How do UE read ETWS Info in SIB10 SIB11

Below are the steps how do UE read when there is a ETWS notification from NW.

SIB 10 and SIB 11 are  the responsible SIB's for ETWS.
Where SIB10 carry info about primary notification and SIB11 will carry info for secondary notification.



This we can get from below test case according 3GPP spec TS-36.523-1
14.1  ETWS reception in RRC_IDLE state / Duplicate detection
14.2 ETWS reception in RRC_CONNECTED state / Duplicate detection

According the Test Case Below is the steps included for the Test case,

       

St	Procedure	Message Sequence		TP	Verdict
		U - S	Message	-	-
1	The SS include an ETWS message with new messageIdentifier and serialNumber in SystemInformationBlockType10 and SystemInformationBlockType11 and transmit a Paging message including etws-Indication on Cell 1 (NOTE1).	<--	Paging	-	-
2	Check: Does the UE indicate the contents of the "warning message" to the user, and alert or activate alerting the user (NOTE2)?	-	-	1	P
3	The SS wait for 10s.	-	-	-	-
4	The SS include an ETWS message with same messageIdentifier and serialNumber in SystemInformationBlockType10 and SystemInformationBlockType11 and transmit a Paging message including etws-Indication on Cell 1 (NOTE1).	<--	Paging	-	-
5	Check: Does the UE indicate the contents of the "warning message" to the user, or alert or activate alerting the user (NOTE2)?	-	-	1	F
NOTE1:     SystemInformationBlockType11 contain 3 segments. NOTE2:     The data indication and user alerting are the UE implementation issues.

Paging Message for the test case will be as below,

Derivation Path: 36.508 Table 4.6.1-7
Information Element	Value/remark	Comment	Condition
Paging ::= SEQUENCE {
pagingRecordList	Not present	Not needed as this is for all the UE
systemInfoModification	Not present
etws-Indication	true	This filed will be true for ETWS notification
nonCriticalExtension SEQUENCE {}	Not present
}

SIB1 Content will be like below,

Derivation Path: 36.508 table 4.4.3.2-3
Information Element	Value/remark	Comment	Condition
SystemInformationBlockType1 ::= SEQUENCE {
schedulingInformation ::= SEQUENCE (SIZE (1..maxSI-Message)) OF SEQUENCE {}	Combination 8 in TS 36.508 section 4.4.3.1	SIB2, SIB3, SIB10 and SIB11 are transmitted
}

1. Paging to UE for ETWS (Paging will be there for both Idle and Connected Mode)
2. UE Reads SIB1 , where  "systemInfoValueTag" will be 1 and will contain scheduling info about
3. SIB10 and SIB11.
4. UE reads  other SIB's accordingly
5. User will be notified via alert messages/tones/both as per UE implementation.

Source: 3GPP TS-36.523-1

Paging in LTE

The purpose of this procedure is:
- to transmit paging information to a UE in RRC_IDLE and/ or;
- to inform UEs in RRC_IDLE and UEs in RRC_CONNECTED about a system information change and/ or;
- to inform about an ETWS primary notification and/ or ETWS secondary notification and/ or;
- to inform about a CMAS notification.
The paging information is provided to upper layers, which in response may initiate RRC connection establishment, e.g.
to receive an incoming call.

Discontinuous Reception for paging

The UE may use Discontinuous Reception (DRX) in idle mode in order to reduce power consumption.
One Paging Occasion (PO) is a subframe where there may be P-RNTI transmitted on PDCCH addressing the paging message.
One Paging Frame (PF) is one Radio Frame, which may contain one or multiple Paging Occasion(s). When DRX is used the UE needs only to monitor one PO per DRX cycle.

PF and PO is determined by following formulae using the DRX parameters provided in System Information:
PF is given by following equation:
SFN mod T= (T div N)*(UE_ID mod N)

Index i_s pointing to PO from subframe pattern , will be derived from following calculation:
i_s = floor(UE_ID/N) mod Ns

System Information DRX parameters stored in the UE shall be updated locally in the UE whenever the DRX parameter
values are changed in SI. If the UE has no IMSI, for instance when making an emergency call without USIM, the UE
shall use as default identity UE_ID = 0 in the PF and i_s formulas above.

The following Parameters are used for the calculation of the PF and i_s:
- T: DRX cycle of the UE. T is determined by the shortest of the UE specific DRX value, if allocated by upper
layers, and a default DRX value broadcast in system information. If UE specific DRX is not configured by upper
layers, the default value is applied.
- nB: 4T, 2T, T, T/2, T/4, T/8, T/16, T/32.
- N: min(T,nB)
- Ns: max(1,nB/T)
- UE_ID: IMSI mod 1024.

IMSI is given as sequence of digits of type Integer (0..9), IMSI shall in the formulae above be interpreted as a decimal
integer number, where the first digit given in the sequence represents the highest order digit.
For example:
IMSI = 12 (digit1=1, digit2=2)
In the calculations, this shall be interpreted as the decimal integer "12", not "1x16+2 = 18".

FDD Sub-frame Patterns

TDD Sub-frame Patterns

Ref: http://www.etsi.org/deliver/etsi_ts/136300_136399/136304/12.02.00_60/ts_136304v120200p.pdf




Upon receiving the Paging message, the UE shall:

1> if in RRC_IDLE, for each of the PagingRecord, if any, included in the Paging message:
2> if the ue-Identity included in the PagingRecord matches one of the UE identities allocated by upper layers:
3> forward the ue-Identity and the cn-Domain to the upper layers;
1> if the systemInfoModification is included:
2> re-acquire the required system information using the system information acquisition procedure as specified in
5.2.2.
1> if the etws-Indication is included and the UE is ETWS capable:
2> re-acquire SystemInformationBlockType1 immediately, i.e., without waiting until the next system information
modification period boundary;
2> if the schedulingInfoList indicates that SystemInformationBlockType10 is present:
3> acquire SystemInformationBlockType10;
2> if the schedulingInfoList indicates that SystemInformationBlockType11 is present:
3> acquire SystemInformationBlockType11;
1> if the cmas-Indication is included and the UE is CMAS capable:
2> re-acquire SystemInformationBlockType1 immediately, i.e., without waiting until the next system information modification period boundary as specified in 5.2.1.5;
2> if the schedulingInfoList indicates that SystemInformationBlockType12 is present:
3> acquire SystemInformationBlockType12;



Paging in LTE
   1. For MT Call(PS/CS)
   2. For SI (System Information) modification
   3. For ETWS (Earthquake and Tsunami Warning System)


Example for Type 1: PS Call
As this is for a specific UE , it includes a paging record list.
Paging record list is an array, so this might include more than UE if needed.

Air Message: AIR_MSG_TYPE_PCCH

 

          pagingRecordList_exist         1

          systemInfoModification_exist 0

          etws_Indication_exist                 0

          nonCriticalExtension_exist         0

        pagingRecordList[0] PagingRecord

            ue_Identity PagingUE_Identity_

              s_TMSI S_TMSI

                mmec MMEC

                  buff[0..0] 01

                TMSI S_TMSIm_TMSI

                  buff[0..3] c2 34 56 78

Example for Type 2: SI Modification 
as it is applicable for all the UE's under that eNB so it doesn't need any UE identifier.


Air Message: AIR_MSG_TYPE_PCCH
        paging Paging
          systemInfoModification PagingsystemInfoModification_true
          pagingRecordList_exist         0
          systemInfoModification_exist 1
          etws_Indication_exist                 0
          nonCriticalExtension_exist         0

Example for Type 3: For ETWS 
as it is applicable for all the UE's under that eNB so it doesn't need any UE identifier.

Air Message: AIR_MSG_TYPE_PCCH
        paging Paging
          systemInfoModification PagingsystemInfoModification_true
          pagingRecordList_exist         0
          systemInfoModification_exist 0
          etws_Indication_exist                 1
          nonCriticalExtension_exist         0



SIB2 Caries Configuration for PCCH - Paging Control Channel

Sib2 contains , RadioResourceConfigCommonSIB

Under PCCH-Config

PCCH-Config ::= SEQUENCE {
defaultPagingCycle ENUMERATED {
rf32, rf64, rf128, rf256},
nB ENUMERATED {
fourT, twoT, oneT, halfT, quarterT, oneEighthT,
oneSixteenthT, oneThirtySecondT}
}

defaultPagingCycle
Default paging cycle, used to derive "T" in TS 36.304 [4]. Value rf32 corresponds to 32 radio frames, rf64 corresponds to 64 radio frames and so on.

nB
Parameter: nB is used as one of parameters to derive the Paging Frame and Paging Occasion according to TS 36.304 [4]. Value in multiples of 'T' as defined in TS 36.304 [4]. A value of fourT corresponds to 4 * T, a value of twoT corresponds to 2 * T and so on.



Either SIB2 configuration or UE upper-layer configuration is considered for nB.

There is concept of paging occasion and paging frame to help UE saving it's power further on DRX mode.

Paging Occasion: Paging Frame: