Transcript IEEE C802.16m-08/977r2

Proposal of the UL Pilot Pattern
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-08_977r2
Date Submitted:
2008-09-05
Source:
Sungho Park, Bin-chul Ihm, Jinsoo Choi
LG Electronic Inc.
E-mail : {Park_SH, bcihm, emptylie}@lge.com
Venue:
PHY: 11.6 – Uplink Physical Structure Responding the TGm Call for Contributions and Comments in 802.16m-08/033
Base Contribution:
N/A
Purpose:
To be discussed and adopted by TGm
Notice:
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contained herein.
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1
Introduction
◙ Baseline
 This contribution only treats the pilot structure on 6x6 tile
 The simulation is based on documents C80216m-UL-PHY-08-003r6
and C80216mUL-PHY-08-018
◙ Evaluation points
 Goodput / PER comparison between various pilot patterns
 Consideration on frequency offset
 Consideration on power limited environment
◙ Performance Metric
 Goodput / PER
2
Simulation Parameters (1)
◙ System Parameters
 Link Type : Open-loop
 Channel Model & Mobility
• Ped B (3km/h)
• Veh A (120km/h)
 Modulation & Channel Coding
• Channel Coding : Turbo Code (R=½ , ¾)
• Modulation Order: QPSK, 16QAM
 Channelization
• LDRU (1 LDRU = 18 Subcarriers x 6 OFDMA Symbols)
• Data Allocation : 2 LDRUs
 Frequency Offset : max. 2% of subcarrier spacing
◙ MIMO Parameters





# of Transmit Antenna : 2
# of Receive Antenna : 2
MIMO Scheme : SM
Channel Estimator : 2-D WIENNER
MIMO Receiver Type : MMSE
3
Simulation Parameters (2)
◙ Pilot Structures
 Pilot Boosting Level : 3dB (Pilot Only Boosting)
 Group A
• Per Stream Pilot Density : 11.11%
• Related Contributions : LGE, MediaTek (New)
[Pattern A1]
[Pattern A2]
 Group B
• Per Stream Pilot Density : 11.11%
• Related Contributions : Huawei, Intel, Cairo University, Wicreo, MeidaTek (Old)
[Pattern B1]
[Pattern B2]
4
Simulation Parameters (3)
 Group C
• Per Stream Pilot Density : 11.11%
• Related Contributions : NSN, Nortel
[Pattern C1]
[Pattern C2]
5
Link Performance – Goodput (1)
2 x2 Sp a t i a l M u l t i p l e xi n g , P e d B ( 3 k m/ h )
1.20E+00
N o rma l i ze d Go o dp u t .
1.00E+00
8.00E-01
A1
A2
6.00E-01
B1
B2
4.00E-01
2.00E-01
0.00E+00
0
2
4
6
8
10 12 14 16 18 20 22 24 26 28 30 32
SN R ( d B )
6
Link Performance – Goodput (2)
2 x 2 S p a t i a l Mul t i p l ex i n g , V eh A ( 1 2 0 k m/h)
1.20E+00
N o r ma l i z e d G o o d p ut
1.00E+00
8.00E-01
A1
A2
6.00E-01
B1
B2
4.00E-01
2.00E-01
0.00E+00
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30 32
S N R ( d B)
7
Link Performance – PER (1)
S M, P ed B ( 3 k m/h) , 1 6 Q AM 1 /2
S M, V eh A ( 1 2 0 k m/h) , 1 6 Q AM 1 /2
1.00E+00
1.00E+00
1.00E-01
1.00E-01
A1
A2
1.00E-02
PER
PER
A1
B1
A2
1.00E-02
B1
B2
B2
1.00E-03
1.00E-03
1.00E-04
1.00E-04
8
10
12
14
16
18
20
22
8
10
12
14
SNR (dB)
16
18
20
22
SNR (dB)
S M, V eh A ( 1 2 0 k m/h) , 1 6 Q AM 3 /4
S M, P ed B ( 3 k m/h) , 1 6 Q AM 3 /4
1.00E+00
1.00E+00
1.00E-01
1.00E-01
A1
A1
PER
PER
A2
B1
A2
1.00E-02
B1
B2
B2
1.00E-02
1.00E-03
1.00E-04
1.00E-03
14
16
18
20
22
24
26
28
30
16
32
18
20
22
24
26
SNR (dB)
SNR (dB)
8
28
30
32
34
Link Performance – Frequency offset (1)
◙ Frequency Offset : 2% of subcarrier spacing per MS [-0.02, 0.02]
Pilot collision region due to frequency offset
 Pilot power boosting problem
 2% frequency offset doesn’t induce
significant performance loss
A1
A2
B1
S M, P ed B ( 3 k m/h) , Q P S K 1 /2
S M, V eh A ( 1 2 0 k m/h) , Q P S K 1 /2
1.00E+00
1.00E+00
A1
A2
B1
B1
A1 (w. freq. offset)
A2 (w. freq. offset)
1.00E-02
A1
1.00E-01
A2
PER
PER
1.00E-01
A1 (w. freq. offset)
A2 (w. freq. offset)
1.00E-02
B1 (w. freq. offset)
1.00E-03
B1 (w. freq. offset)
1.00E-03
0
2
4
6
8
10
12
0
SNR (dB)
2
4
6
SNR (dB)
9
8
10
12
Link Performance – Frequency offset (2)
S M, P ed B ( 3 k m/h) , 1 6 Q AM 1 /2
S M, V eh A ( 1 2 0 k m/h) , 1 6 Q AM 1 /2
1.00E+00
1.00E+00
1.00E-01
A1
A1
A2
A2
B1
1.00E-02
PER
PER
1.00E-01
A1 (w. freq. offset)
B1
1.00E-02
A1 (w. freq. offset)
A2 (w. freq. offset)
A2 (w. freq. offset)
B1 (w. freq. offset)
1.00E-03
B1 (w. freq. offset)
1.00E-03
1.00E-04
1.00E-04
8
10
12
14
16
18
20
22
8
10
12
14
SNR(dB)
16
18
20
22
SNR(dB)
S M, P ed B ( 3 k m/h) , 1 6 Q AM 3 /4
S M, V eh A ( 1 2 0 k m/h) , 1 6 Q AM 3 /4
1.00E+00
1.00E+00
A1
A2
B1
B1
A1 (w. freq. offset)
A2 (w. freq. offset)
1.00E-02
A1
1.00E-01
A2
PER
PER
1.00E-01
A1 (w. freq. offset)
A2 (w. freq. offset)
1.00E-02
B1 (w. freq. offset)
1.00E-03
B1 (w. freq. offset)
1.00E-03
16
18
20
22
24
26
28
30
32
16
SNR (dB)
18
20
22
24
SNR (dB)
10
26
28
30
32
Link Performance – Limited Total Tx Power (1)
◙ Problem for Concentrated Pilot Subcarriers
 In case of pilot structures in Group C, one OFDMA symbol has 6 pilot tones per

stream in a LDRU.
This structures cause large symbol power fluctuation when pilot power is boosted.
 In limited Tx power environment, it can be significantly affected by some
methods such as back-off / clipping / data power stealing, etc
[Concentrated pilot]
[Separated pilot]
pilot overhead = 66.67%
pilot overhead = 33.33%
11
Link Performance – Limited Total Tx Power (2)
S M, V eh A ( 1 2 0 k m/h) , Q P S K 1 /2
1.05E+00
1.20E+00
1.00E+00
1.00E+00
Normalized Goodput
Normalized Goodput
S I MO , P ed B ( 3 k m/h) , 1 6 Q AM 3 /4
9.50E-01
A1
9.00E-01
C1
8.50E-01
8.00E-01
A1
6.00E-01
C1
4.00E-01
2.00E-01
8.00E-01
0.00E+00
7.50E-01
12
14
16
18
20
22
0
24
2
4
6
8
10
12
14
16
SNR (dB)
SNR (dB)
[Pilot only boosting case]
[Transmit power limited]
 Performance of pilot structure C1 is
closed to A1
 Performance of pilot structure C1 is
decreased significantly due to relative
lower data power rather than A1
12
Conclusion
◙ Pilot structure Summary
 In our simulation results, B1 pilot structure outperforms than others for all




cases and the next is A1.
Even though A2 pilot structure has similar to A1, it has lower channel
estimation performance in selective fading environment due to different pilot
offset per antenna.
A2, B2, C1 and C2 have lower performance. Because these have
concentrated or leaning to one side pilot position.
Moreover, if pilot tones don’t disperse through OFDMA symbols such as pilot
structure group C, the power efficiency goes down as if data power is lower
relatively ( symbol power fluctuation problem).
Additionally, we verify the performance loss due to frequency offset. In our
results, when the offset is assumed as maximum 2% of subcarrier spacing,
the effect is negligible. Therefore, it is unnecessary that pilot structure should
be optimized to avoid collision.
13
Proposed SDD Text
Insert the following into SDD Section 11.6.3 in IEEE 802.16m-08/003r4
11.6.3 Pilot Structure
11.6.3.1 Pilot Structure for 6x6 Tile of LDRU
<Figure x_1: 2 transmit pilot pattern>
14