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www.huawei.com
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved.
GPRS EDGE Radio Interface
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page3
Contents
1. GPRS System Overview
2. GPRS Wireless Subsystem
3. GPRS Numbering and Region
4. GPRS Mobility Management
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page4
Circuit Switch (CS)
CS
F
CS
CS CS
CS
A
B
C
D
E
G
H
I
J
K
L
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page5
Packet Switch (PS)
PS
PS
PS
12
3
12
3
1
3
2
2
1 3
2
2
1 3
1 2 3
12
3
PS
PS
PS
PS
PS
PS
PS
12
3
12
3
1
3
2
2
1 3
2
2
1 3
1 2 3
12
3
PS
PS
PS
AC
B D
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page6
GSM Development Evolution
GSM 9.6 Kb/s
GPRS21.4 Kb/s
EGPRS59.2 Kb/s
384 Kb/s UMTS
2 G
2.5 G
2.75 G
3 G
HSCSD14.4 Kb/s
ECSD38.8 Kb/s
CS
PS
EDGE
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page7
What is GPRS?
Abbreviation of General Packet Radio Service GPRS is an end-to-end packet switching technology
provided on the basis of GSM technology GPRS reused the existent network of GSM GPRS provide efficient wireless resource utilization GPRS supports wireless access rate of up to 171.2Kbps Has a lot of interaction with the existing GSM circuit-
switched system GPRS based on standard opening interface
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page8
What is EDGE?
EDGE (Enhanced Data Rates for GSM Evolution) includes EGPRS (Enhanced GPRS)
EGPRS supports wireless access rate of up to
473.6Kbps. ECSD (Enhanced CSD, Enhanced HSCSD-High Speed
Circuit Switched Data) The introduction of EDGE fully taken into account the
original GSM network compatibility and inheritance, the
ECSD and EGPRS has little effect on the core network
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page9
Adjustments of Evolution from GSM to GPRS / EDGE network
BSS CS Core Network
A
PS Core Network
PCU
BSS NSS
Gb
Pb
Gs
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page10
GPRS System Structure
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
BG
GPRSbackbone GGSN X .25 TE
Gi
CGMS BSS
UmFR
Gb
SS7
GGSN
DNS
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page11
The Terminal of GPRS MS (Mobile Station) is the terminal of MT+TE or TE+TA. It can be as a
unit or two unit in physical.
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.
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page12
Modifications in BSS (GSM Evolves into GPRS)
Upgrade BSC software
Add new PCUUpgrade BTS software
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page13
Modifications in BSS (GSM /GPRS Evolves into EDGE)
Upgrade BSC software
Upgrade PCU software
Upgrade BTS software
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page14
1. GPRS System Overview
2. GPRS Wireless Subsystem
3. GPRS Numbering and Region
4. GPRS Mobility Management
Contents
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page15
Contents
2. GPRS Wireless Subsystem
2.1 Packet Channels
2.2 Coding Scheme
2.3 Medium Access Modes
2.4 MS Multi-TS Ability
2.5 Power Control
2.6 Paging Control Modes
2.7 Packet Access
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page16
Physical Channel The same as in GSM
The same frequency Common 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 The modulation mode
GPRS and GSM are modulated by GMSK
EGPRS is modulated by GMSK or 8PSK
Application
IP/X25
SNDCP
LLC
RLC RLC BSSGP
MAC MACFramerelay
PhysicalLayer
PhysicalLayer
PhysicalLayer
MS BSS
Relay
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page17
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,NCH
Packet service channel
PACCH
Packet Logic Channel
Packet control channel
PBCCH
PPCH PRACH PAGCH
PCCCH PDCCH
PDTCH/U PDTCH/D PNCH
PTCCH/U PTCCH/DSACCH
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page18
PDTCH (Packet Data Traffic CHannel)
PDTCH transmits the user data in the
mode of packet switching with a
transmission rate of 0~22.8kbit/s.
All packet data traffic channels are
uni-directional.
Uplink (PDTCH/U) used to
transmit the packet data from
the MS to the network of GPRS.
Downlink (PDTCH/D) used to
transmit the packet data from
the network of GPRS to the MS.
Packet service channel
PDTCH/U PDTCH/D
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page19
PBCCH (Packet Broadcast Control CHannel)
Packet control channel
PBCCH
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.
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page20
PCCCH (Packet Common Control CHannel) 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 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 several PDTCHs.
PNCH Downlink only, used to notify MS of PTM-M call.
PPCH PRACH PAGCH
PCCCH
PNCH
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page21
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
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page22
Combinations of Packet Logic Channel Mode 1: PBCCH+PCCCH+PDTCH+PACCH+PTCCH
Mode 2: PCCCH+PDTCH+PACCH+PTCCH 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 3: PDTCH+PACCH+PTCCH In case of small GPRS traffic, GPRS and circuit services share the
same BCCH and CCCH in the cell. In this case, only combination
mode 3 is needed in the cell
Mode 4: PBCCH+PCCCH
PCCCH=PPCH+PRACH+PAGCH+PNCH
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page23
Packet Channel Config. Principle
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. The initial mode of dynamic PDCH is TCH/F.
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page24
Packet Channel Config. Principles
General principles The cell should be configured with static PDCH to enable
MS to be normally attached 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 in the operation process according to the cell traffic
status. Circuit switching services can seize the channel used by
GPRS services.
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page25
Mapping of Packet Logic Channel
GPRS packet channels using 52 Multi-frame
structure, each group re-channel a total of 52
frames, each frame composed of four blocks of a
wireless (Radio Block), so a wireless radio channel is
divided into 12 blocks
I = Idle frame T = Frame used for PTCCH B0 ~ B11 = Radio blocks
51250
B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11T I T I
456 bits
0 1 2 3 4 5 6 7
1 TDMA frame
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page26
Mapping of Packet Logic Channel
51
4
3
5
6
7
0
1
2 B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11T I T I
500
BCCH
PDCH
TCH
S B B B B C C C C F S C C C C C C C C F S C C CC C C C C F S C C C C C C C C F S C C C C C C C C I
T T T T T T T T T T T S T T T T T T T T T T T T IT
F
25
2512
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page27
Allocation of Radio Packet Resources
Wireless resource allocation and wireless transmission adopt the wireless block
(BLOCK) as the basic 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
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page28
Allocation of Radio Packet Resources
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved.
USF: Uplink State Flag. Its field is three bits in length, rank is 0~7 The USF field is sent in all downlink RLC/MAC blocks and indicates
the owner or use of the next uplink Radio block on the same
timeslot
It is used to control many the MS with wireless channel under
dynamic allocation mode.
Page29
Basic Concepts about Radio Block
How does MS know which PDCH can be used and which wireless blocks on
that PDCH are available?
USF=1
USF=2
USF=3
USF=4
MS1
MS2
MS3
MS4
B11B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
T
I
T
I
UL
DL
USF=1 USF=1 USF=1 USF=2 USF=2 USF=3
USF=3 USF=3 USF=3 USF=4 USF=4 USF=4
T
I
T
I
USF=1
……
B0 I
……
……
UL /DL TimeslotSynchronized
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page30
Basic Concepts about Radio Block TBF (Temporary Block Flow)
A Temporary Block Flow (TBF) is a physical connection used by
the two RR entities( the RR entity of the MS and that of the
BSS) to support the unidirectional transfer of LLC PDUs on packet
data physical channels. The TBF is allocated radio resource on one or more PDCHs and
comprise a number of RLC/MAC blocks carrying one or more LLC
PDUs.
A TBF is temporary and is maintained only for the duration of the
data transfer. TFI (Temporary Flow Identity)
Each TBF is assigned a Temporary Flow Identity (TFI) by the network. The assigned TFI is unique among concurrent TBFs in each directions
and is used instead of the MS identity in the RLC/MAC layer. The same TFI value may be used concurrently for TBFs in opposite
directions.
The TFI field is five bits in length, rank id 0~31
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page31
RLC/MAC Block Generation
Subscriber data RLC/MAC headLLC headSNDCP head
Subscriber IP packet
LLC FCS
SNDCP PDU
LLC PDU
RLC/MAC block
Physical layer
B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10B11T I T I
NB NB NB NB
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page32
Contents
2. GPRS Wireless Subsystem
2.1 Packet Channels
2.2 Coding Scheme
2.3 Medium Access Modes
2.4 MS Multi-TS Ability
2.5 Power Control
2.6 Paging Control Modes
2.7 Packet Access
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page33
GPRS&EDGE Coding Scheme
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-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9
Kbps
GPRS
EGPRS
CS-2
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page34
GPRS and EDGE Share One Channel
If an EGPRS MS and a GPRS MS share one PDCH On this PDCH , the EGPRS MS can only use GMSK, that is
MCS-1 to MCS-4, while the EGPRS MS can still use 8PSK on
the PDCH where there is no GPRS MS USF must point to one of the following uplink radio block for
the commencement of the four uplink radio block Because of the synchronization, if GPRS MSs multipex on the
PDCH, there should appear a wireless block using GMSK at
least every 360ms in the downlink (standard GPRS or MCS-1
to MCS-4)
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page35
The system adjusts GPRS channel coding rate according to TBF retransmission rate and the conversion threshold.
The type of Uplink default CS type :CS2
CS1
CS4
CS3
CS2TBF re-transmission rate :2%
Uplink TBF from CS4 to CS3 re-transmission rate conversion threshold : 5
Uplink TBF from CS3 to CS2 re-transmission rate conversion threshold : 5
Uplink TBF from CS3 to CS4 re-transmission rate conversion threshold : 2
Uplink TBF from CS2 to CS3 re-transmission rate conversion threshold : 3
Uplink TBF from CS2 to CS1 re-transmission rate conversion threshold : 10
Uplink TBF from CS1to CS2 re-transmission rate conversion threshold : 5
GPRS Channel Coding Rate Adjustment
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page36
GPRS Channel Coding Rate Adjustment
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page37
The system adjust EGPRS channel coding rate basing on
BEP(Bit Error Probability). Each radio block contains four bursts, each burst has its
corresponding BEP value MEAN_BEP: mean value of the BEP of the channel
averaged over four bursts, range from 1 to 32, which
indicates the quality of the air interface is good or bad CV_BEP: variation co-efficient for the BEP averaged
over four bursts, range from 1 to 8, which indicates the
stability of the air interface quality.
EGPRS Channel Coding Rate Adjustment
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page38
BEP 8PSK_CV_BEP
1 2 3 4 5 6 7 8
8PSKMEANBEP
1 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5
2 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5
3 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5
4 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5
5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5
6 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-6
7 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-6 MCS-6
8 MCS-5 MCS-5 MCS-5 MCS-5 MCS-5 MCS-6 MCS-6 MCS-6
9 MCS-5 MCS-5 MCS-5 MCS-5 MCS-6 MCS-6 MCS-6 MCS-6
10 MCS-5 MCS-5 MCS-5 MCS-6 MCS-6 MCS-6 MCS-6 MCS-6
11 MCS-5 MCS-5 MCS-6 MCS-6 MCS-6 MCS-6 MCS-6 MCS-7
12 MCS-6 MCS-6 MCS-6 MCS-6 MCS-6 MCS-6 MCS-7 MCS-7
13 MCS-6 MCS-6 MCS-6 MCS-6 MCS-6 MCS-7 MCS-7 MCS-7
14 MCS-6 MCS-6 MCS-6 MCS-6 MCS-7 MCS-7 MCS-7 MCS-7
15 MCS-6 MCS-6 MCS-7 MCS-7 MCS-7 MCS-7 MCS-7 MCS-7
EGPRS Channel Coding Rate Adjustment
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page39
EGPRS Channel Coding Rate Adjustment
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page40
Contents
2. GPRS Wireless Subsystem
2.1 Packet Channels
2.2 Coding Scheme
2.3 Medium Access Modes
2.4 MS Multi-TS Ability
2.5 Power Control
2.6 Paging Control Modes
2.7 Packet Access
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page41
Medium Access Modes
Dynamic allocation (supported by all MSs and all networks) The mobile station detecting an assigned USF value for each
assigned PDCH and block or group of four blocks that it is allowed to
transmit on that PDCH.
Fixed allocation (supported by all MSs and all networks)
Fixed bit mapping is adopted to determine the allocated
blocks in the allocation period without an assigned USF.
Extended dynamic allocation (optional for the network)
The mobile station detecting an assigned USF value for any
assigned PDCH allowing the mobile station to transmit on
that PDCH and all higher numbered assigned PDCHs in the
same block or group of four blocks.
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page42
Contents
2. GPRS Wireless Subsystem
2.1 Packet Channels
2.2 Coding Scheme
2.3 Medium Access Modes
2.4 MS Multi-TS Ability
2.5 Power Control
2.6 Paging Control Modes
2.7 Packet Access
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page43
MS Multi-TS Ability
GPRS systems can take advantage of MAC-layer functionality for users
with a multi-TS works, but the MS response of the terminal must have a
way to support multi-TS the ability to work The type of MS multi-TS
Type 1: Non-simultaneous TRX(the ability of multi-TS:1 to 12,19 to
29) Type 2: Simultaneous TRX(TRX(the ability of multi-TS:13 to 18)
The level of MS multi-TS The multi-TS ability level is 1-29; bigger level, stronger multi-TS ability.
1~12 (Type 1),up to 4 timeslots in any direction 13~18 (Type 2),ranges between 3~8 timeslots 19~29 (Type 1)
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page44
Multi-TS level of MS
Multi-TS
level
Maximum number of slots
TypeRx Tx Sum
1 1 1 2 1
2 2 1 3 1
4 3 1 4 1
8 4 1 5 1
10 4 2 5 1
11 4 3 5 1
29 8 8 NA 1
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page45
Contents
2. GPRS Wireless Subsystem
2.1 Packet Channels
2.2 Coding Scheme
2.3 Medium Access Modes
2.4 MS Multi-TS Ability
2.5 Power Control
2.6 Paging Control Modes
2.7 Packet Access
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page46
Power Control
Power control can improve the spectrum usage and system
capacity as well as reduce MS power consumption. As there is no continuous bi-directional connection in the
packet data transmission 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 lies on the BTS and its algorithm
needs information about downlink, so downlink power
control needs MS sends channel quality reports to BTS.
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page47
Contents
2. GPRS Wireless Subsystem
2.1 Packet Channels
2.2 Coding Scheme
2.3 Medium Access Modes
2.4 MS Multi-TS Ability
2.5 Power Control
2.6 Paging Control Modes
2.7 Packet Access
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page48
Paging In the GPRS system, including packet paging and paging co-ordination
Packet paging When there are downlink data to be transmitted to the MS, packet
paging will be triggered by SGSN to accurately locate the MS If the PCCCH is configured in a cell, paging message is sent via
PPCH, otherwise via PCH Paging co-ordination
Paging Co-ordination means to send circuit-switched paging
message by packet-switched channel. MS access the network via RACH after receiving the paging
message, start circuit connection establishment process, while MS
will launch GPRS SUSPEND process to hang on the GPRS service.
Once the circuit connection releases, MS will resumes GPRS services
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page49
Network Control Modes Networ
k control mode
Circuit Paging Channel
GPRS Paging Channel
Paging co-ordination
I
PPCH PPCH The paging coordination function should be used in Gs interface. CS paging and PS paging are sent via the same paging channel .MS only monitors one paging channel (If PCCCH is configured, paging message is sent via PPCH). If the MS is in packet transfer mode, the CS paging can be sent via PACCH
PCH PCH
PACCH NA
II PCH PCH
No paging coordination function.
CS paging and GPRS paging adopt PCH.
MS only monitors CCCH paging channel.
III
PCH PPCHNo paging coordination function.
CS paging is sent on PCHl; GPRS paging is sent on the PPCH (if configured) or CCCH paging channel.
MS should monitor CCCH paging channel and the packet paging channel.
PCH PCH
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page50
Paging Modes for Different Types of MS in Packet Mode
MS types Packet idle Packet transmission
Class APaging message is delivered via either PPCH (if configured) or CCCH channel
Paging message is delivered via either PACCH or the CCCH
Class B PACCH
Class C
In the GPRS attach, either in idle mode or in packet transfer mode, CS paging can not be delivered, at this time, Class C MS is unavailable for non-GPRS services.
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page51
Contents
2. GPRS Wireless Subsystem
2.1 Packet Channels
2.2 Coding Scheme
2.3 Medium Access Modes
2.4 MS Multi-TS Ability
2.5 Power Control
2.6 Paging Control Modes
2.7 Packet Access
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page52
Packet Access Modes
When upper layer of a MS need to send data, packet access will
be triggered on RLC/ MAC layer Packet Access Modes of MS includes
Short access when the data transmitted are less than 8 RLC blocks
one phase access, two phase access More than 8 RLC data blocks and in RLC ACK mode
Single block without TBF establishment MS to send a measurement report
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page53
The Difference between Different Access Modes
For the short-access and one phase access Radio resources shall be assigned for the MS on the first
phase (for example, TFI, dynamic allocation of USF or fixed
allocation of radio block bit table, etc.) For the two phase access
The first phase, PCU only assigned a radio block for the MS,
MS transmit PACKET RESOURCE REQUEST message in this
assigned radio block The second phase, PCU assign the resource to the MS
(including the TFI, USF or radio block bit table), MS began to
transmit data via the assigned resources
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page54
1. GPRS System Overview
2. GPRS Wireless Subsystem
3. GPRS Numbering and Region
4. GPRS Mobility Management
Contents
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page55
IMSI
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“ MSIN: the MS unique identifier within a PLMN NMSI: the MS unique identifier within a country
Not more than 15 digits
3 digits 2 digits
MCC MNC MSIN
NMSI
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page56
P-TMSI
P-TMSI: attached to the GPRS users ,it will be assigned a
P-TMSI for packet call by the SGSN P-TMSI is only meaningful in a routing area, when the MS’s
routing area is changed,the P-TMSI reallocation procedure
need to be implemented SGSN must be combined P-TMSI and the IMSI ,a mobile
station can be seen as the distribution of the two identity
which are assigned
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page57
GPRS LAC
CELL1
CELL2
CELL1
CELL3
RAC1
RAC2
CELL1
CELL4
RAC3
CELL2
CELL2
CELL3
LAC1 LAC2
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page58
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, which is a fixed length code (of 2
octets) identifying a location area within a GSM PLMN except for
the reserved hexadecimal values 0000, and FFFE
For example: 460008C90
Location Area Identification
MCC MNC LAC
LAI
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved. Page59
RAI Routing area is the sub-set of the location area. In special cases, this
two areas are equal A routing area is controlled by a SGSN The routing area message is a system massage, it will be board on
public control channel
Routing Area Code (RAC) which is a fixed length code (of 1 octets) identifying a routing area within a location area
Location Area Identification
MCC MNC LAC RAC
Routing Area Identification
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CGI/CellID CGI is the unique identifier for one cell in GSM PLMN, including LAI and
CI. If this cell supports GPRS, CGI contains RAC, otherwise, CGI does not
contain the RAC
CGI = LAI + CI
CellID=MCC+MNC+LAC+RAC+CI Such as:4600017A70928FD
Location Area Identification
MCC MNC LAC CI
CGI / Cell ID
RAC
Routing Area Identification
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CGI
Relationship among Location Areas
LAI MCC+ MNC+ LAC
RAI
MCC+ MNC+ LAC+RAC
CGI /CellID
MCC+ MNC+ LAC+{RAC}+CI
LAI
RAI
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Contents
1. GPRS System Overview
2. GPRS Wireless Subsystem
3. GPRS Numbering and Region
4. GPRS Mobility Management
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MM Concepts
The mobility management functions are
used to keep track of the current location
of an MS within the PLMN or within another
PLMN. Mobility management entities
MS SGSN HLR
GMM context It stands for mobility management context. It is an internal and mobility-based database
of the GPRS MS and the SGSN.
IMSI
GMM state
P-TMSI
MSISDN
routing area
cell identity
current SGSN address
VLR Num (MS only)
……
GMM context
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MM State
IDLE GMM context is not established; MS is not reachable.
MS can implement data transmission.
GMM context is established; MS can receive paging but
cannot implement data transmission.
The MS performs MM procedures to provide the network with the
actual selected cell. SGSN performs the MM on cell level.
READY
STANDBY
The location information in the SGSN MM context contains only the
GPRS RAI. Pages for data or signalling information transfers may be received. It
is also possible to receive pages for the CS services via the SGSN.
Data reception and transmission are not possible in this state.
Data transmission to and from the mobile subscriber as well as the
paging of the subscriber are not possible
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GMM State Model
IDLE READY STANDBY
IDLE READY STANDBY
MM State Model of MS
MM State Model of SGSN
GPRS Attach
GPRS Detach
READY timer expiry or
PDU transmission
PDU reception
Implicit Detach or Cancel Location
GPRS Attach
Force to STANDBY
READY timer expiry orForce to STANDBY or
Abnormal RLC condition
GPRS Detach or Cancel Location
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Major Functions of GMM Specific functions
GPRS attachment MM context is established; MM status is changed to ready.
GPRS detachment MM context is deleted; MM status is changed to idle.
Location management Cell updating ,Routing area updating ,Periodical routing area,
Location updating, Combined routing updating and location
updating Security function: identification check, etc
Authentication, encryption P-TMSI assignment Use data and GMM/SM signal ciphering
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GPRS Attach
GPRS attach includes: Normal GPRS attach, which enable the IMSI to be
attached to GPRS service Combined GPRS attach, which enable the IMSI to
be attached to GPRS services and non-GPRS
service
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GPRS Detach GPRS detach function enables the MS to initiate GPRS detach and IMSI
detach. In addition, it also allows the network to initiate MS detach and
IMSI detach. It includes:
IMSI detachment GPRS detachment Combined GPRS / IMSI detach (can only be initiated by the MS)
GPRS detach may be explicit detach or implicit detach Explicit detach, the network or the MS will send an explicit detach
request implicit detach, when reachable timer of the MS expires, or serious
radio link connection error occurs, the network will initiate the detach
procedure without notifying the MS GPRS detach can be initiated by both the MS and the network
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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 attach and Combined IMSI/GPRS
detach Combined routing area/location area updating (including
periodical)
MSC/VLR
Gs
SGSN
BSCPCU
TRAU
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