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www.huawei.com Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved. GPRS Principles 1 Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved. Page1 Foreword 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. 2 Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved. Page2 Objectives 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 3 Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved. Page3 Contents 1. GPRS System Overview 2. GPRS Architecture 3. GPRS Network Interfaces & Protocols 4. GPRS Wireless Subsystem 5. GPRS Location Area 4 Copyright © 2009 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

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www.huawei.comCopyright 2009 Huawei Technologies Co., Ltd. All rights reserved.GPRS Principles1Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page1Foreword GPRS principle is the basic part of the whole GPRS systemand the succeeding products learning. This slide will help us to understand the GPRS systemnetworking and wireless subsystem etc.2Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page2Objectives 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 numbering3Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page3Contents1. GPRS System Overview2. GPRS Architecture3. GPRS Network Interfaces & Protocols4. GPRS Wireless Subsystem5. GPRS Location Area4Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page4Circuit Switch (CS)CSFCSCS CSCSABCDEGHIJKL5Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page5Packet Switch (PS)PSPSPS1 2 31 2 31 3221 3221 31 2 31 2 3PSPSPSPSACB D6Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page6GSM Development EvolutionGSM 9.6 Kb/sGPRS21.4 Kb/sEGPRS59.2 Kb/sUMTS 384 Kb/s2 G2.5 G2.75 G3 GHSCSD14.4 Kb/sECSD38.8 Kb/sCSPSEDGE7Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page7What is GPRS and EDGE? Abbreviation of General Packet Radio Service. GPRS is an end-to-end packet switching technologyprovided on the basis of GSM technology. It has much interactive services with the existing GSMcircuit 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 CircuitSwitched Data)GPRS is the abbreviation of General Packet Radio Service.GPRS network introduces packet switching functional entities in the GSM networkto implement data transmission in the packet mode.GPRS can be regarded as the service expansion based on the GSM network forsupporting mobile subscribers access the Internet of other packet data networks viapacket data mobile terminal. Making full use of the existing GSM network,smallinvestment and quick rewarding,all of these benefit to protect the existinginvestment and obtain maximum benefits for the operators.8Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page8GPRS&EDGE Coding RateGMSK 8PSK9.0513.415.621.48.811.214.817.622.429.644.854.459.20.0010.0020.0030.0040.0050.0060.00CS-1 CS-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9KbpsGPRSEGPRSCS-29Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page9Adjustments to GSM NetworkBSS CS CoreNetworkAPS CoreNetworkPCUBSS NSSGbPbGs10Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page10Most Popular GPRS Applications E-mail Web Browsing Information Services Moving Images Still Images Remote LAN Access File Transfer Job DespatchTraffic InformationSport ReportWeather ForecastStock MarketPublicInformationServiceEmailWeb BrowsingStill ImagesFile TransferMoving BankLive NewsPersonalInformationService11Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page11Advantages and Disadvantages ofGPRS Advantages Share resource with GSM High resource utilization Fast transmission rate Always on line Short access time Disadvantages Slower data rates in practice than anticipated in theory Suboptimal modulation technique12Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page12Contents1. GPRS System Overview2. GPRS Architecture3. GPRS Network Interfaces & Protocols4. GPRS Wireless Subsystem5. GPRS Location Area13Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page13CS & PS Logic StructureHLRAUCGPRSRegisterMSC/VLRBSC AbisDCCSGMSC PSTNBTSBSSCNEAPS GsSGSNGGSNGbGnGcGrGiInternetG-Abis PbPCUTRAU14Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page14GfGn GiGcGpGsMSC/VLRGrSGSNGdSMS-GMSCSMS-IWMSCGGSNEIRSGSNGnGPRSBackboneATM/DDN/ISDN/Ethernet, etcCN-PSGGSNGiCGGPRS System StructureGbSS7HLRGaIntranet/InternetFirewallRADIUSWAP GatewayOther PLMNBTSBSCBSSAbisPCUGbBTSBSS BSCAbisPCUX.25DNS BGMSMS15Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page15GPRS MS Class A The MS is attached to both GPRS and other GSM services and theMS supports simultaneous operation of GPRS and other GSMservices. Class B The MS is attached on GPRS network and GSM networksimultaneously but not enabling circuit switching and packet switchingservices at the same time. services are selected automatically. Class C The MS is attached to either GPRS or other GSM services. Alternateuse only. services are selected manually or default selected service.16Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page16Functions of PCU (Packet Control Unit) Packet wireless resource management function (RLC/MACprotocol function) Wireless resource management functions of GPRS BSS Circuit paging coordination G-Abis interface processing function Function related with GPRS BTS17Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page17Functions of PCU (Packet Control Unit) 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)Provides physical and logical data interface out of the BSS for packet datatrafficLLC layer PDU segmentation/reassembly of RLC blocksPacket data transfer schedulingARQ functionsRadio channel management function18Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page18Functions of SGSN (Serving GPRSSupport Node) Packet routing MS Session management Authentication and Ciphering Mobility management Billing information collection19Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page19Functions of GGSN (GatewayGPRS Support Node) Interface between GPRS backbone and external PDNs. PDP Conversion and context management IP address assignment management Packet routing to/from SGSNs Billing information collection20Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page20Functions of CG (ChargingGateway) Real-time collection of GPRS bills Temporary storage and buffering of GPRS bills Pre-processing of GPRS bills Sending GPRS bills to the billing center21Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page21Functions of MSC/VLR When Gs interface is installed, MSC/VLR can support Establishment and maintenance of the association betweenSGSN 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.22Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page22Functions of HLR/AUC Saving and updating GPRS subscriber subscription data User authentication Providing location/routing information and processingneeded in 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)23Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page23Functions of SMS-GMSC/SMS-IWMSC The SMS-GMSC and SMS-IWMSC are connected to the SGSNvia the Gd interface to enable GPRS MSs to send and receiveSMs over GPRS radio channels. After Gd interface is installed, short messages can be sent viaGPRS, which reduces the occupation on SDCCH and cuts downthe influence on voice services by SMS services. The operator can select to send SMS via MSC or SGSN.MS SGSN SMS-IWMSCSMS-GMSCSMS GdSMS-IWMSC(Interworking MSC For Short Message Service):A function of an MSC capable ofreceiving a short message from within the PLMN and submitting it to the recipient SC.For example:The MSC forwards the SM to the SMS-IWMSC, which is responsible for processingSMs submitted by the MS.SMS-IWMSC:The SMS Interworking MSC acts as an interface between the PLMN and a ShortMessage Service Centre (SC) to allow short messages to be submitted from Mobile Stations to theSC.SMS-GMSC(Gateway MSC For Short Message Service):A function of an MSC capable of receivinga short message from an SC, interrogating an HLR for routing information and SMS info, anddelivering the short message to the VMSC of the recipient MSFor example:The SMS system submitsthe message transfer request to the SMS-GMSC, which is responsible for processing delivered SMs.SMS-GMSC:The SMS Gateway MSC (SMS-GMSC) acts as an interface between a Short MessageService Centre and the PLMN, to allow short messages to be delivered to mobile stations from theService Centre (SC)24Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page24Functions of BG (Border Gateway) BG enables the following protocols necessary for interworking betweenoperators Security protocol: IPSec and firewall are recommended Routing protocol: BGP is recommended Billing protocol: determined by the operators with negotiation; BG might beneeded in collecting billing information It is normally based on routers It can be combined with GGSN in physical. BG does not exclusively belong to the GPRS network.GpPLMN AGSN RBGRBG GSNPLMN BIPsec (IP security) is a standardized framework for securing Internet Protocol (IP)communications by encrypting and/or authenticating each IP packet in a data stream.A protocol for exchanging routing information between gateway host s (each withits own router ) in a network of autonomous system s. BGP is often the protocolused between gateway hosts on the Internet.25Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page25Functions of DNS (Domain Name System) The following two types of DNSs may be adopted in the GPRSnetwork: The DNS between the GGSN and external networks The DNS on the GPRS backbone network. Provides two types offunctions: a. Resolve the GGSN IP address based on the Access Point Name (APN)in the process of the PDP context activation; b. Resolve original SGSN IP address based on the original routing area No.in the process of the update of inter-SGSN routing area. DNS does not exclusivelybelong to the GPRS network.GPRSSGSN BackboneDNS ServerSGSNDNSDomain Name SystemThe following two types of DNSs may be adopted in the GPRS network:The DNS between the GGSN and external networks: Implements resolution of thedomain name of external network, and functions as the ordinary DNS on the Internet.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) inthe process of the PDP context activation;b. Resolve original SGSN IP address based on the original routing area No.in the process of the update of inter-SGSN routing area. The DNS is not aproprietary entity of the GPRS network.26Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page26Functions of RADIUS Server (RemoteAuthentication Dial In User Service Server) It is a protocol used by Remote Access Server's for userAuthentication. The RADIUS server stores the authentication andauthorization information of subscribers. It also performs subscriber identity authentication in thecase of non-transparent access. RADIUS Server does not exclusively belong to the GPRSnetwork.27Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page27Contents1. GPRS System Overview2. GPRS Architecture3. GPRS Network Interfaces & Protocols4. GPRS Wireless Subsystem5. GPRS Location Area28Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page28Contents3. GPRS Network Interfaces & Protocols3.1 Interface and Protocol Stack3.2 Um Interface3.3 G-abis/Pb Interface3.4 Gb Interface3.5 Gs Interface29Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page29Network interface typesGPRS backbonenetworkSSGGSSNNSSGGSSNNGn GGGGSSNNIP interfaceSS7 interfaceBSS MSCSMSGMSCUm APDP network(IP/X.25)GiTEMTMSHLRGsGrGdGcGb30Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page30Interface in GPRS NetworkUm The interface between MS and GPRS network sideGf The interface between the SGSN and EIR (optional).Gs The interface between the SGSN and MSC/VLR (optional).Gr The interface between the SGSN and HLR.Gp The interface between GSNs of different PLMNs.Gn The interface between SGSNs and between SGSN and GGSN in the PLMN.Gi The reference point between the GPRS and external packet dataThe interface between SMS and GMSCGd The interface between SMS-IWMSC and SGSNGc The interface between the GGSN and HLR (optional).Gb The interface between the SGSN and BSS.The reference point between the Mobile Terminal (MT) (for example, mobilephone)and the Terminal Equipment (TE) (for example, the portable computer).RInterface Description31Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page31Data 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 ProtocolApplicationIP/X.25 IP/X.25 IP/X.25SNDCP GTPLLC LLC UDP/TCP UDP/TCPRLC BSSGP BSSGP IP IPMAC MAC NetworkServiceNetworkService L2 L2L2 (MAC)PhysicalLayerPhysicalLayerPhysicalLayerPhysicalLayerPhysicalLayerPhysicalLayerPhysicalLayerMS BSS SGSN GGSNrelayrelaySNDCP GTPUm Gb Gn GiRLCThe Relay function provides buffering and parameter mapping between the RLC/MAC and the BSSGP. For example, on theuplink the RLC/MAC shall provide a TLLI. The Relay function shall then make it available to BSSGP.32Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page32MS-SGSN signaling plane GMM: GPRS Mobility Management SM: Session ManagementMS BSS SGSNBSSGPGMM/SMLLCRLCMACGSM RFGMM/SMLLCBSSGPL1bisUm GbNetworkServiceRLCMACGSM RF L1bisNetworkServiceRreellaayyUm interface:Physical layer: wireless coding/decoding, channel multiplexing and mapping, wireless linkcontrol and wireless measurementRLC/MAC: wireless interface media access and link control functionLLC: providing a reliable logic link between MS and SGSN for data transmission. LLCprotocol can support both acknowledged mode and unacknowledged mode. It supports both encryption anddecryption modesSNDCP: Layer-3 transmission protocol. As the transition between the network layer and thesubnet layer, it implements segmentation/assembling and compression/decompression on IP/X.25 subscriber dataGMM/SM: Layer-3 signaling protocolGb interface:L1bis: physical transmission layer based on E1 or T1NS: based on FR; used to transmit BSSGP PDU of the upper layerBSSGP: On the transmission platform, this protocol is used to provide aconnectionless link between BSS and SGSN for unacknowledged data transmission; on thesignaling platform, it is used to transmit QoS and routing information related with thewireless section; it is also used to process paging requests and implement traffic control ondata transmission33Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page33Contents3. GPRS Network Interfaces & Protocols3.1 Interface and Protocol Stack3.2 Um Interface3.3 G-abis/Pb Interface3.4 Gb Interface3.5 Gs Interface34Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page34Protocol Layer of Um Interface GMM (GPRS Mobility Management): operates in the signallingplane of GPRS supports mobility management functionality. SM (Session Management): processes procedure that GPRSMS connects to the external data network. SNDCP (Subnetwork Dependent Convergence Protocol):Multiplexing of several PDPs, compression / decompressionand Segmentation of user data. LLC (Logical Link Control ): This layer provides a highlyreliable ciphered logical link between an MS and its SGSN. RLC:Segmentation and re-assembly between LLC PDUs andRLC blocks. MAC: defines the procedures that enable multiple mobilestations to share a common transmission medium.LLCRLCMACRFPhysical LinkSNDCPSMSGMM/SMGMM (GPRS Mobility Management)This protocol that operates in the signalling plane of GPRS supportsmobility management functionality such as GPRS attach, GPRS detach,security, routing area update, location update, roaming, authentication, andselection of encryption algorithms.SM (Session Management)It is the processing procedure that GPRS MS connects to the external datanetwork. The main function is to support the processing of PDP mobilescenario.Logical Link Control (LLC): This layer provides a highly reliable cipheredlogical link between an MS and its SGSN.LLC includes functions forthe provision of one or more logical link connections discriminated betweenby means of a DLCI.sequence control, to maintain the sequential order of frames across a logicallink connection.detection of transmission, format and operational errors on a logical linkconnection.recovery from detected transmission, format, and operational errors.notification of unrecoverable errors.flow control.ciphering.35Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page35MM StateIDLEGMM context is not established; MS is not reachable.MS can implement data transmission.GMM context is established; MS can receive paging butcannot implement data transmission. The MS performs MM procedures to provide the network with the actualselected cell. SGSN performs the MM on cell level.READYSTANDBY 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 alsopossible to receive pages for the CS services via the SGSN. Data receptionand transmission are not possible in this state. Data transmission to and from the mobile subscriber as well as the paging ofthe subscriber are not possibleThe Mobility Management (MM) activities related to a GPRS subscriber arecharacterised by one of three different MM states.36Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page36MM State ModelIDLE READY STANDBYIDLE READY STANDBYMM State Modelof MSMM State Modelof SGSNGPRS AttachGPRS DetachREADY timer expiry orPDU transmissionPDU receptionImplicit Detach or Cancel LocationGPRS AttachForce to STANDBYREADY timer expiry orForce to STANDBY orAbnormal RLC conditionGPRS Detach orCancel Location37Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page37RLC/MAC Block GenerationRLC/MAC blockSubscriber data SNDCP head LLC head LLC FCS RLC/MAC headLLC frameSubscriber IP packet (N-PDU)SNDCP PDU(SN-PDU)Network LayerSNDCP LayerLLC LayerRLC/MAC Layer38Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page38Physical 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 ApplicationIP/X25SNDCPLLCRLC RLC BSSGPMAC MAC FramerelayPhysicalLayerPhysicalLayerPhysicalLayerMS BSSRelay39Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page39Packet Logic Channels The specific type of PDCH (except PRACH) is determined byRLC/MAC head and RLC/MAC control message type.TCHBCCHPCH, RACH, AGCH,NCHPacket service channelPACCHPacket Logic ChannelPacket control channelPBCCHPPCH PRACH PAGCHPCCCH PDCCHPDTCH/U PDTCH/D PNCHPTCCH/U PTCCH/DSACCH40Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page40Channel 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/D41Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page41PDTCH (Packet Data Traffic CHannel) All packet data traffic channels areuni-directional. Uplink (PDTCH/U) for a mobileoriginated packet transfer. Downlink (PDTCH/D) for a mobileterminated packet transfer.Packet service channelPDTCH/U PDTCH/D42Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page42PBCCH (Packet Broadcast ControlCHannel) The PBCCH broadcasts parametersused by the MS to access the network forpacket transmission operation. The PBCCH also carries the informationtransmitted via the BCCH to allow circuitswitching operation. The MS in GPRS attached mode monitorsthe PBCCH only, if PBCCH is available,otherwise, the BCCH shall be used tobroadcast information for packet operation. The existence of the PBCCH in the cell isindicated on the BCCH via SI13.Packet control channelPBCCH43Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page43PCCCH (Packet Common ControlCHannel) PPCH Downlink only, used to page MS. PRACH Uplink only, used to request allocation of one orseveral PDTCH/Us or PDTCH/Ds. PAGCH Downlink only, used to allocate one or severalPDTCHs. PNCH Downlink only, used to notify MS of PTM-M call. If no PCCCH is allocated, the information forpacket switching operation is transmitted on theCCCH. If a PCCCH is allocated, it may transmitinformation for circuit switching operation.PPCH PRACH PAGCHPCCCHPNCH44Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page44PDCCH (Packet Dedicated ControlChannels) PACCH Bi-directional, used to transmit the packetsignaling in data transmission. PTCCH/U Used to transmit random access bursts toallow estimation of the timing advance forone MS in packet transfer mode. PTCCH/D Used to transmit timing advance updates forseveral MS. One PTCCH/D is paired withseveral PTCCH/U's.PACCHPDCCHPTCCH/U PTCCH/D45Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page45Combinations of Packet LogicChannelMode 3: PDTCH+PACCH+PTCCHMode 1: PBCCH+PCCCH+PDTCH+PACCH+PTCCHMode 2: PCCCH+PDTCH+PACCH+PTCCHIn case of small GPRS traffic, GPRSand circuit services share the sameBCCH and CCCH in the cell. In thiscase, only combination mode 3 isneeded in the cell.With the increase of traffic, thepacket public channel should beconfigured in the cell. Channelcombination mode 1 and mode 2should be adopted.Mode 4: PBCCH+PCCCH(PCCCH=PPCH+PRACH+PAGCH+PNCH46Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page46Packet Wireless ChannelConfigurations 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 thepercentage of circuit switching services are constantly changing. Dynamic PDCH is not visible for voice services.47Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page47Packet Wireless ChannelConfigurations General principles The cell should be configured with static PDCH to enable MS tobe normally attached on GPRS network as well as certain QoS ofGPRS services. Dynamic PDCH should be configured according to the GPRStraffic forecast, which should be adjusted as TCH or PDCH usablein the operation process according to the cell traffic status. Circuit switching services can seize the channel used by GPRSservices.48Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page48Mapping of Packet Logic Channel A radio block is a 4-normal-burst sequence that carries aRLC/MAC PDU (Protocol Data Unit).I = Idle frameT = Frame used for PTCCHB0 ~ B11 = Radio blocks0 25 51B0 B1 B2 T B3 B4 B5 I B6 B7 B8 T B9 B10 B11 I456 bits0 1 2 3 4 5 6 71 TDMA frame0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 749Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page49Mapping of Packet Logic Channel5143567012 B0 B1 B2 T B3 B4 B5 I B6 B7 B8 T B9 B10 B11 I0 50BCCHPDCHTCHS B B B B CC C C F SCCC C C CC C F S CC CCC C CC F S C C C C CCCC F S C C CCC C CC IT T T T T T T T T T T T S T T T T T T T T T T T T IF2512 2550Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page50Transmission Principle of Data Packeton Um InterfaceSubscriber data SNDCP head LLC head RLC/MAC headSubscriber IP packetLLC FCSSNDCP PDULLC PDURLC/MAC blockPhysical layerB0 B1 B2 T B3 B4 B5 I B6 B7 B8 T B9 B10 B11 INBNBNBNB51Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page51Allocation of Wireless PacketResources 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 thesame time.B1 B2 B3 B4 B5 B6 B7 B8 B9 B10B11B0B1 B2 B3 B4 B5 B6 B7 B8 B9 B10B11B0B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11MS2 MS3TS 0TS 1TS 2MS152Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page52Basic Conceptions about Radio Block USF(Uplink State Flag) is sent in all downlinkRLC/MAC blocks and indicates the owner or useof the next uplink Radio block on the sametimeslot. The USF field is three bits in lengthB11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 T I T IULDLUSF=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 IUSF=1USF=2USF=3USF=4MS1MS2MS3MS4USF=1 B0 I The USF field is three bits in length and eight different USF values canbe assigned, except on PCCCH, where the value '111' (USF=FREE)indicates that the corresponding uplink Radio block contains PRACH.53Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page53Basic Conceptions about Radio Block TBF (Temporary Block Flow) A Temporary Block Flow (TBF) is a physical connection used by thetwo RR entitiesthe RR entity of the MS and that of the BSS tosupport the unidirectional transfer of LLC PDUs on packet dataphysical channels. A TBF is temporary and is maintained only for the duration of the datatransfer. TFI (Temporary Flow Identity) Each TBF is assigned a Temporary Flow Identity (TFI) by the network. The TFI field is five bits in length.The same TFI value may be used concurrently for TBFs in opposite directions. TheTFI is assigned in a resource assignment message that precedes the transfer of LLCframes belonging to one TBF to/from the MS. The same TFI is included in everyRLC header belonging to a particular TBF as well as in the control messagesassociated to the LLC frame transfer (e.g. acknowledgements) in order to addressthe peer RLC entities.54Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page54Contents4. GPRS Wireless Subsystem4.1 Packet Channels4.2 Medium Access Modes4.3 MS Multi-TS Ability4.4 Power Control4.5 Network Control Modes55Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page55Medium Access Modes Uplink resource allocation mode Dynamic allocation (supported by all MSs and all networks) The mobile station detecting an assigned USF value for each assigned PDCH andblock 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 periodwithout an assigned USF. Extended dynamic allocation (optional for the network) The mobile station detecting an assigned USF value for any assigned PDCH allowingthe mobile station to transmit on that PDCH and all higher numbered assignedPDCHs in the same block or group of four blocks. Downlink resource allocation mode Dynamic allocation and fixed allocation.Three medium access modes are supported:- Dynamic Allocation characterised by that the mobile station detecting an assigned USFvalue for each assigned PDCH and block or group of four blocks that it is allowed to transmit on thatPDCH;- Extended Dynamic Allocation characterised by the mobile station detecting an assignedUSF value for any assigned PDCH allowing the mobile station to transmit on that PDCH and allhigher numbered assigned PDCHs in the same block or group of four blocks- Fixed Allocation characterised by fixed allocation of radio blocks and PDCHs in theassignment message without an assigned USF. Fixed Allocation may operate in half duplex mode,characterised by that downlink and uplink TBF are not active at the same time. Half duplex mode isonly applicable for multislot classes 19 to 29.Either the Dynamic Allocation medium access mode or Fixed Allocation medium access mode shallbe supported by mobile stations and all networks that support GPRS. The support of ExtendedDynamic Allocation is optional for the network.The Dynamic Allocation and Fixed Allocation modes shall be supported in all mobile stations. Thesupport of Extended Dynamic Allocation is mandatory for mobile stations of multislot classes 22, 24,25 and 27. The support of Extended Dynamic Allocation for mobile stations of all other multislotclasses are optional and shall be indicated in the MS Radio Access Capability.In the case of a downlink transfer, the term medium access mode refers to the measurement timescheduling, for the MS to perform neighbour cell power measurements56Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page56Contents4. GPRS Wireless Subsystem4.1 Packet Channels4.2 Medium Access Modes4.3 MS Multi-TS Ability4.4 Power Control4.5 Network Control Modes57Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page57MS Multi-TS Ability Concept of MS multi-TS ability Types Type 1: Non-simultaneous TRX Type 2: Simultaneous TRX the multi-TS ability level is 1-29; the bigger the level, the stronger themulti-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) BSS allocates resources according to the MS multi-TS ability,requested QoS and current resource configuration.58Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page58Contents4. GPRS Wireless Subsystem4.1 Packet Channels4.2 Medium Access Modes4.3 MS Multi-TS Ability4.4 Power Control4.5 Network Control Modes59Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page59Power Control Power control can improve the spectrum usage and systemcapacity as well as reduce MS power consumption. As there is no continuous bi-directional connection in the packetdata transmission process, GPRS power control is verycomplicated. Uplink power control includes open-loop and close-loop powercontrol. About downlink power control, there is no specific definition inprotocol. It lies on the BTS and its algorithm needs informationabout downlink, so downlink power control needs MS sendschannel quality reports to BTS.60Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page60Contents4. GPRS Wireless Subsystem4.1 Packet Channels4.2 Medium Access Modes4.3 MS Multi-TS Ability4.4 Power Control4.5 Network Control Modes61Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page61Network Control Modes During the network controlled cell re-selection, the networkmay request measurement reports from the MS and controlits cell re-selection. Hence, three types of mode are definedas follows: NC0: Normal MS controls NC1: MS control with measurement reports NC2: Network control The network subsystem must support NC0 and shouldgradually support NC1 and NC2.During the network controlled cell re-selection, the network may requestmeasurement reports from the MS and control its cell re-selection. Hence, threetypes 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 measurementreports to the network. The MS shall perform autonomous cell re-selection.NC2: Network control. The MS shall send measurement reports to the network. TheMS shall not perform autonomous cell re-selection.The network subsystem must support NC0 and should gradually support NC1 andNC2.62Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page62Network Control ModesMS NC0 NC1NC2The MS shall perform autonomous cell re-selectionMSThe MS shall perform autonomous cell re-selectionThe MS shall sendmeasurement reportsto the networkMS BTSMRCell re-selectioncommandThe MS shall notperform autonomous cellre-selection63Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page63Contents1. GPRS System Overview2. GPRS Architecture3. GPRS Network Interfaces & Protocols4. GPRS Wireless Subsystem5. GPRS Location Area64Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page64Relationship among LocationAreasCELLCELLCELLCELLRA1RA2CELLCELLRA3CELLCELLCELLSGSN1SGSN2BSC1BSC2BSC3LA1 LA265Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page65Location Area IdentificationMCC MNC LACLAI (Location Area Identification) MCCMobile Country Code, it consists of 3 digits. For example: TheMCC of China is "460" MNCMobile Network Code, it consists of 2 digits. For example: TheMNC of China Mobile is "00" LACLocation Area Code, it is a two bytes hex code. The value 0000and FFFF is invalid For example: 460008C9066Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page66RAI Routing area is the sub-set of the location area. In special cases, the twoareas are equal The division of the routing area is related with traffic distribution andSGSN processing abilityLocation Area IdentificationMCC MNC LAC RACRouting Area Identification67Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page67CGI CI (Cell Identity): This code uses two bytes hex code to identify the radiocells within a LAI. RAC is only unique when presented together with LAI. CI is only unique when presented together with LAI or RAI. CGI = MCC+MNC+LAC+{RAC}+CILocation Area IdentificationMCC MNC LAC CICGIRACRouting Area Identification68Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page68CGIRelationship among location areas LAI MCC+ MNC+ LACLAI RAI MCC+ MNC+ LAC+RAC CGI /CellID MCC+ MNC+ LAC+{RAC}+CIRAI69Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page69Summary GPRS System Overview GPRS Architecture GPRS Network Interfaces & Protocols GPRS Wireless Subsystem GPRS Location Area70Thank youwww.huawei.com71www.huawei.comCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved.GPRS EDGE MobileManagementAlgorithm72Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page1Foreword GPRS Mobility Management is a GPRS signalingprotocol that handles mobility issues such as roaming,authentication and selection of encryption algorithms.It is important to enable the network to keep track thecurrent location of the MS in order for the paging to beperformed smoothly. With the proper setting of theGMM parameters, we can shorten the access delay ofthe MS.73Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page2References GBSS8.1 BSC6000 Feature Description74Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page3Objectives Upon completion of this course, you will be able to: Understand the GPRS Mobility Management procedure Familiar with the GMM state model Understand the cell reselection algorithm Recognize the cell update and routing area update flow Realize the GMM related parameters75Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page4Contents1. Overview of GPRS Mobile Management2. Location Update3. GPRS Cell Selection & Reselection76Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page5Overview for GPRS Mobile Management The main purpose of the mobility management is to keep trackof the users current location. Thus, the paging can beperformed. MS perform cell selection and reselection when it movesaround the coverage area. It also sends the location updatemessage to the SGSN so that the network can be alwaysaware of the MSs current location. There are 3 states exist in the GPRS mobility managementand different location information is available in each state(please see the following figure MM State).77Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page6GMM StateIDLE GMM context is not established; MS is not reachable. MS can implement data transmission. GMM context is established; MS can receive paging butcannot implement data transmission. The MS performs MM procedures to provide the network with the actualselected cell. SGSN performs the MM on cell level.READYSTANDBY 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 alsopossible to receive pages for the CS services via the SGSN. Data receptionand transmission are not possible in this state. Data transmission to and from the mobile subscriber as well as the paging ofthe subscriber are not possible.78Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page7GMM State ModelIDLE READY STANDBYIDLE READY STANDBYMM State Modelof MSMM State Modelof SGSNGPRS AttachGPRS DetachREADY timer expiry orPDU transmissionPDU receptionImplicit Detach or Cancel LocationGPRS AttachForce to STANDBYREADY timer expiry orForce to STANDBY orAbnormal RLC conditionGPRS Detach orCancel Location By performing GPRS attach, the MS gets into READY state and if the MS does nottransmit any packet for a long period of time until the READY timer is expired, the MS willget into STANDBY state. It is possible to transmit data only if the MS is in READY state, thus the MS in STANDBYstate can switch back to the READY state, if a PDU transmission occurs and in the sameway, at READY state if the GPRS detach is performed, the MS will be back into IDLEstate and all PDP context will be deleted. In STANDBY state, the MS sends the location update message seldom, so its location isnot known exactly and the paging is necessary for every downlonk packet, resulting in adelivery delay. In READY state, the MS updates its location frequently. Consequently the MSs locationis known precisely and no paging delay during delivery downlonk packet. Howeverm thisconsumes much more the uplink radio capacity and battery of the MS.79Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page8GMM State vs Location Information During GMM IDLE state, MS is detached from GPRS. ThusMS can not receive paging nor data transmission. During GMM STANDBY state, MS is attached to the GPRSnetwork and it will perform routing area update (RAU), MScontrolledcell reselection and monitor paging. It only reportRA changes. During GMM READY state/ packet transfer mode, MS willperform both routing area update (RAU) and cell update (bothMS-controlled and Network-controlled cell reselection). Itreport the cell changes and RA changes.80Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page9Contents1. Overview of GPRS Mobile Management2. Location Update2.1Relationship between Cell, Routing Area & Location Area2.2LAI, RAI, CGI2.3Signaling flow for Cell Update, RA Update & LA Update3. GPRS Cell Selection & Reselection81Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page10Relationship among Location AreasCELLCELLCELLCELLRA1RA2CELLCELLRA3CELLCELLCELLSGSN1SGSN2BSC1BSC2BSC3LA1 LA2 When MS across Location Area border, LAU & RAU is necessary When MS moves within same LA and across Routing Area boarder, RAU is necessary When MS moves within the same LA and RA, cell update may be needed may beneeded. It depends on the current state of the MS.a) READY state: MS updates the location every cell change. This strategy ensures thatthe accurate location of the MS is always known and packet data can be delivered fasteras no paging procedure is necessary. However the MS battery is drained more anduplink radio capacity is wasted for cell updates.b) STANDBY state: MS updates the location only when the MS moves to a new routingarea (RA). In this strategy, when data packet is sent to the MS, paging is required inorder to find out the current location of the MS. Thus, uplink capacity will be wasted forpaging response and every downlink packet requires paging of the mobile delay.82Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page11CGIRelationship among Location Areas LAI MCC+ MNC+ LACLAI RAI MCC+ MNC+ LAC+RAC CGI /CellID MCC+ MNC+ LAC+{RAC}+CIRAI83Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page12Contents1. Overview of GPRS Mobile Management2. Location Update2.1Relationship between Cell, Routing Area & Location Area2.2LAI, RAI, CGI2.3Signaling flow for Cell Update, RA Update & LA Update3. GPRS Cell Selection & Reselection84Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page13Location Area IdentificationMCC MNC LACLAI (Location Area Identification) MCCMobile Country Code, it consists of 3 digits. For example: TheMCC of China is "460" MNCMobile Network Code, it consists of 2 digits. For example: TheMNC of China Mobile is "00" LACLocation Area Code, it is a two bytes hex code. The value 0000and FFFF is invalid For example: 460008C9085Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page14RAI (Routing Area Identification) Routing area is the sub-set of the location area. In special cases, the twoareas are equal. The division of the routing area is related with traffic distribution andSGSN processing abilityLocation Area IdentificationMCC MNC LAC RACRouting Area Identification86Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page15CGI (Cell Global Identity) CI (Cell Identity): This code uses two bytes hex code to identify the radiocells within a LAI. RAC is only unique when presented together with LAI. CI is only unique when presented together with LAI or RAI. CGI = MCC+MNC+LAC+{RAC}+CILocation Area IdentificationMCC MNC LAC CICGIRACRouting Area Identification87Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page16Contents1. Overview of GPRS Mobile Management2. Location Update2.1Relationship between Cell, Routing Area & Location Area2.2LAI, RAI, CGI2.3Signaling flow for Cell Update, RA Update & LA Update3. GPRS Cell Selection & Reselection88Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page17Cell Update FlowMS Old Cell SGSNUplink LLC-PDU[MS ID]SGSN received andrecorded the cell updateNew CellSGSN send thesubsequence serviceto MS through thenew cellPDU (CGI) in BSSGP-PDURLC Radio Block1. When the MS moves from one cell to another within the same RA and LA, cellupdate procedure will happen during the READY state.2. During the READY state/ packet transfer state, MS will keep monitor its currentlocation and cell reselection will happen. When MS discover another better cellaccording to its own measurement. The MS stops listening to the old cell andstart to read the necessary SYSINFO in the new cell.3. MS make an access in the new cell and send a cell update to the SGSN(transparent to the PCU).4. SGSN will obtain the cell update (cell change information) from the uplink LLCPDUand record the cell update information and discovers that there wasalready an ongoing downlink packet transfer.5. SGSN will then sends a Flush message to the respective PCU. The Flushmessage contains the addresses to both the old and new cell as well as the MSidentity.6. The PCU check whether it is responsible for the new cell. In that case all thebuffered frames/ the subsequence service will be moved to a queue towards thenew cell. The PCU assign new resources to the MS in the new cell andtransmission is restarted.7. If the PCU is not responsible for the new cell, it will delete all the framesdestined to the MS ang leave the retransmission to higher layers.89Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page18Intra-SGSN Routing Area Update FlowMS BSS SGSNROUTING AREA UPDATE REQUEST ROUTING AREA UPDATE REQUEST[Old RAI, old P-TMSI, update type] [Old RAI, old P-TMSI, update type, new CI]SECURITY FUNCTIONS (optional)ROUTING AREA UPDATE ACCEPT[P-TMSI, P-TMSI signature]ROUTING AREA UPDATE COMPLETE[P-TMSI] optional]1. When MS moves to new RA, it sends RA update request including the RAI ofthe old RA to its assigned SGSN. When the message arrives at the BSS, theBSS adds the CI of the new cell. Based on the RAI and CI data, SGSN canderived the new RAI. Intra-SGSN routing area update: The MS has moved to an RA, assigned to thesame SGSN as the old RA. In this case, the SGSN knows already all necessaryuser profile, and can assign a new packet temporary mobile subscriber identity(P-TMSI) to the user without the need to inform other network elements. Security function: authentication and ciphering/encrpytion90Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page19Inter-SGSN Routing Area Update FlowMS BSSNewSGSNROUTING AREA UPDATE REQUEST[Old RAI, old P-TMSI, update type]OldSGSN GGSN HLRPDP CTT REQ[GGSN address]PDP CTT ACKPDP CONTEXT UPDATEPDP CONTEXT UPDATE ACKDATABASE UPDATEINSERT SUBCRIBER DATAROUTING AREA UPDATE COMPLETEROUTING AREA UPDATE ACCEPT Inter-SGSN routing area update: In this case, the MS has moved to an RA,assigned to a different SGSN, thus, the new SGSN does not have the userprofile of the MS. The new SGSN contacts the old SGSN and requests the PDPcontext of the user. After receiving the PDP context of the user, the new SGSN informs the involvednetwork elements, GGSN about the new PDP context of the user HLR about the users new SGSN HLR cancels the MS information context in the old SGSN and loads thesubscriber data to the new SGSN. New SGSN acknowledges to the MS The old SGSN is requested to transmit the undelivered data to the new SGSN.91Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page20Contents1. Overview of GPRS Mobile Management2. Location Update3. GPRS Cell Selection & Reselection3.1Cell Reselection Algorithm3.2Parameter for Cell Reselection3.3Type of Cell Reselection92Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page21GPRS Cell Reselection Algorithm If no PBCCH exists, the GPRS cell selection &reselection is basically the same as GSM cellselection & reselection (C1, C2):C2 = C1 + CRO TO*H(PT-T) when PT=/31C2 = C1 CRO when PT=31C1 = RLA_C RxLev_Acc_Min Max((MS_TXPWR_MAX_CCCH P), 0)1. C1 = RLA_C - RxLev_Access_Min - Max((MS_TxPwr_MAX_CCH - P), 0)2. C2 = C1 + CRO - TO * H(PT-T) when PT=/313. C2 = C1 - CRO when PT= 3193Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page22GPRS Cell Reselection Algorithm If no PBCCH exists, the GPRS cell selection & reselection isbasically the same as GSM cell selection & reselection (C1, C2)excepts for the following conditions:a) When MS in STANDBY mode, Cell reselection within the same RA/LA:C2(nei) > C2 (serving) for t>5s Cell reselection between different RA/LA:C2(nei) > C2 (serving) + CRH for t>5sb) When MS in READY mode, Cell reselection within the same RA/LA:C2(nei) > C2 (serving) + CRH for t>5s Cell reselection between different RA/LA:C2(nei) > C2 (serving) + CRH for t>5s1. C1 = RLA_C - RxLev_Access_Min - Max((MS_TxPwr_MAX_CCH - P), 0)2. C2 = C1 + CRO - TO * H(PT-T) when PT=/313. C2 = C1 - CRO when PT= 3194Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page23Cell Reselection in Standby ModeRA 1RA 2Cell ACell BCell CAC2>BC2 CC2>BC2CRH95Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page24Cell Reselection in Ready ModeBC2>AC2CRHRA 1Cell ACell B96Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page25GPRS Cell Reselection Algorithm If PBCCH exists, new cell selection & reselection algorithm(C31, C32) is applicable:C31(s) = RLA_P(s) HCS_THR(s) (Serving cell)C31(n) = RLA_P(n) HCS_THR(n) GPRS_TO(n)*H(GPRS_PENALTY_TIME-T)*L(n) (Neighbor cell)C31 = signal threshold criterionRLA_P = actual received level of the GPRS cellHCS_THR = signal level threshold of cell reselection of HCS GPRSGPRS_TO = GPRS temporary offsetL = 0; when PRIORITY_CLASS (s) = PRIORITY_CLASS (n)L = 1; when PRIORITY_CLASS (s) =/ PRIORITY_CLASS (n) C31 = signal threshold criterion/ signal level threshold criterion of HCS and is used tojudge whether to adopt preference cell reselection HCS_THR = Hierarchical Cell Structure signal level threshold of cell reselection of HCSGPRS. It is broadcast on PBCCH of the service cell. RLA_P = Received level of the GPRS cell TO = Temporary offset given to the neighbor when the neighbor cellsPRIORITY_CLASS is different from the PRIORITY_CLASS of the serving cell97Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page26GPRS Cell Reselection Algorithm If PBCCH exists, new cell selection & reselection algorithm(C31, C32) is applicable:C32(s) = C1 (Serving cell)C32(n) = C1 + GPRS_RESELECT_OFF GPRS_TO*H(GPRS_PENALTY_TIME T) * (1-L) (Neighbor cell)H(X GPRS_PENALTY_TIMEH(X>0) = 1; T < GPRS_PENALTY_TIMEL = 0; when PRIORITY_CLASS (s) = PRIORITY_CLASS (n)L = 1; when PRIORITY_CLASS (s) =/ PRIORITY_CLASS (n)C1 = RxLev GPRS_Acc_Level_Min Max( (GPRS_MS_TXPWR_MAX_CCH P), 0) C32 = Perfection of C2 applied to GSM. It applies the offset and the delay value to thecell reselection which needs execution of cell update program or route update program.When the PBCCH channel does not exist in the service cell, the MS will execute cellreselection according to the C2 algorithm. T = timer with initial value =0. When a cell is recorded by the MS into the 6 strongest cell,the counter corresponding to this cell, T will begin to count at a precision of one TDMAframe (4.62ms). When this cell is removed from the 6 strongest cell list, the timer is reset. GPRS TO = temporary offset, which counts from the counter T. T to the98Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page27GPRS Cell Reselection Algorithm In additional, it is necessary to consider the routing area forthe serving cell and adjacent cell: When MS in STANDBY mode, and within the same RAC32(n) = C32(n) When MS in READY mode, and within the same RAC32(n) = C32(n) - CELL_RESELECT_HYSTERESIS When MS in READY or STANDBY mode, with different RAC32(n) = C32(n) - RA_RESELECT_HYSTERESIS C32(n) = Final calculated/ actual value of the C32 criterion after consider the routingarea of the serving cell and neighbor cell.99Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page28Cell Reselection Trigger Condition Cell reselection triggering condition:Random access attempt is unsuccessfulafter MAX_RETRANSRandom access attempt isunsuccessful after MAX_RETRANS45321With C1, C2 criterion With C1, C31, C32 criterionC1 < 0 C1 < 0Downlink signaling failure Downlink signaling failureBetter cell with the highest C32 among:(a) Highest PRIORITY_CLASS, C31>=0(b) All cell, if no cell fulfils C31 criterionBetter neighbor cell detected:Same RA: C2(n) > C2(s) for t>5sDif RA: C2(n) > C2(s)+CRH for t>5Serving cell is barred Serving cell is barred100Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page29Contents1. Overview of GPRS Mobile Management2. Location Update3. GPRS Cell Selection & Reselection3.1Cell Reselection Algorithm3.2Parameter for Cell Reselection3.3Type of Cell Reselection101Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page30Network Control Mode Cell Attribute -> GPRS Attributes Parameter Name: Network Control Mode Description:In the cell reselection required by the network, the network requests the MS to sendmeasurement reports to control its cell reselection. There are three network controlmodes. nc0: Normal MS control. The MS performs automatic cell reselection.nc1: MScontrol with measurement reports. The MS sends measurement reports to the networkand performs automatic cell reselection.nc2: Network control. The MS sendsmeasurement reports to the network but does not perform automatic cell reselection. GUI Value Range: [nc0,nc1,nc2] Default Value: nc0102Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page31Parameter for GPRS Cell Reselection Network Control Mode (NCO)Controlled byYes Only Ready network Network ControlNC2 ModeControlled byYes Only Ready MS MS Control withNC1 M.R ModeControlled byMSReady &No Standby Normal MSNC0 Control ModeCellSelectionModeMS modeWhether theMS send theM.RMode Definition NC0: MS performs autonomous cell reselection without sending measurement reports tothe network. NC1: MS performs autonomous cell reselection and sends measurement reports tonetwork. NC2: Network controls cell reselection and MS sends measurement reports to thenetwork.103Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page32Support NC2 Cell Attributes ->Other Attributes Parameter Name: Support NC2 Description: This parameter specifies whether the cell supports the Network Control 2 (NC2) function.In NC2, the MS reports the measurement report of the reference cell and neighbor cellsto the BSC. The BSC controls cell reselection (including normal reselections and loadbasedreselections) of the MS. GUI Value Range: [No,Yes] Default Value: No104Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page33NC2 Support in External Neighbour Cell BSC6000 -> Configure2G External Cell Parameter Name: NC2 Support in External Neighbour Cell Description:This parameter specifies whether the GSM external cell supports NC2. GUI Value Range: [Not Support,Support] Default Value: Not Support105Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page34Parameter for GPRS Cell Reselection Cell Attributes -> GPRS Attributes -> Advanced -> PsOther Parameters Parameter Name: Cell Urgent Reselection Allowed Description: This parameter specifies whether enabling thecritical cell reselection algorithm is allowed. GUI Value Range: [Forbid,Permit] Default Value: Permit Parameter Name: Cell Load Reselection Allowed Description: This parameter specifies whether enabling thecell load-based reselection algorithm is allowed. GUI Value Range: [Forbid,Permit] Default Value: Permit Parameter Name: Cell Normal Reselection Allowed Description: This parameter specifies whether enabling thenormal cell reselection algorithm is allowed. GUI Value Range: [Forbid,Permit] Default Value: Permit106Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page35Support NACC Cell Attributes ->Other Attributes Parameter Name: Support NACC Description:This parameter specifies whether the cell support the Network Assisted Cell Change(NACC) function.In network control mode NC0, NC1, or NC2, when the MS is in thepacket transmission mode, the network informs the MS of the system information aboutneighbor cells in advance. Therefore, the cell reselection of the MS is accelerated. GUI Value Range: [No,Yes] Default Value: No107Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page36Contents1. Overview of GPRS Mobile Management2. Location Update3. GPRS Cell Selection & Reselection3.1Cell Reselection Algorithm3.2Parameter for Cell Reselection3.3Type of Cell Reselection108Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page37GPRS Cell Reselection Type There are 3 type of cell reselections: MS controlled cell reselection Network controlled cell reselection Network assisted cell reselection109Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page38MS-Controlled Cell Reselection MS-Controlled Cell Reselection MS periodically measures the RX levels of all the BCCH carriers of theserving cell and its neighboring cells. With no PBCCH configured, MS calculates C2 value. With PBCCH configures, MS calculates C31/C32 value. Based on the calculated value, MS decided whether to reselect a newserving cell. Also call as autonomous cell reselection. Parameter setting: Support NC0/ NC1 to YES110Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page39Network-Controlled Cell Reselection Network-Controlled Cell Reselection MS periodically sends measurement reports to the BSC based on theparameters in the SYSINFO broadcast in the cell. Based on the measurement reports and neighboring cell load, BSCsends a cell change command to the MS if all conditions are met, leadingthe MS to a suitable cell. Parameter setting: Support NC2 to YES111Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page40Network-Controlled Cell Reselection(NC2)MS BSSPACKET MEASUREMENT REPORTPACKET CELL CHANGE ORDERPACKET CELL CHANGE FAILURE[P-TMSI] optional]PACKET NEIGHBOR CELL DATANC2 Cell Reselection AlgorithmPACKET ENHANCED MEASUREMENT REPORT1. MS in the GMM Ready mode state periodically sends PACKETMEASUREMETN REPORT to the BSC.2. After receive the MR, NSC process the MR. According to the NC2 cellreselection algorithm, BSC determines whether to perform cell reselection.3. If BSC determines to initiate a cell reselection, it send PACKET CELL CHANGEORDER to MS to instruct MS to reselect the target cell. If NACC support,PACKET NEIGHBOR CELL DATA containing SYSINFO will be sent before thePACKET CELL CHANGE ORDER so that the reselection can be accelerated.4. If cell reselection fails, MS sends PACKET CELL CHANGE FAILURE messageto BSC. After receive this message, BSC subtracts CELL PENALTY LEVELfrom the RxLev of the target cell.112Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page41NC2 Cell Reselection Algorithm The NC2 cell reselection algorithm follows the prioritysequence in descending order of: Urgent reselection algorithm Load reselection algorithm Normal reselection algorithm Urgent reselection is based on the receive quality of the radio link on the Um interface. IfBER increases, the possible reason is that the signal level is too low or there isinterference on the channel. In the network, load in some cells are heavy and some are light. To balance the load inthese cells, load reselection is performed. In load reselection procedure, MS in heavy-loaded cell are directed to light-loaded cell.MS in neighbouring cell should not be reselected to the heavy-loaded cell. Normal reselection is based on Receive Level. When urgent reselection an loadreselection are not met, normal reseelction is started to handover MS to a neighboringcell with higher signal strength if the RxLev (serving cell) < [Min Access Level Threshold]113Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page42NC2 Cell Reselection AlgorithmYes YesYes Yes YesYes YesNoNo NoNoNo NoNoYesNoMeasure RxLev & RxQualMS in the MR[Cell UrgentReselection Allowed]?MS RxQualdeterioration ratio >[MS Rx Qual WorsenThreshold][Cell Load ReselectAllowed]?[Cell Normal ReselectAllowed]?Channel multiplexingrate>[Load ReselectStart Thres]Any MS RxLev load reselection -> normal reselection Each type of reselection have different trigger condition.114Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page43NC2 Cell Reselection AlgorithmYes Yes YesYesNoNo NoNoRxLev>MAX(RxLev(s),[Min_Acc_Level_Thres])+[Cell Reselect Hyst] ANDnon-congestion stateEc/No>[PS FDD EcNoQuality Thres] orRSCP>[PS FDD RSCPQuality Thres]RSCP>[PS FDD RSCPQuality Thres]Cell reselection successful?Trigger urgent cell reselection and select cellwith the highest priority in cell list.[Cell Penalty Level] given totarget cell with [cell PenaltyLast Time]For GSM Cell For FDD Cell For TDD CellContinueEndEnd The priority of the target cell is determined by receive level and the characteristicsinformation such as cell type, cell priority, support for EDGE, and load status. Different cell type will need to fulfill the specified condition to be the candidate cell. When cell reselection fails, penalty is given to the target cell. If penalty time within [CellPenalty Last Time (s)], [Cell Penalty Level] is subtracted from the receive level of thetarget cell.115Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page44NC2 Cell Reselection AlgorithmServing cell isGSM cell, targetcell is UTRANDifferent BSC,both GSM cellSame BSCServing cell&Target cellpositionIntra-BSC Highest priority in the cell list.ConditionCellReselectionTypeFor FDD cell : Ec/No>[PS FDD EcNo Quality Thres]or RSCP>[PS FDD RSCP Quality Thres]For TDD cell: RSCP>[PS TDD RSCP Quality Thres]GSM toUTRANRxLev (Ext nei) = RxLev (n) MAX(2, [CellReselection Hyst/2])Inter-BSC Each NC2 cell reselection algorithm contains three NC2cell reselection type: Intra-BSC cell reselection:Serving cell and target cell are controlled by same BSC. The selected target cellis the one that has highest priority in the cell list. Inter-BSC cell reselection:Serving cell and target are in different BSC and both is GSM cell. The priority forthe external neighbouring cell is lower. Thus,RxLev (Ext nei) = RxLev (n) external cell reselection offsetRxLev (Ext nei) = RxLev (n) MAX(2, [Cell Reselection Hyst/2]) GSM to UTRAN cell reselection:Serving cell is GSM cell and target cell is UTRAN cell. The 3G MR and the2G/3G cell priority strategy should be processed during the cell reselection.For FDD cell: Ec/No>[PS FDD EcNo Quality Thres] or RSCP>[PS FDDRSCP Quality Thres]For TDD cell: RSCP>[PS TDD RSCP Quality Thres][2G/3G Cell Reselection Strategy] : Preference for 2G cell, Preference for 3G cell116Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page45Network-Assisted Cell Reselection Network-Assisted Cell Reselection It is also known as NACC, Network Assisted Cell Change. MS originates a cell change notification (CCN) procedure, and the BSCsends the system information (SYSINFO) about the neighboring cell tothe MS before the cell reselection. NACC accelerates the cell reselection and shortens the servicedisruption time during cell reselection. Parameter setting: Support NC0/ NC1/ NC2 to YES Support NACC to YES117Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page46Network Assisted Cell Change (NACC) Purposes: MS is able to request BSC to send the target cells SYSINFOduring the cell reselection. Advantages: According to the SYSINFO, MS accelerates the packet serviceaccess in the target cell. Reduce the period of packet service disruption during a cellreselection .118Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page47Network Assisted Cell Change (NACC)Cell A Cell BReceive Systeminformation of cell Bbefore reselection119Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page48Network Assisted Cell Change (NACC) MS can initiate an NACC procedure only when autonomous cellreselection is triggered: In NC0/ NC1 mode and packet transfer mode: C1