1. Proposed Change to 8-stream Pilot Patterns (Section 15.3.5.4.1)
IEEE Presentation Submission Template (Rev. 9)
Document Number: IEEE C80216m-09/1737r1
Date Submitted:
Source:
Chung-Lien Ho, Yan-Xiu Zheng, Yu-Chuan Fang,
Chang-Lan Tsai,
ITRI
Pei-Kai Liao, Chih-Yuan Lin, Paul Cheng
MediaTek
Zhouyue Pi, Jiann-An Tsai
Samsung Electronics
*<
Venue: IEEE Session #63, Jeju, Korea
Re: IEEE P802.16m/D1. Section
Base Contribution: N/A
Purpose: To be discussed and adopted by TGm for the IEEE P802.16m/D1.
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2. Introduction
Pilot patterns for 8 data streams in [1] are designed without considering pilot boosting issue
Suggested DL power settings for data and pilot subcarriers [2]
Table X: DL power settings for data and pilot subcarriers for different number of data streams [2]
Number of data streams Mt
Per stream power on data subcarriers
Per stream pilot power
Per stream pilot boosting level, dB
1 - 2
1/Mt
100.2
2 + 10*log10(Mt)
3 - 4 1
0 + 10*log10(Mt)
5 - 8
The DL peak spectral efficiency may support 30 bps/Hz for 8-Tx MIMO with rate up to 8.
So based on the throughput requirement, the pilot overhead is an important design issue.

3. Original pilot patterns for 8 data streams

4. Pilot boosting level
Based on Table X, per stream pilot booting level is 10*log10(Mt) = , , , (dB) for Mt = 5, 6, 7, 8
This may cause OFDM symbol-by-symbol power fluctuation
OFDM symbol-by-symbol power fluctuation can be avoided only when Mt = 8 and pilot booting level = 10*log10(4) = dB

5. Modified pilot patterns for 8 data streams

6. Pilot boosting level
Based on Table X, per stream pilot booting level is 10*log10(Mt) = , , , (dB) for Mt = 5, 6, 7, 8
No OFDM symbol-by-symbol power fluctuation for Mt = 5, 6, 7, 8

7. Performance Results Simulation parameters Parameter Value
Frame Structure
16m frame structure (10 MHz, 1024 subcarriers)
OFDM symbols/subframe 6
Permutation
None (CRU)
Channel model [16m EMD]
Ped-B with 3 km/h
Veh-A with 30 km/h
Channel estimation (CE)
2D-MMSE (CE over 2 CRUs or 4 CRUs), delay spread perfectly known but actual power delay profile unknown
Power boosting for level
10*log10(4) = dB for original patterns
10*log10(8) = dB for modified patterns
MIMO scheme
8 x 8 spatial multiplexing (8-stream)
Channel coding scheme
16e CTC
Detection scheme
Linear MMSE
MCS Set [1]
QPSK-101/256, QPSK-171/256, 16QAM-128/256, 64QAM-135/256, 64QAM-181/256, 64QAM-225/256 , 64QAM-237/256
Number of CRUs
2 CRUs or 4 CRUs with rate matching
This page shows the simulation parameters.
Here we consider 3 channel models: Indoor hotspot, Ped-B and Veh-A.
We use the 2D-MMSE CE, and delay spread perfectly known but actual power delay profile unknown.
And we use the following MCS set proposed in Reference #1 which has been accepted in the last meeting.

8. Simulation results Ped-B 3 km/h, CE over 2 CRUs
This page shows the throughput performance for indoor hotspot channel with 3 km/h and CE over 2 CRUs.
From this figure, we can see that ITRI and MediaTek patterns can indeed achieve the 30 bps/Hz.
For single PRU-based CE, the performance is shown in the next page.

9. Ped-B 3 km/h, CE over 4 CRUs

10. Veh-A 30 km/h, CE over 2 CRUs
For the Veh-A channel with 30 km/h and CE over 2 CRUs, Samsung and Fujitsu patterns can perform better, but the performance no long is good enough.

11. Veh-A 30 km/h, CE over 4 CRUs
But however, ITRI’s patterns can perform better when the CE is done over 4 CRUs.
So based on the simulation results, we would like to propose our ITRI’s pilot pattern to 16 AWD.

12. Conclusion
The proposed pilot pattern provides the gain in terms of throughput comparing to existing 8 Tx pilot pattern
The pilot pattern also resolves power fluctuation problem
We would like to modify the 8TX pilot pattern in IEEE P802.16m/D1 by the new proposed pilot pattern

13. References
[1] IEEE P802.16m/D1, “DRAFT Amendment to IEEE Standard for Local and metropolitan area networks, Part 16: Air Interface for Broadband Wireless Access Systems,” July 2009.
[2] IEEE C802.16m-09/1681, “Proposed Changes to Pilot Patterns Boosting Values ( ) for the IEEE m/D1,”

14. Proposed Text Replace Figures 422 by following figures
This page shows the proposed text for the 8-Tx pilot pattern!
That’s it! Thank you!