In the previous 2 chapters we learn about MIB and different types of SIBs.
In this chapter we shall learn more about SBI1 and SIB2. As these 2 SIBs play an very important rule in UE power On procedure.
System Information Block Type 1: (cell selection, cell access)
Once UE completes its initial synchronisation with the network, then it will obtain MIB. Then UE starts to listen SIB1. SIB 1 will carry cell access information.
Direction: E-UTRAN => UE
RLC Mode: TM
Logical Channel: BCCH
Transport Channel: DL-SCH
Below are the information that has been sent through SIB1. Officially they are called as IEs (Information Elements)
1. Cell Access Information –
PLMN Identity List
PLMN Identity, TA Code
Tracking Area Code
Cell Identity
Intra Frequency Reselection
Cell Barred: It identifies the cell access status. If it is barred, then UE is not allowed to access the cell.
CSG Indication
CSG Identity
2. Cell Selection Information – Minimum Receiver Level
3. Scheduling Information –
SI message type
SI Periodicity
SIB mapping Info
SI Window length
Every 80ms a new SIB1 is transmitted. Every 20ms retransmission on SIB1 happens. It is always sent in sub-frame #5 of the Radio-Frame.
SIB1 is transmitted through BCCH -> DL-SCH -> PDSCH channels.
Direction: E-UTRAN => UE
RLC Mode: TM
System Information Block Type 2:(RACH, UL frequency Information, MBSFN)
SIB2 has radio resource configuration information that is common for all the UEs.
It will also provides information about uplink carrier frequency and the uplink channel bandwidth in terms of number of Resource Blocks.
1. Access Barring Information –
Access Probability factor
Access Class Baring List
Access Class Baring Time
2. Semi static Common Channel Configuration – Random Access Parameter, PRACH Configuration
3. UL frequency Information –
UL Bandwidth
additional spectrum emission
UE Timers and Constants:
T300: It will start at RRC connection REQ transmit and stops at the receipt of RRC connection setup or reject message.
T301: It will start at RRC connection Re-establishment Request and stops at receipt of RRC connection re-establishment or RRC connection Re-establishment reject.
T310: Started after receiving N310 out of sync indications (0, 50, 100, 200, 500, 1000, 2000 ms)
T311: It will start while initiating RRC CONNECTION RE-ESTABLISHMENT procedure
N310: Number of consecutive out-of-sync indications from lower layers. If reached, it triggers T310 timer.
N311: Number of consecutive in-sync indications from lower layers,time bound by T311.
SIB2 is transmitted through BCCH -> DL-SCH -> PDSCH channels.
Direction: E-UTRAN => UE
RLC Mode: TM