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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved
www.huawei.com
Internal
OMQ000001 GPRS Principle
ISSUE 2.0
HUAWEI TECHNOLOGIES CO., LTD. Page 2All rights reserved
GPRS principle is the basic part of the
whole GPRS system and the
succeeding products learning. This slide
will help us to understand the GPRS
system networking and wireless
subsystem etc.
HUAWEI TECHNOLOGIES CO., LTD. Page 3All rights reserved
References
GPRS principle
31025698 - M900/M1800 PCU Technical
Manual-(V3.35)
GPRS protocol
0360
0464
GSM protocol
0816
0818
HUAWEI TECHNOLOGIES CO., LTD. Page 4All rights reserved
Upon completion of this course, you will
be able to:
Know the GPRS system structure
Describe the GPRS important
interfaces
Understand the GPRS channel
structures
Master the GPRS relevant numbering
HUAWEI TECHNOLOGIES CO., LTD. Page 5All rights reserved
Chapter 1 Chapter 1 GPRS System StructureGPRS System Structure
Chapter 2 Chapter 2 GPRS Network Interfaces & ProtocolsGPRS Network Interfaces & Protocols
Chapter 3 Chapter 3 GPRS Wireless SubsystemGPRS Wireless Subsystem
Chapter 4 Chapter 4 GPRS NumberingGPRS Numbering
Chapter 5 Chapter 5 GPRS Mobility Management (GMM)GPRS Mobility Management (GMM)
HUAWEI TECHNOLOGIES CO., LTD. Page 6All rights reserved
GSM Development Evolution
57.6 kbps
115 kbps
384 kbps
2 Mbps
GSM
HSCSD
GPRS
EDGE
IMT-2000
9.6 kbps
2G
2.5G
3G
HUAWEI TECHNOLOGIES CO., LTD. Page 7All rights reserved
What is GPRS and EDGE?
Abbreviation of General Packet Radio Service.
GPRS is an end-to-end packet switching technology provided on the basis
of GSM technology.
It has much interactive services with the existing GSM circuit switching
system.
GPRS supports wireless access rate of up to 171.2Kbps.
EDGE (Enhanced Data Rates for GSM Evolution)
EGPRS (Enhanced GPRS)
− EGPRS supports wireless access rate of up to 473.6Kbps.
ECSD (Enhanced CSD, Enhanced HSCSD-High Speed Circuit Switched Data)
HUAWEI TECHNOLOGIES CO., LTD. Page 8All rights reserved
Gf
GiGnGb
Gc
Gp
Gs
MSC/VLR
MS BSS TEInternet
Um
Gr
HLR
Other PLMN
SGSN
Gd
SM-SCSMS-GMSCSMS-IWMSC
GGSN
EIR
SGSN
Gn
FR
ATM/DDN/ISDN/
Ethernet, etc
BG
GPRSbackbone
GGSN X .25 TE
Gi
CGMS BSS
Um
GPRS system structure
FR
Gb
SS7
HUAWEI TECHNOLOGIES CO., LTD. Page 9All rights reserved
GPRS MS
Class A
The MS is attached to both GPRS and other GSM services and the MS supports simultaneous operation of GPRS and other GSM services.
Class B
The MS is attached on GPRS network and GSM network simultaneously but not enabling circuit switching and packet switching services at the same time.
services are selected automatically.Class C
The MS is attached to either GPRS or other GSM services. Alternate use only.
services are selected manually or default selected service.
HUAWEI TECHNOLOGIES CO., LTD. Page 10All rights reserved
Functions of GPRS BSS
Packet wireless resources management function (RLC/MAC
protocol function)
System message broadcast
Packet paging processing
Wireless channel configuration
Wireless resources allocation
Wireless link monitoring
Power control
Channel coding/decoding control
Cell rerouting control
Uplink traffic control (wireless QoS guarantee)
HUAWEI TECHNOLOGIES CO., LTD. Page 11All rights reserved
Functions of GPRS BSS
Gb interface processing function
Data packet relay on wireless interface and Gb interface
Mobility management (cell updating procedure)
Downlink traffic control (wireless QoS guarantee)
HUAWEI TECHNOLOGIES CO., LTD. Page 12All rights reserved
Packet processing functions of BTS RF processing function
Function of physical layer of wireless interface
Channel coding/decoding and adjustment
Packet logic channel mapping
time advance value self-adaptive adjustment
Uplink measurement
Downlink power control execution
G-Abis interface processing function
Transmission of RLC/MAC control block and data block
Synchronization mechanism with TDMA block of PCU
Uplink measurement report
Transmission check
Other inner-band signaling functions
HUAWEI TECHNOLOGIES CO., LTD. Page 13All rights reserved
Packet processing functions of BSC
Packet wireless resource management function
Packet channel configuration
TBF establishment procedure when PBCCH is not configured in the cell
Circuit paging coordination
G-Abis interface processing function
G-Ais interface physical layer switching
Pb interface switching function
Similar to the relative functions of PCU
HUAWEI TECHNOLOGIES CO., LTD. Page 14All rights reserved
Functions of PCU
Packet wireless resource management function (RLC/
MAC protocol function)
Wireless resource management functions of GPRS BSS
Circuit paging coordination
G-Abis interface processing function
Function related with GPRS BTS
HUAWEI TECHNOLOGIES CO., LTD. Page 15All rights reserved
Functions of PCU
Pb interface processing function
LAPD link between BSC and PCU
Layer-3 signaling between BSC and PCU
Gb interface processing function
Data packet relay on wireless interface and Gb interface
Mobility management (cell updating procedure)
Downlink traffic control (wireless QoS guarantee)
HUAWEI TECHNOLOGIES CO., LTD. Page 16All rights reserved
Position of PCU
CCU
CCU
CCU=Channel Codec UnitPCU= Packet Control Unit
CCUPCU
BTS BSC GSN
AGb
Um
CCU
CCUPCU
BTS BSC GSN
B
CCUPCU
BTS BSC GSN
C
Abis
Gb
Gb
HUAWEI TECHNOLOGIES CO., LTD. Page 17All rights reserved
Position of Huawei PCU
CCU
CCU
BSCBTS
SGSN
Um
Abis
GbBSC
Pb
CCU
CCU
PCU
BTS
HUAWEI TECHNOLOGIES CO., LTD. Page 18All rights reserved
GPRS(BSS side) upgrade to EDGE
Upgrade BSC software
Upgrade PCU software
upgrade BTS software and hardware - new EDGE TRX
EDGE
TRX
HUAWEI TECHNOLOGIES CO., LTD. Page 19All rights reserved
Functions of SGSN
Network access control (MS side)
Authentication
Billing information collection
IMEI check
Logic link management
SGSN-MS logic link management
Supporting acknowledged/unacknowledged transmission
Route management
SGSN-BSS data transmission route management
Mobility management and session management
HUAWEI TECHNOLOGIES CO., LTD. Page 20All rights reserved
Functions of SGSN
Route and tunnel transmission
Compression and decompression
Encryption and decryption
Storage and transfer of subscriber data
Routing: executed with PDP context
Address translation and mapping: including DNS and GGSN a
ddress induced from APN
Encapsulation and tunnel transmission
HUAWEI TECHNOLOGIES CO., LTD. Page 21All rights reserved
Functions of GGSN
Network access control (external PDN side)
Message filtering
Billing information collection
Mobility management and session management
Routing and transfer
Storage and transfer
Routing
Address translation and mapping
Encapsulation and tunnel transmission
Dynamic allocation of IP addresses
HUAWEI TECHNOLOGIES CO., LTD. Page 22All rights reserved
Functions of CG
Real-time collection of GPRS bills
Temporary storage and buffering of GPRS bills
Pre-processing of GPRS bills
Sending GPRS bills to the billing center
HUAWEI TECHNOLOGIES CO., LTD. Page 23All rights reserved
Functions of BG
BG enables the following protocols necessary for interworking b
etween operators
Security protocol: IPSec and firewall are recommended
Routing protocol: BGP is recommended
Billing protocol: determined by the operators with negotiation; BG mi
ght be needed in collecting billing information
It is normally based on routers
It can be configured in combination with GGSN
HUAWEI TECHNOLOGIES CO., LTD. Page 24All rights reserved
Functions of MSC/VLR
When Gs interface is installed, MSC/VLR can support
Establishment and maintenance of the association between SG
SN and MSC/VLR.
GPRS combined mobility management procedure.
Combined IMSI/GPRS attachment/detachment.
Combined location area/routing area updating.
Circuit paging coordination function.
The wireless resource usage can be greatly improved.
HUAWEI TECHNOLOGIES CO., LTD. Page 25All rights reserved
Functions of HLR/AUC
Saving and updating GPRS subscriber subscription data
User authentication
Providing location/routing information and processing needed i
n mobility management and routing, for example:
Saving and updating user service SGSN number and address
GPRS user location deletion indication
Whether MS is reachable.
Subscriber tracing (optional)
HUAWEI TECHNOLOGIES CO., LTD. Page 26All rights reserved
Functions of SMS-GMSC/SMS-IWMSC
After Gd interface is installed, short messages can be sent via
GPRS, which reduces the occupation on SDCCH and cuts do
wn the influence on voice services by SMS services.
The operator can select to send SMS via MSC or SGSN.
HUAWEI TECHNOLOGIES CO., LTD. Page 27All rights reserved
Chapter 1 Chapter 1 GPRS System StructureGPRS System Structure
Chapter 2 Chapter 2 GPRS Network Interfaces & ProtocolsGPRS Network Interfaces & Protocols
Chapter 3 Chapter 3 GPRS Wireless SubsystemGPRS Wireless Subsystem
Chapter 4 Chapter 4 GPRS NumberingGPRS Numbering
Chapter 5 Chapter 5 GPRS Mobility Management (GMM)GPRS Mobility Management (GMM)
HUAWEI TECHNOLOGIES CO., LTD. Page 28All rights reserved
Network interface types GPRS backbone netwo
rk
SGSNSGSN
SGSNSGSNGGSNGGSNGn
IP interface
SS7 interface
BSS MSCSMS-GMSC
AUm
PDP network (IP/X.25)
Gi
TE
MT
MS
HLR
Gs
Gr
Gd
Gc
Gb
HUAWEI TECHNOLOGIES CO., LTD. Page 29All rights reserved
Data transmission plane
MAC: Media Access Control
RLC: Radio Link Control
LLC: Logical Link Control
BSSGP: BSS GPRS Protocol
SNDCP: Sub-Network Dependency Convergence Protocol
GTP: GPRS Tunneling Protocol
Application
IP/X.25 IP/X.25 IP/X.25
SNDCP GTP
LLC LLC UDP/TCP UDP/TCP
RLC BSSGP BSSGP IP IP
MAC MACNetworkService Network
ServiceL2 L2
L2 (MAC)
PhysicalLayer
PhysicalLayer
PhysicalLayer
PhysicalLayer
PhysicalLayer
PhysicalLayer
PhysicalLayer
MS BSS SGSN GGSN
relay
relaySNDCP GTP
Um Gb Gn Gi
RLC
HUAWEI TECHNOLOGIES CO., LTD. Page 30All rights reserved
MS-SGSN signaling plane
GMM: GPRS Mobility Management
SM: Session Management
MS BSS SGSN
BSSGP
GMM/SM
LLC
RLC
MAC
GSM RF
GMM/SM
LLC
BSSGP
L1bis
Um Gb
NetworkService
RLC
MAC
GSM RF L1bis
NetworkService
Relayrelay
HUAWEI TECHNOLOGIES CO., LTD. Page 31All rights reserved
Functions of physical layer
Physical layer consists of RF sub-layer and physical link sub-layer
RF sub-layer
− modulation and demodulation.
Physical sub-layer
− error check, interleaving.
− Radio channel measurement, including receiving signal level and quality
measurement, TA measurement, physical link layer congestion
measurement.
− Radio management function, including cell selection and reselection
procedures, power control procedure of transmitter, battery power
management procedure, such as DRX.
HUAWEI TECHNOLOGIES CO., LTD. Page 32All rights reserved
Functions of RLC/MAC RLC/MAC layer service
The RLC/MAC function supports two modes of operation
− Unacknowledged operation
− Acknowledged operation
RLC/MAC layer functions
The RLC function defines the procedures for segmentation and reassemble
of LLC PDUs into RLC/MAC blocks and, in RLC acknowledged mode of
operation, for the Backward Error Correction (BEC) procedures enabling the
selective retransmission of unsuccessfully delivered RLC/MAC blocks.
The MAC function defines the procedures that enable multiple mobile stations to share
a common transmission medium, which may consist of several physical channels. The
function may allow a mobile station to use several physical channels in parallel, i.e. use
several timeslots within the TDMA frame.
HUAWEI TECHNOLOGIES CO., LTD. Page 33All rights reserved
NS layer definition
The Network Service performs the transport of NS SDUs(Service Dat
a Unit ) between the SGSN and BSS.
The Network Service entity is composed of the Sub-Network Service
and the Network Service Control.
Network Service Control /
Network Service Control Protocol
Sub-Network Service /
Sub-Network Service Protocol
Network Service
HUAWEI TECHNOLOGIES CO., LTD. Page 34All rights reserved
NS layer composition The Network Service Control
− the peer-to-peer communication between remote NS user entities is
performed over BSSGP Virtual Connections (BVCs).
− A BVC is a virtual communication path between Network Service user peer
entities.
The Sub-Network Service
− The Network Service Control peer entities use the Sub-Network Service for
communication with each other.
− The peer-to-peer communication across the Gb interface between remote
Network Service Control entities is performed over Network Service Virtual
Connections (NS-VCs).
− An NS-VC is a virtual communication path between Network Service Control
peer entities.
HUAWEI TECHNOLOGIES CO., LTD. Page 35All rights reserved
Functions of NS NS is responsible for
NS SDU transmission
− The NS SDUs shall be transmitted on the NS-VCs. The NS SDUs are encapsulated into Network Service Control PDUs which in turn are encapsulated into Sub-Network Service PDUs.
Load sharing
− The load sharing function distributes the NS SDU traffic amongst the available (i.e. unblocked) NS-VCs.
NS-VC management
− A blocking procedure is used when an NS-VC becomes unavailable for NS user traffic.
− An unblocking procedure is used for the reverse operation. Network congestion indication
− Congestion reporting mechanisms available in the Sub-Network Service implementation shall be used by the Network Service to report congestion.
HUAWEI TECHNOLOGIES CO., LTD. Page 36All rights reserved
Functions of BSSGP
The primary function of BSSGP is to provide the radio-
related, QoS, and routeing information that is required to
transmit user data between a BSS and an SGSN.
In the BSS, it acts as an interface between LLC frames and
RLC/MAC blocks.
In the SGSN, it forms an interface between RLC/MAC-derived
information and LLC frames.
A secondary function is to enable two physically distinct
nodes, the SGSN and BSS, to operate node management
control functions.
HUAWEI TECHNOLOGIES CO., LTD. Page 37All rights reserved
Functions of LLC
Logical Link Control (LLC): This layer provides a highly reliable ciphered logical link between an MS and its SGSN.
LLC includes functions for the provision of one or more logical link connections discriminated
between by means of a DLCI. sequence control, to maintain the sequential order of frames
across a logical link connection. detection of transmission, format and operational errors on a
logical link connection. recovery from detected transmission, format, and operational
errors. notification of unrecoverable errors. flow control. ciphering.
HUAWEI TECHNOLOGIES CO., LTD. Page 38All rights reserved
SCCP
MTP2
MTP3
MTP2
MTP3
SCCP
GsSGSN MSC/VLR
BSSAP+ BSSAP+
L1 L1
SGSN ‑ MSC/VLR signaling plane
Gs interface is the optional interface.
It adopts BSSAP+ protocol to enable combined mobility management and
paging functions so as to improve the effective usage of wireless resources.
HUAWEI TECHNOLOGIES CO., LTD. Page 39All rights reserved
Network operation mode (Paging co-ordination)
Paging co-ordination means that the network sends paging messages for
circuit-switched services on the same channel as used for packet-switched
services, i.e., on the GPRS paging channel or on the GPRS traffic channel, and
the MS needs only to monitor that channel.
ModeCircuit Paging
Channel
GPRS Paging
Channel
Paging co-ordination
Network Operation Mode
I
Packet Paging Channel Packet Paging Channel Yes (Gs interface is
present, all MSC-
originated paging of
GPRS-attached MSs shall
go via the SGSN)
CCCH Paging Channel CCCH Paging Channel
Packet Data Channel Not Applicable
Network Operation Mode
II CCCH Paging Channel CCCH Paging Channel No (Gs interface is not
present, all MSC-
originated paging of
GPRS-attached MSs shall
go via the A interface)
Network Operation Mode
III
CCCH Paging Channel Packet Paging Channel
CCCH Paging Channel CCCH Paging Channel
HUAWEI TECHNOLOGIES CO., LTD. Page 40All rights reserved
Chapter 1 Chapter 1 GPRS System StructureGPRS System Structure
Chapter 2 Chapter 2 GPRS Network Interfaces & ProtocolsGPRS Network Interfaces & Protocols
Chapter 3 Chapter 3 GPRS Wireless SubsystemGPRS Wireless Subsystem
Chapter 4 Chapter 4 GPRS NumberingGPRS Numbering
Chapter 5 Chapter 5 GPRS Mobility Management (GMM)GPRS Mobility Management (GMM)
HUAWEI TECHNOLOGIES CO., LTD. Page 41All rights reserved
Physical channel
The same as in GSM
The same frequency
The modulation mode
The same TDMA frame definition
The same burst pulse definition
…
The differences between GPRS and GSM
The Multi-frame structure
The channel coding
…
Application
IP/X25
SNDCP
LLC
RLC RLC BSSGP
MAC MACFramerelay
PhysicalLayer
PhysicalLayer
PhysicalLayer
MS BSS
Relay
HUAWEI TECHNOLOGIES CO., LTD. Page 42All rights reserved
Packet logic channels
The specific type of PDCH (except PRACH) is determined by RLC/MAC head
and RLC/MAC control message type.
TCH
BCCH
PCH, RACH, AGCH
Packet service channel
PACCH
Packet Data CHannel (PDCH)
Packet control channel
PBCCH
PPCH PRACH PAGCH
PCCCH PDCCH
PDTCH/U PDTCH/D PNCH
PTCCH/U PTCCH/DSACCH
HUAWEI TECHNOLOGIES CO., LTD. Page 43All rights reserved
Channel abbreviation
Packet Data Traffic CHannel Uplink - PDTCH/U Packet Data Traffic CHannel Downlink - PDTCH/D Packet Broadcast Control CHannel - PBCCH Packet Common Control CHannel - PCCCH Packet Dedicated Control Channel - PDCCH Packet Paging CHannel - PPCH Packet Random Access CHannel - PRACH Packet Access Grant CHannel - PAGCH Packet Notification CHannel - PNCH Packet Associated Control CHannel - PACCH Packet Timing advance Control CHannel Uplink - PTCCH/U Packet Timing advance Control CHannel Downlink - PTCCH/D
HUAWEI TECHNOLOGIES CO., LTD. Page 44All rights reserved
PDTCH (Packet Data Traffic CHannel)
PDTCH transmits the user data in the
mode of packet switching with a transm
ission rate of 0~22.8kbit/s.
All packet data traffic channels are uni-
directional.
Uplink (PDTCH/U) for a mobile originat
ed packet transfer.
Downlink (PDTCH/D) for a mobile term
inated packet transfer.
Packet service channel
PDTCH/U PDTCH/D
HUAWEI TECHNOLOGIES CO., LTD. Page 45All rights reserved
PBCCH (Packet Broadcast Control CHannel)
The PBCCH broadcasts parameters used by the MS to access the network for packet transmission operation.
The PBCCH also carries the information transmitted via the BCCH to allow circuit switching operation.
The MS in GPRS attached mode monitors the PBCCH only, if PBCCH is available, otherwise, the BCCH shall be used to broadcast information for packet operation.
The existence of the PBCCH in the cell is indicated on the BCCH via SI13.
Packet control channel
PBCCH
HUAWEI TECHNOLOGIES CO., LTD. Page 46All rights reserved
PCCCH (Packet Common Control CHannel) PPCH
Downlink only, used to page MS.
PRACH Uplink only, used to request allocation of one
or several PDTCH/Us or PDTCH/Ds.
PAGCH Downlink only, used to allocate one or severa
l PDTCHs.
PNCH Downlink only, used to notify MS of PTM-M c
all.
If no PCCCH is allocated, the information for packet switching operation is transmitted on the CCCH. If a PCCCH is allocated, it may transmit information for circuit switching operation.
PPCH PRACH PAGCH
PCCCH
PNCH
HUAWEI TECHNOLOGIES CO., LTD. Page 47All rights reserved
PDCCH (Packet dedicated control channels)
PACCH
Bi-directional, used to transmit the
packet signaling in data transmission.
PTCCH/U
Used to transmit random access bursts
to allow estimation of the timing
advance for one MS in packet transfer
mode.
PTCCH/D
Used to transmit timing advance
updates for several MS. One PTCCH/D
is paired with several PTCCH/U's.
PACCH
PDCCH
PTCCH/U PTCCH/D
HUAWEI TECHNOLOGIES CO., LTD. Page 48All rights reserved
Combinations of packet logic channel
Mode 3: PDTCH+PACCH+PTCCH
Mode 1: PBCCH+PCCCH+PDTCH+PACCH+PTCCH Mode 2: PCCCH+PDTCH+PACCH+PTCCH
In case of small GPRS traffic, GPRS and circuit services use the same BCCH and CCCH in the cell. In this case, only combination mode 3 is needed in the cell.
With the increase of traffic, the packet public channel should be configured in the cell. Channel combination mode 1 and mode 2 should be adopted.
Mode 4: PBCCH+PCCCH
(PCCCH=PPCH+PRACH+PAGCH+PNCH )
HUAWEI TECHNOLOGIES CO., LTD. Page 49All rights reserved
Mapping of packet logic channel
X = Idle frame T = Frame used for PTCCH B0 ~ B11 = Radio blocks
PDCH 52 multi-frame mapping
A radio block is a 4-normal-burst sequence that carries a RLC/MAC PDU (Protocol Da
ta Unit).
The mapping of logical channels onto the radio blocks is defined by means of the
ordered list of blocks (B0, B6, B3, B9, B1, B7, B4, B10, B2, B8, B5, B11).
HUAWEI TECHNOLOGIES CO., LTD. Page 50All rights reserved
Multi-frame structure comparison bet. PS and CS
PBCCH+PCCCH (BS_PBCCH_ BLKS=2 、 BS_PAG_BLKS _RES=3 、 BS_PRACH_BLKS=4)
Figure 8b: TDMA fram e m apping for FCCH + SCH + BCCH + CCCH + SDCCH/4(0...3) + SACCH/4(0...3)
IDLE
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(2)
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Figure 8a: TDMA fram e m apping for FCCH + SCH + BCCH + CCCH FCCH+SCH+BCCH+CCCH
FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/4
51 multi-frame mapping of Circuit Switching logic channel
52 multi-frame mapping of Packet Switching logic channel
DL
UL
HUAWEI TECHNOLOGIES CO., LTD. Page 51All rights reserved
Packet wireless channel configurations
Reason of adopting static PDCH
To enable that GPRS MS is constantly online in the cell.
To ensure certain QoS of GPRS services.
Reason of adopting dynamic PDCH
GPRS and GSM share wireless resources.
Wireless resources should be adopted in priority; on the other hand,
QoS of voice services should be ensured.
In a cell, the percentage of packet switching services and the
percentage of circuit switching services are constantly changing.
Dynamic PDCH is not visible for voice services.
HUAWEI TECHNOLOGIES CO., LTD. Page 52All rights reserved
Packet wireless channel configurations
General principles
The cell should be configured with static PDCH to enable MS to be normally a
ttached on GPRS network as well as certain QoS of GPRS services.
Dynamic PDCH should be configured according to the GPRS traffic forecast,
which should be adjusted as TCH or PDCH usable in the operation process a
ccording to the cell traffic status.
Circuit switching services can seize the channel used by GPRS services.
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Allocation of wireless packet resources
Wireless resource allocation and wireless transmission adopt the wireless block (BLOCK) as the b
asic unit.
Each PDCH can be used by several MSs; each MS can use multiple PDCHs at the same time.
B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11B0
B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11B0
B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11B0
MS3MS2
TS 0
TS 1
TS 2
MS1
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Transmission principle of data packet on Um interface
Subscriber dataRLC/MAC head LLC head SNDCP head
Subscriber IP packet
LLC FCS
SNDCP PDU
LLC PDU
RLC/MAC block
Normal burst Normal burst Normal burst Normal burst Physical layer
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RLC/MAC block structure (GPRS)RLC/MAC data block
An RLC/MAC block containing an RLC data block may be encoded using any of the
available channel coding schemes CS-1, CS-2, CS-3, or CS-4. RLC/MAC blocks
encoded using CS-1 do not contain spare bits.
RLC/MAC block
MAC
header
RLC data block
RLC header RLC data unit Spare
bitsRLC/MAC control block
An RLC/MAC control blocks shall always be encoded using the coding scheme CS-1.
RLC/MAC block
MAC header RLC/MAC control block
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RLC/MAC block structure (EGPRS)
RLC/MAC block
RLC/MAC header RLC data block 1 RLC data block 2
(conditional)
RLC/MAC control block
Similar to GPRS
RLC/MAC block
MAC header RLC/MAC control block
RLC/MAC data block
Dissimilar to GPRS
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PDCH coding mode
8PSKGMSK
9.05
13.415.6
21.4
8.811.2
14.817.6
22.4
29.6
44.8
54.4
59.2
0.00
10.00
20.00
30.00
40.00
50.00
60.00
CS-1 CS-2 CS-3 CS-4 MCS-1MCS-2MCS-3MCS-4MCS-5MCS-6MCS-7MCS-8MCS-9
Kbps
GPRS
EGPRS
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Downlink, 4 TS, MCS-9:
Huawei EDGE test result
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Medium access modes
Uplink resource allocation mode
Dynamic allocation : MS determines the blocks on each PDCH.
Fixed allocation : fixed bit mapping is adopted to determine the allocated blocks
in the allocation period.
Extended dynamic allocation : MS determines the blocks on multiple PDCH.
Either the Dynamic Allocation medium access mode or Fixed Allocation
medium access mode shall be supported by all mobile stations and all
networks that support GPRS. The support of Extended Dynamic Allocation is
optional for the network.
Downlink resource allocation mode
Dynamic allocation and fixed allocation.
The difference between the dynamic mode and the fixed mode lies on the dow
nlink measurement time scheduling reserved by MS.
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MS multi-TS ability
Concept of MS multi-TS ability
Definition: the multi-TS ability level is 1-29; the bigger the level, the stro
nger the multi-TS ability.
three elements(1 <= Rx + Tx <= Sum):
− Rx : maximum receiving TS number (downlink TS)
− Tx : maximum transmission TS number (uplink TS)
− Sum : maximum total TS number
BSS allocates resources according to the MS multi-TS ability, requeste
d QoS and current resource configuration.
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Power control
Power control can improve the spectrum usage and system capacity as w
ell as reduce MS power consumption.
As there is no continuous bi-directional connection in the packet data trans
mission process, GPRS power control is very complicated.
Uplink power control includes open-loop and close-loop power control.
About downlink power control, there is no specific definition in protocol. It li
es on the BTS and its algorithm needs information about downlink, so dow
nlink power control needs MS sends channel quality reports to BTS.
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Network control modes
During the network controlled cell re-selection, the network may request measurement reports from the MS and control its cell re-selection. Hence, three types of mode are defined as follows:
NC0: Normal MS controls. The MS shall perform autonomous cell re-selection.
NC1: MS control with measurement reports. The MS shall send measurement reports to the network. The MS shall perform autonomous cell re-selection.
NC2: Network control. The MS shall send measurement reports to the network. The MS shall not perform autonomous cell re-selection.
The network subsystem must support NC0 and should gradually support NC1 and NC2.
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Chapter 1 Chapter 1 GPRS System StructureGPRS System Structure
Chapter 2 Chapter 2 GPRS Network Interfaces & ProtocolsGPRS Network Interfaces & Protocols
Chapter 3 Chapter 3 GPRS Wireless SubsystemGPRS Wireless Subsystem
Chapter 4 Chapter 4 GPRS NumberingGPRS Numbering
Chapter 5 Chapter 5 GPRS Mobility Management (GMM)GPRS Mobility Management (GMM)
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CGI
Location Area Identification
MCC MNC LAC CI
Cell Global Identification
MCC (Mobile Country Code): It consists of 3 digits . For example: The MCC of China is "460"
MNC (Mobile Network Code): It consists of 2 digits . For example: The MNC of China Mobile is "00"
LAC (Location Area Code): It is a two bytes BCD code (hex). The value 0000 and FFFF is invalid.
CI (Cell Identity): This code uses two bytes BCD code (hex) to identify the radio cells within a LAI.
For example : 460-00-0011-0001
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RAI
Routing area is the sub-set of the location area. In special cases, the two
areas are equal
The division of the routing area is related with traffic distribution and
SGSN processing ability
Location Area Identification
MCC MNC LAC RAC
Routing Area Identification
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BSIC
NCC BCC
Base Station Identification Color Code
NCC(PLMN Network Color Code): It comprises 3 bits.
It allows various neighboring PLMNs to be distinguished.
BCC(BTS Color Code): It comprises 3 bits.
It allows distinctions between different radio frequency channels usi
ng the same frequency in neighboring cells.
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Chapter 1 Chapter 1 GPRS System StructureGPRS System Structure
Chapter 2 Chapter 2 GPRS Network Interfaces & ProtocolsGPRS Network Interfaces & Protocols
Chapter 3 Chapter 3 GPRS Wireless SubsystemGPRS Wireless Subsystem
Chapter 4 Chapter 4 GPRS NumberingGPRS Numbering
Chapter 5 Chapter 5 GPRS Mobility Management (GMM)GPRS Mobility Management (GMM)
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GMM concept
Routing area: subset of location area Mobility management entities: SGSN, HLR and MS GMM context
MS identification/ MS location information (routing area ID, cell ID)
Current service SGSN address, VLR number (MS only) Encryption algorithm and authentication parameter GMM status
GMM status Idle: GMM context is not established; MS is not reachable. Standby: GMM context is established; MS can receive
paging but cannot implement data transmission. Ready: MS can implement data transmission.
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GMM status models
Implicit Detachor
Cancel Location
GPRS Attach
PDU reception
GPRS Detachor
Cancel Location
MM State Model of SGSN
IDLE
READY
STANDBY
READY timer expiryor
Force to STANDBYor
Abnormal RLC condition
PDU transmission
GPRS Attach
READY timer expiryor
Force to STANDBY
GPRS Detach
MM State Model of MS
IDLE
READY
STANDBY
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Major functions of GMM
General functions GPRS attachment: MM context is established; MM status is changed to rea
dy. GPRS detachment: MM context is deleted; MM status is changed to idle.
− Originated by MS or network side. Security function: authentication, encryption, identification check, etc. Location management:
− routing area updating
− periodical routing area
− cell updating Specific functions at the network side
GMM context clearing in cooperation with HLR Combined location updating and combined paging in cooperation with
MSC/VLR
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Cooperation between GMM and MM
Objectives
To improve the effective usage of wireless resources
To reduce the network signaling traffic
Pre-condition
SGSN and MSC/VLR support Gs interface
Functions
Combined IMSI/GPRS attachment
Combined IMSI/GPRS detachment
Combined routing area/location area updating (including periodical)
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Summary
GPRS System Structure
GPRS Network Interfaces & Protocols
GPRS Wireless Subsystem
GPRS Numbering
GPRS Mobility Management (GMM)
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