Transcript 11-15-0602

September, 2015
doc.: IEEE 802.11-15/0602r6
HE-LTF Sequence for UL MU-MIMO
Date: 2015-09-13
Authors:
Name
Affiliation
Address
Phone
Qinghua Li
Email
[email protected]
Xiaogang Chen
Robert Stacey
Intel
2111 NE 25th Ave,
Hillsboro OR 97124,
USA
[email protected]
+1-408-765-9698
[email protected]
Po-Kai Huang
[email protected]
Chitto Ghosh
[email protected]
Rongzhen Yang
[email protected]
Hongyuan Zhang
[email protected]
Yakun Sun
[email protected]
Lei Wang
Liwen Chu
Jinjing Jiang
Marvell
5488 Marvell Lane,
Santa Clara, CA,
95054
[email protected]
+408-222-2500
[email protected]
[email protected]
Yan Zhang
[email protected]
Rui Cao
[email protected]
Submission
Slide 1
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Authors (continued)
Name
Affiliation
Address
Phone
Email
Jie Huang
[email protected]
Sudhir Srinivasa
[email protected]
Saga Tamhane
Mao Yu
Marvell
(Cont’d)
5488 Marvell Lane,
Santa Clara, CA, 95054
[email protected]
408-222-2500
[email protected]
Edward Au
[email protected]
Hui-Ling Lou
[email protected]
Ron Porat
[email protected]
Matthew Fischer
[email protected]
Sriram
Venkateswaran
Broadcom
Tu Nguyen
Vinko Erceg
Brian Hart
Cisco Systems
Pooya Monajemi
Submission
170 W Tasman Dr, San
Jose, CA 95134
Slide 2
[email protected]
[email protected]
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Authors (continued)
Name
Affiliation
Address
Phone
Email
Wookbong Lee
[email protected]
Kiseon Ryu
[email protected]
Jinyoung Chun
[email protected]
Jinsoo Choi
[email protected]
Jeongki Kim
LG Electronics
Giwon Park
19, Yangjae-daero 11gil,
Seocho-gu, Seoul 137130, Korea
[email protected]
[email protected]
Dongguk Lim
[email protected]
Suhwook Kim
[email protected]
Eunsung Park
[email protected]
HanGyu Cho
[email protected]
Thomas Derham
Submission
Orange
[email protected]
Slide 3
Qinghua Li,
Li, Xiaogang
Xiaogang Chen,
Chen, et
et al.
al.
Qinghua
September, 2015
doc.: IEEE 802.11-15/0602r6
Authors (continued)
Name
Affiliation
Address
Samsung
Innovation Park,
Cambridge CB4 0DS (U.K.)
Maetan 3-dong; Yongtong-Gu
Suwon; South Korea
1301, E. Lookout Dr,
Richardson TX 75070
Innovation Park,
Cambridge CB4 0DS (U.K.)
1301, E. Lookout Dr,
Richardson TX 75070
Maetan 3-dong; Yongtong-Gu
Suwon; South Korea
Fei Tong
Hyunjeong Kang
Kaushik Josiam
Mark Rison
Rakesh Taori
Sanghyun Chang
Phone
Email
+44 1223 434633
[email protected]
+82-31-279-9028
[email protected]
(972) 761 7437
[email protected]
+44 1223 434600
[email protected]
(972) 761 7470
[email protected]
+82-10-8864-1751
[email protected]
Yasushi Takatori
[email protected]
Yasuhiko Inoue
[email protected]
Yusuke Asai
NTT
1-1 Hikari-no-oka, Yokosuka,
Kanagawa 239-0847 Japan
[email protected]
Koichi Ishihara
[email protected]
Akira Kishida
[email protected]
Akira Yamada
Fujio Watanabe
Haralabos
Papadopoulos
Submission
NTT DOCOMO
3-6, Hikarinooka, Yokosukashi, Kanagawa, 239-8536, Japan
[email protected]
3240 Hillview Ave, Palo Alto,
CA 94304
watanabe@docomoinnovations.
com
hpapadopoulos@docomoinnova
tions.com
Slide 4
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Authors (continued)
Name
Affiliation
Phillip Barber
Address
Phone
pbarber@broadbandmobilete
ch.com
The Lone Star State, TX
Peter Loc
[email protected]
Le Liu
Jun Luo
Yi Luo
Yingpei Lin
Jiyong Pang
Zhigang Rong
Rob Sun
David X. Yang
Yunsong Yang
Zhou Lan
Junghoon Suh
Jiayin Zhang
Submission
Email
Huawei
F1-17, Huawei Base,
Bantian, Shenzhen
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
F1-17, Huawei Base,
Bantian, Shenzhen
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
10180 Telesis Court, Suite
365, San Diego, CA 92121
NA
303 Terry Fox, Suite 400
Kanata, Ottawa, Canada
F1-17, Huawei Base,
Bantian, Shenzhen
10180 Telesis Court, Suite
365, San Diego, CA 92121
NA
F1-17, Huawei Base,
Bantian, SHenzhen
303 Terry Fox, Suite 400
Kanata, Ottawa, Canada
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
Slide 5
+86-18601656691
[email protected]
[email protected]
+86-18665891036
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
+86-18565826350
[email protected]
[email protected]
+86-18601656691
[email protected]
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Authors (continued)
Name
Affiliation
Address
Qualcomm
Straatweg 66-S Breukelen,
3621 BR Netherlands
5775 Morehouse Dr. San
Diego, CA, USA
5775 Morehouse Dr. San
Diego, CA, USA
1700 Technology Drive San
Jose, CA 95110, USA
5775 Morehouse Dr. San
Diego, CA, USA
5775 Morehouse Dr. San
Diego, CA, USA
5775 Morehouse Dr. San
Diego, CA, USA
Straatweg 66-S Breukelen,
3621 BR Netherlands
Straatweg 66-S Breukelen,
3621 BR Netherlands
1700 Technology Drive San
Jose, CA 95110, USA
5775 Morehouse Dr. San
Diego, CA, USA
5775 Morehouse Dr. San
Diego, CA, USA
1700 Technology Drive San
Jose, CA 95110, USA
1700 Technology Drive San
Jose, CA 95110, USA
1700 Technology Drive San
Jose, CA 95110, USA
Albert Van Zelst
Alfred Asterjadhi
Bin Tian
Carlos Aldana
George Cherian
Gwendolyn Barriac
Hemanth Sampath
Menzo Wentink
Richard Van Nee
Rolf De Vegt
Sameer Vermani
Simone Merlin
Tevfik Yucek
VK Jones
Youhan Kim
Submission
Slide 6
Phone
Email
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Authors (continued)
Name
Affiliation
James Yee
Alan Jauh
Address
Phone
Email
No. 1 Dusing 1st Road,
Hsinchu, Taiwan
+886-3-567-0766
[email protected]
[email protected]
Mediatek
Chingwa Hu
[email protected]
m
Frank Hsu
[email protected]
2860 Junction Ave, San
Jose, CA 95134, USA
Thomas Pare
+1-408-526-1899
[email protected]
om
ChaoChun Wang
James Wang
Jianhan Liu
[email protected]
Mediatek
USA
[email protected]
[email protected]
Tianyu Wu
[email protected]
Russell Huang
[email protected]
m
Eric Wong
+1-408-9745967
[email protected]
Chris Hartman
Aon Mujtaba
Apple
Cupertino, CA
Joonsuk Kim
[email protected]
Guoqing Li
Submission
+1-408-974-9164
Slide 7
[email protected]
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Authors (continued)
Name
Affiliation
Address
Phone
Weimin Xing
Kaiying Lv
Email
[email protected]
n
[email protected]
ZTE Corp.
Ke Yao
[email protected]
Bo Sun
[email protected]
Yonggang Fang
Submission
ZTE TX
[email protected]
Slide 8
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Background
• P matrix coded HE-LTF was adopted in last
meeting [1]
– Maximize legacy reuse
• Adding details, we propose HE-LTF sequences for
uplink multiuser MIMO
Submission
Slide 9
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Problem Statement
• In uplink multiuser MIMO, different UL users have
different carrier frequency offsets
• AP may want to estimate the CFOs for demodulating
data and mitigating multiuser interference
• For the CFO estimation, per-stream phase offsets at
different LTF symbol instants need to be obtained
Submission
Slide 10
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Proposed Solution
• Assign orthogonal LTF sequences to different streams
within the UL MU-MIMO burst
– Exploit frequency domain correlation
– Per-stream channel responses can be estimated for each
LTF symbol
– CFO can be estimated by checking the phase difference
between the channel estimates obtained at different LTF
symbols
• Additional benefit — No need to insert pilot tones in LTF
symbols
Submission
Slide 11
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Generating LTF sequences
• Generated from P matrix
– Scramble a common sequence by different rows of P matrix
• Piecewise orthogonal
– Sub-sequences with any K (e.g. 4) contiguous entries are orthogonal
Submission
Slide 12
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Cyclic Orthogonality
• Orthogonal sequences of any length can be generated
by exploiting cyclic orthogonality among P matrix rows
– E.g. 2 users with 26 tones and K=4
[1
X
User 1
L1
L2
X
L3
L4
…
L21
L22
User 2
L1
L2
X
L23
L24
L3
L4
…
L21
L22
L25
L26
[1
X
X
-1]
1]
X
L23
L24
L25
L26
orthogonal
Submission
Slide 13
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Orthogonal Tone Blocks
• By exploiting cyclic orthogonality, we have many
orthogonal tone blocks generating data samples
for CFO estimation
User 1
S1(1)
S1(2)
S1(3)
S1(4)
S1(5)
S1(6)
S1(7)
S1(8)
S1(9)
…
User 2
S2(1)
S2(2)
S2(3)
S2(4)
S2(5)
S2(6)
S2(7)
S2(8)
S2(9)
…
Orthogonal
tone block 1
Submission
Orthogonal …
tone block 2
Slide 14
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
LTF symbols of stream k
Stream index
Sequence common
to all streams
Si(k) Cj(k) 𝐿𝑖
Tone index
LTF symbol index
Subcarrier 1
Subcarrier 2
Time
LTF symbol 1
Submission
LTF symbol 2
Slide 15
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
LTF symbols of multiple streams
• Orthogonal sequences are applied to different streams on each tone block
Orthogonal
sequences
Submission
Slide 16
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
CFO Estimation
• Channel response remains roughly constant over each tone block
• Phase response is estimated from each tone block
• CFO is estimated by averaging the phase rotation rate over tone
blocks and Rx antennas
Orthogonal
sequences
Submission
Slide 17
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
One P matrix for all
• Since the 8×8 P matrix consists of orthogonal 2×2 and 4×4
sub-matrixes, we can use the rows of 8×8 P matrix to define
LTF sequences for up to 8 streams
𝑃4×4
𝑃8×8 =
𝑃4×4
𝑃4×4 =
Submission
𝑃4×4
−𝑃4×4
1 −1 1 1
1 1 −1 1
1 1 1 −1
−1 1 1 1
Slide 18
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Simulation Assumptions
•
•
•
•
•
•
•
•
•
•
Uplink MU-MIMO
8 Rx antennas at AP, 4/6 STAs each sending 1 stream
MCS7/MCS4; 20 MHz bandwidth; ChDNLoS/UMiNLoS
CFO error is modeled as +CFO/-CFO with fixed value
Timing offset is uniformly distributed over [0, Toff ns] for each STA
CSD value follows 11ac & 11ax larger CSD(TBD)
Per STA pilot tracking is enabled
CFO is estimated and compensated for the proposed new LTF sequence
Channel smoothing is not applied
4x/2x (3.2us/1.6us GI) LTF is used
Submission
Slide 19
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
CFO Tolerance
DNLoS; 8Rx@AP; 4STA; MCS7
0
10
-1
10
PER
3.5dB
0.15dB
-2
10
-3
Freqoff
Freqoff
Freqoff
Freqoff
Freqoff
10
0Hz/11ac LTF
400Hz/new LTF
400Hz/11ac LTF
200Hz/new LTF
200Hz/11ac LTF
-4
10
20
21
22
23
24
25
SNR(dB)
26
27
28
29
30
Tolerate +/- 400 Hz CFO within negligible degradation to ideal and >3
dB improvement over legacy
Submission
Slide 20
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Timing Offset Tolerance
DNLoS; 8Rx@AP; 4STA; MCS7
0
10
Freqoff 0Hz/11ac LTF
Freqoff 400Hz/new LTF 0nsToff
Freqoff 400Hz/11ac LTF 0nsToff
Freqoff 400Hz/new LTF 1usToff
Freqoff 400Hz/11ac LTF 1usToff
3 dB
-1
10
PER
Within 1 dB
-2
10
-3
10
20
22
24
26
SNR(dB)
28
30
32
Tolerate 1 μs timing offset at 10% PER with sub-dB degradation to ideal
and 3 dB improvement over legacy
Submission
Slide 21
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Robust to Frequency Selectivity
MCS4;UMiNLoS
0
10
Freqoff 0Hz/ 11ac LTF/0ns Toff
Freqoff 400Hz/ new LTF/600ns Toff
Freqoff 400Hz/ 11ac LTF/600ns Toff
-1
PER
10
-2
10
-3
10
14
15
16
17
18
SNR(dB)
19
20
21
22
Work fine in outdoor channels
Submission
Slide 22
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
With per-stream CSD
ChD; 6x8; CSD; MCS7
0
10
w/o CFO; w/o CSD
400Hz CFO; 11ac CSD [0 -400 -200 -600 -350 -650]
400Hz CFO; 11ax CSD [0 -800 -400 -1000 -600 -1200]
-1
PER
10
-2
10
-3
10
-4
10
28
29
30
31
SNR(dB)
32
33
34
Work fine with CSD
Submission
Slide 23
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
2x LTF
10
ChD 4STA 2x
0
Freqoff 0Hz/ 11ac LTF
Freqoff 400Hz/ new LTF
Freqoff 400Hz/ 11ac LTF
-1
PER
10
2dB
10
10
-2
-3
20
22
24
26
SNR(dB)
28
30
32
Work fine with 2x LTFs
Submission
Slide 24
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
UL transmission with beamforming
4STAs(2Tx->8Rx); ChD; MCS7
0
10
• 20MHz channel
• STA: 2 Tx ant. with
ideal beamforming
• AP: 8 Rx ant.
• 4 STAs
2Tx BF w/o CFO
2Tx BF CFO 400Hz
-1
PER
10
-2
10
0.3 dB
-3
10
•
•
20
21
22
23
SNR(dB)
24
25
26
Rank inverse in BF may cause phase discontinuity, which will break the orthogonality
in frequency domain.
The observation is rank inverse does not occur frequently. Even it happens, only
limited samples are affected.
Submission
Slide 25
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
UL transmission with power offset
6STAs; 8Rx@AP; ChD MCS7
0
10
•
•
•
-10dB w/o CFO
-10dB CFO 400Hz
-6dB w/o CFO
-6dB CFO 400Hz
•
-1
10
PER
•
STA: 1 Tx ant.
AP: 8 Rx ant.
4 STAs received with
0dB power
1 STA received with 10dB power
1 STA received with 6dB power
-2
10
0.2 dB
0.2 dB
-3
10
•
•
26
27
28
29
30
31
SNR(dB)
32
33
34
35
Stronger stream may leak power to the weaker stream due to non-ideal orthogonality;
The CFO estimation is not impacted too much if the power leakage is within moderate range.
– We see some obvious impact for power offset > 10dB
Submission
Slide 26
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
4STAs; 8Rx; MCS7 DNLoS
0
PAPR Issue
0
10
4STAs; 8Rx; MCS0 DNLoS
10
11ac LTF 10bit quantization
Masked LTF 10bit quantization
Masked LTF 10bit quantization
11ac LTF 10bit quantization
Masked LTF 6bit quantization
11ac LTF 6bit quantization
Unquantized
-1
10
-1
PER
PER
10
-2
10
-2
10
-3
10
-3
-4
10
10
21
22
23
24
25
26
27
-4
-3
-2
-1
0
1
2
SNR[dB]
SNR[dB]
• Use fixed point simulation to evaluate if the dynamic range increase in HELTF impacts the overall performance (10/6bits quantization is considered);
• The PAPR increase in the masked LTF has marginal impact to the overall
performance.
– PAPR in the data part is the bottleneck.
Submission
Slide 27
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Summary
• UL MU-MIMO CFO estimation is enabled by assigning
orthogonal LTF sequences to different streams
– Optimal performance
– Maximum reuse of legacy design
– Low complexity
• Propose to use the rows of 8×8 P matrix as the masking
sequences for generating the orthogonal HE-LTF
sequences for UL MU-MIMO
Submission
Slide 28
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Reference
[1] “Specification Framework for TGax,” doc.: IEEE 802.11-15/0132r4,
Section 3.2, March 2015
Submission
Slide 29
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Straw Poll 1
• Do you agree to add to TGax Specification Framework Document?
– The HE-LTF sequences for UL MU-MIMO shall be generated as follows.
For each stream, a common sequence shall be masked repeatedly in a
piece-wise manner by a distinct row of an 8x8 orthogonal matrix. When
the length of the LTF sequence is not divisible by 8, the last M elements
of the LTF sequence (M being the remainder after the division of LTF
length by 8) shall be masked by the first M elements of the orthogonal
matrix row.
– Yes
– No
– Abstain
Submission
Slide 30
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Straw Poll 2
• Do you agree to add to TGax Specification Framework Document?
– The orthogonal matrix used to mask the HE-LTF sequence in SP1 is the
8x8 Pmatrix used in 11ac.
Submission
Slide 31
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
Backup
Submission
Slide 32
Qinghua Li, Xiaogang Chen, et al.
September, 2015
doc.: IEEE 802.11-15/0602r6
4STAs; 8Rx; MCS7 DNLoS
0
10
Unquantized
11ac LTF 10bit
Masked LTF 10bit
-1
PER
10
-2
10
-3
10
21
22
23
24
25
26
27
21
22
23
24
SNR[dB]
Submission
Slide 33
Qinghua Li, Xiaogang Chen, et al.