5G
NR system information in general is discussed in detail in the post 5G NR:System Information. This
post discusses SIB1 in detail.
System
Information (SI) in NR consists of a MIB and a number of SIBs, which are
divided into Minimum SI and Other SI.
Minimum
SI carries basic information required for initial access
and for acquiring any other SI. Minimum SI consists of MIB and SIB1.
For a UE to be allowed to camp on a cell, it
must have acquired the contents of the Minimum SI from that cell.
As
MIB and SIB1 are called as ‘minimum SI’, SIB1 alone
is known as ‘Remaining Minimum System Information’ (RMSI).
SIB1
carries the most critical information required for the UE to access the cell
e.g., random access parameters.
SIB1
includes information regarding the availability and scheduling of other SIBs e.g.
mapping of SIBs to SI message, periodicity, SI-window size etc…
SIB1
also indicates whether one or more SIBs are only provided on-demand, in which
case, it may also provide PRACH configuration needed by the UE to request for
the required SI.
SIB1
also contains radio resource configuration information that is common for all
UEs and cell barring information applied to the unified access control.
SIB1
is transmitted on the DL-SCH (logical channel: BCCH) with a periodicity of 160
ms and variable transmission repetition periodicity within 160 ms.
SIB1
is cell-specific SIB.
In order for the UE to decode SIB1, all the required information is obtained from MIB. Visit 5G NR: PBCH and MasterInformation Block (MIB).
Contests of SIB1
Overview
of SIB1 contents presented below. Most of the SIB1 contents are
discussed in detail in subsequent sections.
| 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} |
cellSelectionInfo
The
following table summarizes cellSelectionInfo fields.
| cellSelectionInfo | ||
| q-RxLevMin | Q-RxLevMin | INTEGER (-70 … -22) |
| q-RxLevMinOffset | INTEGER (1 … 8) | |
| q-RxLevMinSUL | Q-RxLevMin | INTEGER (-70 … -22) |
| q-QualMin | Q-QualMin | INTEGER (-43 … -12) |
| q-QualMinOffset | INTEGER (1 … 8) |
Q-RxLevMin is used to indicate the required ‘minimum received RSRP
level’ (in dBm) in the (NR) cell for cell selection and re-selection. Actual value Qrxlevmin
= field value * 2 [dBm]. Refer to 38.304 cell
selection/re-selection criterion.
q-RxLevMinOffset is an offset (in dB) that needs to be added to the signaled
(not actual) value of Qrxlevmin. This is taken into account
in the Srxlev evaluation (38.304) after a periodic search for a higher
priority PLMN while the UE is camped normally on a VPLMN. If this field is
absent, the UE applies a (default) value of 0 dB as an offset.
Q-RxLevMinSUL: If the UE supports SUL frequency for this cell, Qrxlevmin
(explained above) is obtained from this field. Actual value Qrxlevmin = field value * 2
[dBm].
Q-QualMin is used to indicate the required ‘minimum received RSRQ
level’ (in dB) in the (NR) cell for cell selection and re-selection. If this
field is absent, the UE applies the (default) value of negative infinity for Qqualmin
which means that quality (RSRQ) check will always pass irrespective of the
received signal quality. Refer to 38.304 cell selection/re-selection criterion.
q-QualMinOffset is an offset (in dB) that needs to be added to the
signaled value of Qqualmin. This is taken into account in the
Squal evaluation (38.304) after a periodic search for a higher priority
PLMN while the UE is camped normally on a VPLMN. If this field is absent, the
UE applies a (default) value of 0 dB as an offset.
CellAccessRelatedInfo
CellAccessRelatedInfo
is used to indicate cell access related information for the serving cell. The
following table summarizes
CellAccessRelatedInfo contents.
| CellAccessRelatedInfo | |
| plmn-IdentityList | List of 1 to 12 PLMN-IdentityInfo |
| cellReservedForOtherUse | ENUMERATED {true} |
cellReservedForOtherUse indicates whether the cell
is reserved. The field is applicable to all PLMNs. If a cell is reserved, camping
is not allowed except for particular UEs.
plmn-IdentityList used to configure a set of PLMN-IdentityInfoList elements.
Each of those elements contains a list of one or more PLMN identities and
additional information associated with those PLMNs such as TAC, RANAC, cellIdentity
etc...
| PLMN-IdentityInfo | ||
| plmn-IdentityList | List of 1 to 12 PLMN-Identity (s) | |
| trackingAreaCode | TrackingAreaCode | BIT STRING (SIZE (24)) |
| ranac | RAN-AreaCode | INTEGER (0 … 255) |
| cellIdentity | CellIdentity | BIT STRING (SIZE (36)) |
| cellReservedForOperatorUse | ENUMERATED {reserved,notReserved} | |
cellReservedForOperatorUse indicates whether the cell is reserved for operator
use (per PLMN). If a cell is reserved, camping is not allowed except for
particular UEs.
plmn-IdentityList within PLMN-IdentityInfo indicates a list of
PLMN identities, each of those is identified by an MCC and an MNC.
trackingAreaCode indicates
Tracking Area Code to which the cell indicated by cellIdentity belongs
to. It is used to identify a tracking area within the scope of a PLMN. The absence of the field indicates that the cell only supports PSCell/SCell functionality (per PLMN).
RAN-AreaCode is used to identify a RAN area within the scope of a Tracking
Area. RAN area code is used when configuring RAN Notification Area. When a UE
in RRC_INACTIVE state reselects to a new cell that belongs to a different RAN
Notification area, the UE needs to perform RNA update.
CellIdentity is used to unambiguously identify a cell within a
PLMN.
ConnEstFailureControl
ConnEstFailureControl is
used to configure parameters for connection establishment failure control. When
an RRCSetupRequest is sent by the UE, timer T300 is started and
the UE considers the connection establishment attempt as failed if it doesn’t
receive a response from the gNB before T300 expires.
If
the timer T300 expires connEstFailCount times, then the UE starts
a timer given by connEstFailOffsetValidity and reduces RSRP/RSRQ quality
by connEstFailOffset parameter Qoffsettemp in 38.304)
when performing cell selection/re-selection. Basically, for a period of time
given by connEstFailOffsetValidity, the UE makes the cell a bit worse by
adding a negative offset to Srxlev and Squal. The following table summarizes ConnEstFailureControl
fields.
| ConnEstFailureControl | |
| connEstFailCount | ENUMERATED {n1, n2, n3, n4} |
| connEstFailOffsetValidity | ENUMERATED {s30, s60, s120, s240, s300, s420, s600, s900} |
| connEstFailOffset | INTEGER (0..15) |
connEstFailCount is number of times that the UE detects T300 expiry on
the same cell before applying connEstFailOffset.
connEstFailOffset is the parameter Qoffsettemp in
38.304. If this field is absent, the value of infinity shall be used for Qoffsettemp.
connEstFailOffsetValidity is the amount of time (in
seconds) that the UE applies connEstFailOffset before removing the
offset from evaluation of the cell.
SI-SchedulingInfo
SI-SchedulingInfo
contains information needed for acquisition of SI
messages. SI scheduling procedure is thoroughly discussed in
the post 5G NR: SystemInformation. The following table summarizes SI-SchedulingInfo
contents.
| SI-SchedulingInfo | |
| schedulingInfoList | List of 1 to 32 SchedulingInfo |
| si-WindowLength | ENUMERATED {s5, s10, s20, s40, s80, s160, s320, s640, s1280} |
| si-RequestConfig | SI-RequestConfig |
| si-RequestConfigSUL | SI-RequestConfig |
| systemInformationAreaID | BIT STRING (SIZE (24)) |
si-WindowLength is
the length of the SI scheduling window in slots. Value s5 corresponds to
5 slots, value s10 corresponds to 10 slots and so on. The network always
configures si-WindowLength to be shorter than or equal to the si-Periodicity.
systemInformationAreaID
indicates the system information area that the cell
belongs to, if any. Any SIB with areaScope within the SI is considered
to belong to this systemInformationAreaID. The systemInformationAreaID
is unique within a PLMN.
Schedulinginfolist
contains a list of scheduling information (maximum 32)
for SI-messages. SchedulingInfo provides
information whether the corresponding SI-message is being broadcasted or not,
periodicity of SI-message and a list of SIBs mapped to this SI-message. For
each SIB, SIB type, valueTag, areaScope flag are provided.
areaScope indicates whether the SIB is area specific or not.
si-RequestConfig is
the configuration of Msg1 resources that the UE uses for requesting
SI-messages for which si-BroadcastStatus is set to notBroadcasting. If
the field is absent the UE uses Msg3 to request SI-messages. The IE si- RequestConfigSUL is the corresponding
configuration on SUL. The table below provides overview of SI-RequestConfig.
| SI-RequestConfig | |
| rach-ConfigSI | RACH-ConfigGeneric |
| ssb-perRACH-Occasion | ENUMERATED {oneEighth, oneFourth, oneHalf, one, two, four, eight, sixteen} |
| si-RequestPeriod | ENUMERATED {one, two, four, six, eight, ten, twelve, sixteen} |
| si-RequestResources | List of 1 to 32 SI-RequestResources |
| RACH-ConfigGeneric | |
| prach-ConfigurationIndex | INTEGER (0..255) |
| msg1-FDM | ENUMERATED {one, two, four, eight} |
| msg1-FrequencyStart | INTEGER (0..maxNrofPhysicalResourceBlocks-1) => INTEGER (0..274) |
| zeroCorrelationZoneConfig | INTEGER (0..15) |
| preambleReceivedTargetPower | INTEGER (-202 .. -60) |
| preambleTransMax | ENUMERATED {n3, n4, n5, n6, n7, n8, n10, n20, n50, n100, n200} |
| powerRampingStep | ENUMERATED {dB0, dB2, dB4, dB6} |
| ra-ResponseWindow | ENUMERATED {sl1, sl2, sl4, sl8, sl10, sl20, sl40, sl80} |
| SI-RequestResources | |
| ra-PreambleStartIndex | INTEGER (0..63) |
| ra-AssociationPeriodIndex | INTEGER (0..15) |
| ra-AssociationPeriodIndex | INTEGER (0..15) |
The table
below provides overview of SchedulingInfo.
| SchedulingInfo | |
| si-BroadcastStatus | ENUMERATED {broadcasting, notBroadcasting} |
| si-Periodicity | ENUMERATED {rf8, rf16, rf32, rf64, rf128, rf256, rf512} |
| sib-MappingInfo | List of 1 to 32 SIB-TypeInfo |
| SIB-TypeInfo | |
| type | ENUMERATED {sibType2, sibType3, … ,sibType9, spare8, spare7, …, spare1} |
| valueTag | INTEGER (0..31) |
| areaScope | ENUMERATED {true} |
ServingCellConfigCommonSIB
The
IE ServingCellConfigCommonSIB is used to configure cell specific
parameters of a UE's serving cell in SIB1. The contents of this IE are given in
the below table.
| ServingCellConfigCommonSIB | |
| downlinkConfigCommon | DownlinkConfigCommonSIB |
| uplinkConfigCommon | UplinkConfigCommonSIB |
| supplementaryUplink | UplinkConfigCommonSIB |
| n-TimingAdvanceOffset | ENUMERATED {n0, n25600, n39936} |
| ssb-PositionsInBurst | inOneGroup BIT STRING (SIZE (8)) |
| groupPresence BIT STRING (SIZE (8)) | |
| ssb-PeriodicityServingCell | ENUMERATED {ms5, ms10, ms20, ms40, ms80, ms160} |
| tdd-UL-DL-ConfigurationCommon | TDD-UL-DL-ConfigCommon |
| ss-PBCH-BlockPower | INTEGER (-60 .. 50) |
DownlinkConfigCommonSIB: As show in the following
table, this IE provides common downlink parameters of a cell.
| DownlinkConfigCommonSIB | |
| frequencyInfoDL | FrequencyInfoDL-SIB |
| initialDownlinkBWP | BWP-DownlinkCommon |
| bcch-Config | modificationPeriodCoeff ENUMERATED {n2, n4, n8, n16} |
| pcch-Config | PCCH-Config |
The IE FrequencyInfoDL-SIB provides basic parameters
of a downlink carrier and transmission thereon. As shown in the below table, it
consists of offsetToPointA, frequencyBandList which
is a list of one or multiple frequency bands to which this carrier(s) belongs, scs-SpecificCarrierList
which is set of carriers for different SCSs (numerologies) defined in
relation to Point A.
| FrequencyInfoDL-SIB | |
| frequencyBandList | MultiFrequencyBandListNR-SIB |
| offsetToPointA | INTEGER (0 … 2199) |
| scs-SpecificCarrierList | List of 1 to 5 SCS-SpecificCarrier |
| SCS-SpecificCarrier | |
| offsetToCarrier | INTEGER (0 … 2199) |
| subcarrierSpacing | ENUMERATED {kHz15, kHz30, kHz60, kHz120, kHz240, spare3, spare2, spare1} |
| carrierBandwidth | INTEGER (1 … 275) |
The IE initialDownlinkBWP is used
to configure the common parameters of initial downlink BWP. As shown in
the below table, it contains cell specific PDCCH and PDSCH parameters of this
BWP. PDCCH/PDSCH common parameters and IE BWP. The IE BWP is
used to configure generic parameters for this BWP such as frequency domain
location and bandwidth, SCS to be used, and an indication whether to use the
extended CP.
| BWP-DownlinkCommon | |
| genericParameters | BWP |
| pdcch-ConfigCommon | SetupRelease { PDCCH-ConfigCommon } |
| pdsch-ConfigCommon | SetupRelease { PDSCH-ConfigCommon } |
| BWP | |
| locationAndBandwidth | INTEGER (0 … 37949) |
| subcarrierSpacing | ENUMERATED {kHz15, kHz30, kHz60, kHz120, kHz240, spare3, spare2, spare1} |
| cyclicPrefix | ENUMERATED {extended} |
- bcch-config provides system information modification period related configuration. Actual
modification period (in no. of radio frames) m = modificationPeriodCoeff * defaultPagingCycle.
-
pcch-config
provides paging
related configuration.
UplinkConfigCommonSIB: As show in the following
table, this IE provides common uplink parameters of a cell.
| UplinkConfigCommonSIB | |
| frequencyInfoUL | FrequencyInfoUL-SIB |
| initialUplinkBWP | BWP-UplinkCommon |
| timeAlignmentTimerCommon | TimeAlignmentTimer |
The IE FrequencyInfoUL-SIB provides basic parameters
of a uplink carrier and transmission thereon. As shown in the below table, it
consists of the following fields.
| FrequencyInfoUL-SIB | |
| frequencyBandList | MultiFrequencyBandListNR-SIB |
| absoluteFrequencyPointA | INTEGER (0 … 3279165) |
| scs-SpecificCarrierList | List of 1 to 5 SCS-SpecificCarrier |
| p-Max | P-Max |
| frequencyShift7p5khz | ENUMERATED {true} |
| SCS-SpecificCarrier | |
| offsetToCarrier | INTEGER (0 … 2199) |
| subcarrierSpacing | ENUMERATED {kHz15, kHz30, kHz60, kHz120, kHz240, spare3, spare2, spare1} |
| carrierBandwidth | INTEGER (1 … 275) |
-
frequencyBandList provides
the frequency band indicator and a list of additionalPmax and
additionalSpectrumEmission values.
-
absoluteFrequencyPointA
is the absolute
frequency of the reference resource block (CRB 0). Its lowest subcarrier is
also known as Point A.
-
frequencyShift7p5khz
enables the NR
UL transmission with a 7.5 kHz shift to the LTE raster. If the field is absent,
the frequency shift is disabled.
-
p-Max
is the max value
in dBm applicable for the cell. If this field is absent, the UE applies the
maximum power according to TS 38.101-1.
-
scs-SpecificCarrierList is a set of carriers for different SCSs
(numerologies), defined in relation to Point A. The network configures this for
all SCSs that are used in UL BWPs configured in this serving cell.
The
IE initialUplinkBWP is
used to configure the common parameters of initial uplink BWP. As shown
in the below table, it contains cell specific RACH, PUCCH and PUSCH parameters
of this BWP. It contains PUCCH/PUSCH/RACH common parameters and IE BWP.
The IE BWP is
used to configure generic parameters for this BWP such as frequency domain
location and bandwidth, SCS to be used, and an indication whether to use the
extended CP.
| BWP-UplinkCommon | |
| genericParameters | BWP |
| rach-ConfigCommon | SetupRelease { RACH-ConfigCommon } |
| pusch-ConfigCommon | SetupRelease { PUSCH-ConfigCommon } |
| pucch-ConfigCommon | SetupRelease { PUCCH-ConfigCommon } |
| BWP | |
| locationAndBandwidth | INTEGER (0 … 37949) |
| subcarrierSpacing | ENUMERATED {kHz15, kHz30, kHz60, kHz120, kHz240, spare3, spare2, spare1} |
| cyclicPrefix | ENUMERATED {extended} |
n-TimingAdvanceOffset: Value of N_TA-Offset to be applied for random access on this
serving cell. If this field is absent, the UE applies the value defined for the
duplex mode and frequency range of this serving cell according to Table 7.1.2-2
from 38.133.
ssb-PositionsInBurst defines time
domain positions of the transmitted SSBs in an SS-burst set. ssb-PeriodicityServingCell configures the UEs with SSB periodicity. For more
information, refer to 5GNR: Synchronization Signal/PBCH block (SSB)
tdd-UL-DL-ConfigurationCommon defines cell-specific TDD UL/DL configuration (shown
in the table below). For more details see section 11.1 from 38.213.
| TDD-UL-DL-ConfigCommon | |
| referenceSubcarrierSpacing | SubcarrierSpacing |
| pattern1 | TDD-UL-DL-Pattern |
| pattern2 | TDD-UL-DL-Pattern |
referenceSubcarrierSpacing configures
reference SCS and is used to determine the time domain boundaries in the UL-DL
pattern which must be common across all subcarrier specific carriers, i.e.,
independent of the actual subcarrier spacing using for data transmission. Only
the values 15, 30 or 60 kHz (FR1), and 60 or 120 kHz (FR2) are applicable.
TDD-UL-DL-Pattern
provides the
following configuration;
| TDD-UL-DL-Pattern | ||
| dl-UL-TransmissionPeriodicity | ENUMERATED {ms0p5, ms0p625, ms1, ms1p25, ms2, ms2p5, ms5, ms10} | |
| nrofDownlinkSlots | INTEGER (0 … maxNrofSlots) | INTEGER (0 … 320) |
| nrofDownlinkSymbols | INTEGER (0 … maxNrofSymbols-1) | INTEGER (0 … 13) |
| nrofUplinkSlots | INTEGER (0 … maxNrofSlots) | INTEGER (0 … 320) |
| nrofUplinkSymbols | INTEGER (0 … maxNrofSymbols-1) | INTEGER (0 … 13) |
| dl-UL-TransmissionPeriodicity-v1530 | ENUMERATED {ms3, ms4} | |
-
dl-UL-TransmissionPeriodicity: provides slot configuration periodicity i.e., periodicity
of the DL-UL pattern. If the dl-UL-TransmissionPeriodicity-v1530
is signalled, UE shall ignore this field.
-
nrofDownlinkSlots: Number of consecutive full DL slots at the beginning
of each DL-UL pattern. In release 15.7, the maximum value for this field is 80.
-
nrofDownlinkSymbols:
Number of
consecutive DL symbols in the beginning of the slot following the last full DL
slot (as derived from nrofDownlinkSlots). The value 0 indicates that
there is no partial- downlink slot.
-
nrofUplinkSlots:
Number of
consecutive full UL slots at the end of each DL-UL pattern. In release 15.7,
the maximum value for this field is 80.
-
nrofUplinkSymbols:
Number of
consecutive UL symbols in the end of the slot preceding the first full UL slot
(as derived from nrofUplinkSlots). The value 0 indicates that there is
no partial-uplink slot.
ss-PBCH-BlockPower provides average EPRE of the resources elements that
carry SSS (in dBm) that the NW used for SSB transmission.
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.
eCallOverIMS-Support: Indicates
whether the cell supports emergency call over IMS services.
UE-TimersAndConstants: This
IE contains timers and constants used by the UE in RRC_CONNECTED, RRC_INACTIVE
and RRC_IDLE. The table below summarizes different timers and constants from
38.331. Check section 7.1.1 from 38.331 for the purpose of the different timers
and constants.
| UE-TimersAndConstants | |
| t300 | ENUMERATED {ms100, ms200, ms300, ms400, ms600, ms1000, ms1500, ms2000} |
| t301 | ENUMERATED {ms100, ms200, ms300, ms400, ms600, ms1000, ms1500, ms2000} |
| t310 | ENUMERATED {ms0, ms50, ms100, ms200, ms500, ms1000, ms2000} |
| n310 | ENUMERATED {n1, n2, n3, n4, n6, n8, n10, n20} |
| t311 | ENUMERATED {ms1000, ms3000, ms5000, ms10000, ms15000, ms20000, ms30000} |
| n311 | ENUMERATED {n1, n2, n3, n4, n5, n6, n8, n10} |
| t319 | ENUMERATED {ms100, ms200, ms300, ms400, ms600, ms1000, ms1500, ms2000} |
uac-BarringInfo
contains information (shown below) about cell barring
based upon Unified Access Barring (UAC).
| uac-BarringInfo | ||
| uac-BarringForCommon | UAC-BarringPerCatList | |
| uac-BarringPerPLMN-List | UAC-BarringPerPLMN-List | |
| uac-BarringInfoSetList | UAC-BarringInfoSetList | |
| uac-AccessCategory1- |
plmnCommon | UAC-AccessCategory1-SelectionAssistanceInfo |
| individualPLMNList | List of 2 to 12 of UAC-AccessCategory1-SelectionAssistanceInfo | |
useFullResumeID: Indicates
which resume identifier and Resume request message should be used when UE wants
to transit to connected state from inactive state. The UE uses fullI-RNTI
and RRCResumeRequest1 if the field is present, or shortI-RNTI and
RRCResumeRequest if the field is absent. For more information, visit 5G NR: UE RRC States and StateTransitions.
Reference: 3GPP TS 38.331, 38.304. 38.213 and 38.300
