arcitecture Overview
GPRS Mobile Operation
Attach/Dettach
PDP Context Activation
GPRS Mobile States
GPRS Mobile Class
S/W architecture
GPRS Overview

3. GPRS Features Sits on existing GSM network Many users – Multiflexing
Packet Switched
Uses a packet mode technique
Fast switching of Resources
Interworking compatible with other Data networks
TCP/IP, X.25, etc
High data rates – 171.2kbps
Supports a wide range of Applications
Quality of Service
Charging is based on the amount of data transferred
GPRS Overview

4. GPRS Applications Mobile office Applications Internet Online banking
Web browsing, File transfer,…
Online banking
Moving or still images
Upload, Download
Traffic information
Vehicle positioning
GPS
Information Services
News,Ticketing,…
GPRS Overview

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

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

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

11. PDP Context Activation
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)
GPRS Overview

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

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

14. GPRS Operation GPRS Attach PDNs 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
data Packets are equipped with
GPRS-specific protocol information
and transferred between MS and GGSN
3. Data Transfer Gb Gn
SGSN
GGSN
BTS
BSC
PCU
GPRS Overview

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

16. Packet Signaling Channels – control
Packet Broadcast Control Channel (PBCCH)
Broadcasts in the downlink direction packet data System Info’s.
If not allocated, the info’s are broadcasted on the BCCH.
Packet Common Control Channel (PCCCH)
Comprises of the following packet logical channels for common control signaling :
PCCCH=PPCH+PRACH+PAGCH+PNCH
Packet Paging Channel (PPCH)
Used to page a mobile prior to downlink packet transfer.
Uses paging groups in order to allow usage of DRX mode.
Can be used for paging of both circuit switched and packet data services.
GPRS Overview

17. Packet Signaling Channels – control
Packet Access Grant Channel (PAGCH)
Used in the packet transfer establishment phase (downlink only) to send resource assignment to a mobile prior to packet transfer.
Packet Notification Channel (PNCH)
Used to send a PTM-M (Point To Multipoint - Multicast) notification to a group of mobiles prior to a PTM-M packet transfer.
Packet Random Access Channel (PRACH)
Used by the mobile to initiate uplink transfer for sending data or signaling information.
Packet access and extended packet access bursts are used on the PRACH.
GPRS Overview

18. Packet Traffic Channels
Packet Data Traffic Channel (PDTCH)
Allocated for data transfer. In multislot operation, one MS may use multiple PDTCHs in parallel for individual packet transfer.
All packet data traffic channels are uni-directional, either uplink (PDTCH/U), for a mobile originated packet transfer or downlink (PDTCH/D) for a mobile terminated packet transfer.
Packet Associated Control Channel (PACCH)
Conveys signaling information related to a given mobile.
Shares resources with PDTCHs that are currently assigned to the mobile.
A mobile that is currently involved in packet transfer can be paged for circuit switched services on the PACCH.
GPRS Overview