8Tx Pilot Pattern Performance for IEEE 802.16m

IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number:

IEEE C802.16m-09/0544Date Submitted:

2009-03-02Source:

Jerry Pi, Taeyoung Kim, Hai Wang zpi@sta.samsung.com Samsung Electronics

Venue:Re : 802.16m AWD

Base Contribution:IEEE C802.16m-08/0544

Purpose:To be discussed in TGm in support of the IEEE 802.16m amendment text proposed in C80216m-09_0515

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Background

• Downlink 8Tx MIMO is adopted in SDD– IEEE 802.16m-08/003r6, section 11.8.1.1, page 98,

line 12

• 8Tx pilot pattern is yet to be defined• This contribution proposes the 8Tx pilot

pattern for IEEE 802.16m downlink

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8Tx Pilot Pattern (1)• 8 pilot streams

– Overhead: 3/108 = 2.78% each– Total overhead 24/108 = 22.22%

• Mirrored pilot patterns– Pilot patterns for P1, P2, P3, P4 mirror in time

and frequency– Pilot patterns for P5, P6, P7, P8 mirror in time

and frequency– Low complexity implementation of channel

estimation• Easy to adapt for 5-symbol subframes (by

removing the 3rd or 4th symbol in the pilot pattern for 6-symbol subframes)

P2P5P7

P8

P1

P1

P1

P2

P2P3

P3

P3

P4

P4

P4

P5

P5

P6

P6

P6

P7

P7

P8

P8

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8Tx Pilot Pattern (2)• 8 pilot streams

– Overhead: 4/108 = 3.7% each– Total overhead 32/108 = 29.63%

• Mirrored pilot patterns– Reuse the 4Tx pilot patterns for P1, P2, P3, P4

(See next page for updated 4Tx pilot pattern)

– Pilot patterns for P1, P2, P3, P4 mirror in time and frequency

– Pilot patterns for P5, P6, P7, P8 mirror in time and frequency

– Low complexity implementation of channel estimation

– Easy to adapt for 5-symbol subframes (by removing the 3rd or 4th symbol in the pilot pattern for 6-symbol subframes)

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P6

P6

P5

P5

P5

P5

P6

P6P7

P7

P7

P7

P8

P8

P8

P8

P1 P2P4 P3

P1P2 P4P3

P1 P2P4 P3

P1P2 P4P3

8Tx Pilot Pattern (3)

• Proposed by Fujitsu– C80216m-09/0215, 0277

• Pilot tones are placed in the middle of a subframe– resulting in more extrapolation

instead of interpoloation– Making it difficult to adapt the

pilot pattern to 5-OFDM symbol subframe

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P6

P5

P7

P8

P1

P2

P4

P3

P5

P7P1

P3 P6

P8P2

P4

P6

P8P2

P4 P5

P7P1

P3

Simulation Assumptions• 8Tx Pilot Pattern

– Pilot Pattern 1 vs. Pilot Pattern 2 vs. Pilot Pattern 3– The same number of information bits are transmitted using different pilot patterns– The difference in pilot density are taken into account by rate matching

• Pilot Pattern 2 results in less number of resource elements available for data and thus higher code rate• Pilot Pattern 1 & 3 have the same number of resource elements for data and thus the same code rate

– Rank-8 precoder cycling– Channel models:

• Ped A 3kmph, Ped B 3kmph, Veh A 30kmph, Veh A 120kmph, Veh A 350kmph– MCS

• QPSK 1/2, QPSK 1/3, 16QAM 1/2, 16QAM 1/3, 64QAM 1/2, 64QAM 1/3– 3 contiguous PRUs– 2D MMSE channel estimator per PRU

• Metric:– BLER– MSE

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Summary• 8Tx Pilot Patterns– Pilot Pattern 1 & 3 (3 pilot tones per stream)

outperforms Pilot Pattern 2 (4 pilot tones per stream) in Rank 8 transmissions

– Pilot Pattern 3 is more sensitive to high speed channel conditions

• Recommendation– Adopt the proposed pilot pattern as in the next page

into 802.16m AWD– The detailed text proposal is provided in C80216m-

09_0515

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SIMULATION RESULTS – 8TX PILOT PATTERNS (RANK 8)

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Observation

• Pilot Pattern 1 & 3 (3 pilot tones per stream) outperforms Pilot Pattern 2 (4 pilot tones per stream) in Rank 8 transmissions

• Pilot Pattern 3 is more sensitive to high speed channel conditions (esp. for higher order modulations)

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