doc.: ieee 802.11-14/0647r2 submissionslide 1 phy abstraction method comparison date: 2014-05-12...
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doc.: IEEE 802.11-14/0647r2
Submission Slide 1
PHY abstraction method comparison
Date: 2014-05-12Authors:
Tianyu Wu etc. MediaTek
May 2014
Name Affiliations Address Phone EmailTianyu Wu MediaTek San Jose, CA, USA [email protected] Liu MediaTek San Jose, CA, USA [email protected] Thomas Pare MediaTek San Jose, CA, USA [email protected]
doc.: IEEE 802.11-14/0647r2
Submission
Background
• General idea of PHY abstraction: Effective SINR Mapping (ESM)
• A number of PHY abstraction methods has been proposed– EESM is introduced in [2, 3]– RBIR/ RBIR-BICM is recommended in [1, 3, 6]– MMIB is proposed in [5]– Capacity based mapping is proposed in [4]
• In this contribution, we compare different PHY abstraction methods.
Slide 2 Tianyu Wu etc. MediaTek
1
1
1 Nn
effn
SINRSINRN
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doc.: IEEE 802.11-14/0647r2
Submission
List of PHY abstraction methods
Tianyu Wu, etc. MediaTek
Slide 3
PHY Abstract SINR Mapping
EESM Exponential mapping
CM based RBIR Mutual information assuming CM
BICM based RBIR
Mutual information assuming BICM
MMIB Mutual information per bit
CESM Capacity based mapping
expx x
1 1
1i
M K
b k ki k
x I x a J c xM
22
2 21 1
1log log exp
M M
U k mm k
x M E U x s s UM
2 2
2
log log 11
2 2 21 1 0
exp1
; log logexp
ib
ik b
M
M M kk
i Ui i b s S
ks S
x s s Ux I b Y M E
M x s s U
xx 1logC (x) 2
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doc.: IEEE 802.11-14/0647r2
Submission
Comparison of the Φ function
• The Φ functions for RBIR-CM, RBIR-BICM and MMIB are similar. (Φ functions are normalized by the information bits carried by the modulation)
• The MMIB parameters for 256 QAM is from [5].
Tianyu Wu, etc. MediaTek
Slide 4
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-20 -10 0 10 20 30 400
0.1
0.2
0.3
0.4
0.5
0.6
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1
SINR (dB)
Phi
EESM
RBIR-CMRBIR-BICM
MMIB
-20 -10 0 10 20 30 400
2
4
6
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10
12
SINR (dB)
Phi
CE
SM
CESM
doc.: IEEE 802.11-14/0647r2
Submission
PHY abstraction selection criteria
• Criteria for PHY abstraction method selection– Channel type irrelevant
• Good effective SINR mapping function shall be channel irrelevant. The PER mapping shall have acceptable accuracy for all channel types.
• There are many channel types:– Channel model A-F, Uma, Umi etc– Beamformed MIMO channels– Possibly OFDMA sub channels
• It’s impossible to optimize the SINR mapping function for each channel type.
– Instantaneous mapping accuracy• The set of {channel realization, average SINR} combinations that map to an effective
SINR shall have small PER difference from the predicted PER.
Tianyu Wu, etc. MediaTek
Slide 5
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doc.: IEEE 802.11-14/0647r2
Submission
PHY abstractions comparison – Channel irrelevance
• In this simulation, we show the results for RBIR, RBIR-BICM, MMIB and CESM under different channel models and compare to the PER curve for AWGN channel.
• Simulation settings:– Channel models: B-NLOS, D-NLOS, E-LOS– 80MHz@5GHz, 1 by 1, 1024 Bytes packet, BCC– Independent Channel realization for each effective snr.
• For each effective snr, simulate 2000 packets pass independent channel realizations.– α=1; β=1
Tianyu Wu, etc. MediaTek
Slide 6
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doc.: IEEE 802.11-14/0647r2
Submission
RBIR-CM with channel B,D,E
Tianyu Wu, etc. MediaTek
Slide 7
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-5 0 5 10 15 20 25 3010
-3
10-2
10-1
100
Effective SNR
PE
R
AWGN
B-NLOS, RBIR-CMD-NLOS, RBIR-CM
E-LOS, RBIR-CM
doc.: IEEE 802.11-14/0647r2
Submission
RBIR-BICM with channel B,D,E
Tianyu Wu, etc. MediaTek
Slide 8
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-5 0 5 10 15 20 25 3010
-3
10-2
10-1
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Effective SNR
PE
R
AWGN
B-NLOS, RBIR-BICMD-NLOS, RBIR-BICM
E-LOS, RBIR-BICM
doc.: IEEE 802.11-14/0647r2
Submission
MMIB with channel B,D,E
Tianyu Wu, etc. MediaTek
Slide 9
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-5 0 5 10 15 20 25 3010
-3
10-2
10-1
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Effective SNR
PE
R
AWGN
B-NLOS, MMIBD-NLOS, MMIB
E-LOS, MMIB
doc.: IEEE 802.11-14/0647r2
Submission
RBIR,RBIR-BICM,MMIB with channel D
Tianyu Wu, etc. MediaTek
Slide 10
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-5 0 5 10 15 20 25 3010
-3
10-2
10-1
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Effective SNR
PE
R
AWGN
D-NLOS, RBIR-CMD-NLOS, RBIR-BICM
D-NLOS, MMIB
doc.: IEEE 802.11-14/0647r2
Submission
CESM with channel B,D,E
Tianyu Wu, etc. MediaTek
Slide 11
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-5 0 5 10 15 20 25 30 35 4010
-3
10-2
10-1
100
Effective SNR
PE
R
B-NLOS, CESM
D-NLOS, CESME-LOS, CESM
doc.: IEEE 802.11-14/0647r2
Submission
Observations
• Results for RBIR , RBIR-BICM and MMIB are very similar and these 3 methods are more channel irrelevant comparing to CESM
• There is still a distance from AWGN channel– For RBIR, all the results are shifted left side about 0.4 dB– A channel and MCS irrelevant fitting parameter α might be helpful to further
improve the accuracy. – For MMIB,
• the gap from the reference line is MCS dependent. • For 256QAM, the result seems less accurate and the parameters may need further
optimization
• For CESM, it seems harder to obtain a smooth curve. May need more simulation points compare to other methods.
• RBIR-CM and RBIR-BICM are more mature and can provide good accuracy for average PER prediction.
Tianyu Wu, etc. MediaTek
Slide 12
May 2014
doc.: IEEE 802.11-14/0647r2
Submission
Example of channel irrelevant curve fitting
• For RBIR-CM, shift the curves by 0.4 dB (set α=1.0965 in the effective SNR mapping function) can obtain a more accurate result.
Tianyu Wu, etc. MediaTek
Slide 13
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-5 0 5 10 15 20 25 3010
-3
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10-1
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Effective SNR
PE
R
= 0.4
AWGN
B-NLOS, RBIR-CMD-NLOS, RBIR-CM
E-LOS, RBIR-CM
doc.: IEEE 802.11-14/0647r2
Submission
PHY abstractions comparison – Instantaneous accuracy
• In this simulation, we compare the results for RBIR, RBIR-BICM, MMIB and CESM under channel model D.– For a given effective SINR, simulate the PER distribution of the channels that map
to a fixed effective SINR.
• Simulation settings:– Channel model: D-NLOS– MCS 4, 80MHz@5GHz, 1 by 1, 1024 Bytes packet, BCC
Tianyu Wu, etc. MediaTek
Slide 14
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doc.: IEEE 802.11-14/0647r2
Submission Tianyu Wu, etc. MediaTek
Slide 15
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0 20 40 60 80 100 120-3.5
-3
-2.5
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-1.5
-1
-0.5
0
Trials
PE
R
RBIR-CM
0 20 40 60 80 100 120-3.5
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Trials
PE
R
RBIR-BICM
0 20 40 60 80 100 120-3.5
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-0.5
0
Trials
PE
R
MMIB
0 20 40 60 80 100 120-3.5
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-2.5
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-1.5
-1
-0.5
0
Trials
PE
R
CESM
doc.: IEEE 802.11-14/0647r2
Submission Tianyu Wu, etc. MediaTek
Slide 16
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-4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.50
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PER
Num
ber
of t
rials
-4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.50
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PER
Num
ber
of t
rials
-4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.50
5
10
15
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25MMIB
PER
Num
ber
of t
rials
-4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.50
5
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15CESM
PER
Num
ber
of t
rials
doc.: IEEE 802.11-14/0647r2
Submission
Observations
• The results shows that RBIR-CM, RBIR-BICM and MMIB provide similar accuracy on instantaneous PER prediction.– MMIB seems slightly better and CESM is a little bit worse than other methods.
• The PHY accuracy and SLS simulation complexity is a tradeoff
• How accurate for PHY abstraction do we need for SLS?
Tianyu Wu, etc. MediaTek
Slide 17
May 2014
doc.: IEEE 802.11-14/0647r2
Submission
Other observations: Effect of BW
• Simulation settings: – Ch D, MCS 0,2,4,6,8
• From the results we find that the effective SNR mapping is irrelevant to bandwidth.
Tianyu Wu, etc. MediaTek
Slide 18
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-5 0 5 10 15 20 25 3010
-4
10-3
10-2
10-1
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Effective SNR
PE
R
20MHz
40MHz
80MHz
doc.: IEEE 802.11-14/0647r2
Submission
Other observations: Effect of Packet Length (1)
Tianyu Wu, etc. MediaTek
Slide 19
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Effective SNR
PE
R
Pkt length: 256Bytes
Pkt length: 1024Bytes
Pkt length: 4096Bytes
-5 0 5 10 15 20 25 3010
-8
10-6
10-4
10-2
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Effective SNR
BE
R
Pkt length: 256Bytes
Pkt length: 1024BytesPkt length: 4096Bytes
doc.: IEEE 802.11-14/0647r2
Submission
Effect of Packet Length (2)
• The PER for an arbitrary packet length PL can be given by:
where PL0 is the reference packet length and PERPL0 is the PER for the reference packet length PL0.
• One problem for this method is that when PL/PL0 is too small to too large, the inaccuracy on the reference curve will be amplified.
• Take 1024 Bytes as reference packet length and generate the PER curve for 256 and 4096 bytes as shown in next slide.
Tianyu Wu, etc. MediaTek
Slide 20
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doc.: IEEE 802.11-14/0647r2
Submission
Effect of Packet Length (3)
• The error will be amplified when L/L0 is too big or too small.– We may need a set
of reference curves for different size of packets.
Tianyu Wu, etc. MediaTek
Slide 21
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2 4 6 8 10 12 14 1610
-4
10-3
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Effective SNR
PE
R
Pkt length: 256Bytes
Pkt length: 256Bytes,adjusted from 1024Bytes
Pkt length: 1024BytesPkt length: 1024Bytes,adjusted from 1024Bytes
Pkt length: 4096Bytes
Pkt length: 4096Bytes,adjusted from 1024Bytes
doc.: IEEE 802.11-14/0647r2
Submission
Conclusion
• RBIR can provide quite accurate prediction for average performance
• An channel irrelevant curve fitting method can be used to further improve the accuracy
• Instantaneous PER is hard to be precisely predicted.• Other observations:
– PHY abstraction methods are irrelevant to BW.– PHY abstraction for different packet length might be calculated from a set of tables
for several fixed packet length.
• Prediction accuracy and simulation complexity is a tradeoff.– Shall we consider to include other simple PHY abstraction method?
Tianyu Wu, etc. MediaTek
Slide 22
May 2014
doc.: IEEE 802.11-14/0647r2
Submission
References
[1] 11-13-1131-00-0hew-phyabstraction-for-hew-system-level-simulation
[2] 11-14-0043-02-0hew-phy-abstraction-in-system-level-simulation-for-hew-study
[3] 11-14-0117-00-0hew-phy-abstraction-for-hew-system-level-simulation
[4] 11-14-0330-03-0hew-hew-phy-abstraction
[5] 11-14-0353-00-0hew-suggestion-on-phy-abstraction-for-evaluation-methodology
[6] 11-14-0527-00-00ax-phy-abstraction-for-tgax-system-level-simulations
Slide 23 Tianyu Wu etc. MediaTek
May 2014