SIB1 carries information required for UE to access the cell and random access parameters.
It will also include the avaibility and scheduling of other SIBs.
It will also inform if one or more SIBs are on-demand and will provide PRACH configuration needed by the UE to request for other SI.
SIB1 is cell specific SIB.
MIB will provide all the required information to UE for decoding SIB1.
It is transmitted with a periodicity of 160ms and will be repeated within 160ms
PDSCH resources for SIB 1 arc allocated using a PDCCH DCI Format I_ 0 transmission within a ‘Type O’ Common Search Space Set.
Transmission Details
Signalling radio bearer: Not Applicable
RLC-SAP: TM
Logical channels: BCCH
Transport Channel: DL-SCH
Physical Channel: PDSCH
Scrambling RNTI : SI-RNTI
Direction: gNB to UE
Contents of SIB1
cellSelectionInfo
cellAccessRelatedInfo CellAccessRelatedInfo
connEstFailureControl ConnEstFailureControl
si-SchedulingInfo SI-SchedulingInfo
servingCellConfigCommon ServingCellConfigCommonSIB
ims-EmergencySupport ENUMERATED {true}
eCallOverIMS-Support ENUMERATED {true}
ue-TimersAndConstants UE-TimersAndConstants
uac-BarringInfo UAC-BarringInfo
useFullResumeID ENUMERATED {true}
We shall understand each IEs in details below:
1. cellSelectionInfo
cellSelectionInfo SEQUENCE {
q-RxLevMin Q-RxLevMin,
q-RxLevMinOffset INTEGER (1..8) OPTIONAL, -- Need R
q-RxLevMinSUL Q-RxLevMin OPTIONAL, -- Need R
q-QualMin Q-QualMin OPTIONAL, -- Need R
q-QualMinOffset INTEGER (1..8) OPTIONAL -- Need R
}
q-RxLevMin: It is used to indicate for cell selection/ re-selection the required minimum received RSRP level in the (NR) cell.
q-RxLevMinOffset: It is an offset in db. Actual value Qrxlevminoffset = field value * 2 [dB]. If absent, the UE applies the (default) value of 0 dB for Qrxlevminoffset. Affects the minimum required Rx level in the cell.
q-RxLevMinSUL: If the UE supports SUL frequency for this cell, Qrxlevmin is obtained from this field. Actual value Qrxlevmin = field value * 2 [dBm].
q-QualMin: It is used to indicate the required ‘minimum received RSRQ level’ (in dB) in the (NR) cell for cell selection and re-selection.
q-QualMinOffset: It is an offset (in dB) that needs to be added to the signaled value of Qqualmin.
2. CellAccessRelatedInfo
The IE CellAccessRelatedInfo indicates cell access related information for this cell.
-- ASN1START
-- TAG-CELLACCESSRELATEDINFO-START
CellAccessRelatedInfo ::= SEQUENCE {
plmn-IdentityList
PLMN-IdentityInfoList,
cellReservedForOtherUse
ENUMERATED {true} OPTIONAL, -- Need R
...,
[[
cellReservedForFutureUse-r16
ENUMERATED {true} OPTIONAL, -- Need R
npn-IdentityInfoList-r16
NPN-IdentityInfoList-r16 OPTIONAL -- Need R
]]
}
plmn-IdentityList: It is used to configure a set of PLMN-IdentityInfo elements. Each of those elements contains a list of one or more PLMN Identities and additional information associated with those PLMNs.
cellReservedForOtherUse: Indicates whether the cell is reserved, as defined in 38.304 [20] for future use. The field is applicable to all PLMNs and NPNs.This field is ignored by IAB-MT.
–PLMN-IdentityInfoList
The IE PLMN-IdentityInfoList includes a list of PLMN identity information.
PLMN-IdentityInfoList ::= SEQUENCE (SIZE (1..maxPLMN)) OF PLMN-IdentityInfo
PLMN-IdentityInfo ::= SEQUENCE {
plmn-IdentityList SEQUENCE (SIZE (1..maxPLMN)) OF PLMN-Identity,
trackingAreaCode TrackingAreaCode OPTIONAL, -- Need R
ranac RAN-AreaCode OPTIONAL, -- Need R
cellIdentity CellIdentity,
cellReservedForOperatorUse ENUMERATED {reserved, notReserved},
...,
[[
iab-Support-r16 ENUMERATED {true} OPTIONAL -- Need S
]]
}
plmn-IdentityList: It will have the list of PLMN identities that are identified by MCC and MNC.
PLMN-Identity ::= SEQUENCE {
mcc
MCC OPTIONAL, -- Cond MCC
mnc
MNC
}
TrackingAreaCode: The IE TrackingAreaCode is used to identify a tracking area within the scope of a PLMN
RAN-AreaCode: The IE RAN-AreaCode is used to identify a RAN area within the scope of a tracking area.
CellIdentity: The IE CellIdentity is used to unambiguously identify a cell within a PLMN.
cellReservedForOperatorUse: If a cell is reserved, camping is not allowed except for particular UEs.
3. ConnEstFailureControl
The IE ConnEstFailureControl is used to configure parameters for connection establishment failure control.
ConnEstFailureControl ::= SEQUENCE {
connEstFailCount
ENUMERATED {n1, n2, n3, n4},
connEstFailOffsetValidity
ENUMERATED {s30, s60, s120, s240, s300, s420, s600, s900},
connEstFailOffset
INTEGER (0..15) OPTIONAL -- Need S
}
connEstFailCount: Number of times that the UE detects T300 expiry on the same cell before applying connEstFailOffset.
connEstFailOffset: Parameter “Qoffsettemp” in TS 38.304 [20]. If the field is absent, the value of infinity shall be used for “Qoffsettemp”.
connEstFailOffsetValidity: Amount of time that the UE applies connEstFailOffset before removing the offset from evaluation of the cell. Value s30 corresponds to 30 seconds, value s60 corresponds to 60 seconds, and so on.
4. SI-SchedulingInfo
The IE SI-SchedulingInfo contains information needed for acquisition of SI messages.
It is discussed in detail in next chapter.
5. ServingCellConfigCommonSIB
The IE ServingCellConfigCommonSIB is used to configure cell specific parameters of a UE’s serving cell in SIB1.
ServingCellConfigCommonSIB ::= SEQUENCE {
downlinkConfigCommon DownlinkConfigCommonSIB,
uplinkConfigCommon UplinkConfigCommonSIB OPTIONAL, -- Need R
supplementaryUplink UplinkConfigCommonSIB OPTIONAL, -- Need R
n-TimingAdvanceOffset
ENUMERATED { n0, n25600, n39936 } OPTIONAL, -- Need S
ssb-PositionsInBurst
SEQUENCE {
inOneGroup
BIT STRING (SIZE (8)),
groupPresence
BIT STRING (SIZE (8)) OPTIONAL -- Cond FR2-Only
},
ssb-PeriodicityServingCell ENUMERATED {ms5, ms10, ms20, ms40, ms80, ms160},
tdd-UL-DL-ConfigurationCommon TDD-UL-DL-ConfigCommon
DownlinkConfigCommonSIB: The IE DownlinkConfigCommonSIB provides common downlink parameters of a cell.
UplinkConfigCommonSIB: The IE UplinkConfigCommonSIB provides common uplink parameters of a cell.
UplinkConfigCommonSIB: The IE UplinkConfigCommonSIB provides common uplink parameters of a cell.
Source TS 38.331
