LTE: System Information Block Type 1

Direction: E-UTRAN => UE
Signalling Radio Bearer: N/A
RLC Mode: TM
Logical Channel: BCCH
Transport Channel: DL-SCH

SystemInformationBlockType1 (SIB1) contains information relevant when evaluating if a UE is allowed to access a cell. Also, it supplies the UE with the scheduling of other system information. SIBs other than SIB1 are carried in SystemInformation (SI) messages and mapping of SIBs to SI messages is flexibly configurable by schedulingInfoList included in SIB1

SIB1 uses a fixed schedule with a periodicity of 80ms and repetitions made within 80ms. The first transmission of SIB1 is scheduled in subframe #5 of radio frames for which the SFN_mod8 = 0, and repetitions are scheduled in subframe #5 of all other radio frames for which SFN_mod2 = 0

SIB1 contains cell access related information (e.g. a PLMN identity list, tracking area code, cell identity, etc.), information for cell selection (e.g. minimum required Rx level in the cell and offset), p-Max, frequency band indicator, scheduling information, TDD configuration, SI-window length and system information value tag etc...

Upon receiving the SIB1 message the UE shall check the IE freqBandIndicator. The UE shall consider the cell as barred if the frequency band indicated in the freqBandIndicator is not part of the frequency bands supported by the UE

Some of the IEs in SystemInformationBlockType1 message:

PLMN-IdentityList: List of PLMN identities. The first listed PLMN-Identity is the primary PLMN

TrackingAreaCode: A trackingAreaCode that is common for all the PLMNs listed

Cellidentity: Identity of the cell

CellBarred: 'barred’ means the cell is barred

IntraFreqReselection: Used to control cell reselection to intra-frequency cells when the highest ranked cell is barred, or treated as barred by the UE

CSG-Indication: If this IE is set to TRUE the UE is only allowed to access the cell if the CSG identity matches an entry in the CSG whitelist that the UE has stored

p-Max: Maximum power value applicable for the cell. If this IE is absent, then the UE applies the maximum power according to the UE capability

freqBandIndicator: Operating frequency band of the cell as defined in TS 36.101 [Table 5.5-1].

si-Periodicity: Periodicity of the SI-message in radio frames, such that rf8 denotes 8 radio frames, rf16 denotes 16 radio frames, and so on

sib-MappingInfo: List of the SIBs mapped to this SystemInformation message. There is no mapping information of SIB2; it is always present in the first SystemInformation message listed in the schedulingInfoList list.

si-WindowLength: Common SI scheduling window for all SIs. Unit in milliseconds, where ms1 denotes 1 millisecond, ms2 denotes 2 milliseconds and so on

systemInfoValueTag: Common for all SIBs other than MIB, SIB1, SIB10, SIB11 and SIB12. Change of MIB and SIB1 is detected by acquisition of the corresponding message

csg-Identity: Identity of the Closed Subscriber Group within the primary PLMN the cell belongs to. This field is present in a CSG cell

ims-EmergencySupport: Indicates whether the cell supports IMS emergency bearer services for UEs in limited service mode. If absent, IMS emergency call is not supported by the network in the cell for UEs in limited service mode

Reference: 3GPP TS 36.331

Example: SystemInformationBlockType1 message