Telecom Tutorials by Samir Amberkar

Intra-BSC Handover [Under GSM >> Signaling >> Handover]

Intra BSC Handover is between two BTSs located in one location area or BSC. From the measurement results sent by MS, BSC deducts that the neighboring cell to which HO is to be done lie within its own area. So it triggers Intra-BSC HO.

MS

BTS1

BSC

BTS2

MSC

SACCH, RR - Measurement Report DCM - Measurement Result (DL + UL) DCM - Channel Activate DCM - Channel Activate Ack RLM (Handover Command) FACCH, RR - Handover Command Layer 1 frame of new FACCH - HO Access1 L1 frame - PHYS INFO2 Layer 1 frame of new FACCH - HO Access L1 frame - PHYS INFO (new)FACCH, L2 establish RLM - Establish Ind FACCH, RR - Handover Complete RLM (Handover Complete) BSSMAP - HO Performed DCM - (old) TCH release TCH - Call continues

1: MS keep sending HO Access till it is not able to receive PHYS INFO
2: BTS keep sending PHYS INFO till MS does not start L2 establishment.

References: GSM Networks book by Heine, GSM book by Mouly and Pautet, Signaling diagrams from 24.007/24.008 (R99), 04.18 (RR procedures).

© Copyright Samir Amberkar 2010

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