layer 3 messages (2g)

Prepared by Abdulrahman Fady

L3 Messages is the messages transferred between MS and Network (BSC or MSC ) to control the MS behavior in idle mode and in dedicated mode as well as tell MS when to do Location update

L3 Messages are UL and DL and conveyed on Control channels◦ BCCH ◦ PCH◦ SDCCH◦ SACCH◦ FACCH

What are system Information Messages ◦ Downlink messages ◦ sent on BCCH channel or SACCH channel◦ Used to inform MS by all the needed information to

enable it to do its operations in normal way ◦ SI messages transmitted periodically from BTS and MS

reads them every 30 sec for serving cell and every 5 minutes for six strongest cells ◦ There are a lot of SI types e.g. SI type 1, SI type 2

Direction : DL Channel : BCCH Contents ◦ BCCH Frequency◦ Available frequencies ◦ RACH Control

parameters as MAXRET◦ Cell Barring ◦ Emergency

Direction : DL Channel : BCCH Contents◦ BCCH frequency ◦ MAXRET ◦ Call re-establishment

control ◦ NCC permitted range ◦ Cell Barring

Direction : DL Channel : BCCH Contents

PLMN ID (MCC & MNC) Cell ID LAC MFRMS AGBLK Mapping Method ATT T3212 RL_timeout

Selection Parameters ACCMIN MAX-TX-PWR-UL CRH

Cell reselection CRO PT TO

Half rate support SI scheduling

Direction : DL Channel : BCCH Contents

PLMN ID (MCC & MNC) Cell ID LAC Cell Selection Parameters Cell Reselection Parameters

Direction : DL Channel : BCCH Contents

Other Band BA list

Direction : DL Channel : BCCH Contents

Same Band BA list

Direction : DL Channel : BCCH Contents

GPRS Information EGPRS Supported Power control Network Mode

Direction : DL Channel : SACCH Contents

GPRS Information Cell ID LAC PLMN ID RL timeout DTX info Band

Direction : DL Channel : SACCH Contents

BA list

Direction : DL Channel : SACCH Contents

Part from Active BA list

Direction : DL Channel : SACCH Contents

Part from Active BA list

Multi band reporting

Immediate Assignment ◦ SDCCH assignment during Call Setup

Measurement Report ◦ MS should report 6 strongest neighbors cells to BSC

Handover Command ◦ BSC instruct the MS to do HO to certain Cell

Handover Access ◦ MS starts HO process

Handover Complete ◦ Message sent after HO completed Successfully

Direction : DL Channel : AGCH Contents

Inform MS about SDCCH that will be used in call Setup

Direction : UL Channel : SACCH Contents

Six strongest neighbors

Direction : DL Channel : SACCH Contents

Instruct the MS to handover to a certain cell by sending its information

BCCH BSIC MAIO /HSN

Direction : UL Channel : FACCH Contents

MS tries to access the new cell using this message

Direction : UL Channel : FACCH Contents

MS inform the network that the HO has been completed successfully