IEEE m Sounding Channel Designs Document Number: IEEE C802.16m-09/0140r1 Date Submitted: Source: Chih-Yuan Lin Pei-Kai Liao ), Yu-Hao Chang Ciou-Ping Wu and Paul Cheng MediaTek Inc. Venue: IEEE m-08/052: Call for Comments on Project m SDD (802.16m-08/003r6), Section UL Sounding Channel. Base contribution: N/A Purpose: Propose to be discussed and adopted by TGm for the use in Project m SDD Notice: This document does not represent the agreed views of the IEEE Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and. Further information is located at and.

Outline ▪ Design considerations of sounding channel ▪ FDM sounding PHY structures ▪ Simulation results ▪ Summary ▪ Text proposal ▪ Appendix

Design Considerations (1/2) ▪ 1. Sounding signals are not allowed to collide with original pilots which are allocated in various kinds of UL tile structures –If collision happens, qualities of channel estimations for data transmission would degrade and thus data recovery would be unreliable –Three types of tile structures for UL transmission 2 18x6 tiles and 1 6x6 tile

Design Considerations (2/2) ▪ 2. Maximally maintain sounding pattern consistency between each DRU tile (6x6) –Since sounding is designed based on 18x6 tile, sounding patterns in 6x6 tiles may vary if we don’t carefully design –Sounding consistency is recommended to be maintained such that there is no need to memorize several data mapping rules at MS ▪ 3. Cannot affect other users’ UL behaviors after allocating sounding signals –E.g., utilization of SFBC Note: MS should memorize 3 mapping rules for DRU when sounding mode is enabled

Sounding PHY Structure (1/1) ▪ Example of FDM sounding PHY structure –Based on design considerations, we have following example of FDM sounding structure Frequency-direction decimation can be used for multiuser (or multi-antenna) sounding Sounding signal

Simulation Results (1/6) ▪ Comparative sounding structures Motorola’s ExampleProposed FDM Example CDM Example One CDMA code

Simulation Results (2/6) ▪ Simulation parameters –Number of users 3 and 6 –Channel estimation: 2D-MMSE Optimized to predefined velocity speed 15 km/hr Optimized to predefined channel delay spread 5 us –Channel model PB 3 km/hr VA 30 km/hr –Performance metric Channel estimation mean square error (MSE) System throughput –Code sequences of CDM Length-6 Zadoff-Chu sequences –5 MCS levels QPSK 1/2, QPSK 3/4, 16QAM 1/2, 16QAM 3/4, 64QAM 2/3

Simulation Results – CE MSE (3/6) ▪ PB 3 km/hr –In FDM sounding category, MTK and Motorola perform highly similarly –FDM performs better than CDM, especially when number of users increases 3 users6 users

Simulation Results – CE MSE (4/6) ▪ VA 30 km/hr –Performance tendency is the same as under PB 3 channel model 3 users 6 users

Simulation Results – Throughput (5/6) ▪ PB 3 km/hr –8 BS antennas and 3 single-antenna MSs (8x3 MIMO) BS performs ZF beamforming two subframes (12 symbol durations) later than sounding –Two companies’ proposals have highly similar performance 3 users

Simulation Results – Throughput (6/6) ▪ VA 30 km/hr –MTK’s proposal perform very slightly better than Motorola’s one 3 users

Summary (1/1) ▪ For FDM sounding, MTK’s and Motorola’s sounding designs have similar performances –MTK’s sounding can have very slightly better performance at mobility case –Motorola’s design seems to restrict MS’s behavior Cannot apply STBC when sounding is enabled ▪ Simulations also show that FDM sounding can largely outperform CDM sounding, especially when number of users increases –Since code orthogonality is destroyed by channel frequency/time selectivity, multi-user interference is severe

Text Proposal … Sounding from single or multiple antennas and multiple users are supported to provide MIMO channel information for DL transmission. The allocation of sounding signals should not collide with the pilots for data transmission, so as to maintain data recovery quality. Sounding signals also should be allocated such that the sounding pattern in each DRU is kept the same. Moreover, the UL behaviors of other non-sounding MSs (e.g., using SFBC) should not be affected when sounding channel is enabled. Power allocation, sounding sequence design and mapping to subcarriers is TBD.

Appendix ▪ Channel estimation for CDM sounding is not channel estimate of these tones, and so channel mismatches occur 2D-MMSE channel estimator thus performs poorly