![7. If the target RAT is GERAN and DTM is not supported, the UE starts the Suspend procedure.
This triggers the SGS to send a Suspend Request message to the MME, The MME returns a
Suspend Response to the SGSN even though the GUTI cannot be derived from the P-TMS1 and
RAI pair
RAI pair
8. If the S1 -AP UE Context Release Request message, received from the eNodeB in step 4,
indicates that the UE is not available for the PS service in the target cell the MME starts the
ti d i f GBR b d th d ti ti f GBR b t d
preservation and suspension of non-GBR bearers and the deactivation of GBR bearers towards
S-GW and P-GW(s). The MME stores in the UE context that UE is in suspended status.
9. The UE continues with the MO call setup procedure with sending CM Service Request.
p p g q
10a. if the UE is not registered in the MSG serving the 2G/3G cell or the UE is not allowed in
the LA, the MSG shall reject the service request, if implicit location update is not performed.
10b. A UE detecting that the MSG rejected the service request shall perform the Location Area
Update or a Combined RA LA procedure according to existing GERAN or UTRAN procedures for
the different Network Modes of Operation (NMO).
p
10c The UE initiates the CS call establishment procedure.
11 Aft th CS i ll i t i t d d if th UE i i GERAN d PS i
11. After the CS voice call is terminated and if the UE is in GERAN and PS services are
suspended, then the UE shall resume PS services as specified in TS 23.060 [3]. A Gn/Gp -SGSN
will follow TS 23.060 [3] to resume the PDP Contexts). An S4 SGSN will follow TS 23.060 [3]
to resume the bearers, and informs the S-GW and P-GW(s) to resume the suspended bearers. If
th UE h t d t E UTRAN ft th CS i ll t i t d th th UE h ll
the UE has returned to E-UTRAN after the CS voice call was terminated, then the UE shall
resume PS service by sending TAU to MME. The MME will in addition inform S-GW and P-
GW(s) to resume the suspended bearers](https://image.slidesharecdn.com/lteflowprocedures-240618125304-0acb5da7/85/LTE-Call-Flow-Procedures-Intra-LTE-HO-procedure-15-320.jpg)
LTE Call Flow Procedures ,Intra LTE HO procedure
- 1. LTE Call Flow Procedures LTE Call Flow Procedures R d • Random access • Attach process D t h • Detach process • Intra LTE HO procedure CSFB • CSFB • Events
- 2. LTE Random Access LTE Random Access
- 4. Step 1: Msg1 UE selects one of the 64 available RACH preambles p Step 2: Msg2 The message carries following information g g Temporary C-RNTI Timing Advance Value Uplink Grant Resource Step 3: Msg3 Using UL-SCH, UE sends "RRC connection request message" to eNodeB UE i id tifi d b t C RNTI ( i d i th i t b UE is identified by temporary C-RNTI (assigned in the previous step by eNodeB) The message contains following UE identity (TMSI or Random Value ) UE identity (TMSI or Random Value ) Connection establishment cause Step 4: Msg4 Step 4: Msg4 eNodeB responds with contention resolution message to UE whose message was successfully received in step 3. This message is address towards TMSI value or Random number (from previous steps) but contains the new C value or Random number (from previous steps) but contains the new C RNTI which will be used for the further communication
- 6. The detach procedure is either initiated by the UE or by the network The detach procedure is either initiated by the UE or by the network. The network initiates the detach procedure: To detach the UE for EPS services or non-EPS services or both To disconnect the UE from the last PDN to which it is connected To inform the UE to re-attach to the network and re-establish all PDN To inform the UE to re attach to the network and re establish all PDN connections. The UE initiate the detach procedure when: p the UE is switched off the USIM is removed from the UE the EPS capability of the UE is disabled
- 8. Intra LTE HO procedure Intra LTE HO procedure
- 9. • The source eNB configures the UE measurement procedures according to the area restriction information. UE sends MEASUREMENT REPORT by the rules set by i.e. system information, specification etc. set by i.e. system information, specification etc. • Source eNB makes decision based on MEASUREMENT REPORT and RRM information to hand off UE and issues a HANDOVER REQUEST message to the target eNB passing necessary information to prepare the HO at the target side. • Admission Control may be performed by the target eNB dependent on the received E-RAB QoS information to increase the likelihood of a successful HO. The target eNB configures the required resources according to the received E- RAB QoS information RAB QoS information. • Target eNB prepares HO with L1/L2 and sends the HANDOVER REQUEST ACKNOWLEDGE to the source eNB. The HANDOVER REQUEST ACKNOWLEDGE message includes a transparent container to be sent to the ACKNOWLEDGE message includes a transparent container to be sent to the UE as an RRC message to perform the handover. • The UE receives the RRCConnectionReconfiguration message with necessary parameters (i.e. new C-RNTI, target eNB security algorithm identifiers, and p g y g optionally dedicated RACH preamble, target eNB SIBs, etc.) and is commanded by the source eNB to perform the HO. • The source eNB sends the SN STATUS TRANSFER message to the target eNB to co ve the pli k PDCP SN eceive stat s a d the dow li k PDCP SN to convey the uplink PDCP SN receiver status and the downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies (i.e. for RLC AM). • After receiving the RRCConnectionReconfiguration message including the After receiving the RRCConnectionReconfiguration message including the mobilityControlInformation , UE performs synchronisation to target eNB and accesses the target cell via RACH.
- 10. • The target eNB responds with UL allocation and timing advance. • UE sends the RRCConnectionReconfigurationComplete message (C-RNTI) t fi th h d t th t t NB t i di t th t th h d to confirm the handover to the target eNB to indicate that the handover procedure is completed for the UE. The target eNB verifies the C-RNTI sent in the RRCConnectionReconfigurationComplete message. The target eNB can now begin sending data to the UE. g g • The target eNB sends a PATH SWITCH message to MME to inform that the UE has changed cell. • The MME sends an UPDATE USER PLANE REQUEST message to the Serving Gateway Serving Gateway. • The Serving Gateway switches the downlink data path to the target side. The Serving gateway sends one or more "end marker" packets on the old path to the source eNB and then can release any U-plane/TNL resources t d th NB towards the source eNB. • Serving Gateway sends an UPDATE USER PLANE RESPONSE message to MME. • The MME confirms the PATH SWITCH message with the PATH SWITCH The MME confirms the PATH SWITCH message with the PATH SWITCH ACKNOWLEDGE message. • By sending UE CONTEXT RELEASE, the target eNB informs success of HO to source eNB and triggers the release of resources by the source eNB. The target eNB sends this message after the PATH SWITCH ACKNOWLEDGE target eNB sends this message after the PATH SWITCH ACKNOWLEDGE message is received from the MME. • Upon reception of the UE CONTEXT RELEASE message, the source eNB can release radio and C-plane related resources associated to the UE i d f di i p context. Any ongoing data forwarding may continue.
- 11. CSFB Inter-connected nodes CSFB Inter-connected nodes The support CS fallback in EPS a new interface SGs is added in LTE architecture. SGs interface is the reference point between the MME and MSC server. SGs interface is used for the mobility management and paging procedures between EPS and CS domain and is based on the Gs interface procedures between EPS and CS domain, and is based on the Gs interface procedures
- 12. CS Fallback and IMS based services can co-exist in the same operator network. Although its not very straight forward to support CS fallback, all i i i l i d participating elements i.e UE, MME, MSC & E-UTRAN needs to support additional functionalities. UE UE supports access to E-UTRAN/EPC as well as access to the CS domain over GERAN and/or UTRAN. Combined procedures for EPS/IMSI attach, update and detach. CS fallback and SMS procedures for using CS domain services. CS fallback and SMS procedures for using CS domain services MME Deriving a VLR number and LAI from the GUTI received from the UE or from a default LAI. Maintaining of SGs association towards MSC/VLR for EPS/IMSI attached UE. Initiating IMSI detach at EPS detach. Initiating paging procedure towards eNodeB when MSC pages the UE for CS services. Support of SMS procedures Rejecting CS Fallback call request (e g due to O&M reasons) Rejecting CS Fallback call request (e.g. due to O&M reasons) Use of the LAI and a hash value from the IMSI to determine the VLR number when multiple MSC/VLRs serve the same LAI. MSC Maintaining SGs association towards MME for EPS/IMSI attached UE. Support of SMS procedures as provided in 3GPP specification E-UTRAN F di i t d SMS t th UE Forwarding paging request and SMS to the UE. Directing the UE to the target CS capable cell.
- 13. CSFB message flow CSFB message flow
- 14. 1a. The UE sends an Extended Service Request (CS Fallback Indicator) to the MME. Extended Service Request message is encapsulated in RRC and S 1 -AP messages. CS Fallback Indicator indicates MME to perform CS Fallback. 1b. The MME sends an S1-AP UE Context Modification Request message to eNB that includes a CS Fallback Indicator. This message indicates to the eNB that the UE should be moved to UTRAN/GERAN Th l f th CS F llb k I di t i t t "CS F llb k ith t PS HO UTRAN/GERAN . The value of the CS Fallback Indicator is set to "CS Fallback without PS HO Required" 1c. The eNB shall reply with S 1 -AP UE Context Modification Response message p y p g 2. The eNodeB may optionally solicit a measurement report from the UE to determine the target GERAN/UTRA cell to which the redirection procedure will be performed. 3. If the UE and network support inter-RAT cell change order, The eNodeB triggers an inter- RAT cell change order 4. The eNodeB sends an S1-AP UE Context Release Request message to the MME. 5. The MME releases the UE Context in the eNodeB as well as all eNodeB related information in h the S-GW 6a. (Step 6a is performed if step 3a, Cell Change Order to GERAN, was performed) The UE moves to the new cell in GERAN The UE uses the NACC information and/or receives the The UE moves to the new cell in GERAN. The UE uses the NACC information and/or receives the broadcast System Information and when it has all of the necessary information to access the GERAN cell, establishes a radio signaling connection.
- 15. 7. If the target RAT is GERAN and DTM is not supported, the UE starts the Suspend procedure. This triggers the SGS to send a Suspend Request message to the MME, The MME returns a Suspend Response to the SGSN even though the GUTI cannot be derived from the P-TMS1 and RAI pair RAI pair 8. If the S1 -AP UE Context Release Request message, received from the eNodeB in step 4, indicates that the UE is not available for the PS service in the target cell the MME starts the ti d i f GBR b d th d ti ti f GBR b t d preservation and suspension of non-GBR bearers and the deactivation of GBR bearers towards S-GW and P-GW(s). The MME stores in the UE context that UE is in suspended status. 9. The UE continues with the MO call setup procedure with sending CM Service Request. p p g q 10a. if the UE is not registered in the MSG serving the 2G/3G cell or the UE is not allowed in the LA, the MSG shall reject the service request, if implicit location update is not performed. 10b. A UE detecting that the MSG rejected the service request shall perform the Location Area Update or a Combined RA LA procedure according to existing GERAN or UTRAN procedures for the different Network Modes of Operation (NMO). p 10c The UE initiates the CS call establishment procedure. 11 Aft th CS i ll i t i t d d if th UE i i GERAN d PS i 11. After the CS voice call is terminated and if the UE is in GERAN and PS services are suspended, then the UE shall resume PS services as specified in TS 23.060 [3]. A Gn/Gp -SGSN will follow TS 23.060 [3] to resume the PDP Contexts). An S4 SGSN will follow TS 23.060 [3] to resume the bearers, and informs the S-GW and P-GW(s) to resume the suspended bearers. If th UE h t d t E UTRAN ft th CS i ll t i t d th th UE h ll the UE has returned to E-UTRAN after the CS voice call was terminated, then the UE shall resume PS service by sending TAU to MME. The MME will in addition inform S-GW and P- GW(s) to resume the suspended bearers
- 16. LTE Events LTE Events A1 & A2 A1 & A2
- 17. A3 & A4 A3 & A4 Offset
- 18. A5 A5
- 19. B1 & B2 B1 & B2
- 20. LTE/WCDMA Events comparison LTE/WCDMA Events comparison