Simulation Results for 8 Tx Antenna Pilots Document Number: IEEE C802.16m-09/0786 Date Submitted: Source: Jie Zhang Hua Zhou Yanling Fujitsu R & D Center. 13/F Ocean International Center, No. 56 Dongsihuan Zhong Rd, Chaoyang District, Beijing, P. R. China Re: TGm SDD: Other; in response to the TGm Call for Contributions and Comments for Session 61. 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. 1 1

Introduction ▪ In current SDD and AWD draft, 8-stream pilot is not specified yet. ▪ This contribution propose 8-stream pilot pattern in the amendment for IEEE m downlink. ▪ Moreover, some concerns on the performance, implementation issue are listed and simulation comparisons in MSE performance are given as well 2 2

8Tx Pilot Pattern 1—P1 ▪This pilot structure is what we propose in this contribution. ▪Overhead: –2/108 = 1.85% per Tx antenna –16/108 = 14.8% for all antennas ▪The time-frequency structure to that for 4-Tx antenna case: same –The same subcarrier permutation in resource allocation as that in 4 Tx antenna case –The same rate matching as in 4 Tx case ▪Extension to 5 or 7-symbol RU: easy –For 5-symbol sub-frame remove 3rd OFDM symbol –For 7-symbol sub-frame, append the 3rd OFDM symbol to the end of the 6-symbol sub-frame ▪Suitable for SFBC usage: yes –Adjacent data subcarriers can be paired 3 3

8Tx Pilot Pattern 2—P2 ▪This pilot structure is what we proposed in #59 session. ▪Overhead: –3/108 = 2.78% per Tx antenna –24/108 = 22.2% for all antennas ▪The time-frequency structure to that for 4-Tx antenna case: different –Different subcarrier permutation in resource allocation from 4-Tx case –Different rate matching from that in 4-Tx case ▪Extension to 5 or 7-symbol RU: easy but make the number of pilot on each antenna imbalanced –For 5-symbol sub-frame remove 3rd OFDM symbol –For 7-symbol sub-frame, append the 3rd OFDM symbol to the end of the 6-symbol sub-frame ▪Suitable for SFBC usage: no –Not all adjacent data subcarriers can be paired 4 4

8Tx Pilot Pattern 3—P3 ▪This pilot structure is proposed in last session, “C80216m-09_0515.doc”. ▪Overhead: –3/108 = 2.78% per Tx antenna –24/108 = 22.2% for all antennas ▪The time-frequency structure to that for 4-Tx antenna case: different –Different subcarrier permutation in resource allocation from 4-Tx case –Different rate matching from that in 4-Tx case ▪Extension to 5 or 7-symbol RU: easy –For 5-symbol sub-frame remove 3rd OFDM symbol –For 7-symbol sub-frame, append the 3rd OFDM symbol to the end of the 6-symbol sub-frame ▪Suitable for SFBC usage: yes –Adjacent data subcarriers can be paired 5 5

8Tx Pilot Pattern 4—P4 ▪This pilot structure is proposed in “C80216m-09_0570.ppt” in last session. ▪Overhead: –2/108 = 1.85% per Tx antenna –16/108 = 14.8% for all antennas ▪The time-frequency structure to that for 4-Tx antenna case: different –Different subcarrier permutation in resource allocation from 4Tx case –The same rate matching as in 4-Tx case ▪Extension to 5 or 7-symbol RU: easy –For 5-symbol sub-frame remove 3rd OFDM symbol –For 7-symbol sub-frame, append the 3rd OFDM symbol to the end of the 6-symbol sub-frame ▪Suitable for SFBC usage: no –Not all adjacent data subcarriers can be paired 6 6

8Tx Pilot Pattern 4’—P4’ ▪This pilot structure is proposed in C80216m-09_0499.ppt in last session. ▪Overhead: –2/108 = 1.85% per Tx antenna –16/108 = 14.8% for all antennas ▪The time-frequency structure to that for 4-Tx antenna case: different –Different subcarrier permutation in resource allocation from 4Tx case –The same rate matching as in 4-Tx case ▪Extension to 5 or 7-symbol RU: easy –For 5-symbol sub-frame remove 3rd OFDM symbol –For 7-symbol sub-frame, append the 3rd OFDM symbol to the end of the 6-symbol sub-frame ▪Suitable for SFBC usage: no –Not all adjacent data subcarriers can be paired 7 7

Simulation Assumptions ▪MSE of channel estimation is the metric ▪Pilot Patterns: P1, P2, P3, P4, P4’ –Due to very similar structure of P4 and P4’, their performance in channel estimation MSE and BLER is rather similar each other –We just show the simulation results of P4 in following figures. ▪ITU Channel Models –Ped-B in 3km/h velocity with 2G Hz carrier. –Veh-A in 30km/h velocity with 2G Hz carrier –Veh-A in 120km/h velocity with 2G Hz carrier ▪2D-MMSE channel estimation per 1, 2, 3, and 4RUs –In some scenarios, the number of RU allocated to one user maybe larger than 1 –User can estimate the channel cross several RUs allocated to itself. –The correlation statistics in time and frequency domain are assumed known in advance. 8 8

Simulation results 9 MSE performance under ITU PB 3km/h channel using 1 and 2 RUs for channel estimation 9

10 MSE performance under ITU PB 3km/h channel using 3 and 4 RUs for channel estimation 10

11 MSE performance under ITU VA 30km/h channel using 1 and 2 RUs for channel estimation 11

12 MSE performance under ITU VA 30km/h channel using 3 and 4 RUs for channel estimation 12

13 MSE performance under ITU VA 120km/h channel using 1 and 2 RUs for channel estimation 13

14 MSE performance under ITU VA 120km/h channel using 3 and 4 RUs for channel estimation 14

Single-link Throughput Analysis ▪MSE analysis –For 2 pilot structures, P1 and P4 have almost the same MSE performance –For 3 pilot structures, P2 and P3 have almost the same MSE performance, especially in low speed channel scenarios. ▪Single-link throughput –Due to the fact that, the larger number of pilot in one RU is, the better channel estimation performance –It’s necessary to compare single-link throughput spectral efficiency performance between 2 pilots/RU and 3 pilots/RU cases. –As shown in in last session, the throughput of 2 pilots/RU pattern is better than that of 3 pilots/RU under indoor hotspot channel with velocity 3 km/h. 15

Conclusion ▪From observations above, we suggest to adopt pilot structure 1 (P1) as the pilot pattern for 8-stream case in IEEE m. 16 Metric Pilot Total Overhead MSEThroughputDifferent resource allocation Different rate matching Extension to 5 or 7- symbol SFC support P114.8%MediumGoodNo EasyYes P414.8%MediumGoodYes EasyNo P4’14.8%MediumGoodYes EasyNo P222.2%GoodMediumYes Easy/imbalan ced pilot # No P322.2%GoodMediumYes EasyYes 16