1. Active Call Hand-in in cdma2000 1x Airvana Qualcomm October 27 th, 2008 3GPP2 Seoul, Korea Notice ©2008. All rights reserved. The contributors 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. The contributors 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 Partner’s standard which incorporates this contribution. This document has been prepared by the contributors 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 the contributors. The contributors 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 the contributors other than provided in the copyright statement above.

2. 1x Hand-in Overview When MS moves from macro BS into femto AP coverage while on active voice call, how does handoff occur? Main problem: Many femtos over a few available PN offsets –Source BS is currently configured with mapping between target BS/MSC and the corresponding PN offset in the pilot report –Hand-in target is ambiguous if just rely on PN Solution needs to –Support of legacy 1x terminals –No change to legacy macro 1x system –Accurately identify handoff target

3. ‘Current’ Solutions Blind Handoff –Blindly setup traffic channel in possible target femto(s), and perform handoff In the closed access model, this results in a large number of handoff failures In open access, this results in wasted PHY resources in a large number of femtos, since only one of the femtos is the likely target. Narrowing candidate target set –Use round-trip and/or IS-801 to estimate AT location –Use intelligent PN planning for further optimization Standardize additional messages (APIDM, HSIN etc.) These techniques do not satisfy every goal in the previous slide

4. What can we do for hand-in without changing legacy macro 1x BS or MS? Observations on the air-interface –If MS reports Pilot Strength measurement to macro BS containing PN from a femto in proximity (say Femto 1), then Femto 1 should be able to see RL signal from MS also –Another Femto AP (say Femto 2) which emits the same PN as Femto 1 will either Cannot detect RL signal from MS because it is too far, or Detect RL signal but since Femto 2 is much farther away from MS, therefore –Detected RL power from Femto 1 (based on the MS RL Long Code Mask) would be much stronger than Femto 2 –Estimated path loss from Femto 1 to MS would be much smaller than Femto 2 to MS –We refer to this concept in general as Proximity Detection Observations on the network –MFIF and Femto APs are all new entities –All information needed to detect MS RL signal (e.g., MS Long Code Mask) are already in messages for supporting hand-off (e.g., Handoff Request and IS-41 FacDir2 messages) –MFIF knows PNs that Femtos under it are using

5. A possible solution Combine Proximity Detection (to determine handoff target) with existing IS-41 Handoff Procedures –MFIF can be enhanced to initiate hand-in with many Femto APs (which uses the same ambiguous PN) at the same time –Femto APs can detect and report proximity metrics (e.g., RL pilot strength of the mobile RL LCM and path loss) before committing to handoff –MFIF can compare proximity metrics from multiple femtos and decide to handoff to the femto AP that has the best metric Additional standard needed to report proximity metrics from femto to MFIF but no changes to 1x macro system

6. A possible call flow – note that existing macro 1x does not change

7. Possible Further Enhancements Macro BS uses IS-41 Handoff Measurement Request to target femto AP before deciding to handoff In a dense deployment, hand-in candidate ambiguity can be further reduced based on heuristics –Use of Downlink Radio Environment information to further restrict target femto candidates –How often the MS uses a particular target femto? Frequency of use Most recent use –Is the MS home femto within the source cell coverage?