1. C30-20090330-051 Date:30 March, 2009 Abstract: This contribution contains the active set management proposal for cdma2000 1x Rev E Notice Contributors grant 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. 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 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 Contributors. 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 Contributors other than provided in the copyright statement above. Active Set Management Modifications for 1x Rev E Recommendation : Review and adopt Source:Shu Wang and Tony Lee VIA Telecom Contact: shuwang@via-telecom.com shuwang@via-telecom.com

2. C30-20090330-051 Active Set Management Modifications for 1x Rev. E Source: Shu Wang and Tony Lee VIA Telecom

3. Outline The dilemma in the existing active set management Suggested modifications  Solution 1: Add some mechanisms for mobiles to configure/recommend the size of Forward Active Set.  Solution 2: Mobiles dynamically send commands to temporally suspend unnecessary forward link transmission from some base stations in the active set when doing soft handoff.

4. Active Set Management The existing Active Set management in C.S0005-E  3.6.6.2.4.1 Receiving During Soft Handoff  [ … ] Each base station in the Active Set shall demodulate the Reverse Traffic Channel. The base station should provide diversity combining of the demodulated signals obtained by each base station in the Active Set. [ … ]  3.6.6.2.4.2 Transmitting During Soft Handoff  [ … ] The base station shall use the same long code mask on all Forward Traffic Channels whose associated pilots are in the Active Set. [ … ] Proposed Modifications  3.6.6.2.4.1 Receiving During Soft Handoff  [ … ] Each base station in the Active Set shall demodulate the Reverse Traffic Channel. The base station should provide diversity combining of the demodulated signals obtained by each base stations. [ …]  3.6.6.2.4.2 Transmitting During Soft Handoff  [ … ] The base station shall use the same long code mask on all Forward Traffic Channels whose associated pilots are in the Active Set. [ … ]

5. The Dilemma in Active Set Management The Active Set Size should be large enough to maximize reverse link macro- diversity gain.  This is well understood in the industry. And it is desired for both 1x and DO reverse link design.  “… For EV-DO Rev A, the voice capacity in a single 1.25 MHz carrier increases from 41 [1] to 66 per sector with 4-way RX diversity. In this case, the number of MAC indices is the limiting factor for voice capacity.” --- Source: Qualcomm Incorporated, VoIP white paper “VoIP Overview” [1] EVRC, RL 2-way diversity, no IC, no DTX/DRX, inter-base station distance of 2 km.  However, it is well-known that high order receiver diversity at BS is hard to achieved due to the limitation of antenna array design. The Active Set Size should be small enough to avoid unnecessary inter-cell interference in forward link.  If the active set size is too large, there will be more users in soft handoff and more interference to other users in the same or different base stations. Soft handoff incurs extra load on the system due to the increase in the number of channels occupied and reserved for macro-diversity. –Too many SHO users may block the admission of new traffics and decrease the actual user capacity. With more users in SHO, both transmission power and interference increases. –More interference to the adjacent cells.  Active Set Size 2 or 3 can be the good number.

6. User Capacity Gain (1/2) VoIP User Capacity, Outage Based, T_ADD=-18dB, Channel B, RAKE finger number = 6

7. User Capacity Gain (2/2)

8. The Remedies Modification 1:  Add some mechanisms for mobiles to configure/recommend the size of Forward Active Set. MSs send its recommendation or configuration for the size of Forward Active Set. Modification 2:  Cell Selection Handoff help the system to achieve the optimal operation point between reliability and throughput as well as minimize inter-cell interference.  CSHO help achieve more spatial diversity gain in soft handoff in addition to the time diversity explored by the frame early termination with R-ACKCH.