Telecom Tutorials by Samir Amberkar

Location Update continued [Under GSM >> Signaling]    §

Step 3: TMSI reallocation, Location Update Accept and release

MS

BTS

BSC

MSC

VLR

MAP - Forward New TMSI DTAP (TMSI Reallocation Command) RLM (TMSI Reallocation Command) SDCCH, MM - TMSI Reallocation Command SDCCH, MM - TMSI Reallocation Complete RLM (TMSI Reallocation Complete) DTAP (TMSI Reallocation Complete) MAP - TMSI Ack

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VLR1

HLR

VLR2

MAP - Update Location MAP - Cancel Location MAP - Cancel Location done MAP - Insert Subscriber Data MAP - Insert Subscriber Data done MAP - Update Location done

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MS

BTS

BSC

MSC

VLR

DTAP (Location Update Accept) RLM (Location Update Accept) SDCCH, MM - Location Update Accept BSSMAP (Clear Command) RLM (Channel Release) SDCCH, RR - Channel Release DCM - deact SDCCH L2 Disconnect1 RLM (Release) BSSMAP (Clear Complete) DCM Release SCCP Release

1: To disconnect Layer 2, MS sends DISC frame and BTS acknowledges release with UA frame.

We will continue "Voice Call" in next article.

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

© Copyright Samir Amberkar 2010

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