Doc.: IEEE 802.11-14/0647r2 SubmissionSlide 1 PHY abstraction method comparison Date: 2014-05-12...

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]

mailto:[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

May 2014

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

May 2014

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].


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Phi

EESM

RBIR-CMRBIR-BICM

MMIB

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SINR (dB)

Phi

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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.


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


Slide 6

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doc.: IEEE 802.11-14/0647r2

Submission

RBIR-CM with channel B,D,E


Slide 7

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10-2

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PE

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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


Slide 8

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10-2

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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


Slide 9

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-5 0 5 10 15 20 25 3010

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10-2

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Effective SNR

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AWGN

B-NLOS, MMIBD-NLOS, MMIB

E-LOS, MMIB

doc.: IEEE 802.11-14/0647r2

Submission

RBIR,RBIR-BICM,MMIB with channel D


Slide 10

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AWGN

D-NLOS, RBIR-CMD-NLOS, RBIR-BICM

D-NLOS, MMIB

doc.: IEEE 802.11-14/0647r2

Submission

CESM with channel B,D,E


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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.


Slide 12

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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.


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= 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


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

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RBIR-CM

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RBIR-BICM

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MMIB

0 20 40 60 80 100 120-3.5

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CESM

doc.: IEEE 802.11-14/0647r2

Submission Tianyu Wu, etc. MediaTek

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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?


Slide 17

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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.


Slide 18

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20MHz

40MHz

80MHz

doc.: IEEE 802.11-14/0647r2

Submission

Other observations: Effect of Packet Length (1)


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Pkt length: 256Bytes



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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.


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.


Slide 21

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Pkt length: 256Bytes,adjusted from 1024Bytes

Pkt length: 1024BytesPkt length: 1024Bytes,adjusted from 1024Bytes


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?


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

Doc.: IEEE 802.11-14/0647r2 SubmissionSlide 1 PHY abstraction method comparison Date: 2014-05-12...

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