1. Comparison Between FDM and CDM Sounding Methods
Document Number: IEEE C802.16m-09/0979
Date Submitted:
Source:
Chih-Yuan Lin Pei-Kai Liao ), Yu-Hao Chang
Ciou-Ping Wu and Paul Cheng
MediaTek Inc.
Venue: Category: AWD comments / Area: Chapter (Uplink Control Channel)
“Comments on AWD (Multiplexing for Multi-antenna and Multi-AMS)”
Base Contribution: N/A
Purpose: Propose to be discussed and adopted by TGm for the use in Project m AWD
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2. Two Comparative Methods
FDM and CDM examples
FDM: Frequency decimation
CDM
Length-6 Zadoff-Chu code

3. Simulation Parameters
Noise-limited scenario
6 serving AMSs
For CDM, length-6 Zadoff-Chu sequences
Interference-limited scenario (SNR = inf)
6 serving AMSs and 6 interfering AMSs
Interference power is equally assigned to 6 interfering AMSs (see Appendix II for illustration)
SIR = (total received signal power) / (total received interference power over 18 subcarriers)
For CDM, use length-6 Zadoff-Chu sequences and generate two binary random sequences for masking two cells
Channel estimation: 2D-MMSE
Optimized to predefined velocity speed 3 km/hr
Optimized to predefined channel delay spread 5 us
Channel model
PB 3 km/hr
Performance metric
Tone-wise channel estimation mean square error (at data tones of a subframe)

4. Simulation Results (1/2)
Noise-limited scenario

5. Simulation Results (2/2)
Interference-limited scenario

6. Conclusion
In noise-limited and interference-limited scenarios, FDM performs better than CDM
Suggest only keeping FDM for sounding multiplexing

7. Text Proposal
Multiplexing for multi-antenna and multi-AMS
The uplink sounding channels of multiple AMS and multiple antennas per AMS can be multiplexed through [Option 1: decimation separation or cyclic shift separation] decimation separation in each sounding allocation. Also, in case of multiple UL subframes for sounding, time division separation can be applied by assigning different AMS to different UL subframe. For cyclic shift separation each AMS occupies all subcarriers within sounding allocation and uses the different sounding waveform [Editor's note: remove this sentence if Option 2 will be adopted]. For frequency decimation separation each AMS uses decimated subcarrier subset from the sounding allocation set with different frequency offset. For antenna switching capable AMS, ABS can command the AMS to switch the physical transmit antenna(s) for sounding transmission. The details for supporting antenna switching on sounding is TBD.

8. Appendix I Channel estimation for CDM sounding
Used for 2D-MMSE channel estimation

9. Appendix II
SIR definition