The document provides an overview of the paging procedures in LTE, detailing processes governed by the RRC and NAS layers, and discusses various paging scenarios like s-tmsi, imsi, and cs fallback. It explains the structure of paging messages, including how to initiate paging and manage responses in different situations. Additionally, the document includes detailed examples and testing scenarios for validating the paging mechanism.

1. 3GPP LTE Training
RRC Paging
By
3GNetwork Solutions
3 G
Net
Prerequisite:
1. Basics of LTE Overview knowledge is required.
Scope:
1. Gives Summary of Paging Procedures in NAS, RRC, L2 Processing
Paging- 3G Network Solutions 1

2. Paging ToC
1.Purpose & Initiation
2.Paging Scenarios –S-TMSI, IMSI, CSFB, SMS
3.RRC Paging Procedure
4.Paging Occasion & Paging Frames
5.Paging Message & Structure
Paging- 3G Network Solutions 2

3. RRC Paging Procedure
1. Paging procedure (MME initiated)
1. MME sends the PAGING message to each eNB with cells in UE registered TA(s).
2. Each eNB can contain cells belonging to different TA, but a cell can only belong to one
TA.
3. eNB forwards paging response back to MME, initiated on NAS layer of UE based on
NAS-level routing.
eNB MME
UE
[S1AP] PAGING
Paging Response (NAS means)
Paging- 3G Network Solutions 3

4. Paging with S-TMSI
1. Paging procedure - Purpose
1. NW requests establishment of a NAS connection to UE, (even to send CDMA2000 message).
2. to prompt UE to reattach if necessary. If UE is not attached during paging, ignore paging.
3. to initiate MT CS fallback procedure or SMS.
2. Paging through E-UTRAN using S-TMSI
1. initiate paging using S-TMSI for "PS" when NAS signalling, cdma2000® signalling or pending user
data Tx toUE.
2. EMM in MME asks lower layer to start paging and starts T3413 for this paging.
3. EMM provides list of CSG IDs.
4. Upon paging reception, UE stops T3346, & initiate SR to respond & start S1AP.
5. If paging was received during EMM specific procedure(Attach/Detach/TAU) or SR, ignore paging &
proceed with specific procedure. Paging not allowed yet.
6. NW stop T3413 for paging UE response received.
7. Upon expiry of T3413 without response, NW reinitiates paging.
UE AS MME
Request paging
Paging
Start T3413
SERVICE REQUEST
Stop T3413
Paging- 3G Network Solutions 4

5. Paging with IMSI, Paging for SMS
1. Paging through E-UTRAN using IMSI
1. Paging using IMSI is abnormal. Only used for error recovery.
2. NW initiate paging if S-TMSI not available due to network failure.
3. EMM requests lower layer to start paging. If no TAI available, may page in all TAI with
MME.
4. UE stops T3346, locally deactivates B-context(s) and detach.
5. Delete last visited registered TAI, TAI list, GUTI and KSIASME. Set UpdateStatus=EU2 NOT
UPDATED and Enter EMM-DEREGISTERED. Stop T3396.
6. After local detach, Perform ATTACH or COMBINED ATTACH.
7. UE does not respond to paging except with attach request, hence T3413 in NW is not
used when paging with IMSI.
UE AS MME
Request paging
Paging
ATTACH
2. Paging for SMS
1. NW initiate paging on incoming MT SMS with with CN domain ="PS" to UE, When
1. IMSI attached for non-EPS services or "SMS only", and It is in EMM-Idle.
Paging- 3G Network Solutions 5

6. Paging for CS fallback to A/Gb/Iu mode
1. Paging for CS fallback to A/Gb/Iu mode
1. Initiate paging for CS fallback when UE is IMSI attached for non-EPS services.
2. When no connection exists.
1. Paging message includes UE-id and CN domain ="CS“
3. On MT CS service on SGs when NAS connection exists, UE is notified
1. EMM sends a CS SERVICE NOTIFICATION.(May include CLI, SS or LCS Parms).
4. UE On Paging receive, IMSI attached for non-EPS services:
1. Stop T3346, Initiate SR.
2. If in EMM-IDLE mode, respond immediately.
5. If CS SERVICE NOTIFICATION comes in eMM-CONNECTED, upper layers to accept or reject CSFB.
1. Response includes CSFB-IE in EXTENDED SR in both EMM-IDLE and CONNECTED.
UE AS MME
Request paging
Paging
EXTENDED SERVICE REQUEST
2. Abnormal cases in UE – If UE Attach/TAU was “SMS Only”,
1. may ignore NOTIFICATION or paging with CN domain="CS".
3. Abnormal cases on NW side – On non delivery of message to lower layers, discard message.
Paging- 3G Network Solutions 6

7. PAGING IE Structures
PCCH-Message ::= SEQUENCE { message PCCH-MessageType }
PCCH-MessageType ::= CHOICE {
c1 CHOICE { paging Paging },
messageClassExtension SEQUENCE {} }
Paging ::= SEQUENCE {
pagingRecordList PagingRecordList OPTIONAL, -- Need ON
systemInfoModification ENUMERATED {true} OPTIONAL, -- Need ON
etws-Indication ENUMERATED {true} OPTIONAL, -- Need ON
nonCriticalExtension Paging-v890-Ies OPTIONAL }
Paging-v890-IEs ::= SEQUENCE {
lateNonCriticalExtension OCTET STRING OPTIONAL, -- Need OP
nonCriticalExtension Paging-v920-Ies OPTIONAL }
Paging-v920-IEs ::= SEQUENCE {
cmas-Indication-r9 ENUMERATED {true} OPTIONAL, -- Need ON
nonCriticalExtension SEQUENCE {} OPTIONAL -- Need OP }
PagingRecordList ::= SEQUENCE (SIZE (1..maxPageRec)) OF PagingRecord
PagingRecord ::= SEQUENCE {
ue-Identity PagingUE-Identity,
cn-Domain ENUMERATED {ps, cs}, }
PagingUE-Identity ::= CHOICE {
s-TMSI S-TMSI,
imsi IMSI, }
IMSI ::= SEQUENCE (SIZE (6..21)) OF IMSI-Digit
IMSI-Digit ::= INTEGER (0..9)
Paging- 3G Network Solutions 7

8. Discontinuous Reception for paging
1. UE may use DRX in idle mode.
2. Paging Occasion (PO) is a subframe where P-RNTI may be transmitted on
PDCCH with paging.
3. Paging Frame (PF) is one Radio Frame, which may contain one or multiple
Paging Occasion(s).
4. In DRX, UE needs only to monitor one PO per DRX cycle.
5. DRX parameters are provided in SI.
6. SI DRX parameters stored in UE is updated locally whenever changed in SI.
7. DRX parameter may be specific to UE, in case UE is sent different default
Paging Cycle in “RRCConfigDedicated”.
8. For UE without IMSI (for instance in emergency call without USIM), UE_ID = 0.
Paging- 3G Network Solutions 8

9. Discontinuous Reception for paging
1. PF is an SFN when: SFN(PF) mod T = (T div N)*(UE_ID mod N)
2. Index i_s pointing to PO = i_s = floor(UE_ID/N) mod Ns
3. Params used for calculation of PF and i_s:
1. T: DRX cycle UE.
1. T = min(UE specific DRX value, default DRX value broadcast in SI).
2. If there is no UE specific DRX configured, default value is applied.
2. nB: 4T, 2T, T, T/2, T/4, T/8, T/16, T/32.= (#paging sf/frame) * T.
3. N: min(T,nB)
4. Ns: max(1,nB/T)
5. UE_ID: IMSI mod 1024 (or 0 in case no IMSI).
6. IMSI is given as sequence of decimal integer digits(0..9), not Hexadecimal.
Paging- 3G Network Solutions 9

10. Paging Example – First Subscriber
IMSI cur UE_ID Tc Tue More LHS = nB fact nB = T * N = min T/N UE_ID RHS PF =
T = min Frms - (SFN + mod
SFN = IMSI (Tc, Tue) nB Fact. (T, nB) cur_SFN
mod Calc more) N
+ more
1024 mod T
4096000147 100 147 256 256 256 47 147 4 1024 256 1 147 147 147
4096000147 100 147 256 128 128 47 19 2 256 128 1 19 19 147
4096000147 100 147 256 128 128 47 19 1 128 128 1 19 19 147
4096000148 100 148 256 128 128 68 40 0.5 64 64 2 20 40 168
4096000276 100 276 256 128 128 68 40 0.5 64 64 2 20 40 168
4096000150 101 150 256 128 128 71 44 0.5 64 64 2 22 44 172
UE_ID/ nB/ T Ns = i_s=
N max (1, (UE_id/N)
PO
1.SFN(PF) mod T = (T/N) × (UE_ID mod N)
nB/T) mod Ns
2.i_s = floor(UE_ID/N) mod Ns
4096000147 0.57 4 4 0 0 3.T = min(Tc, Tue)
4096000147 1.15 2 2 1 9 4.N = min(T , nB (#paging subframes per frame × T))
4096000147 1.15 1 1 0 9 5.Ns = max(1, #paging subframes per frame(nB/T))
4096000148 2.31 0.5 1 0 9 6.UE_ID = IMSI mod 1024
4096000276 4.31 0.5 1 0 9
4096000150 2.34 0.5 1 0 9
Ns PO PO PO PO when Ns (TDD) PO PO PO PO
(FDD) when when when i_s=3 when when when when
i_s=0 i_s=1 i_s=2 i_s=0 i_s=1 i_s=2 i_s=3
1 9 N/A N/A N/A 1 0 N/A N/A N/A
2 4 9 N/A N/A 2 0 5 N/A N/A
4 0 4 5 9 4 0 1 5 6
Paging- 3G Network Solutions 10

11. Paging Example – ....148 & ....276
IMSI cur UE_ID Tc Tue More LHS = nB fact nB = T * N = min T/N UE_ID RHS PF =
T = min Frms - (SFN + mod
SFN = IMSI (Tc, Tue) nB Fact. (T, nB) cur_SFN
mod Calc more) N
+ more
1024 mod T
4096000147 100 147 256 256 256 47 147 4 1024 256 1 147 147 147
4096000147 100 147 256 128 128 47 19 2 256 128 1 19 19 147
4096000147 100 147 256 128 128 47 19 1 128 128 1 19 19 147
4096000148 100 148 256 128 128 68 40 0.5 64 64 2 20 40 168
4096000276 100 276 256 128 128 68 40 0.5 64 64 2 20 40 168
4096000150 101 150 256 128 128 71 44 0.5 64 64 2 22 44 172
UE_ID/ nB/ T Ns = i_s=
N max (1, (UE_id/N)
PO
1.SFN(PF) mod T = (T/N) × (UE_ID mod N)
nB/T) mod Ns
2.i_s = floor(UE_ID/N) mod Ns
4096000147 0.57 4 4 0 0 3.T = min(Tc, Tue)
4096000147 1.15 2 2 1 9 4.N = min(T , nB (#paging subframes per frame × T))
4096000147 1.15 1 1 0 9 5.Ns = max(1, #paging subframes per frame(nB/T))
4096000148 2.31 0.5 1 0 9 6.UE_ID = IMSI mod 1024
4096000276 4.31 0.5 1 0 9
4096000150 2.34 0.5 1 0 9
Ns PO PO PO PO when Ns (TDD) PO PO PO PO
(FDD) when when when i_s=3 when when when when
i_s=0 i_s=1 i_s=2 i_s=0 i_s=1 i_s=2 i_s=3
1 9 N/A N/A N/A 1 0 N/A N/A N/A
2 4 9 N/A N/A 2 0 5 N/A N/A
4 0 4 5 9 4 0 1 5 6
Paging- 3G Network Solutions 11

12. Paging Collection and Dispensing design in eNB-RRC
Curr SFN Curr sub
100 frame= 0
NAS Paging->
Q Index PF PO (Sub Timer Ue-Id Link
Paging UE-ID 1 (SFN) Frame) (ms) List Ptr
Paging UE-ID 1
Paging UE-ID 1 PF 1 147 0 470 Ue-1
Paging UE-ID 1
Paging UE-ID 1 and
Paging UE-ID 1 PO 2 147 9 478 Ue-2, Ue-3
Paging UE-ID m
Calc 3 168 9 689 Ue-4, Ue-5
Paging UE-ID n 4 172 9 719 Ue-6
1. SFN(PF) mod T = (T/N) ×
(UE_ID mod N)
2. i_s = floor (UE_ID/N) mod
Ns
1. nB: 4T, 2T, T, T/2, T/4,
T/8, T/16, T/32. Timer PCCH to L2-L1
2. N: min(T,nB)
3. Ns: max(1,nB/T)
Handler
4. UE_ID: IMSI mod 1024.
Paging- 3G Network Solutions 12

13. High Level Paging Path
Start
Receive
Page
Records
Paging- 3G Network Solutions 13

14. Sample Paging Testing..1
8.1.1.1.1 Test Purpose (TP)
(1) with { UE in E-UTRA RRC_IDLE state }
ensure that { when { UE receives a Paging message including an ue-Identity set an unmatched S-
TMSI i.e. other than the one allocated to the UE at the UE registration procedure }
then { UE does not establish an RRC connection } }
(2) with { UE in E-UTRA RRC_IDLE state }
ensure that { when { UE receives a Paging message including an ue-Identity set to the S-TMSI which
was allocated to the UE at the UE registration procedure }
then { UE establishes an RRC connection } }
8.1.1.2.1 Test Purpose (TP)
(1) with { UE in E-UTRA RRC_IDLE state }
ensure that {
when { UE receives a Paging message including a systemInfoModification }
then { UE re-acquires and applies the new system information about the correct prach-ConfigIndex
in random access }
}
Paging- 3G Network Solutions 14

15. Sample Paging Testing..2
8.1.1.4.1 Test Purpose (TP)
(1) with { UE in E-UTRA RRC_IDLE state having been registered in the TA of the current cell which has
broadcasted a SystemInformationBlockType1 message including multiple PLMN identities }
ensure that { when { UE receives a Paging message including an IE ue-Identity set to the S-TMSI
which was allocated to the UE at the UE registration procedure }
then { UE establishes an RRC connection } }
8.1.1.6.1 Test Purpose (TP)
(1)with { the UE is in E-UTRA RRC_CONNECTED }
ensure that { when { the UE receives a Paging message including the systemInfoModification }
then { the UE re-acquires the MasterInformationBlock, SystemInformationBlockType1 and
SystemInformationBlockType2 }
Paging- 3G Network Solutions 15

16. 3 G
Net
Thank you
Any Questions?
Surya.patar@3gnets.in +91 9886212362
www.3gnets.in
Paging- 3G Network Solutions 16