gsm networks
TRANSCRIPT
GSM NetworksGSM NetworksGSM NetworksGSM Networks
Slide 5
GSM Network OverviewGSM Network Overview
BSCBTS
BTS
Mobile
Station
Access Network:Base Station Subsystem
HLR VLR EIR AuC
MSCPSTN
Um Abis A
Core Network:GSM CS network
SS7
Slide 29
GSM Network ProtocolsGSM Network Protocols
Slide 30
GSM Signaling ProtocolsGSM Signaling Protocols
Layer 1 (physical layer)
Uses many channel structures
Layer 2 (data link layer)
Across Um interface uses LAPDm (a slight modification of LAPD protocol used in ISDN)
Across Abis uses LAPD
Across A interface, uses MTP and SCCP of SS7
SAPI=0 Identifies radio signaling procedures
Layer 3 is sub-divided into 3 sub-layers
Slide 31
Layer 3 Signaling ProtocolsLayer 3 Signaling Protocols
RR: Radio Resources ManagementEstablishment, maintenance, and termination of radio channels that allow point-to-point dialogue between network and mobile stations; including cell selection and handover procedures
MM: Mobility ManagementManages location updating, registration, security and authentication procedures
CM: Connection ManagementHandles general call control, similar to CCITT Recommendation Q.931, and provides supplementary services & Short Message Services (SMS)
Slide 32
HandoverHandover
Four types of handovers:
Channels (time slots) in same cell
Between cells within same BSC
Between BSCs, within same MSC
Between MSCs
PSTN
BTS
BTS
BTS
BTS
BTS
BTS
BTS
BSC BSC
MSC
BTS
BTS
BTS
BTS
BTS
BTS
BTS
BSC BSC
MSC
Slide 33
MAP (Mobile Application Part)MAP (Mobile Application Part)
SS7 top layer protocol
Responsible for signaling between different entities in network, such as between HLR and VLR
MAP specification is complex
Several variants for the big manufacturers (Ericsson, Motorola …)
Slide 35
SummarySummary
GSM is the dominant cellular technology today
GSM offers high quality voice with advanced services
GSM is the stepping-stone to 3G networks