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Huawei Confidential. All Rights Reserved
OMP000001 GPRS Fundamental
ISSUE 2.0
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1 Internal Use
GPRS principle is the basic part of the whole system and the later products learning. This slide will help us to understand the GPRS system networking and some important procedure.
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2 Internal Use
objectobject
Upon completion of this course, you will be able to:¦ Describe the GPRS networking structure
¦ Know the GPRS mobility management procedure
¦ Know the GPRS session management procedure
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3 Internal Use
References References
q 3GPP protocol 23060
q 3GPP protocol 29060
q 3GPP protocol 24008
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4 Internal Use
ChapterChapter 1 GPRS Network Structure1 GPRS Network Structure
Chapter 2 Mobility Management
Chapter 3 Location Management
Chapter 4 Session Managment
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5 Internal Use
GPRS Network StructureGPRS Network Structure
FR
EIREIRHLRHLRSMS-GMSCSMS-IWMSCSMS-GMSCSMS-IWMSC
MSC/VLRMSC/VLR
BSSBSS
UTRANUTRAN
SGSNSGSN
SGSNSGSN
GGSNGGSN
BGBG
CGCG
TETEPDN
SS7
ATM
DDN
ISDN
Ethernet.etc
GPRSBackbone
Gs Gd Gr Gf Gc
Gb
Iu
Um
Um
Gp
Gi
Gn
Gn
ATM Ga
SCPSCP GMLCGMLC
Ge Lg
Ga
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6 Internal Use
GPRS Network StructureGPRS Network Structureq Some Abbreviation
¦ GPRS[General Packet Radio Service
¦ BSS[Base Station Subsystem
¦ UTRAN[UMTS Terrestrial Radio Access Network
¦ SGSN[Service GPRS Support Node
¦ GGSN[Gateway GPRS Support Node
¦ CG[Charging Gateway
¦ BG[Bordering Gateway
¦ PDN[Packet Data Network
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7 Internal Use
GPRS Network StructureGPRS Network Structureq Some Abbreviation
¦ MSC/VLR
[Mobile Switch Center/Visitor Location Register¦ SMS-GMSC
[Gateway MSC For Short Message Service¦ SMS-IWMSC
[Short Message Service Interworking MSC¦ SCP
[Service Control Point¦ GMLC
[Gateway Mobile Location Center¦ HLR
[Home Location Register¦ EIR
[Equipment Identity Register
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8 Internal Use
Chapter 1 GPRS Network Structure
Chapter 2 Mobility Management
Chapter 3 Location Management
Chapter 4 Session Managment
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9 Internal Use
GMM (GPRS Mobility Management)GMM (GPRS Mobility Management)
q Function of the Mobility Management¦ The Mobility Management (MM) activities related to a subscriber are
characterised by one of three different MM states. In A/Gb mode, the
MM states for a GPRS subscriber are IDLE, STANDBY, and READY.
Each state describes a certain level of functionality and information
allocated.
¦ keep track of the current location of an MS within the PLMN or within
another PLMN
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10 Internal Use
GMM (GPRS Mobility Management)GMM (GPRS Mobility Management)
q GMM specific procedures¦ Attach procedure
¦ RAU and periodic RAU
¦ Detach
q GMM common procedures¦ P-TMSI reallocation procedure
¦ Authentication procedure
¦ Identification procedure
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11 Internal Use
Mobility Management Timer FunctionMobility Management Timer Function
q Periodic RA Update Timer Function¦ Monitors the periodic routing area update procedure in the MS¦ Upon its expiry, the MS shall start a periodic routing area update procedure.¦ The length of the timer is set in SGSN; The value of the timer is sent to MS
in attach accept message or routing update accept messageq Mobile Reachable Timer Function
¦ Upon the expiry of this timer, the MS is detached¦ This is reset and started when the state returns to STANDBY ¦ The timer shall be slightly longer than the periodic RA update timer used by
an MS¦ The length of the timer is set in SGSN
q Purge Timer Function¦ Allows the SGSN to inform the HLR that it has deleted the MM and PDP
contexts of a detached MS.¦ The purge timer is set longer than the mobile reachable timer
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12 Internal Use
2G Network States Transition2G Network States Transition
PDU transmission
Implicit Detachor
Cancel Location
GPRS Attach
READY timer expiryorForce to STANDBY
GPRS Detach GPRS Attach
PDU reception
GPRS Detachor
Cancel Location
MM State Model of MS MM State Model of SGSN
IDLE
READY
STANDBY
IDLE
READY
STANDBY
READY timer expiryorForce to STANDBYorAbnormal RLC condition
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13 Internal Use
Attach ProcedureAttach Procedure
q Function
¦ An MS shall perform a GPRS Attach to the SGSN in order to obtain access
to the GPRS services. It shall perform a GSM GPRS Attach procedure.
¦ Only MS can initiate the Attach Procedure
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14 Internal Use
Attach ProcedureAttach Procedure
(IMSI or PTMSI+RAI) (PTMSI)
(IMSI)
(Identity Type = IMSI)
(IMSI)
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15 Internal Use
Attach ProcedureAttach Procedure
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16 Internal Use
Attach ProcedureAttach Procedure
q Results after any attach procedure¦ SGSN get subscriber data from HLR¦ HLR recorded the MS’s serving SGSN number¦ SGSN and MS create MM context for the MS
q MS can request Session Management services
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17 Internal Use
Detach ProcedureDetach Procedure
q Function ¦ The GPRS Detach procedure allows an MS to inform the network that it
does not want to access the SGSN-based services any longer¦ The GPRS Detach procedure allows the network to inform an MS that it
does not have access to the SGSN-based services any more
q The following three entity can initiate the detach procedure¦ MS¦ SGSN¦ HLR
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18 Internal Use
Detach Procedure (MS Initiation)Detach Procedure (MS Initiation)
2. Delete PDP Context Response
1. Detach Request
2. Delete PDP Context Request
3. Detach Accept
MS BSS/UTRAN GGSN SGSN
4. PS Signalling Connection Release
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19 Internal Use
Detach ProcedureDetach Procedure
q Results after any detach procedure¦ The SGSN shall not service the detached MS, unless reattach¦ The MS is in idle state
q The MS is detached either explicitly or implicitly:¦ Explicit detach: The network or the MS explicitly requests detach¦ Implicit detach: The network detaches the MS, without notifying the MS, a
configuration-dependent timer after the mobile reachable timer expired, or after an irrecoverable radio error causes disconnection of the logical link.
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20 Internal Use
Purge FunctionPurge Function
q Function¦ The Purge function allows an SGSN to inform the HLR that it has deleted
the MM and PDP contexts of a detached MS
q After the MS detach from the network:¦ The SGSN may delete the MM/PDP context immediately¦ the SGSN may keep the MM/PDP context for some time of the detached
MS
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21 Internal Use
Purge Function Purge Function (clear or remove)(clear or remove)
1. Purge MS
2. Purge MS Ack
SGSN HLR
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22 Internal Use
Authentication Function (2G)Authentication Function (2G)
q Function¦ "GSM authentication" implies authentication of the MS by the network
and establishment of a new GSM ciphering key (Kc) agreement between
the SGSN and the MS.
¦ "GSM authentication" ensure that the user is authorised to use the
particular network services
¦ Each triplet contains RAND, SRES and Kc¦ Authentication triplets are stored in the SGSN
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23 Internal Use
Authentication Function (2G)Authentication Function (2G)
1. Send Authentication Info
2. Authentication and Ciphering Request 1. Send Authentication Info Ack
2. Authentication and Ciphering Response
MS BSS/UTRAN HLRSGSN
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24 Internal Use
Identity CheckIdentity Check
q Function¦ Get IMSI from MS
¦ Check the IMEI
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25 Internal Use
Identity CheckIdentity Check
1. Identity Response 2. Check IMEI
1. Identity Request
2. Check IMEI Ack
MS BSS/UTRAN EIRSGSN
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26 Internal Use
PP--TMSI ReallocationTMSI Reallocation
2. P-TMSI Reallocation Complete
1. P-TMSI Reallocation Command
MS BSS/UTRAN SGSN
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27 Internal Use
PP--TMSI ReallocationTMSI Reallocation
q Function¦ The SGSN may reallocate the P-TMSI at any time
¦ The reallocation procedure can be performed by the P-TMSI
Reallocation procedure
¦ The P-TMSI can be included in the Attach or Routeing Area Update
procedures.
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28 Internal Use
Chapter 1 GPRS Network Structure
Chapter 2 Mobility Management
Chapter 3 Location Management
Chapter 4 Session Managment
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29 Internal Use
Location ManagementLocation Management
q Function¦ A mechanism that allows the system to keep track of the location
information of MS¦ A mechanism that allows the system to keep synchronization of the
states of MS‘s MM context
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30 Internal Use
Layered Location Management Mode (2G)Layered Location Management Mode (2G)
•SGSN
•HLR
•BSS
•MS
•SGSN number
•ready state: cell number
•Standby state: RAI
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31 Internal Use
RouteingRouteing Area Update ProcedureArea Update Procedure
MS
RAI 2 RAI 4
SGSN SGSN
RAI 1 RAI 3
cell
Intra SGSN-RAU
Inter SGSN -RAU
Gn
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32 Internal Use
RouteingRouteing Area Update ProcedureArea Update Procedure
q RAU procedure will happen in the following two case:¦ MS entered a new Route Area
¦ Periodic RAU ( after periodic timer expires)
q Inter-SGSN RAU
¦ The new SGSN find the old SGSN from the old RAI
¦ Old SGSN stop downlink signaling, transfer MM context and PDP
context to new SGSN
¦ Tunnelling N-PDU to the new SGSN
¦ Update PDP context and subscriber data
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33 Internal Use
Chapter 1 GPRS Network Structure
Chapter 2 Mobility Management
Chapter 3 Location Management
Chapter 4 Session Managment
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34 Internal Use
Session ManagementSession Management
q Function ¦ Manage the connection between MS, SGSN and GGSN and
allocate system resource for the service transmission
q Important Procedure¦ PDP Context Activation¦ PDP Context Modification¦ PDP Context Deactivation
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35 Internal Use
Session ManagementSession Management
DNS
BTS
SGSN
MS
DNS
BSC
GGSN (B)BackboneBackboneDNS
ISP BISP B
ISP AISP A
Corp.Network
Corp.Network
GGSN (A)
••APNAPN--NINI
••APN APN == GGSN IP addressGGSN IP address
••APNAPN--NINI
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36 Internal Use
PDP ContextPDP Context
q PDP Context ¦ The PDP context is Packet Data Protocol context
¦ PDP context contains all the information needed to transfer user data
between MS and GGSN.
¦ The context includes parameters such as Routing, QoS (Quality of
Service), Charging ID etc.
¦ PDP context exists in MS, SGSN, GGSN
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37 Internal Use
PDP ContextPDP Context
XXThe quality of service profile subscribed.QoS Profile Subscribed
XXSpecifies whether the MS is allowed to use the APN in the domainof the HPLMN only, or additionally the APN in the domain of the VPLMN.
VPLMN Address Allowed
XXThe IP address of the GGSN currently used.GGSN Address in Use
XTunnel Endpoint Identifier for the Iu interface.TEID for Iu
XXTunnel Endpoint Identifier for the Gn and Gp interfaces.TEID for Gn/Gp
XXTransaction Identifier.TI
XXNetwork layer Service Access Point Identifier.NSAPI
XXThe APN currently used. This APN shall be composed of the APNNetwork Identifier and the APN Operator Identifier.
APN in Use
XXThe APN received from the HLR.APN Subscribed
XXPDP address, e.g. an IP address.PDP Address
XXPDP type, e.g. PPP or IP.PDP Type
XXPacket data protocol state, INACTIVE or ACTIVE.PDP State
XXIndex of the PDP context.PDP Context Identifier
Each MM context contains zero or more of the following PDP contexts:
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38 Internal Use
PDP ContextPDP Context
XThe IP address of the RNC currently used.RNC Address in Use
XXThe charging characteristics of this PDP context, e.g. normal, prepaid, flat-rate, and/or hot billing.
PDP Context Charging Characteristics
XXCharging identifier, identifies charging records generated by SGSN and GGSN.
Charging Id
XSequence number of the next uplink in-sequence PDCP-PDU expected from the MS.
PDCP-SNU
XSequence number of the next downlink in-sequence PDCP-PDU to be sent to the MS.
PDCP-SND
XXGTP-U sequence number of the next uplink N-PDU to be sent to the GGSN.
GTP-SNU
XXGTP-U sequence number of the next downlink N-PDU to be sent to the MS.
GTP-SND
XSNDCP sequence number of the next uplink N-PDU expected from the MS.
Receive N-PDU Number
XSNDCP sequence number of the next downlink N-PDU to be sent to the MS.
Send N-PDU Number
XThe aggregate BSS quality of service profile negotiated for the packet flow that this PDP context belongs to.
Aggregate BSS QoS Profile Negotiated
XPacket flow identifier.Packet Flow Id
XThe RLC/MAC radio priority level for uplink user data transmission.Radio Priority
XXThe quality of service profile negotiated.QoS Profile Negotiated
XXThe quality of service profile requested.QoS Profile Requested
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39 Internal Use
MM Context and PDP ContextMM Context and PDP Context
HLR
SGSNBSC
or RNC
MS GGSNGnGb/ IuUu
PDP context #2
.
.
PDP context #1
MM context
PDP context #2
.
.
PDP context #1
MM context
PDP context #2
.
.
.
PDP context #1
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40 Internal Use
Important Concept __ APNImportant Concept __ APN
q APN structure: APN_NI+APN_OI
cmnet.mnc<MNC>.mcc<MCC>.gprs
APNNetwork ID
APNOperator ID
•Operator ID : fixed extension, must end with “.gprs”
•Network ID shall not end with “.gprs”
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41 Internal Use
Important Concept __ APNImportant Concept __ APN
MS SGSN
GGSN1
GGSN2
GGSN3
DNS
APN1
APN2
APN3
APN1=GGSN1 IP
APN2=GGSN2 IP
APN3=GGSN3 IP
APN
APN GGSN IP
APN1
APN2
APN3
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42 Internal Use
Important Concept __ APNImportant Concept __ APN
SGSN
MS
SGSN
MS
•internet
GGSN GGSN
Roaming
APN:CMNET
•GuangDong province
q General APN
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43 Internal Use
Important Concept __ APNImportant Concept __ APN
SGSN
MS
SGSN
MS
GGSN GGSN
Roaming
APN:test.xy
VPN tunnel
Province 1
q Area APN
Province 2
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44 Internal Use
Important Concept __ PDP StateImportant Concept __ PDP State
Deactivate PDP Contextor
MM state change to IDLEor PMM-DETACHED
Activate PDPContext
INACTIVE
ACTIVE
q PDP state¦ inactive:cannot transmit data ¦ active:can transmit data
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45 Internal Use
Important Concept __ PDP Type and PDP AddressImportant Concept __ PDP Type and PDP Address
q PDP Type¦ IPV4 ¦ IPV6¦ PPP
q PDP Address¦ Static IP
[Public IP[Allocate by the operator
¦ Dynamic IP[Private IP[Allocate by GGSN, DHCP or Radius
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46 Internal Use
Important Concept __ Important Concept __ QoSQoS
q QoS is quality of service
q It is a group of parameters that can define the network ability, such
as the bit rate for downlink or uplink data transmission and the
reliability class and so on
q It is end to end concept
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47 Internal Use
Activation ProcedureActivation Procedure
q PDP context activation procedure¦ To establish a PDP context between the MS and the SGSN, the GGSN
¦ The first PDP context for a given PDP address and APN
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48 Internal Use
PDP Active Procedure (2G)PDP Active Procedure (2G)
2G-GGSN
9. Activate PDP Context Accept
4. Create PDP Context Response
4. Create PDP Context Request
1. Activate PDP Context Request
2G-SGSNBSS
2. Security Functions
MS
7. BSS Packet Flow Context Procedures
C1
C2
3. Invoke Trace
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49 Internal Use
Handle in MSHandle in MS
q MS start and send “Active PDP context request” to SGSN¦ Provide QoS parameter
¦ Provide a APN-NI
¦ Provide a static IP or null
q Receive ACCEPT from SGSN¦ If the QoS not accept by MS, then starts deactive procedure.
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50 Internal Use
Handle in SGSNHandle in SGSNq Check subscriber data q APN selection
¦ According to TS 23.060 ¦ default APN,APN provide from MS and the APN subscribed in HLR¦ APN-NI.APN-OI
q Interrogate DNS¦ Hostfile/Cache/DNS server
q QoS negotiation¦ QoS provided from MS, default QoS ,QoS subscribed in HLR
q Send message “create PDP context request” to GGSNq Send message “active PDP context accept” to MS
¦ Dynamic IP address¦ QoS
q RAB assignment
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51 Internal Use
Handle in GGSNHandle in GGSN
q Check the APN provided by SGSNq QoS negotiationq Allocate a dynamic IP to the MS q Allocate a charging ID for the PDP contextq Return a CREATE PDP CONTEXT ACCEPT message to SGSN
¦ Dynamic IP¦ QoS¦ Charging ID¦ Other information
q Update PDP context
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52 Internal Use
SummarySummary
q In the whole GPRS fundamental, you should remember some important concept and the basic signalling procedure
SummarySummary
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Huawei Confidential. All Rights Reserved
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