Layer 3 messages (2G)
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Transcript of 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