Upload
clifton-thompson
View
223
Download
0
Embed Size (px)
DESCRIPTION
Communication Protocol Engineering Lab. Taek-su Shin 3 Overview Mobility management -Location update (registration) -Call origination -Call termination Fault tolerance -Location database fail Can’t GSM service -Failure restoration procedure Algorithm to speed up the HLR failure recovery procedure Database overflow -Fail registration -VLR overflow control scheme
Citation preview
Taek-su Shin 1CommunicationProtocolEngineering Lab.
GSM Mobility Management
April, 15, 2003 Taek-su Shin
([email protected])Communication Protocol Engineering Lab.
Taek-su Shin 2CommunicationProtocolEngineering Lab.
Contents Overview GSM Location Update Mobility Databases Failure Restoration VLR Identification Algorithm VLR Overflow Control
Taek-su Shin 3CommunicationProtocolEngineering Lab.
Overview Mobility management
- Location update (registration)- Call origination- Call termination
Fault tolerance- Location database fail
• Can’t GSM service- Failure restoration procedure
• Algorithm to speed up the HLR failure recovery procedure Database overflow
- Fail registration- VLR overflow control scheme
Taek-su Shin 4CommunicationProtocolEngineering Lab.
Contents Overview GSM Location Update Mobility Databases Failure Restoration VLR Identification Algorithm VLR Overflow Control
Taek-su Shin 5CommunicationProtocolEngineering Lab.
LA2
Basic Location Update Procedure(1/3)
Case 1: Inter-LA Movement
HLR
VLR1 VLR1
MSC1 MSC2
LA1 MS
HLR: Home Location RegisterVLR: Visitor Location RegisterMSC: Mobile Switching CenterLA: Location AreaMS: Mobile Station
A location update request messageMAP_UPDATE_LOCATION_AREAMAP_UPDATE_LOCATION_AREA_ackA location update request message_ack
Taek-su Shin 6CommunicationProtocolEngineering Lab.
Basic Location Update Procedure(2/3)
Case 2: Inter-MSC Movement
LA2
HLR
VLR1 VLR1
MSC1 MSC2
LA1 MS
A location update request messageMAP_UPDATE_LOCATION_AREAMAP_UPDATE_LOCATIONMAP_UPDATE_LOCATION_ackMAP_UPDATE_LOCATION_AREA_ackA location update request message_ack
Taek-su Shin 7CommunicationProtocolEngineering Lab.
Basic Location Update Procedure(3/3)
Case 3: Inter-VLR Movement
LA2
HLR
VLR1 VLR1
MSC1 MSC2
LA1 MS
A location update request messageMAP_UPDATE_LOCATION_AREAMAP_SEND_IDENTIFICATIONMAP_SEND_IDENTIFICATION_ackMAP_UPDATE_LOCATIONMAP_UPDATE_LOCATION_ack
MAP_UPDATE_LOCATION_AREA_ack
MAP_CANCEL_LOCATIONMAP_CANCEL_LOCATION_ack
A location update request message_ack
Taek-su Shin 8CommunicationProtocolEngineering Lab.
Basic Call Origination Procedure Call origination operation
VLR
u1
MSC
MSu1
PSTN
the call origination requestMAP_SEND_INFO_FOR_OUTGOING_CALLMAP_SEND_INFO_FOR_OUTGOING_CALL_ackIAM
Taek-su Shin 9CommunicationProtocolEngineering Lab.
Basic Call Termination Procedure Call termination message flow
MSCMSu1
PSTN HLR VLR1GMSC
ISUP IAMMAP_SEND_ROUTING_INFORMATIONMAP_PROVIDE_ROAMING_NUMBERMAP_PROVIDE_ROAMING_NUMBER_ackMAP_SEND_ROUTING_INFORMATION_ackISUP IAM
Taek-su Shin 10CommunicationProtocolEngineering Lab.
Contents Overview GSM Location Update Mobility Databases Failure Restoration VLR Identification Algorithm VLR Overflow Control
Taek-su Shin 11CommunicationProtocolEngineering Lab.
HLR Home location register
Mobile station information- IMSI (International Mobile Subscriber Identity)- MSISDN (MS ISDN number)
Location information- ISDN number of the VLR- ISDN number of the MSC
Service information- Service subscription- Service restrictions- Supplementary services
Taek-su Shin 12CommunicationProtocolEngineering Lab.
VLR Visitor location register
Mobile station information- IMSI- MSISDN- TMSI (Temporary Mobile Subscriber Identity)
Location information- MSC number- Location area ID (LAI)
Service information- Subset of the service information stored in the HLR
Taek-su Shin 13CommunicationProtocolEngineering Lab.
Contents Overview GSM Location Update Mobility Databases Failure Restoration VLR Identification Algorithm VLR Overflow Control
Taek-su Shin 14CommunicationProtocolEngineering Lab.
VLR Failure Restoration(1/2) MS registration
- A case of inter-VLR movement- Recovered by the normal registration procedure- Can’t be recognized TMSI- Be asked to send IMSI
MS call origination- System error : “unidentified subscriber”- Be asked to initiate the location registration procedure
Taek-su Shin 15CommunicationProtocolEngineering Lab.
VLR Failure Restoration(2/2) MS call termination
MSCMSu1
PSTN HLR VLRGMSC
ISUP IAMMAP_SEND_ROUTING_INFORMATIONMAP_PROVIDE_ROAMING_NUMBER
MAP_PROVIDE_ROAMING_NUMBER_ack
MAP_RESTORE_DATAMAP_RESTORE_DATA_ackMAP_INSERT_SUBSCRIBER_DATAMAP_INSERT_SUBSCRIBER_DATA_ack
MAP_SEND_ROUTING_INFORMATION_ackISUP IAMMAP_SEND_INFO_FOR_INCOMING_CALLMAP_SEARCH_FOR_MOBILE_SUBSCRIBERMAP_PROCESS_ACCESS_REQUESTMAP_PROCESS_ACCESS_REQUEST_ack
Taek-su Shin 16CommunicationProtocolEngineering Lab.
HLR Failure Restoration Uncovered period
HLR restoration procedure
HLR VLR
MAP_RESETMAP_UPDATE_LOCATIONMAP_UPDATE_LOCATION_ack
Taek-su Shin 17CommunicationProtocolEngineering Lab.
Contents Overview GSM Location Update Mobility Databases Failure Restoration VLR Identification Algorithm VLR Overflow Control
Taek-su Shin 18CommunicationProtocolEngineering Lab.
VIA VLR Identification Algorithm
HLR architectureMS VLR
VLRV1
V2
V3
V4
MS PVLR VLRtsVLRV1
V2
V3
V4
Count3147
TS
HLR*VLR_List*
HLRVLR_Counter
Backup (Nonvolatile Storage)
Taek-su Shin 19CommunicationProtocolEngineering Lab.
VIA Procedure(1/4) Check-pointing
Step 1. For every location entry p in HLR* do:HLR[p]* · VLR ← HLR[p] · VLR;
Step 2. TS ← current time;
Step 3. For every location entry p in HLR do:HLR[p] · ts ← TS;HLR[p] · PVLR ← HLR[p] · VLR;
Step 4. VLR_Counter ← Ø, VLR_List* ← Ø;
Taek-su Shin 20CommunicationProtocolEngineering Lab.
VIA Procedure(2/4) Registration
Step 1. Update HLR:Vold ← HLR[p] · VLR; Send message, MAP_CANCEL_LOCATION, to cancel the VLR entry of p at Vold:HLR[p] · VLR ← Vnew;told ← HLR[p] · ts;HLR[p] · ts ← t;
Step 2. Update the Vnew Count field in VLR_Counter: IfHLR[p] · VLR ≠ HLR[p] · PVLR then: Step 2.1. If VLR_Counter[Vnew] exists, then: VLR_Counter[Vnew] · Count ← VLR_Counter[Vnew] · Count + 1; Step 2.2 Else create VLR_Counter[Vnew] and VLR_List*[Vnew];VLR_Counter[Vnew] ← 1;
Taek-su Shin 21CommunicationProtocolEngineering Lab.
VIA Procedure(3/4) Registration
Step 3. Update the Vold counter entry: If told > TS and Vold ≠ HLR[p] · PVLR then: Step 3.1. VLR_Counter[Vold] · Count ← VLR_Counter[Vold] · Count –
1; Step 3.2. If VLR_Counter[Vold] · Count = 0 then:
Step 3.2.1. Delete VLR_Counter[Vold] and
VLR_List*[Vold];
Taek-su Shin 22CommunicationProtocolEngineering Lab.
VIA Procedure(4/4) Restore
Step 1. TS ← current time;
Step 2. For every location entry p in HLR, do:HLR[p] · PVLR = HLR[p] · VLR ← HLR[p]* · VLR;HLR[p] · ts ← TS;
Step 3. For every VLR entry V in VLR_List*, send an SS7 TCAP MAP_RESET message to V;
Taek-su Shin 23CommunicationProtocolEngineering Lab.
Contents Overview GSM Location Update Mobility Databases Failure Restoration VLR Identification Algorithm VLR Overflow Control
Taek-su Shin 24CommunicationProtocolEngineering Lab.
Algorithm O-I Registration
VLR V2
u3
HLRu1u3
V1V2 MS
Request
u1
V2
Response
Taek-su Shin 25CommunicationProtocolEngineering Lab.
Algorithm O-II Cancellation
HLR* u1 V1V2
Taek-su Shin 26CommunicationProtocolEngineering Lab.
Algorithm O-III Call Origination
VLR V2 MS
MAP_SEND_INFO_FOR_OUTGOING_CALLMAP_SEND_INFO_FOR_OUTGOING_CALL_ack(deny_reason: no record)
MAP_UPDATE_LOCATION_AREAMAP_UPDATE_LOCATION_AREA_ackMAP_SEND_INFO_FOR_OUTGOING_CALLMAP_SEND_INFO_FOR_OUTGOING_CALL_ack
Taek-su Shin 27CommunicationProtocolEngineering Lab.
Algorithm O-IV Call Termination
Originatingswitch
VLR V2
u3
HLR**
u1u3
V2V2
Location query
u1
Location response
MSC MSu1