doc.: ieee 802.11-08/1140r0 submission 11n 40 mhz and bt coexistence test results authors:

doc.: IEEE 802.11-08/1140r0

Submission

11n 40 MHz and BT coexistence test results

Name Affiliation Address Phone Email

Harish Ramamurthy

Marvell Semiconductor,

Inc.

5488 Marvell Lane, Santa Clara, CA 95054

408-222-9683 [email protected]

Raja Banerjea Marvell

Semiconductor, Inc.

5488 Marvell Lane, Santa Clara, CA 95054


Ed Reuss Plantronics 345 Encinal St. Santa Cruz, CA 95060


Eldad Perahia Intel Corporation 2111 NE 25th Ave Hillsboro, OR 97124


Authors:

Harish Ramamurthy, Marvell Semiconductor Inc.Slide 2

doc.: IEEE 802.11-08/1140r0

Submission

Objective

• Measure performance impact on 802.11n and Bluetooth (BT) when 802.11n operates in 20 MHz and 40 MHz

• Measurements made in accordance to test scenarios specified in [1] and [2]

• Test Scenarios– BT Profiles: SCO, ACL and A2DP

– 802.11n: 20 MHz/40 MHz


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup

• Anechoic shielded room used

• Separation of WLAN devices is 3m due to test facility constraints

• 11g performance not measured due to time constraints

• Laptop is the primary 802.11n transmitter

• 802.11n Setup– Throughput test using IxChariot

– Aggregation ON and video priority used to maximize medium utilization

~0.5m

~0.5m

~3m

~0.8m


doc.: IEEE 802.11-08/1140r0

Submission

BT Adaptive Frequency Hopping (AFH) Definitions

• AFH off– All 79 MHz channels are used and none of the channels are

blocked

• AFH on: Two types of AFH used– Manual AFH

– Manually remove or blacklist channels that get affected by 802.11 and some margin at the edges.

– For e.g. when using 40 MHz with 2, 6 channel, block all lower channels (except for first four) and enable all higher channels (top twenty seven)

– Regular AFH

• Present results with both regular and manual AFH


doc.: IEEE 802.11-08/1140r0

Submission

Tests Outline

• Quantitative Test Setups– #1: SCO: Measure Mean Opinion Score (MOS)

– #2: ACL: Measure BT throughput

• Qualitative Test Setups– #4: SCO

– #5.1: A2DP: Distance between BT and 802.11n = 0.5 meters




doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #1: BT SCO performance

• Refers to use-case 1 of [1] & [2]. Adjustments– 22 Mbps data rate not measured due to time constraints

• Setup– Refer slide 3.

– Bluetooth Setup• SCO link: MOS measured using PESQ P.862 method

• AFH on: Manual AFH was used

– The tester was standing between bluetooth devices


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #1: BT SCO performance

No 802.11n throughput throttling

Baseline

(AFH off)

802.11n 20MHz

(AFH off)

802.11n 40MHz

(AFH off)

Baseline

(AFH on)

802.11n 20MHz

(AFH on)

802.11n 40MHz

(AFH on)

BT MOS Average

3.6 2.1 1.7 4.2 4.1 4.1

802.11n Mbps Throughput

20 MHz: 98.4 40 MHz: 178.4

68.8 135.14 20 MHz: 98.4 40 MHz: 178.4

94.7 176

802.11n throughput: 1 Mbps

Baseline

(AFH off)

802.11n 20MHz

(AFH off)

802.11n 40MHz

(AFH off)

Baseline

(AFH on)

802.11n 20MHz

(AFH on)

802.11n 40MHz

(AFH on)

BT MOS Average

3.6 3.5 3.5 4.2 4.2 4.1


1 1 1 1 1 1


doc.: IEEE 802.11-08/1140r0

Submission

• Setup– Refer slide 3.

– Bluetooth Setup• ACL link: 10000 packets of length 160 bytes of type DH5

• Maximum achievable throughput in this configuration is about 315 kbps

• BT performance: Measure throughput

• AFH on: Manual AFH was used

Test Setup #2: ACL performance


doc.: IEEE 802.11-08/1140r0

Submission


No 802.11n throughput throttling

Baseline

(AFH Off)

802.11n 20MHz

(AFH off)

802.11n 40MHz

(AFH off)

Baseline

(AFH on)

802.11n 20MHz (AFH on)


BT Average (kbps)

308 159 47 315 312.2 260.5

802.11 Average (Mbps)

20 MHz: 97.06 40 MHz: 175

68 132 20 MHz: 97.06 40 MHz: 175

98.7 174.5

802.11n throughput 1 Mbps

Baseline

(AFH Off)

802.11n 20MHz

(AFH off)

802.11n 40MHz

(AFH off)

Baseline

(AFH on)



BT Average (kbps)

308 302 301 315 314 311

802.11 Average (Mbps)

1/1 1 1 1/1 1 1


doc.: IEEE 802.11-08/1140r0

Submission

Discussion: Quantitative Test Results

• 802.11n High medium utilization (No throughput throttling)– Without AFH, performance of BT degrades in the presence of 802.11n for

both 20 and 40MHz• MOS is not acceptable for both 20 MHz and 40 MHz

• 802.11n throughput also gets severely affected (down 30 %)

– Manual AFH greatly improves the performance of BT in the presence of 802.11n for both 20 and 40MHz

• MOS is comparable for 20 MHz and 40 MHz

• 802.11n throughput has slight degradation

• 802.11n Low medium utilization (1 Mbps)– 802.11n and BT performance are not degraded considerably (<10%)


doc.: IEEE 802.11-08/1140r0

Submission

Qualitative Tests

• Perception tests for audio quality of BT SCO and A2DP in presence of 802.11n 20 MHz and 40 MHz

• The data presented here is for reference only and it is not intended to be interpreted as comparing different implementations and their performance. Results are presented for limited number of scenarios

• Note– “blips”: minor interruption in audio of duration <2 second – “dropouts”: major interruption in audio of duration >= 2seconds


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #4: BT SCO – Qualitative Tests

• Equipment– Plantronics Voyager 855 headset and Marvell BT

• Setup similar to use-case 1 of [1] & [2]. Adjustments• 22 Mbps data rate not measured due to time constraints

• AFH– Regular AFH


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #4: BT SCO – Qualitative Test Results

• AFH Disabled– 802.11n: No throughput throttling

• 20 MHz: Audio is distorted but remains intelligible (on the threshold of being acceptable/unacceptable)

• 40 MHz: Audio is heavily distorted and marginally intelligible (unacceptable)– Running 1 Mbps (Both 20 MHz and 40 MHz)

• Audio quality is very good but do hear occasional dropouts (not often)

• AFH Enabled– Regular AFH– 802.11n: No throughput throttling

• Audio quality was very good for both 20 MHz and 40 MHz• With 40 MHz hear slightly higher number of dropouts

– 802.11n: 1 Mbps throughput. For both 20 MHz and 40 MHz:• No audible effect


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #5.1: BT A2DP

• Equipment– Marvell BT Devices

• Setup similar to use-case 3 of [1] & [2]. Refer slide 4.

• AFH– Manual AFH


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #5.1: BT A2DP – No 802.11n throughput throttling – Qualitative Test Results

AFH 802.11 Mode

802.11 Throughput (Mbps) BT Performance

OFF Baseline 20 MHz: 98.6 (802.11n only)

40 MHz: 179.2 (802.11n only)

Good audio quality, Rare blips

(BT Only)

OFF 20 MHz 87.3 Lower number of blips- ~10% - Audio quality is good

OFF 40 MHz 119 Several blips and some dropouts - ~25% - Audio quality is not good

ON Baseline 20 MHz: 98.6 (802.11n only)

40 MHz: 179.2 (802.11n only)


(BT Only)

ON 20 MHz 96.5 Good audio quality, Rare blips

ON 40 MHz 176.7 Good audio quality, Very few blips


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #5.1: BT A2DP – Varying Throughput – Qualitative Test Results

AFH 802.11 Mode

802.11 Throughput (Mbps)

BT Performance

OFF Baseline 20 MHz: 98.6 (802.11n only)

40 MHz: 179.2 (802.11n only)


(BT only)

OFF 20 MHz < 60 Mbps* Good audio quality, Very few blips

OFF 40 MHz < 90 Mbps* Good audio quality, Very few blips

* Empirical search: Throughput was varied in steps of 5 Mbps


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #5.2: BT A2DP – Qualitative Tests

• Equipment– Plantronics Pulsar 590A headset and stereo adapter

• Setup similar to use-case 3 of [1] & [2]. Adjustments:• 22 Mbps data rate not measured due to time constraints

• AFH– Regular AFH


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #5.2 : BT A2DP – Qualitative Test Results

• AFH Disabled– 802.11n: No throughput throttling. For both 20 MHz and 40 MHz

• Lots of dropouts. Audio quality was not acceptable

– 1 Mbps (Both 20 MHz and 40 MHz)• Audio quality is very good but hear dropouts occasionally

• AFH Enabled– 802.11n: No throughput throttling

• 20 MHz: Periods of music and periods of dropouts.

• 40 MHz: Lots of dropouts. Audio quality was not acceptable

– Regular AFH algorithm i.e. no manual blacklisting


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #5.3: BT A2DP

• Equipment– Plantronics Pulsar 590A headset and stereo adapter

• Setup similar to use-case 3 of [1] & [2]. Adjustments:• Increased distance between 802.11 tx and BT tx to 1.5m• 22 Mbps data rate not measured due to time constraints

• AFH– Regular AFH algorithm i.e. no manual blacklisting


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #5.3: BT A2DP –Qualitative Test Results

• AFH Disabled– 802.11n: No throughput throttling

• 20 MHz: Audio quality is good but do hear blips

• 40 MHz: Audio quality is good but because of higher dropouts it is not acceptable

• AFH Enabled– 802.11n: No throughput throttling

• 20 MHz: Audio quality is very good

• 40 MHz: Audio quality is good to very good with some blips


doc.: IEEE 802.11-08/1140r0

Submission

Discussion: Qualitative Test Results

• SCO– No tests were done with manual AFH– With regular AFH enabled, the audio went from unacceptable to near

perfect

• A2DP– With regular AFH

• With distance between BT Tx and 802.11 Tx equal to 0.5 m, audio quality for both 20 MHz and 40 MHz was unacceptable

• With distance increased to 1.5 m, audio quality improved significantly for both 20 MHz and 40 MHz

• Note: The headset remained 0.5 m away from 802.11n Tx. This still emulates a user working on a laptop while listening to music and amounts to moving the BT tx (stereo) away by 1m

– With manual AFH• Audio quality is good in both 20 MHz and 40 MHz


doc.: IEEE 802.11-08/1140r0

Submission

References

[1] “11n 40MHz BT test cases”, Eldad Perahia (Intel) et al– Available at

https://mentor.ieee.org/802.11/file/08/11-08-0971-00-000n-11n-40mhz-bt-test-cases.ppt

[2] “Bluetooth test cases for 802.11n 40 MHz”, John R. Barr (Motorola) et al– Available at

https://mentor.ieee.org/802.11/file/08/11-08-0984-00-000n-bluetooth-test-cases-for-802-11n-40-mhz.ppt

doc.: IEEE 802.11-08/1140r0

Submission

Backup Slides

Setup, detailed test results etc.


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #1: SCO performance

Baseline

(AFH off)

11n 20MHz

(AFH off)

11n 40MHz

(AFH off)

Baseline

(AFH on)

11n 20MHz

(AFH on)

11n 40MHz

(AFH on)

3.41 2.12 1.54 4.28 4.27 4.28

3.69 2 1.94 4.08 4.11 4

3.92 2.42 1.44 4.16 4.01 4.27

3.87 1.97 2.11 4.28 4.27 4.27

3.87 1.75 1.89 4.28 3.89 3.91

3.87 1.93 1.85 4.26 4.29 4.09

3.47 2.02 1.86 4.29 4.28 4.27

3.53 2.36 1.66 4.28 4.28 4.23

3.26 2.4 1.69 4.29 4.27 4.26

3.81 2.54 1.47 4.28 4.12 4.26

BT MOS Average

3.6 2.1 1.7 4.2 4.1 4.1


98.4/178.4 68.8 135.14 98.4/178.4 94.7 176


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #1: SCO performance with 1Mbps 11n Throughput

Baseline

(AFH off)

11n 20MHz

(AFH off)

11n 40MHz

(AFH off)

Baseline

(AFH on)

11n 20MHz

(AFH on)

11n 40MHz

(AFH on)

3.41 3.23 3.41 4.28 4.27 4.28

3.69 3.64 3.42 4.08 4.29 4

3.92 3.58 3.68 4.16 4.28 4.27

3.87 3.64 3.39 4.28 4.29 4.27

3.87 3.48 3.71 4.28 4.29 3.91

3.87 3.42 3.65 4.26 4.2 4.09

3.47 3.74 3.53 4.29 3.79 4.27

3.53 3.36 3.76 4.28 4.28 4.23

3.26 3.74 3.56 4.29 4.27 4.26

3.81 3.53 3.43 4.28 4.26 4.26

BT MOS Average

3.6 3.5 3.5 4.2 4.2 4.1


1/1 1 1 1/1 1 1


doc.: IEEE 802.11-08/1140r0

Submission


Baseline

(AFH Off)

802.11n 20MHz

(AFH off)

802.11n 40MHz

(AFH off)

Baseline

(AFH on)



309 156 48 313 310 274

309 163 46 314 312 247

307 159 48 316 314 262

317 313 259

BT Average (Kbps) 308 159 47 315 312.2 260.5

802.11 Average (Mbps) 97.06/175 68 132 97.06/175 98.7 174.5


doc.: IEEE 802.11-08/1140r0

Submission

Test Setup #2: ACL performance – 802.11n 1 Mbps throughput

Baseline

(AFH Off)

802.11n 20MHz

(AFH off)

802.11n 40MHz

(AFH off)

Baseline

(AFH on)



309 303 301 313 315 312

309 299 302 314 314 312

307 304 300 316 315 310

317 315 311

BT Average (Kbps) 308 302 301 315 314 311

802.11 Average (Mbps) 1/1 1 1 1/1 1 1

doc.: ieee 802.11-08/1140r0 submission 11n 40 mhz and bt coexistence test results authors:

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