Title:System Selection Record/MMSS Interaction with EUTRA-Record for eHRPD to LTE Idle Reselection Source: George Cherian, Ravi Patwardhan, Young Yoon {gcherian, rpatward, QUALCOMM Incorporated Date:July 20 th, 2009 Recommendation: Review and Discuss Notice ©2009. All rights reserved. QUALCOMM Incorporated 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. QUALCOMM Incorporated is 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 Partner’s standard which incorporates this contribution. This document has been prepared by QUALCOMM Incorporated 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 QUALCOMM Incorporated. QUALCOMM Incorporated specifically reserves the right to amend or modify the material contained herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to any intellectual property of QUALCOMM Incorporated other than provided in the copyright statement above.

Summary System Selection Record (such as MMSS) rules define the system the UE shall be selecting at any point of time throughout the lifecycle of the mobile System Selection Record lists the priority ordering of different systems for initial selection and re-selection of systems. The UE shall follow the rules defined by the System Selection Record for initial acquisition as well as for better service reselection(BSR) as well as for cell-reselection from one RAT to another The UE shall not perform cell-reselection to a system that is not allowed by the System Selection Record, even if the air interface E-UTRAN record advertises the E- UTRAN channels for that PLMN E-UTRAN record sent on eHRPD air-interface defines the rule for the UE to scan and select the E-UTRAN system if the System Selection Record indicates that the LTE is a higher priority RAT than eHRPD on that system If the System Selection Record indicates that LTE is lower priority than the eHRPD, then the UE does not perform LTE reselection based on E-UTRAN records In this case, UE reselects LTE, when the AT declares a loss of eHRPD system UE may declare ‘failure’ earlier, to avoid large break UE may use the E-UTRAN record information sent on eHRPD for doing this reselection This is to avoid a loop where BSR will kick-in and bring the UE back to eHRPD, if the UE chooses to transition to LTE based on air-interface EUTRAN record information Cell-reselection remains consistent with the System Selection rules (e.g. MMSS) 2

Use-case-1 3 System Selection Record (e.g., MMSS) System Selection Record indicates that LTE is higher priority than eHRPD eAN sends the EUTRAN records that indicate the following: EUTRAN record contains three EARFCNs {LTE, EARFCN, EARFCN-priority, Threshold} = {(ef1, p1, T1), (ef2, p2, T2), (ef4, p4, T4) } eHRPD serving threshold = p3; eHRPD serving threshold=Tserv p4> p3 > p2 > p1 UE behavior UE will search for ef4 irrespective of the strength of eHRPD If UE finds ef4 meeting the reselection criteria, UE will perform idle-handoff to LTE If the eHRPD signal strength < Tserv, then AT will scan for ef1, ef2, ef4 UE will perform idle handoff in the following order If (Tef4 > T4), then UE will go to ef4 Otherwise, if (Tef2 > T2), then UE will go to ef2 Otherwise if (Tef1 > T1), then UE will go to ef1

Use-case-2 System Selection Record (e.g., MMSS) System Selection Record indicates that LTE is higher priority than eHRPD eAN does not indicate any priority UE behavior UE will apply ‘all LTE channels’ to be higher priority than ‘eHRPD channels’ This is because System Selection Record indicated that the LTE is higher priority UE may select the LTE channel that has the greatest strength UE may also use other criteria This is implementation specific 4

Use-case-3 5 System Selection Record (e.g., MMSS) System Selection Record indicates that eHRPD is higher priority than E-UTRAN eAN sends the EUTRAN records that indicate the following: [same as use-case-1] EUTRAN record contains three EARFCNs {LTE, EARFCN, EARFCN-priority, Threshold} = {(ef1, p1, T1), (ef2, p2, T2), (ef4, p4, T4) } eHRPD serving threshold = p3; eHRPD serving threshold=Tserv p4> p3 > p2 > p1 UE behavior UE is not required to search for E-UTRAN irrespective of the strength of eHRPD UE may store the E-UTRAN records internally. UE may do background search in an implementation specific manner After the UE declares loss of eHRPD, then UE will scan for ef1, ef2, ef4 UE is not required to follow the E-UTRAN record information But, UE may perform idle handoff in the following order If (Tef4 > T4), then UE will go to ef4 Otherwise, if (Tef2 > T2), then UE will go to ef2 Otherwise if (Tef1 > T1), then UE will go to ef1

Use-case-4 6 System selection Record (e.g.,MMSS) System Selection Record indicates that LTE is same priority as eHRPD eAN sends the EUTRAN records that indicate the following: EUTRAN record contains three EARFCNs {LTE, EARFCN, EARFCN-priority, Threshold} = {(ef1, p1, T1), (ef2, p2, T2), (ef4, p4, T4) } eHRPD serving threshold = p3; eHRPD serving threshold=Tserv p4> p3 > p2 > p1 UE behavior UE will search for ef4 irrespective of the strength of eHRPD If UE finds ef4 meeting the reselection criteria, UE will perform idle-handoff to LTE If the eHRPD signal strength < Tserv, then AT will scan for ef1, ef2, ef4 UE will perform idle handoff in the following order If (Tef4 > T4), then UE will go to ef4 Otherwise, if (Tef2 > T2), then UE will go to ef2 Otherwise if (Tef1 > T1), then UE will go to ef1

Alternate Option and Issues eHRPD to LTE cell reselection is controlled completely by E- UTRAN records sent on the eHRPD air interface Issues with this approach In a roaming scenario, if the UE is allowed to roam only on the eHRPD system and not on the LTE system: If the UE follows the EUTRAN records sent on eHRPD air interface, then the UE will transition to LTE and attempt to attach on LTE. This attempt will fail since the UE is not allowed to operate on LTE and hence the UE will go back to eHRPD. Potentially lead to ping-pong loop. Additional battery consumption due to un-necessary LTE scan In a roaming scenario, if the UE selects the LTE system that is less preferred than the eHRPD, then the Better Service Reselection will bring the UE back to eHRPD periodically Potentially lead to ping-pong Additional battery consumption due to LTE and eHRPD scan 7