Doc.: IEEE 802.11-08/1140r0 Submission 11n 40 MHz and BT coexistence test results Authors:
Transcript of 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
408-222-3713 [email protected]
Ed Reuss Plantronics 345 Encinal St. Santa Cruz, CA 95060
831-458-7483 [email protected]
Eldad Perahia Intel Corporation 2111 NE 25th Ave Hillsboro, OR 97124
503-712-8081 [email protected]
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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 3
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 4
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 5
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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
– #5.2: A2DP: Distance between BT and 802.11n = 0.5 meters
– #5.3: A2DP: Distance between BT and 802.11n = 1.5 meters
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 6
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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 7
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
802.11n Mbps Throughput
1 1 1 1 1 1
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 8
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 9
doc.: IEEE 802.11-08/1140r0
Submission
Test Setup #2: ACL 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 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)
802.11n 20MHz (AFH on)
802.11n 40MHz (AFH on)
BT Average (kbps)
308 302 301 315 314 311
802.11 Average (Mbps)
1/1 1 1 1/1 1 1
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 10
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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%)
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 11
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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 12
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 13
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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 14
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 15
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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)
Good audio quality, Rare blips
(BT Only)
ON 20 MHz 96.5 Good audio quality, Rare blips
ON 40 MHz 176.7 Good audio quality, Very few blips
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 16
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)
Good audio quality, Rare blips
(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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 17
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 18
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 19
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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 20
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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 21
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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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 22
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.
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 24
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
802.11n Mbps Throughput
98.4/178.4 68.8 135.14 98.4/178.4 94.7 176
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 25
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
802.11n Mbps Throughput
1/1 1 1 1/1 1 1
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 26
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Submission
Test Setup #2: ACL performance
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)
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
Harish Ramamurthy, Marvell Semiconductor Inc.Slide 27
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)
802.11n 20MHz (AFH on)
802.11n 40MHz (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