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Outline Evolution of IN GPRS overview CAMEL in GPRS Discussion
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Plain Old Telephone Service Service logic were hardwired in switching systems.
Network operators discuss services customers required with switch vendors. (no standard)
Once services were implemented, they were not easily modified.
service logichardwired
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Stored Program Control In the mid-1960s, stored program control (SPC) switching systems were introduced.
As a result, it was easier to introduce new services.
Service logic was not modular.
service logicprogrammable
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Common Channel Signaling In the mid-1970s, common channel signaling
network (CCSN) was introduced. Signaling system number 7 (SS7) is the protocol
that runs over the CCSN. SS7 network separates the call setup information
and talk path from the common trunk that runs between switching systems.
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SS7 network components signal switching points (SSPs)—SSPs are telephone
switches equipped with SS7-capable software and terminating signaling links. They generally originate, terminate, or switch calls.
signal transfer points (STPs)—STPs are the packet switches of the SS7 network. They receive and route incoming signaling messages to destination.
signal control points (SCPs)—SCPs are databases providing information necessary for advanced call-processing capabilities
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SS7 network
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The Introduction of IN During the mid-1980s, Telcordia Technologies responded to RBOCs’s request and developed the concept of Intelligent Network 1 (IN/1).
Service logic splits from switching system, now resides in service control points (SCP).
service logicnow here
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Call Model PICs represent switching system states that a call goes
through from origination to termination. SSPs check TDPs to see if there are any active triggers. If an active trigger is detected, normal switching syste
m call processing is suspended until the SSP and SCP complete communications.
SSP suspended,and ask SCP what to do in next step
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GPRS logical architecture
Gf
Uu
Um
D
Gi
Gn
Iu Gc
C E
Gp
Gs
Signalling and Data Transfer Interface Signalling Interface
M SC/VLR
TE M T UTRAN TE PDN
Gr Iu
HLR
Other PLM N
SGSN
GGSN
Gd
SM -SC SM S-GM SC SM S-IW M SC
GGSN
EIR SGSN
Gn CGF
Ga Ga
Billing System
Gb TE M T BSS
R
A R
CAM EL GSM -SCF
Ge
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Transmission plane in 2.5G
Relay
NetworkService
GTP-U
ApplicationIP
SNDCP
LLC
RLC
M AC
GSM RF
SNDCP
LLC
BSSGP
L1bis
RLC
M AC
GSM RF
BSSGP
L1bis
Relay
L2
L1
IPL2
L1
IP
GTP-U
IP
Um Gb Gn GiM S BSS SGSN GGSN
NetworkService
UDPUDP
Frame relay
Radio dep
Radio indep
Multiplexing layer
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Signaling plane in 2.5G
BSSGPRelay
GM M /SMLLC
RLC
M AC
GSM RF
GM M /SMLLC
BSSGP
L1bisUm Gb
M S BSS 2G-SGSN
NetworkService
RLC
M AC
GSM RF L1bis
NetworkService
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Multiplexing of network protocols
Packet DataProtocol
SNDCP
LLC Information
Signalling SM S
LLC
NSAPI
NSAPI + Control
DataControl
SNDC Header
LLC HeaderTLLI
RLC or BSSGP
Data
N-PDU
SAPI
IP/X.25
Transmission planeSignaling plane
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User plane in 3G
L1
RLC
PDCP
M AC
E.g., IP,PPP
Application
L1
RLC
PDCP
M ACATM
UDP/IP
GTP-U
AAL5
Relay
L1
UDP/IPL2
GTP-U
E.g., IP,PPP
3G-SGSNUTRANM SIu-PSUu Gn Gi
3G-GGSN
ATM
UDP/IP
GTP-U
AAL5L1
UDP/IP
GTP-U
L2
Relay
ATM
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Control plane in 3G
RLCRRC
L1
GM M /SM / SM S
RRC
M AC
ATM
RANAP
AAL5
Relay
ATMAAL5
3G SGSNRNSM SIu-PsUu
RLC SCCPSignallingBearer
M AC
L1
SignallingBearer
RANAPSCCP
GM M /SM / SM S
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CAMEL architectureHLR gsm SCF
M S
Visiting NetworkInterrogating Network
Hom e Network
C AP
Hom e/Interrogating/Visiting Network
SG SNgprsSSF
M AP
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MAP/CAP protocol stack
M AP
TCAP
SCCP
M TP3
M TP2
L1
M AP
TCAP
SCCP
M TP3
M TP2
L1
SGSN HLRGr
CAP has the same underlying protocol stack as MAP. Ge interface is first defined in 3G, but didn’t appear in 2.5G.
CAP
TCAP
SCCP
M TP3
M TP2
L1
CAP
TCAP
SCCP
M TP3
M TP2
L1
gprsSSF gsmSCFGe
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Overall CAMEL Architecture
gsmSCF
GPRSDialogueHandler
gprsSSF
SGSN GGSNM obileStation
CAP Interface
Internal CAP Interface
Internal Interface
GTP
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Detection Points (DPs) GPRS events maybe made visible to gsmSCF. DPs are points at which these events are detected.
DPs can be armed to notify gsmSCF GPRS event was encountered, and to allow gsmSCF to influence subsequent handling of GPRS session/PDP Context.
If DP isn’t armed, processing entity continues processing without gsmSCF involvement at the DP.
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Detection Points (DPs) 3 different types of DP:
Trigger Detection Point-Request (TDP-R)
Event Detection Point-Request (EDP-R)
Event Detection Point-Notification (EDP-N)
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Detection Points (DPs) TDP-R
Statically armed, initiate a CAMEL control relationship
When GPRS event is encountered, processing is suspended
EDP-R Dynamically armed within CAMEL control relationship When GPRS event is encountered, processing is suspended and gprsSSF waits for inst from gsmSCF
EDP-N Dynamically armed within CAMEL control relationship When GPRS event is encountered, processing is not suspended.
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GPRS Attach/Detach State Model
3 DPs are defined: DP Attach DP Change of Position GPRS session
DP Detach
Inter SG SNRouteing areaupdate
Attached
Attach request
Detached
User- or network initiateddetach
AD_Exception
Attach
Detach
Change of Position GPRS S ession
Intra SGSN Routeingarea update
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GPRS PDP Context State Model
4 DPs are defined: DP PDP Context Establishment
DP PDP Context Establishment Ack
DP PDP Context Disconnection
DP Change of Position Context
PDP ContextSetup Req
PDP_Context_Setup
PDP_Context_Established
Idle
C_ExceptionPDP Context Est.
PDP ContextSetup Ack.
PDP Context Est. Ack.
Routeing area update
User or networkinitiated disc.
PDP ContextDisconnection
Routeing area update
Change ofPosition context
Change of Position Context
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GPRS CAMEL Scenarios 2 scenarios for CAMEL control of GPRS
Scenario 1 Allows CAMEL control of GPRS session and of multiple PDP contexts within 1 GPRS dialogue
Scenario 2 Allows CAMEL control of a single PDP contexts Multiple PDP contexts are controlled via multiple GPRS dialogues.
Scenario 1 and scenario 2 are mutually exclusive.
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GPRS CAMEL Scenario 1 Involves Attach/Detach state model Uses less resource (tcap dialogue) More complicated when implementation
SGSN / SSP SCP
A/DSM
PDP#2SM
PDP#1SM
GPRS Dialogue
Inform ation flow related toPDP Context #1
Inform ation flow related tothe Session
Inform ation flow related toPDP Context #2
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GPRS CAMEL Scenario 2 Doesn’t involves Attach/Detach state model Uses more resource (tcap dialogue) Simpler when implementation
SGSN / SSP SCP
PDP#2SM
PDP#1SM
G PRS Dialogue #2
Inform ation flow related toPDP context #1
Inform ation flow related toPDP context #2
G PRS Dialogue #1
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GPRS Attach The message sequence chart is too large to fit in this slide. Please see the supplementary document from 3GPP 23060 spec.
Notice the “Insert subscriber data” procedure, GPRS-CSI (CAMEL Subscription Information) is sent from HLR to SGSN.
2.5G HLR does not keep GPRS-CSI, nor does it send GPRS-CSI to SGSN.
3G HLR could keep GPRS-CSI, also it sends GPRS-CSI when doing “Insert subscriber data” procedure.
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GPRS-CSI GPRS-CSI contains following information
gsmSCF Address Service Key Default GPRS Handling TDP List CAMEL Capability Handling CSI state Notification flag gsmSCF address list for CSI
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PDP Context Activation in 2.5G
C1 :DP for CAMEL_GPRS_PDP_Context_Establishment C2 :DP for CAMEL_GPRS_PDP_Context_Establishment_Acknowledgement
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
M S
7. BSS Packet Flow Context Procedures
C1
C2
3. Invoke Trace
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PDP Context Activation in 3G
C1 :DP for CAMEL_GPRS_PDP_Context_Establishment. C2 :DP for CAMEL_GPRS_PDP_Context_Establishment_Acknowledgement
3G-GGSN
9. Activate PDP Context Accept
4. Create PDP Context Response
4. Create PDP Context Request
1. Activate PDP Context Request
3G-SGSNUTRANM S
5. Radio Access Bearer Setup
C1
C2
6. Invoke Trace
8. Update PDP Context Response
8. Update PDP Context Request
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CAMEL procedures for charging activities
Procedure ssf -> scf
scf ->ssf
ApplyChargingGPRS -ApplyChargingReportGPRS
-
InitialDPGPRS -ContinueGPRS -EventReportGPRS -RequestReportGPRSEvent
-
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