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

L3

Messages

CM

SI

RR

MM

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