System Information Block Type 1 in LTE

• SIB1 is sent with the periodicity of 80 ms when SFN mod 8=0 and is repeated when SFN mod 2 =0. In other words, a new SIB1 is sent every 80 ms and within the 80 ms period, the same SIB1 is repeated every 20 ms. SIB1 is always sent in sub frame 5.
• The MIB is carried on the Broadcast Channel (BCH) mapped into the Physical Broadcast Channel (PBCH). This is transmitted with a fixed coding and modulation scheme and can be decoded after the initial cell search procedure.
• With the information obtained from the MIB the UE can now decode the Control Format Indicator (CFI), which indicates the Physical Downlink Control Channel (PDCCH) length. This allows the PDCCH to be decoded, and searched for Downlink Control Information (DCI) messages. A DCI message CRC masked with System Information Radio Network Temporary Identifier (SI-RNTI) indicates that a SIB is carried in the same sub frame. The SIBs are transmitted in the Broadcast Control Channel (BCCH) logical channel. Generally, BCCH messages are carried on the Downlink Shared Channel (DL-SCH) and transmitted on the Physical Downlink Shared Channel (PDSCH).

Below is the diagram for SIB-1 for every 10 ms radio frame

SystemInformationBlockType1 {

CellAccessRelatedInfo {

               plmn_IdentityList [0] {

plmn_IdentityList {

mcc[0] = 1

                     mcc[1] = 2

mcc[2] = 3

mnc[0] = 1

mnc[1] = 2

mnc[2] = 3

                  }

CellReservedForOperatorUse = notReserved

               }

TrackingAreaCode = {16, 0x32 0x31 }

CellIdentity = {28, 0x00 0x01 0x90 0001xxxx}

CellBarred= notBarred

IntraFreqReselection = notAllowed

csg_Indication = FALSE

            }

CellSelectionInfo {

               q_RxLevMin = -45

               q_RxLevMinOffset = 1

            }

            p_Max = 23

FreqBandIndicator = 7

SchedulingInfoList [0] {

               si_Periodicity = rf64

               sib_MappingInfo [0] = sibType3

               sib_MappingInfo [1] = sibType4

               sib_MappingInfo [2] = sibType5

            }

SchedulingInfoList [1] {

               si_Periodicity = rf128

               sib_MappingInfo [0] = sibType6

               sib_MappingInfo [1] = sibType7

               sib_MappingInfo [2] = sibType8

            }

            si_WindowLength = ms5

SystemInfoValueTag = 1

NonCriticalExtension {

NonCriticalExtension {

                  cellSelectionInfo_v920 {

                     q_QualMin_r9 = -24

                     q_QualMinOffset_r9 = 7

                  }

                                                 }

                                  }

  }

ib-MappingInfo List of the SIBs mapped to this System Informationmessage. There is no mapping information of SIB2; it is always present in the first System Information message listed in the schedulingInfoList list.

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.

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.

trackingAreaCode A trackingAreaCode that is common for all the PLMNs listed.