1. June 12 2001DENSO Dynamic T_TDROP1 Dynamic Pilot Drop Timer for cdma2000 June 12th, 2001 Notice The proposals in this submission have been formulated by DENSO INTERNATIONAL AMERICA, Inc. to assist the 3GPP2 Standards Committee. This document is offered to the committee as a basis for discussion and is not binding on DENSO INTERNATIONAL AMERICA. The requirements are subject to change in form and in numerical values after more study. DENSO INTERNATIONAL AMERICA specifically reserves the right to add to, or amend, the quantitative statements made herein. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any patent, whether or not the use of information herein necessarily employs an invention of any existing or later issued patent. GRANT OF LICENSE: The contributor grants a free, irrevocable license to the 3GPP2 to incorporate text contained in this contribution and any modifications thereof in the creation of a 3GPP2 standards publication; to copyright in 3GPP2’s name any 3GPP2 standards publication even though it may include portions of this contribution; and at 3GPP2’s sole discretion to permit others to reproduce in whole or in part the resulting 3GPP2 standards publication. Jason F. HunzingerAnna Tee Ramon Khalona (760) 804-2430(760) 804-2549 (760) 929-3347 (760) 929-3355 (fax)(760) 804-2500 (fax) (760) 804-2500 (fax) jason_hunzinger@densolabs.com anna_tee@densolabs.com ramon_khalona@densolabs.com

2. June 12 2001DENSO Dynamic T_TDROP2 Dynamic Pilot Drop Timer for Soft Handoff in CDMA 2000 Objective:To enhance soft handoff procedure in CDMA 2000 cellular networks Method:Allow some flexibility for mobile terminals to determine the best time to remove a base station sector from its active set, i.e., time to drop a degrading pilot. Detailed descriptions and explanations have been discussed in the contribution: “C30-20010212-006_Denso_Dyn_TTDROP_Presentation.ppt”

3. June 12 2001DENSO Dynamic T_TDROP3 Simulation Parameters Cell layout: 8 hexagonal cells, with omni- directional antennas; Path loss model: Cost-231, PL(d) = 28.6+ 35log10(d) dB, d >= 35m; [1] Data rate: 9600 bps Shadowing model: Log-normal distribution with mean: 0 dB, standard deviation: 8 dB, Correlation coefficient between base stations = 0.5; Jakes’ model to simulate Rayleigh fading channel, computed at 1.25 ms steps; Outer power control loop not simulated; Short-term frame error rate is computed using quasi-static method, averaged over 100 frames.

4. June 12 2001DENSO Dynamic T_TDROP4

5. June 12 2001DENSO Dynamic T_TDROP5 Summary of simulation results Mobile terminals traveling on paths along the cell boundary were simulated. Channel models include log-normal shadowing; and random blocking. The flexibility of choosing T_TDROP value to be lower than the nominal value enables the mobile terminal to reduce the average size of its active set appropriately, while still maintaining the call quality within the required limit, as indicated by the cumulative distribution of the short-term FER. When the call quality is not sufficient, the mobile terminal can select a T_TDROP value above the nominal value, so as to maintain a larger active set, to improve the call quality and to avoid the call being dropped, through diversity gain. The use of a larger static T_TDROP is not optimum as it increases the average size of the active set unnecessary, i.e., even when the call quality has satisfied the required specification. The capacity would thus be adversely affected in this case.

6. June 12 2001DENSO Dynamic T_TDROP6 Absolute Performance Improvement

7. June 12 2001DENSO Dynamic T_TDROP7 Relative Performance Improvement * Improvements relative to static 4s cases.

8. June 12 2001DENSO Dynamic T_TDROP8 CDF of FER Shadowing Blocking LEGEND - Dynamic - Static 4s - Static 7s

9. June 12 2001DENSO Dynamic T_TDROP9 Algorithm Recommendations Adapt based on recent history of handoff statistics Collect statistics on the relative timing of handoffs involving each pilot (sector) that has recently been in the active set. Before dropping a pilot, predict, based on the collected statistics, if the pilot is likely to be required in the near future. Do not drop the pilot if it will be required again soon. Drop the pilot if it will not be required again soon. Optionally: Remember past decisions and adapt.

10. June 12 2001DENSO Dynamic T_TDROP10 Algorithm Validation

11. June 12 2001DENSO Dynamic T_TDROP11 Conclusions Dynamic T_TDROP concept can offer more flexibility when deleting pilots from the MS active set by retaining pilots that may be needed later or discarding unneeded pilots sooner Call quality results are comparable to static drop timer results, or better In some cases, the average active set size is not significantly different with the dynamic drop timer (i.e., when unneeded pilots are discarded sooner) The handoff rate can be significantly reduced through the use of dynamic drop timer Thus, the processing load at both MS and BS can be reduced, and the probability of lost handoff messages (PSMM, UHDM etc.) can be lowered Loss of handoff messages was not included in the simulation. The performance improvement by dynamic pilot drop timer is likely to be even more significant if this is taken into account. The use of Dynamic T_TDROP may be beneficial in terms of improving the Soft Handoff distribution

12. June 12 2001DENSO Dynamic T_TDROP12 References [1] WG5 Evaluation AHG, "1xEV-DV Evaluation Methodology (Rev. 26)", May 9, 2001. [2] “C30-20010212-006_Denso_Dyn_TTDROP_Presentation.ppt”, Feb 12, 2001 [3] IS-2000-5 “Upper Layer (Layer3) Signaling Standard for cdma2000 Spread Spectrum Systems”, 2000. [4] IS-2000-2 “Physical Layer Standard for cdma2000 Spread Spectrum Systems-Release A”, 2000. [5] S. Maric, I. Seskar, V. Erceg, “Vehicular Traffic Influence on the Propagation and Handoff Characteristics of a CDMA System for PCS in an Urban Environment”, IEEE 2nd ISSSTA, Nov 1992. [6] Deepa Ramakrishma, “On Improving Call Drop Rates in CDMA2000”, Proceedings, IEEE WCNC 1999. [7] A. Chheda, “A Performance Comparison of the CDMA IS-95B and IS-95A Soft Handoff Algorithms”, Proceedings, IEEE VTC 99, pp. 1407-1412. [8] S. Soliman, “Performance of the Proposed (IS-95-B) New Soft Handoff Algorithm”, TR45.5.3.1/97.03.18.02, March 18, 1997.