Support for CSFBTony Lee aslee@via-telecom.comDavid Wang davidwang@via-telecom.comJune/15/2009VIA Telecom grants a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner's name any Organizational Partner's standards publication even though it may include all or portions of this contribution; and at the Organizational Partner's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner's standards publication. VIA Telecom are also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partners standard which incorporates this contribution.This document has been prepared by VIA Telecom to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on VIA Telecom. VIA Telecom specifically reserves the right to amend or modify the material contained herein and to any intellectual property of VIA Telecom other than provided in the copyright statement above.

IntroductionThis contribution list out some stage two concepts that needs to be incorporate into C.P0087 v2.0 to support CSFB

CSFB backgroundTS 23.272 CSFB in EPS stage 2, it contains the requirements for E-UTRAN to 1xRTT CSFB, which includes:ArchitectureUEE-UTRANMME

Architecture

1xCS CSFB UE

1xCS CSFB UE

Tunnelled 1xRTT messages

A1

A1

S1-U

S1-MME

S11

S102

1xCS IWS

1xRTTMSC

1xRTT CS Access

SGi

Serving/PDN GW

MME

E-UTRAN

CSFB call flow: Pre-registration

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Text

1xCS CSFBUE

E-UTRAN

MME

1xCSIWS

1xRTTMSC

3. 1xRTT CS registration request

5. 1xRTT CS registration response

5c. UL/DL InformationTransfer

3a. UL/DL InformationTransfer

5b UL/DL S1 cdma2000Tunnelling

4. Location update to 1xRTT CS domain

5a. S102 Direct Transfer

1. UE attaches to E-UTRAN as specified in TS 23.401

Pre-registration1.UE attaches to E-UTRAN as specified in TS23.401[2];2.Based on a radio layer trigger (e.g. an indication from the E-UTRAN when the UE is in connected state or an indication over the broadcast channel), the UE decides to register with the 1xRTT CS domain;3.UE generates a 1xRTT CS registration request.3a.The 1xRTT CS message is transferred from the UE to E-UTRAN.3b.E-UTRAN forwards the 1xRTT CS message to the MME including the Reference CellID.3c.MME selects a 1xCS IWS node based on Reference CellID. The IMSI is used to distinguish S102 signalling transactions belonging to different UEs. The MME sends a S102 Direct Transfer message (IMSI, 1xCS message) to the 1xCS IWS node.4.1xRTT CS registration is then performed by the 1xCS IWS node based on 3GPP2 A.S0008[16].5a.1xRTT CS registration response is tunnelled back to the MME in a S102 Direct Transfer message (IMSI, 1xCS message).5b.MME forwards the 1xRTT CS message to the E-UTRAN.5c.E-UTRAN forwards the 1xRTT CS message to the UE.If the triggers for 1xCS registration change over time, the UE (both in idle or active state), uses this information to update the 1xCS registration via the tunnel.

CSFB call flow: Mobile Origination

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Text

1xCS CSFBUE

E-UTRAN

MME

1xCSIWS

1xRTTMSC

11. 1x MO call establishment per 3GPP2 specifications

1. UE is E-UTRAN attached and registered with 1xRTT CS

10. S1 UE Context Release

Mobile Origination1.UE is EUTRAN attached and registered with 1xRTT CS as defined in clauseB.2.1.1.2.UE makes a decision to perform a mobile originated CS call.3.UE sends a Service Request (CS Fallback Indicator) to the MME.4.MME sends S1-AP: UE Context Modification (UE capabilities, CS Fallback Indicator) to indicate the EUTRAN to move the UE to 1xRTT.5.E-UTRAN may optionally solicit a measurement report from the UE to determine the target 1xRTT cell to which the CS Fallback will be performed.6.E-UTRAN triggers RRC connection release with redirection to 1xCS or inter-RAT Cell Change Order to a 1xRTT neighbour cell.7.E-UTRAN sends an S1 UE Context Release Request (Cause) message to the MME. Cause indicates that the S1 UE Context Release was caused by CS fallback to 1xRTT.8.MME sets the UE context to suspended status and sends to the S-GW a Suspend Request (IMSI) message that requests the suspension of EPS bearers for the UE.9.S-GW acknowledges the Suspend Request message and marks the UE as suspended. When a downlink data arrives at the S-GW, the S-GW should not send a downlink data notification message to the MME if the UE is marked as suspended.10.S1 UE Context in the E-UTRAN is released as specified in TS23.401[2].11.UE moves to 1xRTT and performs the procedure for mobile originating call as specified in 3GPP2A.S0013[18].Once CS service ends in the 1xCS domain, the UE returns to EUTRAN by performing reselection. The EPS service is resumed as described in clause6.5.

Mobile Termination

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Text

1xCS CSFBUE

E-UTRAN

MME

1xCSIWS

1xRTTMSC

3. 1xRTT CS Paging

5. 1xRTT CS Paging

5b. UL/DL InformationTransfer

15. 1x MT call establishment per 3GPP2 specifications

4. If UE is idle, MME performs Network-initiated service request

1. UE is E-UTRAN attached and registered with 1xRTT CS

Mobile TerminationUE is E-UTRAN attached and pre-registered with 1xRTT CS as defined in clause B.2.1.1.2.1xMSC sends a paging request to the 1xCS IWS node.3.1xCS IWS node forwards the 1x RTT CS paging request via the S102 tunnel to the MME. 4.If the UE is in idle state, the MME performs the network initiated Service Request procedure in order to bring the UE to active state prior to tunnelling of the 1x RTT CS paging request toward the UE.5.MME forwards the 1xRTT CS paging request to the UE.6.UE sends a Service Request (CS Fallback Indicator) to the MME.7.MME sends S1-AP: UE Context Modification (UE capabilities, CS Fallback Indicator) to indicate the E UTRAN to move the UE to 1xRTT.8.E-UTRAN may optionally solicit a measurement report from the UE to determine the target 1xRTT cell to which the CS Fallback will be performed.9.E-UTRAN triggers RRC connection release with redirection to 1xCS or Inter-RAT Cell Change Order to a 1xRTT neighbour cell.10.E-UTRAN sends an S1 UE Context Release Request (Cause) message to the MME. Cause indicates that the S1 UE Context Release was caused by CS fallback to 1xRTT.11.MME sets the UE context to suspended status and sends to the S-GW a Suspend Request (IMSI) message that requests the suspension of EPS bearers for the UE.12.S-GW acknowledges the Suspend Request message and marks the UE as suspended. When a downlink data arrives at the S-GW, the S-GW should not send a downlink data notification message to the MME if the UE is marked as suspended.13.S1 UE Context in the E-UTRAN is released as specified in TS 23.401 [2].14.UE tunes to 1xRTT and acknowledges the page by transmitting a 1xRTT Paging Response message over the 1x Access Channel.15.Subsequently UE performs the procedure for mobile terminated call establishment as specified in 3GPP2 A.S0013 [18].

CSFB backgroundTS 36.331 Radio Resource Control, it contains requirement for:Messages and parameters to set up 1x registrationSIB 8System timeLong Code StateCSFB registration parameters

Requirements for 1xSynchronize with base station using information provided by SIB 8Need to send LAC encapsulated message over E-UTRAN tunnelPerform pilot measurement during E-UTRAN gapTrack registration statusPerform origination or page response with minimum delay

Proposal Overview

Proposal: Data plane view

Proposal detailsCSTDPCircuit Switch Tunneling Data ProtocolEncapsulate LAC messages with parameters similar to CSNA:ARQ parametersLogical channelProtocol revision numberCSTCPInterface between E-UTRAN and 1xBase station: generate necessary 1x overhead parametersMobile: process 1x parameter and pass this on to L3

Proposal detailsChanges to 1x mobileBypass pilot acquisitionUse SIB 8 information to synchronize with base stationNo need to monitor control channel, this includes paging and BCCHNo need to start any supervision timerObtain parameters from CSTCP

Additional changes for C.S0087Need to add MobilityParametersCDMA2000 in C.S0087 to support TS 36.331In TS 36.331 RRC document has two messages related to CSFBCSFBParametersRequestCDMA2000 ( UE to eNB)CSFBParametersResponseCDMA2000MobilityParametersCDMA2000 is defined, but refers to C.S0087 for details. The parameters are necessary to generate the registration message

THANK YOU!

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