Telecom Tutorials by Samir Amberkar

Inside MS Layer 3 - MT [Under GSM >> Signaling]

Let us have a brief look at primitive interfaces inside MS Layer 3 for Mobile Terminated Call.

MN

CC

MM

RR

AIR

PCH, PAG REQ Paging is done in all cells within location area to which MS is currently located. RACH, CHAN REQ Reason: Page response AGCH, IMM ASS SDCCH, PAGE RES Got dedicated signaling channel. L2 connection established with SABM/UA. RR-EST-IND MM/AUTH REQ MM/AUTH RES RR/CIPH MODE CMD RR/CIPH MODE CMP RR-SYNC-IND MMCC-EST-IND contain SETUP message. CC/SETUP MNCC-SETUP-IND RR/ASSIGN CMD L2 SABM/UA RR/ASSIGN CMP TCH assigned, Signaling will be over FACCH. RR-SYNC-IND MN informs incoming call to user with AT+CRING indication MS ringing now. MM-SYNC-IND MNCC-ALERT-REQ User accepts the call. CC/ALERT MNCC-SETUP-RES CC/CONNECT CC/CONNECT ACK MNCC-SETUP-CMPL-IND Call in progress. Measurment, TA and Power control over SACCH.

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

Copyright © Samir Amberkar 2010

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