System Information Blocks (SIBs) in LTE

In this article, i am going to explain each parameter meaning used in System Information Blocks (SIBs) in LTE layer 3 messages and events used.

SIB 1 – Cell Access and Scheduling of other System Information.

PLMN-IdentityConsists of MCC and MNC. The first listed one is the Primary PLMN.
p-MaxValue applicable for the cell. If absent the UE applies the maximum power
according to the UE capability. If eNodeB configures the value more than the value
supported by the UE then UE will set the max value supported by the UE
capability. Example UE Category 3 supports max 23 db.
cellReservedForOperatorUseAs defined by operator (Reserved /Not_reserved).
trackingAreaCodeTAC which is common to the PLMN Identities.
cellIdentityIdentifies a cell within the PLMN.
intraFreqReselectionIf enabled, UE will be able to perform Cell-reselection to INTRA-frequency cells.
q_RxLevMinMinimum required RX level in the cell.
q_RxLevMinOffsetActual value Qrxlevminoffset = IE value * 2 [dB]. Only applied when a cell is
evaluated for cell selection as a result of a periodic search for a higher priority
PLMN while camped normally in a VPLMN [5]. During this periodic search for
higher priority PLMN the UE may check the S criteria of a cell using parameter
values stored from a different cell of this higher priority PLMN. Affects the
minimum required Rx level in the cell.
freqBandIndicatorIndicates the E-UTRA operating band.
schedulingInfoListInformation regarding the presence of SIB type; other than SIB1.
si_PeriodicityPeriodicity of the SI-message in radio frames (SI will be transmitted within the
specified radio frame).
sib_MappingInfoCarries the List of the SIBs mapped. SIB2 is always present in the first element of
schedulingInfoList.
si_WindowLengthSpecifies that a SIB should be transmitted somewhere within the specified window
length. Value is in ms. This window starts at the starting sub-frame of the
mentioned si_periodicity. SIBs can be received in any of the sub-frame as
mentioned in the WindowLength.
systemInfoValueTagIndicates if a change has occurred in the SI messages. UEs may use systemInfoValueTag, e.g. upon return from out of coverage, to verify if the previously stored SI messages are still valid. Additionally, the UE considers stored system information to be invalid after 3 hours from the moment it was successfully confirmed as valid, unless specified otherwise. Common for all SIBs other than MIB, SIB1, SIB10, SIB11 and SIB12.

SIB 2 – Radio Resource Configuration Information.

  ac-BarringInfo  Access Class Barring configuration
radioResourceConfigIt is used to specify common radio resource configurations in the system information and in the mobility control information.
numberOfRA_PreamblesNumber of non-dedicated random access preambles.
preamblesGroupAConfig_existProvides the configuration for preamble grouping. If the field is not signalled, the size of the random access preambles group A is equal to numberOfRA-Preambles.
powerRampingParameters 
powerRampingStep  Power ramping factor.
preambleInitialReceivedTargetPower  Initial preamble power.
ra_SupervisionInfo 
preambleTransMaxMaximum number of preamble transmission.
ra_ResponseWindowSizeDuration of the RA response window. Value in subframes. Value sf2 corresponds to 2 subframes.
mac_ContentionResolutionTimerTimer for contention resolution. Value in subframes. Value sf8 corresponds to 8 subframes.
  maxHARQ_Msg3Tx 4Maximum number of Msg3 HARQ transmissions, used for contention based random access.

bcch_Config

modificationPeriodCoeffActual modification period, expressed in number of radio frames =
modificationPeriodCoeff * defaultPagingCycle. n2 corresponds to value 2.
  pcch_Config
defaultPagingCycleDefault paging cycle, used to derive ‘T’. Value rf32 corresponds to 32 radio frames.
nB   It is used as one of parameters to derive the Paging Frame and Paging Occasion.
prach_ConfigUsed to specify the PRACH configuration in the system information and in the mobility control information.

rootSequenceIndex

prach_ConfigIndex                    It mentions the:
Preamble format: 0-4 (For frame structure 1 preamble format is 0-3 and for frame structure 2 it is 0-4).
SFN: Whether it will be EVEN no. frame OR any frame.
Subframe number: carrier the subframe no. within the SFN
(Look for the table in TS36.211 – Table 5.7.1-2)
highSpeedFlagTRUE corresponds to Restricted set and FALSE to Unrestricted set.
 
zeroCorrelationZoneConfig
It is used for Preamble generation.
pdsch_Config       It is used to specify the common and the UE specific PDSCH configuration.
pusch_ConfigIt is used to specify the common PUSCH configuration and the reference signal configuration for PUSCH and PUCCH.
pucch_ConfigIt is used to specify the common and the UE specific PUCCH configuration.
soundingRS_UL_ConfigIt is used to specify the uplink Sounding RS configuration.
uplinkPowerControlIt is used to specify parameters for uplink power control in the system information and in the dedicated signalling.
ue_TimersAndConstantsTimer values.
freqInfoUL carrier frequency and bandwidth.
timeAlignmentTimerCommonIt is used to control how long the UE is considered uplink time aligned. Value in subframes.

SIB3: Cell-Reselection Parameters for INTRA-Frequency, INTER-Frequency and Inter-RAT.

cellReselectionInfoCommonCell re-selection information common for cells.
q_HystSpeed dependent reselection parameters. If this field is absent then mobility State Parameters is not present. If q_hystSF is present then it is added to q_hyst. Carrier () value so as to reduce the ranking of the serving cell and allows cellreselection to occur easily.
cellReselectionServingFreqInfoInformation for Cell re-selection to inter-frequency and inter-RAT cells.
s_NonIntraSearchUsed to trigger Interfrequency and IRATfrequency measurements for cell
reselection when:
TARGET Interfreq. has lower or equal priority.
IRAT freq. has a lower priority.
Specifies the Srxlev threshold (in dB) for E-UTRAN inter-frequency and inter-RAT
measurements.
If the field s-NonIntraSearchP is present, the UE applies the value of sNonIntraSearchP.
# Otherwise if neither s-NonIntraSearch
nor s-NonIntraSearchP is present, the UE
applies the (default) value of infinity for SnonIntraSearchP.
threshServingLowThis specifies the Srxlev threshold (in dB) below which the serving cell must fall
before reselecting towards a lower priority RAT/ frequency. Value in between 0-31dB.
Actual value=signalled value*2.
cellReselectionPriorityExplains the absolute priority of the concerned serving cell frequency /set of
frequencies (GERAN)/ bandclass (CDMA2000), as used by the cell reselection procedure. Corresponds with parameter “priority”. Value is between 0-7 where 0 means: lowest priority.
intraFreqCellReselectionInfoCell re-selection information common for intra-frequency cells.
q_RxLevMinMinimum required RSRP for cell reselection. value -70 – 22 dbm, Actual
value=signalled value*2.
s_IntraSearch1. Used to trigger intrafreq. measurements.
2. Specifies the Srxlev threshold (in dB) for intra-frequency measurements.
3. If the field s-IntraSearchP is present, the UE applies the value of sIntraSearchP
instead. Otherwise if neither 09s-IntraSearch nor sIntraSearchP
is present, the UE applies the (default) value of infinity for
SIntraSearchP.
presenceAntennaPort1is used to09 indicate whether all the neighbouring cells use 09Antenna Port.
When set to TRUE, the UE may assume that at least two cell-specific
antenna ports are used in all neighbouring cells.
neighCellConfigUsed to provide the information related to MBSFN and TDD UL/DL
configuration of neighbour cells.
t_ReselectionEUTRA1. Specifies the cell reselection timer value.
2. Defines time to trigger for cell reselection.
3. The parameter can be set per E-UTRAN frequency.
p_MaxMax. allowed UL transmit power for intra-frequency neighbouring E-UTRA
cells. If absent the UE applies the maximum power according to the UE
capability.

SIB4: Cell-Reselection Parameters for Neighbouring INTRAFrequency.

intraFreqNeighCellList [1-16 instances]List of intra-frequency neighbouring cells with specific cell reselection
parameters.
IntraFreqNeighCellInfo
physCellIdPhysical CellID of the neighbour cell.
q-OffsetCellspecifies the offset between the two cells. Value -24 – +24dB.
intraFreqBlackCellList [1-16 instances]List of blacklisted intra-frequency neighbouring cells. These type
of cells are not considered for cell re-selection.
csg_PhysCellIdRangeSet of physical cell identities reserved for CSG cells on the frequency on which this field was received. The received csgPhysCellIdRange applies if less than 24 hours has elapsed since it was received and it was received in the same primary PLMN. This field is Optional (mandatory for CSG cell).
intraFreqNeighCellList [1-16 instances]List of intra-frequency neighbouring cells with specific cell reselection
parameters.

SIB5: Cell-Reselection Parameters for INTER-Frequency.

InterFreqCarrierFreqInfoIt can be specified upto 8 carrier frequencies.
dl-CarrierFreqCarrier frequency helps the UE to search the cells.
q-RxLevMinMinimum RSRP value of the inter-frequency cell. Value -70 to
-22 dBm.
Actual value: signalled value * 2
p-MaxMaximum allowed UL transmit power of the cell.
t-ReselectionEUTRAdefines the time to trigger for cell reselection. Value 0 to 7 sec.
t-ReselectionEUTRA-SFscaling factors for Medium and High mobility.
threshX-High1. Threshold (in dB) used by UE for cell re-selection to a HIGHER priority.
2. The Srxlev of the candiate cell is greater then threshX_High.
3. Value 0 to 31 dB. Actual value= Signaled value * 2.
threshX-Low1. Threshold (in dB) used by UE for cell re-selection to a LOWER priority.
2. Cell re-selection is allowed only when Srxlev of the candiate cell is greater then
threshX_Low and RSRP of serving cell is less than the value of ThreshServingLow
singalled within SIB3.
3. Value 0 to 31 dB. Actual value= Signaled value * 2.
allowedMeasBandwidthDefined in terms of Resource blocks associated with a specific channel bandwidth.
cellReselectionPriorityDefines the Absolute priority of the frequency layer.
neighCellConfigDefines the Abolute priority of the frequency layer.
neighCellConfigInformation regarding the neighbouring cells.
q-OffsetFreqDefines the RSRP measurement offset, applied to all cells on the specified RF carrier.
interFreqBlackCellListThe mentioned cells are no considered for cell reselection.

SIB6: Cell-Reselection Parameters INTER RAT Frequency.

carrierFreqListUTRA_FDD/TDDInformation specified for up to 16 instances of RF carriers for FDD or TDD.
carrierFreqCarrier frequency helps the UE to search.
cellReselectionPriorityDefines the absolute priority of the UMTS. Value 0-7, 0 is the lowest priority.
threshX_HighThreshold (in dB) used by UE for cell re-selection to a HIGHER priority UMTS
frequency.
The Srxlev of the candiate cell is greater then threshX_High.
Value 0 to 31 dB. Actual value= Signaled value * 2.
threshX_Low1. Threshold (in dB) used by UE for cell re-selection to a LOWER priority UMTS frequency.
2. Cell re-selection is allowed only when Srxlev of the candiate cell is greater then
threshX_Low and RSR of serving cell is less than the value of ThreshServingLow
singalled within SIB3.
3. Value 0 to 31 dB. Actual value= Signaled value * 2.
q_RxLevMinMinimum RSCP requirement for candiate UMTS cell. Value -60 to -13 dB. Actual value = Signaled value * 2 +1.
p_MaxValue applicable for the intra-frequency neighbouring E-UTRA cells. If absent the UE applies the maximum power according to the UE capability.
q_QualMin1. Minimum Ec/Io requirement for candiate UMTS cell. Value -24 to 0 dB
2. Applicable for FDD only
t_ReselectionUTRA1. Defines the time to trigger cell re-selection.
2. value 0 – 7 seconds.
t_ReselectionUTRA_SF1. defines the time to trigger cell re-selection.
2. value 0 – 7 seconds
3. Scaling factors used for Medium and High mobility.
4. Scaling Factors value 0.25, 0.5, 0.75, 1.0. These values decrease the value of
T_reselection which allows more rapid cell re-selections.

SIB7: Cell Reselection Parameters INTER RAT Frequency (GERAN).

t_ReselectionGERANTime to trigger for reselection. Value 0 to 7 sec.
carrierFreqsInfoList[0]carries upto 16 instances of GERAN freq.
carrierFreqs
startingARFCNStart of the ARFCN
bandIndicatordcs1800 or pcs1900
followingARFCNsARFCN groups
cellReselectionPriorityabsolute priority of the GERAN layer. Value 0 to 7, whereas 0 is the lowest priority.
ncc_PermittedNetwork Color Code. Is a bitmap value.
q_RxLevMinminimum RSSI value required.
p_MaxGERANmaximum allowed UL transmit power
threshX_High1. Threshold (in dB) used by UE for cell re-selection to a HIGHER priority frequency.
2. The Srxlev of the candiate cell is greater then threshX_High.
3. Value 0 to 31 dB. Actual value= Signaled value * 2.
threshX_Low1. Threshold (in dB) used by UE for cell re-selection to a LOWER priority frequency.
2. Cell re-selection is allowed only when Srxlev of the candiate cell is greater then
threshX_Low and RSRP of serving cell is less than the value of ThreshServingLow
singalled within SIB3.
3. Value 0 to 31 dB. Actual value= Signaled value * 2.

SIB9: Home eNB Name.

hnb-NameCarries the name of the home eNB.

SIB10: ETWS Primary Notification.

messageIdentifierIdentifies the source and type of ETWS notification (earthquake,
tsunami warning, any emergency or test message).
serialNumberIdentifies variations of an ETWS notification.
Uses various mechanisms to alert the user (display message, play a
tone or vibrate, location where the message is applicable, also
contains an update number which specifies whether a change is in
the message content or not).
warningTypeIdentifies the warning type of the ETWS primary notification (earthquake, tsunami, etc.) and provides information on emergency user alert and UE popup.
arningSecurityInfoIt is optional, only applied when security is applied. Provides security information for the ETWS notification.

SIB11: ETWS Secondary Notification.

messageIdentifierIdentifies the source and type of ETWS notification (earthquake,
tsunami warning, any emergency or test message).
serialNumberIdentifies variations of an ETWS notification.
-uses various mechanisms to alert the user (display message, play a
tone or vibrate, location where the message is applicable, also
contains an update number which specifies whether a change is in
the message content or not).
warningMessageSegmentType
[last/not last]
Indicates whether the included ETWS warning message segment is
the last segment of the complete segment or not.
warningMessageSegmentNumber1. allows oedering of the message segments.
2. Segment number of the ETWS warning message segment contained
in the SIB. A segment number of zero corresponds to the first
segment, one corresponds to the second segment, and so on
warningMessageSegmentcarries actual segment of the message
dataCodingSchemeIdentifies the alphabet/coding and the language applied variations of
an ETWS notification.

SIB12: CMAS notification

sageIdentifierIdentifies the source and type of CMAS notification
serialNumberIdentifies variations of a CMAS notification
warningMessageSegmentTypeIndicates whether the included CMAS warning message segment is the last segment or not
warningMessageSegmentNumberSegment number of the CMAS warning message segment
contained in the SIB. A segment number of zero corresponds to the first segment, one corresponds to the
second segment, and so on.
warningMessageSegmentCarries a segment of the Warning Message.
dataCodingSchemeIdentifies the alphabet/coding and the language applied
variations of a CMAS notification.

SIB13: MBMS control information.

Contains the information required to acquire the MBMS control information associated
with one or more MBSFN areas.

  • mbsfn-AreaInfoList

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