diff --git a/specification/stage-3/05_Idle_and_Inactive_Mode/05.02 System Information.md b/specification/stage-3/05_Idle_and_Inactive_Mode/05.02 System Information.md new file mode 100644 index 0000000000000000000000000000000000000000..c5411312aed93c5b709333d2489cd8f3e6cba2b7 --- /dev/null +++ b/specification/stage-3/05_Idle_and_Inactive_Mode/05.02 System Information.md @@ -0,0 +1,60 @@ +## 5.2 System information + +### 5.2.1 Introduction + +System Information (SI) is divided into the *MIB* and a number of SIBs and posSIBs where: + +- the *MIB* is always transmitted on the BCH with a periodicity of 80 ms and repetitions made within 80 ms (TS 38.212 \[17\], clause 7.1) and it includes parameters that are needed to acquire *SIB1* from the cell. The first transmission of the *MIB* is scheduled in subframes as defined in TS 38.213 \[13\], clause 4.1 and repetitions are scheduled according to the period of SSB; + +**NOTE** 1: If the period of SSB is larger than 80 ms, the MIB is transmitted with the same periodicity as that of SSB. + +- the *SIB1* is transmitted on the DL-SCH with a periodicity of 160 ms and variable transmission repetition periodicity within 160 ms as specified in TS 38.213 \[13\], clause 13. The default transmission repetition periodicity of *SIB1* is 20 ms but the actual transmission repetition periodicity is up to network implementation. For SSB and CORESET multiplexing pattern 1, *SIB1* repetition transmission period is 20 ms. For SSB and CORESET multiplexing pattern 2/3, *SIB1* transmission repetition period is the same as the SSB period (TS 38.213 \[13\], clause 13). *SIB1* includes information regarding the availability and scheduling (e.g. mapping of SIBs to SI message, periodicity, SI-window size) of other SIBs with an indication whether one or more SIBs are only provided on-demand and, in that case, the configuration needed by the UE to perform the SI request. *SIB1* is cell-specific SIB; + +- SIBs other than *SIB1* and posSIBs are carried in *SystemInformation* (SI) messages, which are transmitted on the DL-SCH. Only SIBs or posSIBs having the same periodicity can be mapped to the same SI message. SIBs and posSIBs are mapped to different SI messages, i.e. an SI message contains either only SIBs or only posSIBs. Each SI message is transmitted within periodically occurring time domain windows (referred to as SI-windows with same length for all SI messages). Each SI message is associated with an SI-window and the SI-windows of different SI messages do not overlap. That is, within one SI-window only the corresponding SI message is transmitted. An SI message may be repeated with the same content a number of times within the SI-window. Any SIB or posSIB except *SIB1* can be configured to be cell specific or area specific, using an indication in *SIB1*. The cell specific SIB is applicable only within a cell that provides the SIB while the area specific SIB is applicable within an area referred to as SI area, which consists of one or several cells and is identified by s*ystemInformationAreaID*; + +- The mapping of SIBs to SI messages is configured in *schedulingInfoList* and *schedulingInfoList2*, while the mapping of posSIBs to SI messages is configured in *posSchedulingInfoList* and *schedulingInfoList2. *Each SIB and each posSIB is mapped to a single SI message. posSIBs of the same *posSibType* carrying GNSS Generic Assistance Data for different GNSS/SBAS (identified by *gnss-id/sbas-id*, see TS 37.355 \[49\]) are mapped to different SI messages. Each SIB and posSIB is contained at most once in an SI message. For SIBs and posSIBs with segments, the segments contained in SI messages are transmitted according to the SI message periodicity, with one segment of a particular *sibType*/*posSibType* in each SI message; + +- For a UE in RRC_CONNECTED, the network can provide system information through dedicated signalling using the *RRCReconfiguration* message, e.g. if the UE has an active BWP with no common search space configured to monitor system information, paging, or upon request from the UE. + +- For PSCell and SCells, the network provides the required SI by dedicated signalling, i.e. within an *RRCReconfiguration* message. Nevertheless, the UE shall acquire *MIB* of the PSCell to get SFN timing of the SCG (which may be different from MCG). Upon change of relevant SI for SCell, the network releases and adds the concerned SCell. For PSCell, the required SI can only be changed with Reconfiguration with Sync. + +**NOTE** 2: The physical layer imposes a limit to the maximum size a SIB can take. The maximum *SIB1* or *SI message* size is 2976 bits. + +### 5.2.2 System information acquisition + +#### 5.2.2.1 General UE requirements + +![Figure 5.2.2.1-1: System information acquisition](./figures/xx.02.02.01-01%20System%20information%20acquisition.svg) + +***Figure 5.2.2.1-1: System information acquisition*** ([Link to MSC Version](./figures/xx.02.02.01-01%20System%20information%20acquisition.msc)) + +The UE applies the SI acquisition procedure to acquire the AS, NAS- and positioning assistance data information. The procedure applies to UEs in RRC_IDLE, in RRC_INACTIVE and in RRC_CONNECTED. + +The UE in RRC_IDLE and RRC_INACTIVE shall ensure having a valid version of (at least) the *MIB*, *SIB1* through *SIB4,* *SIB5* (if the UE supports E-UTRA), *SIB11* (if the UE is configured for idle/inactive measurements), *SIB12* (if UE is capable of NR sidelink communication/discovery and is configured by upper layers to receive or transmit NR sidelink communication/discovery), and *SIB13*, *SIB14* (if UE is capable of V2X sidelink communication and is configured by upper layers to receive or transmit V2X sidelink communication), *SIB15* (if UE is configured by upper layers to report disaster roaming related information), *SIB16* (if the UE is capable of slice-based cell reselection and the UE receives NSAG information for cell reselection from upper layer), *SIB17* or *SIB17bis* (if the UE is using TRS resources for power saving in RRC_IDLE and RRC_INACTIVE), *SIB19* (if UE is accessing NR via NTN access), *SIB22* (for ATG access), and *SIB23* (if UE is capable of NR sidelink positioning and is configured by upper layers to receive or transmit SL-PRS). + +The UE capable of MBS broadcast which is receiving or interested to receive MBS broadcast service(s) via a broadcast MRB shall ensure having a valid version of *SIB20*, regardless of the RRC state the UE is in. + +The UE shall ensure having a valid version of the posSIB requested by upper layers. + +#### 5.2.2.2 SIB validity and need to (re)-acquire SIB + +##### 5.2.2.2.1 SIB validity + +The UE shall apply the SI acquisition procedure as defined in clause 5.2.2.3 upon cell selection (e.g. upon power on), cell-reselection, return from out of coverage, after reconfiguration with sync completion, after entering the network from another RAT, upon receiving an indication that the system information has changed, upon receiving a PWS notification, upon receiving request (e.g., a positioning request) from upper layers; and whenever the UE does not have a valid version of a stored SIB or posSIB or a valid version of a requested SIB. +The UE shall apply the SI acquisition procedure as defined in clause upon cell selection (e.g. upon power on), cell-reselection, return from out of coverage, after reconfiguration with sync completion, after entering the network from another RAT, upon receiving an indication that the system information has changed, upon receiving a PWS notification, upon receiving request (e.g., a positioning request) from upper layers; and whenever the UE does not have a valid version of a stored SIB or posSIB or a valid version of a requested SIB. + +When the UE acquires a *MIB* or a *SIB1* or an SI message in a serving cell as described in clause 5.2.2.3, and if the UE stores the acquired SIB, then the UE shall store the associated *areaScope*, if present, the first *PLMN-Identity* in the *PLMN-IdentityInfoList* for non-NPN-only cells or the first NPN identity (SNPN identity in case of SNPN, or PNI-NPN identity in case of PNI-NPN) in the *NPN-IdentityInfoList* for NPN-only cells, the *cellIdentity*, the *systemInformationAreaID*, if present, and the *valueTag*, if present, as indicated in the *si-SchedulingInfo* for the SIB. If the UE stores the acquired posSIB, then the UE shall store the associated *areaScope*, if present, the *cellIdentity*, the *systemInformationAreaID*, if present, the *valueTag*, if provided in *assistanceDataSIB-Element*, and the *expirationTime* if provided in *assistanceDataSIB-Element*. The UE may use a valid stored version of the SI except *MIB*, *SIB1*, *SIB6*, *SIB7* or *SIB8* e.g. after cell re-selection, upon return from out of coverage or after the reception of SI change indication. The *valueTag* and *expirationTime* for posSIB is optionally provided in *assistanceDataSIB-Element*, as specified in TS 37.355 \[49\]. + +A L2 U2N Remote UE in RRC_IDLE or RRC_INACTIVE can inform the interested SIB(s) to the connected L2 U2N Relay UE as defined in clause 5.8.9.8.2 and receive the SIB(s) from the L2 U2N Relay UE as defined in clause 5.8.9.9.3. A L2 U2N Remote UE in RRC_CONNECTED receives SIB1 and other SIB(s) in *RRCReconfiguration* message and performs on-demand SI request if required, as defined in clause 5.2.2.3.5 and 5.2.2.3.6. The L2 U2N Remote UE in RRC_IDLE or RRC_INACTIVE or RRC_CONNECTED (when MP is not configured) is not required to obtain SI over Uu interface, but it may decide to perform the SI acquisition procedure over Uu interface as defined in clause 5.2.2.3 by UE implementation. + +*NOTE*: The storage and management of the stored SIBs in addition to the SIBs valid for the current serving cell is left to UE implementation. + +The UE shall: + +- delete any stored version of a SIB after 3 hours from the moment it was successfully confirmed as valid; + +- for each stored version of a SIB: + + - if the first *NetworkIdentity* in the *networkIdentityList*, the *cellIdentity* and *valueTag* that are included in the *si-SchedulingInfo* for the SIB received from the serving cell are identical to the *PLMN-Identity,* the *cellIdentity* and the *valueTag* associated with the stored version of that SIB: + + - consider the stored SIB as valid for the cell; diff --git a/specification/stage-3/05_Idle_and_Inactive_Mode/figures/xx.02.02.01-01 System information acquisition.msc b/specification/stage-3/05_Idle_and_Inactive_Mode/figures/xx.02.02.01-01 System information acquisition.msc new file mode 100644 index 0000000000000000000000000000000000000000..9b3fae6eb3045abcbc4affbb2fefd632096bb6b8 --- /dev/null +++ b/specification/stage-3/05_Idle_and_Inactive_Mode/figures/xx.02.02.01-01 System information acquisition.msc @@ -0,0 +1,18 @@ +hscale="auto"; +defstyle hgap [text.gap.left=20, text.gap.right=20]; +defstyle entity [text.font.face="Arial", text.size.normal=14, text.wrap=no, text.bold=yes]; +defstyle b2 [text.font.face="Arial", text.size.normal=13, vspacing=7, text.wrap=no, hgap]; +defstyle ac [text.font.face="Times", text.size.normal=15, text.italic=yes, vspacing=5, arrow.type=sharp, hgap]; +defstyle au [text.font.face="Arial", text.size.normal=13, vspacing=5, hgap]; +defstyle n1 [text.font.face="Arial", text.size.normal=13, vspacing=5, weak, text.italic=no, hgap]; + +U: UE; +N: Network; + +|||; +U<-N:MIB [au]; +UN:SystemInformationRequest [au]; +U + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +