Telecom Tutorials by Samir Amberkar

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

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

MN

CC

MM

RR

AIR

User dials call. Adaptation layer (MN) receive ATD command. MN sends setup-req to PS/CC. MNCC-SETUP-REQ MMCC-EST-REQ RR-EST-REQ (CM SERV REQ) RACH, CHAN REQ Reason: MO call AGCH, IMM ASS SDCCH, CM SERV REQ Got dedicated signaling channel. L2 connection established with SABM/UA. RR-EST-CNF RR connection established MM/AUTH REQ MM/AUTH RES RR/CIPH MODE CMD RR/CIPH MODE CMP RR-SYNC-IND MMCC-EST-CNF MM connection established CC/SETUP CC/CALL PROC MNCC-CALL-PROC-IND RR/ASSIGN CMD L2 SABM/UA RR/ASSIGN CMP TCH assigned, Signaling will be over FACCH. RR-SYNC-IND MMCC-SYNC-IND FACCH, CC/ALERT Called party ringing. MNCC-ALERT-IND CC/CONNECT Called party answered. MNCC-SETUP-CNF CC/CONN ACK 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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