HUAWEI EQUIPMENT INSTALLATION

Χηαπτερ 1 GPRS Fundamentals1.1 GPRS Overview The General Packet Radio Service GPRS allows GSM subscribers access to datacommunication applications such as e-mail, and Internet using thei

GPRS Fundamentals

ISSUE 1.0

Table of Contents

Chapter 1 GPRS Fundamentals 1

1.1 GPRS Overview 1

1.2 Evolution of GPRS Standards and Services 1

1.3 Comparison Between GPRS and HSCSD 2

1.4 EDGE Overview 2

1.5 Advantages and Disadvantages of the GPRS 2

Chapter 2 GPRS Network Architecture 4

2.1 Overall GPRS Structure 4

2.2 Logical System Architecture of the GPRS 5

2.3 Major Network Entities of GPRS 5

Chapter 3 GPRS Protocol Layers 9

3.1 GPRS Data Transmission Plane 9

3.2 GPRS Signaling Plane 10

3.3 GPRS Network Interface Protocols 12

3.3.1 Um Interface 12

3.3.2 Gb Interface 17

3.3.3 Gs Interface 19

3.3.4 Gn/Gp Interface 19

3.3.5 Gi Interface 21

3.3.6 Gr Interface 21

3.3.7 Gd Interface 21

3.3.8 Gc Interface 21

3.3.9 Gf Interface 21

Chapter 4 GPRS Radio Subsystem 22

4.1 GPRS Radio Interface Channels 22

4.2 Channel Coding 24

4.2.2 Channel Coding of GPRS PDTCH 24

4.2.3 Channel Coding of EGPRS PDTCH 26

4.2.4 Channel Coding for PACCH, PBCCH, PAGCH, PPCH, PNCH and PTCCH/D 33

4.2.5 Channel Coding for the PRACH 33

4.3 Media Access Control Mode 34

4.4 Multislot Capability of MS 34

4.4.1 Multislot Configuration 34

4.4.2 MS Classes for Multislot Capability 34

4.5 Power Control 37

4.6 Paging Handling 37

4.6.1 Packet Paging 37

4.6.2 Paging Co-ordination 38

4.6.3 Network Operation Modes 38

4.7 Packet Access Modes 39

4.8 GPRS Cell Selection and Reselection 40

4.8.1 Relationship Between GPRS Cell Selection and GSM Cell Selection 40

4.8.2 Relationship Between GPRS Cell Reselection and GSM Cell Reselection 40

4.8.3 Network Control Modes 40

Chapter 5 GPRS Contents and Quality 42

5.1 Bearer Services 42

5.2 GPRS Supplementary Services 43

5.3 Applications of GPRS Services 43

5.4 Relations Between GPRS Network and Circuit Switching Service 44

5.5 GPRS Service Quality 45

Confidential Information of Huawei No Spreading without Permission

Chapter 6 GPRS Numbering Plan and Functions 49

6.1 IMSI 49

6.2 P-TMSI 50

6.3 NSAPI/TLLI 50

6.4 PDP Address and Type 51

6.5 Tunnel Identifier (TID) 51

6.6 Routing Area Identifier (RAI) 51

6.7 Cell Identifier 52

6.8 GSN Address and Numbering 52

6.9 Access Point Name (APN) 52

Chapter 7 GPRS Entity Information Storage 53

7.1 HLR 53

7.2 MS 54

7.3 GGSN 54

7.4 SGSN 55

Chapter 8 GPRS Mobility Management Flow 57

8.1 Overview 57

8.2 MM Status and MM Context 57

8.3 GPRS Attach/Detach 60

8.3.1 GPRS Attach 60

8.3.2 GPRS Detach 60

8.4 GPRS Location Management Function 60

8.4.1 Cell Updating Procedure 61

8.4.2 Routing Area Updating Procedure 61

8.4.3 Periodical RA/LA Updating Procedure 62

8.4.4 User Data Management Procedure 62

8.4.5 MS Class Mark Processing Function 62

8.5 Security Management 63

8.5.1 GPRS Authentication and Encryption 63

8.5.2 P-TMSI Reallocation 63

8.5.3 User Data and GMM/SM Signaling Privacy 63

Chapter 9 GPRS PDU Transmission 65

Appendix Frame Relay 67

A.1 Frame Relay Concept 67

A.2 Frame Relay Structure 68

A.3 Frame Relay Working Principle 68

A.4 Congestion Control 69

A.5 Frame Relay Technical Feature 70

A.6 FR Application on GPRS Gb Interface 71

Χηαπτερ 1 GPRS Fundamentals

1.1 GPRS Overview

The General Packet Radio Service (GPRS) allows GSM subscribers access to datacommunication applications such as e-mail, and Internet using their mobile phones.The GPRS introduces the packet switching and transmission capabilities to theexisting GSM network As one of the contents implemented by GSM Phase2.1standard, the GPRS offers higher data rate than the 9.6 kbit/s of existing GSMnetwork By utilizing the same frequency band, band width, burst structure, radiomodulation standards, frequency hopping rule and TDMA frame structure as theGSM, the GPRS features the following:

 High resource utilization

 Always online and always connected

 High transmission rate

 Reasonable cost

1.2 Evolution of GPRS Standards and Services

As the second generation of digital mobile cellular communication system, the GSMhas found wide application across the world But with the development of mobilecommunication technologies and service diversification, the demand for data service

is continually on the rise To address this demand, the GSM, primarily supporting thevoice service, proposes two types of high-speed data service models in PHASE2 andPHASE2+ specifications, that is, the High Speed Circuit Switched Data (HSCSD)based on high-speed data bit rate and circuit switching, and the GPRS based onpacket switching

Early in 1993, operators in Europe have taken the lead in proposing the concept ofdeploying the GPRS over the GSM network In 1997, great progress has been made

on the GPRS standardization In October of the same year, the ETSI released theGSM02.60 GPRS Phase1 service description By the end of 1999, the GPRS Phase2was finalized

The GPRS standards contain three phases, during which 18 new standards areestablished and dozens of existing standards revised to implement the GPRS Table1.1 lists the three phases of the GPRS standards:

Table 1.1 Three phases of GPRS standards

02.60 service

description

03.60 system description and network structure

04.60 RLC/MAC protocol

01.61 encryption requirement; SAGE algorithm; lawful interception.

03.20 security 03.22 idle mode program 04.04–07 GPRS system and time schedule information 04.08: MAC, RLC and layer-

3 mobility management

　 03.64 radio interfacedescription 04.61 PTM-M service

03.61 multipoint-broadcast service 04.62 PTM-G service　 03.62 point-to-multipoint group call 04.64 LLC

point-to-04.65SNDCP

Phase 1 Phase 2 Phase 3 Major revised standards

05 series: Radio interface physical layer

08.58&08.60: Abis interface and TRAU frame structure change

09.02: Add the Gr and Gd protocols

11.10: TBR-19 MS test 11.2X BSS test 11.11 SIM 12.XX O&M

3) Technical advantages of the GPRS

By introducing the packet-switched transmission mode, the GPRS brings radicalchanges to the original circuit-switched-based GSM data transmission and featuresthe following:

 High resource utilization

In the circuit-switched mode, an MS connected to the system shall occupy a radiochannel even if there is no data transmission In the packet-switched mode, an MSonly occupies radio resource during data transmitting or receiving This meansseveral MSs can share the same radio channel, enhancing the resource utilization

 High transmission rate

The GPRS provides a transmission rate up to 115 kbit/s (maximum rate: 171.2 kbit/s,excluding the FEC) The circuit-switched data service rate is only 9.6 kbit/s TheGPRS users can quickly access Internet and browse web pages with portablecomputers as the ISDN users, and make possible the transmission-rate-sensitivemobile multimedia applications

 Short access time

The access time of packet switching is less than one second, greatly enhancing theefficiency of processing some transactions (for example, credit card check andremote monitoring) It also enables convenient and smooth Internet applications (forexample, E-mail and Internet access)

4) Disadvantages of the GPRS

Though the GPRS dramatically enhances the spectrum utilization in comparison withthe existing non-voice data service, yet it still cannot get rid of the followingdisadvantages:

 Actual transmission rate is lower than the theoretical one:

To reach the theoretical transmission rate of 171.2 Kbps, a subscriber shall occupythe whole 8 TSs without any error protection program In practice, it is impossible for

a single GPRS subscriber to occupy all TSs In addition, there are constraints on the

TS support capability of the GPRS terminals Therefore, the theoretical maximum rateneeds re-proving by taking account of the practical environmental constraints

 The terminal does not support the wireless termination function

After a subscriber confirms the volume-based charging for the service contents whenenabling the GPRS, the subscriber has to pay for undesired spam contents Whetherthe GPRS terminal supports the wireless termination threatens the application andmarket exploration of the GPRS

 The modulation is not optimal

The GPRS adopts the GMSK modulation mode The EDGE employs a newmodulation mode eight-phase-shift keying (8 PSK), and allows higher bit rate on theradio interface The 8 PSK modulation is also used in the UMTS

 Transmission delay:

The GPRS packet switching technology transmits data in different directions but to reach the same destination, so the data of one or several packets may be lost during the radio link transmission

Χηαπτερ 2 GPRS Network Architecture

2.1 Overall GPRS Structure

When constructing the GPRS on the existing GSM network, you only need to performsoftware upgrade for most of the parts on the GSM network instead of hardwarechanges To build the GPRS system, you need to:

 Introduce 3 major components to the GSM network:

5) Serving GPRS Supporting Node (SGSN)

6) Gateway GPRS Support Node (GGSN)

7) Packet Control Unit (PCU)

 Perform software upgrade of related components of the GSM network

Figure 1.1 shows the GPRS network architecture:

Circuit-switched service path

Internet X.25 Packet-switched

service path

Other GPRS networks

GPRS network

GTP

Figure 1.1 GPRS network architecture

As shown in the above figure, the portable computer connects to the GPRS cellularphone through serial or radio mode

The GPRS cellular phone communicates with the BTS Different from the switched data calls, the GPRS packets are transmitted from the BTS to the SGSNinstead of being transmitted to the voice network through the MSC

circuit-The SGSN communicates with the GGSN

The GGSN handles the packet data before transmitting them to the destinationnetwork, for example, the Internet or X.25 network

Upon receiving the IP packets from the Internet with the MS address, the GGSNforwards them to the SGSN which then transmits the packets to the MS

2.2 Logical System Architecture of the GPRS

The GPRS is implemented by adding two nodes SGSN and GGSN and the PCU tothe GSM network New interfaces shall be defined after these network nodes areadded Figure 1.1 shows the logical system architecture of the GPRS

Figure 1.1 Logical system architecture of the GPRS

Table 1.1 lists the interfaces defined in the GPRS network architecture

Table 1.1 List of interfaces defined in the GPRS network architecture

R The reference point between the Mobile Terminal (MT) (for example, mobile phone) and the Terminal Equipment (TE) (for example, the portable

computer)

Gb The interface between the SGSN and BSS

Gc The interface between the GGSN and HLR

Gd The interface between SMS and GMSC; the interface between SMS-IWMSC and SGSN

Gi The interface between the GPRS and external packet data

Gn The interface between SGSNs and between SGSN and GGSN in the PLMN

Gp The interface between GSNs of different PLMNs

Gr The interface between the SGSN and HLR

Gs The interface between the SGSN and MSC/VLR

Gf The interface between the SGSN and EIR

Um The interface between MS and GPRS network side

2.3 Major Network Entities of GPRS

The major network entities of the GPRS include the GPRS MS, PCU, GPRS SupportNode (GSN), Charging Gateway (CG), Border Gateway (BG), Domain Name Server(DNS), and Remote Authentication Dial-In User Service (RADIUS) server

8) GPRS MS

The GPRS MS consists of the TE and MT The MS is actually an integrated MT afterthe TE functions are integrated into the MT.

The TE, used to transmit and receive the packet data of the end user, refers to thecomputer operated and used by the end user The TE can either be a stand-alonedesktop computer, or integrated with the handset MT In a sense, the GPRS networkprovides all functions for the sake of establishing a path between the TE and externaldata network to transmit packet data

The MS can be regarded as the device that integrates the functions of both MT and

TE It can either be an independent entity or two entities (TE + MT) The MS can beclassified into the following three categories based on the capabilities of the MS andnetwork:

Class-A GPRS MS: The Class-A MSs can attach to the GSM and GPRS networksimultaneously, activate and receive system messages from two systems, andimplement Packet Switched Service (PS) and Circuit Switched Service (CS)concurrently

Class-B GPRS MS: The Class-B MSs are similar to Class A MSs with the exceptionthat Class-B MSs will not support simultaneous traffic

If there is a circuit-switched call incoming to a Class-B MS, the MSC/VLR sends a

“Suspend” message to the SGSN Upon receiving the “Suspend” message, theSGSN suspends (temporarily terminates) the GPRS connection After the circuitswitching, the MSC/VLR then sends a “Restore” message to the SGSN to restore theGPRS connection

Class-C GPRS MS: The Class-C GPRS MSs cannot attach to the GPRS and GSMnetworks concurrently, and they only support manual switching between the PS andCS

9) Packet Control Unit (PCU)

As a processing unit added on the BSS side, the PCU implements the PS processing

on the BSS side and management of packet radio channel resources Currently thePCU networking structure includes the following three types: A Integrated into theBTS; B Integrated into the BSC; C Independently configured, as shown in Figure1.1 Huawei GPRS adopts the type C networking mode

CCU CCU PCU

A

Gb Um

PCU

C Abis

be classified into the following two types: SGSN and GGSN

The SGSN is the node that provides services for the MS (that is, the Gb interface issupported by the SGSN)

The SGSN establishes a mobility management environment, containing the mobilityand security information of the MS, when the GPRS is activated The SGSN recordscurrent location information of the MS, and transmits and receives packet databetween the MS and SGSN The SGSN can transmit location information to andreceive the paging request from the MSC/VLR over any Gs interface

The GGSN is the gateway for the GPRS network to connect with external PDN

It may connect with different data networks, for example, ISDN and LAN The GGSN

is also known as the GPRS router The GGSN can implement protocol translation forthe GPRS packet data packets in the GSM network, and then transmit them to theremote TCP/IP or X.25 network The GGSN can be accessed by the Packet DataNetwork (PDN) through configuration of a PDP address It stores the routinginformation of the GPRS subscriber, and transmits the PDU to current Service AccessPoint (SAP) of the MS, that is, the SGSN, by utilizing the tunnel technology TheGGSN can query current address information of the subscriber from the HLR over the

Gc interface

The functions of both SGSN and GGSN can either by integrated into one physicalnode or implemented on different nodes They both shall support the IP routingfunction and can connect with the IP router When the SGSN and GGSN are located

in different PLMNs, they are interconnected over the Gp interface

11) Charging Gateway (CG)

The CG implements the collection, combination and pre-processing of the bills fromthe GSNs and provides communication interface to network with the billing center.Originally there is no CG in the GSM network The bill for Internet access of a GPRS

subscriber will be generated from multiple NEs, and moreover, each NE maygenerate a lot of bills The CG is thus introduced to combine and pre-process billsbefore they are sent to the billing center so as to relieve the load on the billing center.

In addition, NEs such as SGSN and GGSN do not have to interface with the billingcenter after the CG is configured

12) Border Gateway (BG)

The BG acts as a router to implement routing between SGSN and GGSN of differentGPRS networks as well as security management The BG is not a proprietary entity ofthe GPRS network

13) Domain Name Server (DNS)

The following two types of DNSs may be adopted in the GPRS network:

 The DNS between the GGSN and external networks: Implements resolution ofthe domain name of external network, and functions as the ordinary DNS on theInternet

 The DNS on the GPRS backbone network: Provides two types of functions: a.Resolve the GGSN IP address based on the Access Point Name (APN) in theprocess of the PDP context activation; b Resolve original GGSN IP addressbased on the original routing area No in the process of the update of inter-SGSNrouting area The DNS is not a proprietary entity of the GPRS network

14) RADIUS server

The RADIUS server stores the authentication and authorization information ofsubscribers It also performs subscriber identity authentication in the case of non-transparent access The RADIUS server is not a proprietary entity of the GPRSnetwork

Χηαπτερ 3 GPRS Protocol Layers

The GPRS adds new features of packet switching and transmission to the GSMnetwork, that is, the data and signaling are based on a uniform plane The protocolstructures below the LLC layer are the same for the data and signaling The protocolstructures for the data and signaling are only the same on the physical layer on theGSM network

3.1 GPRS Data Transmission Plane

The GPRS data and signaling plane enables the transmission of subscriberinformation and consists of standard protocols such as IP and some new, GPRS-specific protocols including GTP, LLC, RLC and so on

Relay

Network Service

SNDCP LLC BSSGP

L1bis

RLC MAC GSM RF

BSSGP

L1bis

Relay

L2 L1

IP

L2 L1 IP

UDP / TCP

UDP / TCP

Figure 1.1 GPRS data transmission plane

The functional entities are described as follows:

1) GSM RF: The physical layer, the RF interfaces, enables data transmission over

Um interface, while the LLC provides various logical channels for Um interface.The carrier bandwidth of the GSM Um interface is 200kHz, and a carrier isdivided into 8 physical channels

2) RLC/MAC: Provides RLC and MAC functions The RLC layer supports theacknowledged and unacknowledged transmission between the MS and BSS,and provides a reliable link independent of the radio solution The MAC layerdefines and allocates the GPRS logical channels of the Um interface so that theycan be shared among MSs The MAC also maps the LLC frames into thephysical channel of the GSM The RLC/MAC is standardized in the GSM04.60.3) SNDCP: Implements such functions as segmentation and compression ofsubscriber data The SNDCP is defined in the GSM04.65

4) LLC: Provides end-to-end reliable error-free logical data links Based on theHigh-level Data Link Control, the LLC provides highly reliable encrypted logicallinks The LLC builds the LLC address and frame field on the SNDC data unitfrom the SNDC layer to generate the complete LLC frame In addition, the LLCcan implement point-to-multipoint addressing and data frame retransmissioncontrol, and support several types of QoS delay registration The LLC isstandardized in the GSM04.64

5) Base Station System Application GPRS Protocol (BSSGP) layer: Contains the

functions of the network layer and partial functions of the transport layer, andinterprets the routing and QoS information The BSSGP is standardized in theGSM08.18.

6) Network Service: The data link layer protocol adopts the frame relay mode The

NS is standardized in the GSM08.16

7) L1: Physical layer

8) L2: Data link layer protocol The common Ethernet protocols can be adopted.9) IP: Network layer protocol, used for routing of subscriber data and controlsignaling

10) UDP/TCP: Transport layer protocol The UDP/TCP is used to set up the end reliable link The connection-oriented TCP features the protection and trafficcontrol functions to ensure accurate data transmission As the non-connection-oriented protocol, the UDP provides no error recovery capability and only acts asthe transmitter/receiver of datagram without concerning whether packets arecorrectly received

end-to-11) GPRS Tunnel Protocol (GTP): The GTP transmits the packet data by utilizing thetunnel established between GSNs The GTP is standardized in the GSM09.60

3.2 GPRS Signaling Plane

The signaling protocol plane describes the signaling transmission layers, andcontains the protocols used to control and support the transmission plane Thesignaling protocol plane can be classified into the following seven types, as shownfrom Figure 1.2 to Figure 1.7

Table 1.1 Functions implemented on the signaling planes

SGSN-MSC/VLR

Adopt the Base Station System Application+ (BSSAP+) to implement joint mobility management and paging functions, and use the SS7 to transmit data packets

GSN-GSN

Adopt the GTP to transmit related signaling message of the backbone network, and use the lower layer UDP to provide unacknowledged transmission Specify the tunnel mechanism and management protocol requirements for the MS to access the GPRS network The signaling implements such functions as establishing, modifying and deleting tunnels

GGSN-HLR

Generally there are two signaling path implementation methods: If the SS7 interface is installed on the GGSN, adopt the MAP-based GGSN-HLR signaling; if the SS7 interface is not installed on the GGSN, any GSN with the SS7 interface and in the same PLMN as the GGSN can be used as GTP-to-MAP translator, and the GTP- based GGSN-HLR signaling is adopted

Figure 1.2 MS-SGSN-GGSN signaling protocol plane

Figure 1.3 Signaling plane between SGSN and HLR, EIR, and SMS-GMSC/ SMS-IWMSC

Figure 1.4 Signaling plane between SGSN and MSC/VLR

Figure 1.5 Signaling plane between GSNs

Figure 1.6 MAP-based signaling plane between GGSN and HLR

Figure 1.7 GTP-based signaling plane between GGSN and HLR

3.3 GPRS Network Interface Protocols

3.3.1 Um Interface

Figure 1.1 GPRS MS-network reference module shows the Um interface of theGPRS The communication between the MS and network involves the RF, PhysicalLink, RLC/MAC, LLC and SNDCP layers

SNDCP LLC RLC MAC

Physical link

Physical RF

Um

SNDCP LLC RLC MAC

Physical link

Physical RF

Defined in GSM0465 Defined in GSM0464

Defined in GSM0460

Defined in GSM0364

Network MS

Figure 1.1 GPRS MS-network reference module

I Physical layer

The physical layer consists of the physical RF and physical link sub-layers Thephysical RF layer modulates and demodulates the physical waveform It modulatesthe bit sequence received at the physical link layer into waveform, or demodulates thereceived waveform into the bit sequence required at the physical link layer

Defined by the GSM05 series specifications, the physical RF layer contains thefollowing contents: Carrier frequency features and GSM channel structure;modulation mode of transmitting waveform and data rate of GSM channel; featuresand requirements of the transmitter and receiver

The physical link layer provides the information transmission services on the physicalchannel between the MS and network

 Forward Error Correction (FEC) coding; detecting and correcting transmittedcode words and providing indication of error code words; block interleaving;performing quadrature interleaving on the four consecutive burst TDMA frames

 Radio channel measurement: Includes receive signal quality and level,measurement time advance, and physical link layer congestion detection

 Wireless management: Includes cell selection and reselection, power control oftransmitter, and battery power management, for example, the DiscontinuousReception (DRX) process

2 Data link layer

The data link layer contains the RLC and MAC layers

1) MAC layer

The MAC layer defines the process that several MSs share the transmission media(that is, PDCH) It also provides the MS contention arbitration and conflict avoidance,detection and recovery methods on the uplink The contention arbitration is notrequired for the downlink transmission from network to several MSs The MAC layerfunctions also allow a single MS to concurrently use several physical channels.The MAC layer of the GPRS provides the following functions:

 Provide highly efficient data and signaling multiplexing on the uplink anddownlink, and leave the multiplexing control to the network side On thedownlink, the multiplexing is controlled based on the scheduling mechanism; onthe uplink, the multiplexing is controlled by allocating media to a single user

 For the mobile-initiated channel access, the MAC layer performs contentionarbitration for channel access attempts, including conflict detection and recovery

 For the mobile-terminated channel access, the MAC layer allocate resources bythe sequential access attempts

The RLC layer implements the assembly and disassembly of the LLC-PDU packets,and transmits data between peer layers over the sliding window protocol by adoptingthe acknowledged or non-acknowledged mode The size of the RLC sliding window is

64 Huawei PCU supports the acknowledged and non-acknowledged modes of theRLC layer It can specify the RLC modes of the uplink and downlink data transmissionbased on the MS requests and downlink LLC-PDU packet type respectively If theacknowledged mode is adopted, each transmitted data block of the Temporary BlockFlow (TBF) must be acknowledged by the peer; otherwise re-transmission is required

The TBF is released after all data are transmitted and acknowledged by the peer Ifthe non-acknowledged mode is adopted, the transmitted data blocks do not have to

be acknowledged by the peer, and the lost or incorrectly transmitted data blocks arereplaced with the fill bits The TBF is released after the data transmission is complete.3) RLC/MAC radio block structure:

The radio block is the basic unit for radio transmission and allocation of radioresources The RLC/MAC block consists of the MAC header, and RLC data block (orRLC/MAC control block) and generally contains four normal bursts Each radio blockconsists of four consecutive TDMA frames The transmission data and controlinformation have different radio block structures, as shown in the following figure:

Radio block

RLC data

Radio blockRLC data block

RLC/MAC control information

RLC/MAC control block

MAC header

MAC header

RLC header



Figure 2.1 Radio block structures

The control block is uniformly called the “RLC/MAC control block” because it containsthe resource allocation information (handled at the MAC layer) and protocolACK/NACK information (handled at the RLC layer)

3 LLC layer

LLC: Transport layer protocol Based on the High-level Data Link Control, the LLCprovides highly reliable encrypted logical links The LLC builds the LLC address andframe field on the SNDC data unit from the SNDC layer to generate the complete LLCframe In addition, the LLC can implement point-to-multipoint addressing and dataframe retransmission control, and support several types of QoS delay registration.The LLC is standardized in the GSM04.64 Figure 3.1 shows the function model ofthe LLC layer

SGSN

MS

GPRS Mobility Management

Logical Link Management Entity

RLC/MAC

Logical Link Entity SAPI=11

Logical Link Entity SAPI=9

Logical Link Entity SAPI=5

Logical Link Entity SAPI=3

Logical Link Entity SAPI=1

GRR LLGMM

RLC/MAC layer LLC layer

Layer 3 LLC layer

BSSGP

BSSGP

BSSGP layer

Signalling Signalling and data transfer

Figure 3.1 Function model of the LLC layer

The layer-3 users can adopt the SubNetwork Dependent Convergence Protocol(SNDCP), GMM/SM and SMS services The LLC provides logical links for theseservices

The LLC frame structure is shown as follows:

Figure 3.2 LLC frame structure

The PD (protocol indication bit) indicates whether current frame is an LLC frame orinvalid frame The C/R (command/response bit) indicates whether current frame is acommand or response frame The Service Access Point Identity (SAPI) contains 4bits and 16 values Currently only 6 values are adopted The above figure shows theservices in relation to the 6 values

The “RLC Data Transmission Performance Measurement” and “LLC DataTransmission Performance Measurement” in Huawei GPRS traffic measurementreflect the transmission features of the LLC layer

4 SNDCP

The SNDCP is located between the network layer and LLC layer It supports variousnetwork layers which share the same SNDCP Therefore, the multivariate data fromdifferent data sources can pass the LLC layer

The SNDC implements the following functions:

 Map the SNDC primitive from the network layer to the LLC primitive of the LLClayer, or vice versa

 Multiplex the N-PDUs from one or several NSAPIs into one LLC SAPI byadopting the multichannel technology

 Compress the redundant control information and subscriber data

 Segmentation and reassembling

Figure 4.1 shows the transmission platform of the SNDCP and LLC layers

Figure 4.1 SNDCP and LLC layer protocol platform

The SNDCP adopts the services provided by the LLC layer to multiplex the transmitted data from different sources The Network layer Service Access PointIdentifier (NSAPI) is the index of the PDP context The PDP employs the servicesprovided by the SNDCP layer The PDP of the same type may have several PDPcontexts and NSAPIs Several different PDPs may adopt the same NSAPI, as shown

1) Physical layer protocol L1

The several physical layer configurations and protocols defined in GSM 08.14 areavailable here The physical resources shall be configured through the Operation andMaintenance (O&M) process

2) FR (NS layer subnet service protocol)

The Frame Relay (FR) sub-layer of the Gb interface belongs to the NS Sub-NetworkService protocol The FR module enables the interworking of sub-network so that thePCU may connect to the SGSN through point-to-point connection or the frame relay

network The point-to-point connection refers to the direct connection between thePCU and SGSN Generally the PCU acts as the DTE and the SGSN the DCE Youmay flexibly set the network features of the PCU and SGSN Huawei PCU supportsthe above two connection modes.

The link layer protocol of the Gb interface is based on the FR and defined in the GSM08.16 Establish a FR virtual circuit between the SGSN and BSS, which is to bemultiplexed by the LLC PDU from multiple subscribers This virtual circuit may bemulti-hop and traverse the network consisting of FR switching nodes The frame relay

is used for signaling and data transmission

3) Network Service (NS) layer

The NS here particularly refers to the network service control part of the NS protocol.The NS layer protocol implements such functions as NS Service Data Unit (SDU)data transmission, NS-VC link management, load sharing of subscriber data andnetwork congestion status indication and network status report

 NS SDU data transmission

All messages transmitted over the Gb interface are sent at the NS layer in the form ofvirtual circuit The normal running of the NS layer guarantees the stable running of theupper layer protocols In normal cases, the NS layer ensures the sequence of the NSSDUs transmitted through the Link Selection Parameters (LSP); in exceptional cases(for example, load sharing), the sequence cannot be well ensured

 Load sharing of subscriber data

One of the most important functions of the NS layer is to perform load sharing of thesubscriber data When upper layer subscribers transmit data to the NS layer, thesystem allocates an LSP for each subscriber and encapsulates it to the data packet.The NS layer ensures the sequence of subscriber data transmission based on theLSPs The NS layer selects one or several available NS-VCs to transmit thesubscriber data packets based on the LSP and BVCI so that the load is sharedamong all unblocked NS-VCs of the same NSE

 Congestion status indication

Upon detecting the lower layer link failure or congestion, the NS layer notifies the NSlayer subscribers through the congestion indication and status message, and at thesame time informs them of the transmission capability of the NS layer so that thesubscribers can handle accordingly

4) BSSGP layer

The BSSGP provides radio-specific data, QoS and selection information to satisfy therequirements of data transmission between the BSS and SGSN In the BSS, it is used

as the interface between the LLC frame and RLC/MAC block; in the SGSN, it is used

as the interface between the RLC/MAC information and LLC frame The BSSGP has

a one-to-one relationship between the SGSN and BSS That is, if a SGSN handlesseveral BSSs, the SGSN must have a BSSGP in relation to each BSS

Though distributed on both sides of the Gb interface, the BSSGP has asymmetricalfunctions on two sides of the Gb interface The BSSGP implements the followingfunctions:

 Signaling message and subscriber data transmission

 Traffic control of downlink data

 Blocking and unblocking of the BVC

 Dynamic configuration and management of the BVC

 Error detection of interface messages



The BSSGP contains the following basic procedures:

 Uplink and downlink data transmission procedure

 Paging procedure

 Radio access capability notification procedure

 Radio access capability request and response procedure

 Radio status procedure

 Suspension and restoration procedure

 FLUSH_LL (Logic Link) procedure

 Traffic control procedure

 Blocking and unblocking of the PTP BVC

 Reset procedure of the BVC

 Tracing procedure

3.3.3 Gs Interface

As the interface between the SGSN and MSC/VLR, the Gs interface adopts the SS7

to carry the BSSAP+ The SGSN implements mobility management of the MS throughthe cooperation between the Gs interface and MSC, including such operations asjoint Attach/Detach and update of joint routing area/location area The SGSN alsoreceives the CS paging information from the MSC and transmits it to the MS throughthe PCU If the Gs interface is not introduced, the paging coordination and update ofjoint location area/routing area will be unavailable, and this hinders the improvement

of connection rate and decrease of signaling load

3.3.4 Gn/Gp Interface

1) GTP:

The GTP (core protocol of Gn/Gp interface) is adopted between the GSNs in theGPRS backbone network The Gn refers to the interface between the SGSNs andbetween SGSN and GGSN in the same PLMN The Gp refers to the interface usedbetween GSNs of different PLMNs The Border Gateway and firewall are added The

BG routing protocol is provided through the BG to implement the communicationbetween GSNs of different PLMNs

The subscriber data and signaling between GSNs in the GPRS backbone network aretransmitted by adopting the GTP The GTP is standardized in the GSM09.60

The GTP signaling platform implements the GTP signaling processing, includingsession establishment, modification and deletion as well as tunnel maintenance The GTP data transmission platform implements the GPRS tunnel encapsulation/decapsulation and forwarding of packet data

Figure 1.1 shows the GTP message format: The first 20 bytes are the header

Figure 1.1 GTP message format

 Version: Protocol version bit

 PT: Protocol type bit, including GTP and GTP’

 Spare bit: Set to “111” currently

 N-PDU sequence number of the SNN and SNDCP

For the signaling message: SNN is 0; the SNN of the N-PDU transmitting end is 255,and that at the receiving end is omitted

For data N-PDU: If the SNN is set to 1, the GTP header contains SNDCP N-PDU SN;

if the SNN is set to 0, the N-PDU will be transmitted in non-acknowledged mode atthe LLC layer, and the N-PDU SN shall be set to 255

Message Type: Indicates whether the signaling message or data N-PDU tails the GTPheader

For signaling message: Set based on the signaling message type (path managementsignaling message, tunnel management signaling message, location managementsignaling message and mobility management signaling message)

For subscriber data N-PDU: Set it to “255”

 Length: Refers to the number of bytes (excluding header) of the GTP signaling orsubscriber data packets

 Sequence number: Refers to the incremental sequence number of the signalingmessages and tunnel transmitted N-PDUs

 Flow label: Refers to the flow flag

The flow label is not used in the path management and location managementmessages, and is thus set to “0”; in the tunnel management and mobilitymanagement messages, the flow label is set in the signaling request message toindicate a GTP flow, exclusive of the established PDP and SGSN context requestmessages

In the data message, the flow label is used to identify the N-PDU flow It isestablished and updated by the recipient in the context and selected in the case ofSGSN change

 TID: Refers to the tunnel ID

In the signaling message, the TID of path management, location management andmobility management messages is set to 0; in the tunnel management message, theTID indicates the destination GSN of the MM and PDP context

In the data messages, the TID indicates the tunnel where the N-PDU is located.

 Information Elements /N-PDU

The signaling message consists of the GTP header, followed by informationelements The data message prefixes a GTP header to the data N-PDU andencapsulates the message into the G-PDU so as to add subscriber-specificinformation, such as the IMSI, NSAPI and session-related flow label

2) UDP/IP and TCP/IP

The GTP signaling messages are transmitted over the UDP/IP The subscriber packetdata can be transmitted over the UDP/IP connectionless path or TCP/IP connection-oriented path In addition, the GTP-based IP networking technology is adopted toencapsulate the IP addresses of the source and destination GSNs

3.3.5 Gi Interface

The Gi interface refers to the interface between the GPRS and external PDN TheGPRS interconnects with various public packet networks such as Internet or ISDNthrough the Gi interface, on which such operations as protocol encapsulation/de-capsulation, address translation (for example, translating IP address of privatenetwork into that of public network), user access authentication and authorizationshall be performed

3.3.6 Gr Interface

As the interface between the SGSN and HLR, the Gs interface adopts the SS7 tocarry the MAP+ The SGSN obtains the MS-related data from the HLR through the Grinterface The HLR stores the GPRS subscriber data and routing information In thecase of update of inter-SGSN routing area, the SGSN will update related locationinformation in the HLR In the case of any data change, the HLR will also inform theSGSN to handle accordingly

3.3.7 Gd Interface

The Gd refers to the interface between the SGSN and Short Message Service Gateway MSC (SMS-GMSC)/Short Message Service - InterWorking MSC (SMS-IWMSC) The SGSN receives short messages over the Gd interface and forwardsthem to the MS The SMS of the GPRS is implemented through the coordinationamong the SGSN, SMS-GMSC, SMS-IWMSC and Short Message Center (SMC)over the Gd interface If the Gd interface is not provided, the Class-C MSs cannotreceive/transmit short messages after they attach to the GPRS network

-3.3.8 Gc Interface

As the interface between the GGSN and HLR, the Gc interface is used by the GGSN

to request current SGSN address information of the subscriber from the HLR by usingthe IMSI when the network initiates service request to the MS In mobile data service,this interface is used when the network initiates service request to the MS

3.3.9 Gf Interface

As the interface between the SGSN and EIR, the Gf interface is used to authenticatethe IMEI of the MS

Χηαπτερ 4 GPRS Radio Subsystem

4.1 GPRS Radio Interface Channels

1) Types of radio packet logical channels

The Packet Data Channel (PDCH) contains the following four types:

 Packet Data Traffic Channel (PDTCH)

The PDTCH is used to transmit the subscriber data in the packet switching mode,with the transmission rate of 0kbit/s – 59.2kbit/s All PDTCHs are unidirectional, that

is, either uplink (that is, PDTCH/U, used to transmit data from MS to the GPRSnetwork) or downlink (that is, PDTCH/D, used to transmit data from GPRS network tothe MS)

 Packet Broadcast Control CHannel (PBCCH)

The PBCCH is used to broadcast the necessary parameters for the MS to access thenetwork in packet switching mode as well as the parameters broadcast on theBroadcast Control Channel (BCCH) for circuit switching services If the PBCCH isconfigured in a cell, then the MS in the GPRS Attach mode only monitors the PBCCHinstead of the BCCH

If the PBCCH is present in the cell, there must be related prompt in the messagestransmitted on the BCCH, that is, inform the MS of the presence of the PBCCH in thecell through the system message SI13 If the PBCCH is not configured, theparameters of the packet switching service will be broadcast over the BCCH

 Packet Common Control CHannel (PCCCH)

The PCCCH contains the following types of channels:

Packet Paging CHannel (PPCH): Only used for downlink to page the MS

Packet Random Access CHannel (PRACH): Only used for uplink to request allocation

 Packet Dedicated Control Channel

The packet dedicated control channel contains the following types:

Packet Associated Control CHannel (PACCH): Bidirectional; used to transmit packetsignaling during data transmission

Packet Timing advance Control CHannel Uplink (PTCCH/U): Used to transmit randomaccess pulse to estimate the time advance of the MS for the packet switching service.Packet Timing advance Control CHannel Downlink (PTCCH/D): Used to transmit timeadvance information for several MSs One PTCCH/D corresponds to severalPTCCH/Us

Huawei PCU supports all packet channel functions.

2) The combinations of Packet Data Logical Channel:

The third combination is used for uplink and downlink packet data transmission One

or several channels in such a combination can be configured in a cell

The GPRS PCU supports all the above channel combinations The channels in thethird combination can be divided into fixed PDCH and dynamic PDCH The fixedPDCH is used to transmit the GPRS packet data and cannot be preempted by thecircuit switching service The dynamic PDCH can be dynamically switched betweenthe TCH and PDTCH based on the service requirements The TCH is used duringsystem initialization and may switch to the PDCH when there is a demand for packetswitching service, or vice versa

3) Mapping of logical channels to physical channels

The GPRS packet channel adopts the structure of 52 multiframes, and each packetchannel contains 52 multiframes Each four frames form a radio block Therefore, aradio channel consists of 12 radio blocks and 4 idle frames, as shown in Figure 1.1

B0– B11 = Radio block T= Frames used for PTCCH; X= Idle frames

Figure 1.1 PDCH multiframe structure

PBCCH: The PBCCH can be mapped onto such radio blocks as B0, B3, B6 and B9,with the number subject to the busy/idle degree of the broadcast channels Themapping is performed based on the above sequence

PCCCH: The PAGCH and PPCH can be mapped onto any radio block (except theradio block occupied by the PBCCH) of the downlink channel The PRACH is mappedonto the uplink frame in relation to the radio blocks occupied by PBCCH, PAGCH andPPCH

PDTCH: The PDTCH can be mapped onto any radio block to transmit packet data.PACCH: The PACCH can be mapped onto any radio block to transmit air interfaceradio signaling

PTCCH: The 12th and 38th uplink frames of each 52 multiframes constitute a uplinkPTCCH and those of two neighboring 52 multiframes a downlink PTCCH

4) Important terms of radio block

Temporary Block Flow (TBF): A TBF is a physical connection used by the two RRpeer entities (MS and BSS) to support the unidirectional transfer of LLC PDUs on

packet data physical channels The TBF consists of the RLC/MAC block carrying one

or several LLC PDUs, and only exists during data transmission

Temporary Flow Identity (TFI): Refers to the flag of the TBF The TFI is used todifferentiate the data flows when they share the same resources One TFI is allocatedfor one TBF (each radio block contains one TFI), and it shall be unique among allTBFs in the same direction of the PDCH occupied by this TBF The same TFI isallowed in the same direction of other PDCHs or in the reverse direction of currentPDCH The TBF is uniquely identified through the TFI and data transmissiondirection The TFI contains 5 bits, with the value ranging from 0 to 31

Uplink State Flag (USF): The Uplink State Flag (USF) is used on PDCH channel(s) toallow multiplexing of uplink radio blocks (generally 4 consecutive burst pulses) fromdifferent mobile stations The USF is transmitted in all downlink radio blocks toindicate the user of the next uplink radio block in the same timeslot The USFcontains three bits to indicate eight states It can be used for multiplexing of uplinkradio blocks That is, eight MSs can be multiplexed in the same timeslot on the uplinkchannel through the USF, and the network dynamically adjust the uplink radioresources allocated to certain MS by changing the value of the USF But on thePCCH, the value of the USF can only be ‘111’ to indicate that related uplink radioblocks contain the PRACH

4.2 Channel Coding

A burst in a TDMA frame can carry 114 bits of data and each radio block consists offour bursts, so a radio block can only carry 456 bits of data, containing user data andthe coding information used for error detection and correction These channel codesprovides the error detection and correction mechanism for radio transmission

Four coding schemes, CS-1 to CS-4, are defined for the packet data service channel.The higher the coding scheme version, the poorer the error correction capability.Table 1.1 lists the features of these four coding schemes

CS-1 features the strongest error correction capability Generally, a GSM network innormal running status can meet the C/I requirement but its data throughput is thesmallest The error correction overhead of CS-2 and CS-3 is less than that of CS-1,and their error correction capability is also poorer than that of CS-1 CS-2 and CS-3raise a high requirement for radio environment and their data throughput is improved.For CS-4, its data throughput is the largest but it only provides error detection instead

of error correction, so it raises the highest requirement for radio environment

Table 1.1 GPRS channel coding scheme

carrying RLC/MAC data blocks, that is, the PDTCH The RLC/MAC blocks containingthe RLC data block can adopt these four coding schemes, but the radio blocksadopting CS-1 does not contain the reserved part For the radio blocks carryingRLC/MAC Control blocks, all control channels except PTCCH/U and PRACH adoptCS-1.

The first step of the coding procedure is to add a Block Check Sequence (BCS) forerror detection For CS-1 - CS-3, the second step consists of pre-coding USF (exceptfor CS-1), adding four tail bits and a convolutional coding for error correction that ispunctured to give the desired coding rate For CS-4 there is no coding for errorcorrection

1) CS-1 coding

CS-1 is the same coding scheme as specified for SDCCH Add 40 BCS bits to 184information bits (including 3 USF bits) through the FIRE code, and then add four tailbits to constitute 228 bits Then the 228 bits, after 1/2 convolutional coding, becomes

456 bits

2) CS-2 coding

Add 16 BCS bits used to detect errors in 271 information bits (including 3 USF bits),perform pre-coding for the 3 USF bits to get 6 bits, and add 4 tail bits to constitute 294bits Then the 294 bits, after the 1/2 convolutional coding, becomes 588 bits.Puncture 132 bits from the 588 bits to output 456 bits

3) CS-3 coding

Add 16 BCS bits used to detect errors in 315 information bits (including 3 USF bits),perform pre-coding for the 3 USF bits to get 6 bits, and add 4 tail bits to constitute 338bits Then the 338 bits, after the 1/2 convolutional coding, becomes 676 bits.Puncture 220 bits from the 676 bits to output 456 bits

Figure 1.1 shows the channel coding from CS-1 to CS-3

rate 1/2 convolutional coding

Figure 1.2 shows the channel coding of CS-4

Figure 1.2 Radio channel coding of CS-4

4.2.3 Channel Coding of EGPRS PDTCH

Nine different modulation and coding schemes, MCS-1 to MCS-9, are defined for theEGPRS Radio Blocks (4 bursts, 20ms) carrying the RLC data blocks The blockstructures of these schemes are shown in Figure 1.2 to Figure 1.10 and Table 10.1 Ageneral description of the MCSs is given in Figure 1.1

The MCSs are divided into families A, B and C Each family has a different basic unit

of payload: 37 (and 34), 28 and 22 octets respectively Different code rates within infamily are achieved by transmitting a different number of payload units within oneRadio Block For family A and B, 1, 2 or 4 payload units are transmitted; for family C,only 1 or 2

When 4 payload units are transmitted (MCS-7, MCS-8 and MCS-9), they are split intotwo separate RLC blocks (for example, with different serial numbers and BSCs).These blocks, in turn, are interleaved over two bursts only, for MCS-8 and MCS-9 ForMCS-7, these blocks are interleaved over four bursts When switching to MCS-3 orMCS-6 from MCS-8, three or six padding octets are added to the data octets,respectively

37 octets 37 octets 37 octets

37 octetsMCS-3

MCS-6Family A

MCS-9

28 octets 28 octets 28 octets

28 octetsMCS-2

MCS-5

MCS-7Family B

22 octets

22 octetsMCS-1

MCS-4Family C

34+3 octets 34+3 octets

Figure 1.1 General description of the EGPRS modulation and coding scheme

To allow incremental redundancy, the header part of the radio block is independently

coded from the data part Three different header formats are used, one for MCS-7,

MCS-8 and MCS-9, one for MCS-5 and MCS-6, and one for MCS-1 to MCS-4 Thefirst two formats are for 8-PSK modes, the difference being in the number Sequence

Numbers carried (2 for MCS-7, -8 and -9; 1 for MCS-5 and -6) The third format is

common to all GMSK modes The header is always interleaved over four bursts.The following figures show the coding and truncating procedures in all modulationand coding schemes

P2 P3 P1 P2

puncturing puncturing

FBI E Data = 592 bits BCS TB FBI

puncturing puncturing

FBI E Data = 544 bits BCS TB FBI

P2 P3 P1 P2

puncturing puncturing

FBI E Data = 448 bits BCS TB FBI

3 bits

1248 bits +1 bit

Figure 1.5 MCS-6 coding and truncating process; 8-PSK at 0.49 data rate; one RLC block per

20ms

P2 P1

3 bits

1248 bits +1 bit

Figure 1.6 MCS-5 coding and truncating process; 8-PSK at 0.37 data rate; one RLC block per

3 bits

372 bits 372 bits puncturing

Figure 1.7 MCS-4 coding and truncating process; un-encoded GMSK; one RLC block per 20ms

3 bits

372 bits 372 bits puncturing

Figure 1.8 MCS-3 coding and truncating process; GMSK at 0.85 data rate; one RLC block per

The Final Block Indicator (FBI) bit and extended (E) bit are encoded with the datapart.

The first step of the coding procedure is to add a Block Check Sequence (BCS) forerror detection The second step consists of adding six tail bits (TB) and a 1/3 rateconvolutional coding for error correction that is punctured to give the desired codingrate Each MCS uses different truncating schemes, which is represented by Pi, to givethe desired coding rate In both 8-PSK and GMSK modes, the stealing bits (SBs) inblocks denote block header formats In 8-PSK mode, 8 SBs are used to denote fourtypes of block header formats In GMSK mode, 12 SBs are used to denote two types

of block header formats, where the first 8 bits denotes CS-4

The details of the EGPRS coding schemes are shown in Table 10.1

Table 10.1 Coding parameters for the EGPRS coding schemes

Note: The italic captions indicate the padding

MCS-1 to MCS-4 apply the GMSK modulation mode, but their data rates differ fromthose of the CS-1 and CS-4 This data rate variation is specially designed for the linkadaptation control algorithm of the EGPRS

The data in the GPRS can only be re-transmitted in the original coding mode, so itmay never succeed in the case of radio transmission environment degradation Toaddress the problem, the EGPRS coding mode is designed to split a data block thatoriginally uses a coding mode with a higher data rate into two data blocks using acoding mode with a lower data rate For example, a RLC block using MCS-9 can bedivided into two RLC blocks using MCS-6 during re-transmission

In view of the poor performance of MCS-9 in adverse radio transmission environment,the MCS-8 is designed with some protection capabilities and smaller valid data MSC-

8 and MCS-9 belong to the same family When switching to MCS-3 or MCS-6, 3 or 6padding octets shall be added to the data octets, respectively

According to the specification, all control logical channels in both EGPRS and GPRSadopt CS-1

4.2.4 Channel Coding for PACCH, PBCCH, PAGCH, PPCH, PNCH and

PTCCH/D

The channel coding for the PACCH, PBCCH, PAGCH, PPCH, PNCH, and PTCCH/D

is corresponding to the coding scheme CS-1 The channel coding for the PTCCH/U isidentical to PRACH

4.2.5 Channel Coding for the PRACH

Two types of packet random access burst may be transmitted on the PRACH: an 8information bits random access burst or an 11 information bits random access burstcalled the extended packet random access burst The MS shall support both randomaccess bursts The channel coding used for the burst carrying the 8 information bitpacket random access uplink message is identical to the coding of the randomaccess burst on the GSM The channel coding used for the burst carrying the 11information bit packet random access uplink message is a punctured version of thecoding of the random access burst on the GSM

The channel coding for an 8 information bits random access burst: Input 8 informationbits to get 63 color bits Add the 63 color bits and 4 tail bits, in turn, behind the 8information bits to get 18 bits Use the 18 bits to perform 1/2 convolutional coding andconstitute 36 bits

The channel coding for a 11 information bits random access burst: Input 11information bits to get 6 parity check bits Use the 6 parity check bits and 6 BSICs to

perform the Exclusive-OR operation to get 6 color bits Suffix the 6 color bits and 4 tailbits (four of them are 0), in turn, to the 11 information bits to get 21 bits Use the 21bits to perform 1/2 convolutional coding and get 42 bits Puncture 6 bits (with serialnumbers: 0, 2, 5, 37, 39 and 41) from the 42 bits to constitute 36 bits.

4.3 Media Access Control Mode

Three media access control (MAC) modes are supported: Dynamic allocation,extended dynamic allocation and fixed allocation All the GPRS-capable networkssupport the dynamic allocation and fixed allocation, while the extended dynamicallocation is optional The MS shall support the dynamic allocation and fixedallocation

 Fixed allocation: The BSS allocates the radio block used by the MS in advance,and then notifies the MS through an allocation message in the form of resourcebit list If any data needs to be transmitted after the radio blocks are depleted, theBSS shall allocate radio blocks again

 Dynamic allocation: The radio block used by the MS is temporarily allocated bythe BSS When allocating radio resources for the MS, the BSS also assignssome radio channels and related USF values Upon receiving the allocationmessage, the MS starts to monitor the USF values in downlink radio blocks ofthe allocated channels If the monitored USF values are the same with theallocated ones, the MS transmits data in the corresponding uplink radio blocks

 Extended dynamic allocation: The resource allocation mechanism of theextended dynamic allocation is consistent with that of the dynamic allocation, butthe number of timeslots used by the MS may be beyond the multislot capability.Upon receiving the USF value of a channel, the MS can transmit data on thischannel or another with a larger serial number

4.4 Multislot Capability of MS

The MSs are divided into 29 classes based on the multislot capability For details, seeETSI GSM 05.02 specifications The MSs at diversified classes can concurrently usedifferent number of packet channels When the PCU allocates radio resources for the

MS, multiple aspects shall be taken into account, including the data transmissionvolume of the MS, the required service quality level, and the number of availableradio channels On the premise of full use of radio resources, the multislot capability

of the MS shall be achieved

4.4.1 Multislot Configuration

Multislot configurations are defined as multiple packet channels and related controlchannels allocated to the same MS An MS can be configured with a maximum of 8physical channels, which are assigned with different timeslot numbers (TNs) but thesame frequency parameter (ARFCN or MA, MAIO and HSN) and training sequence(TSC)

An MS can be allocated with several PDTCH/Us and PDTCH/Ds for sending andreceiving packet data, respectively

4.4.2 MS Classes for Multislot Capability

Huawei PCU supports the MSs with multislot capability from class 1–12 (Class-AMS)