doc.: ieee 802.11-08/1132r0 submission september 2008 eldad perahia (intel)slide 1 measurements of...
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September 2008
Eldad Perahia (Intel)
Slide 1
doc.: IEEE 802.11-08/1132r0
Submission Slide 1
Measurements of Coexistence between 802.11n 40MHz and Bluetooth SCO
Date: 2008-09-10Authors:
Name Company Address Phone email Mohammad Mansour
Intel [email protected]
York Liu Intel [email protected]
Eldad Perahia Intel [email protected]
September 2008
Eldad Perahia (Intel)
Slide 2
doc.: IEEE 802.11-08/1132r0
Submission Slide 2
Abstract
Over-the-air measurements of Bluetooth SCO voice performance in the presence of 802.11n 40 MHz link. Results show no difference in impact to quality of nearby Bluetooth SCO voice link due to neighboring 802.11n 40MHz link as that of 802.11n 20 MHz link
September 2008
Eldad Perahia (Intel)
Slide 3
doc.: IEEE 802.11-08/1132r0
Submission Slide 3
Setup: Test Case I
• Wired controlled network on Gigabit switch• IxChariot 6.5 traffic is managed on controlled
network• WiFi link is 2.4GHz/40MHz capable• SCO session is created over BT link with
ability to control AFH on/off.• Windows XP SP2 with Chariot endpoint is
used for all stations• Clean RF (2.40-2.48GHz) environment
verified with spectrum analyzer
Gigabit Ethernet
Chariot Server/ConsoleChariot Endpoint
802.11n AP
11n WiFi Link
BT Control
BT
Lin
k
BT Master
WiFi STA
BT ControlBT Slave
September 2008
Eldad Perahia (Intel)
Slide 4
doc.: IEEE 802.11-08/1132r0
Submission Slide 4
Setup: Test Case II
• Wired controlled network on Gigabit switch• IxChariot 6.5 traffic is managed on controlled
network• WiFi link is 2.4GHz/40MHz capable• SCO session is created over BT1 link with
ability to control AFH on/off.• BT2 link used as an additional source of
interference.• Windows XP SP2 with Chariot endpoint is
used for all stations• Clean RF (2.40-2.48GHz) environment
verified with spectrum analyzer
Gigabit Ethernet
Chariot Server/ConsoleChariot Endpoint
802.11n AP
11n WiFi Link
WiFi STA
BT Control
BT
1 Li
nk
BT1 Master
BT ControlBT1 Slave
Gigabit Ethernet
BT2 Slave BT2 MatserBT2 Link
Chariot Management
September 2008
Eldad Perahia (Intel)
Slide 5
doc.: IEEE 802.11-08/1132r0
Submission
Deployment Layout
• Test setup is contained entirely in screen room.
• Lab room is a basic room– 15 ft x 15 ft
WiFi STASCO BT
Devices
WiFi AP
BT Link
Case II
September 2008
Eldad Perahia (Intel)
Slide 6
doc.: IEEE 802.11-08/1132r0
Submission Slide 6
Test Procedure : Case I• Controlled network:
– All nodes are on the same network– Chariot management traffic is on the controlled network
• Bluetooth baseline procedure:– All WiFi nodes are powered down– Bi-directional SCO link using HV3
• Voice traffic over SCO BT link from master to slave (~72sec standard reference wav file transmission)
• No silence cancellation, so there is still traffic from slave to master
– MOS score calculated based on comparison of reference file sent and received file using Opticom’s OPERA v3.5 voice quality analyzer (PESQ Algorithm).
– MOS score averaged over 5 iterations.
• Bluetooth with 802.11 traffic procedure:– Bluetooth procedures are the same as baseline– Add WiFi traffic for 90 Seconds– 802.11n (max and 22mbps) traffic: 4 pairs – two per direction (Tx, Rx), high
performance throughput.scr script– 802.11n (1 mbps) traffic: 1 pairs – one per direction (Tx, Rx), throughput.scr script
September 2008
Eldad Perahia (Intel)
Slide 7
doc.: IEEE 802.11-08/1132r0
Submission Slide 7
Test Procedure : Case II• Controlled network:
– All nodes are on the same network– Chariot management traffic is on the controlled network
• Bluetooth baseline procedure:– All WiFi nodes are powered down– Bi-directional SCO link using HV3
• Voice traffic over SCO BT link from master to slave (~72sec standard reference wav file transmission)
• No silence cancellation, so there is still traffic from slave to master– Bidirectional voice traffic on second BT link (1 pair Tx/Rx Chariot voice) as a
source of interference.– MOS score calculated based on comparison of reference file sent and received file
using Opticom’s OPERA v3.5 voice quality analyzer.– MOS score averaged over 5 iterations.
• Bluetooth with 802.11 traffic procedure:– Bluetooth procedures are the same as baseline– Add WiFi traffic for 90 Seconds– 802.11n (max and 22mbps) traffic: 4 pairs – two per direction (Tx, Rx), high
performance throughput.scr script– 802.11n (1 mbps) traffic: 1 pairs – one per direction (Tx, Rx), throughput.scr script
September 2008
Eldad Perahia (Intel)
Slide 8
doc.: IEEE 802.11-08/1132r0
Submission Slide 8
Test Methodology
• Measurements made in accordance with test scenarios outlined in 08/971r0
• Bluetooth devices comprised of two development platforms from leading BT vendor
• Bluetooth devices forming Bluetooth link separated by 1 m to model typical distance between headset and cell phone
• Bluetooth link separated from the 802.11 link by 0.5 m to model scenario where WLAN connectivity is being using simultaneously with Bluetooth voice call
• Test measurements conducted for 802.11n 40 MHz and 802.11n 20 MHz• Test conducted with a range of 802.11 throughput
– Max throughput for each 802.11 system– Comparable throughputs for each system to compare impact based on the same
offered load– Minimum 802.11 throughput tested is 1 Mbps to model typical internet access
September 2008
Eldad Perahia (Intel)
Slide 9
doc.: IEEE 802.11-08/1132r0
Submission Slide 9
Measurement Baseline
BT Mean Opinion Score (MOS) - No 802.11 present
802.11n Throughput – no BT present
Test Scenario 1 4.0 40 MHz: 155 Mbps
20 MHz: 71 MbpsTest Scenario 2 4.0
September 2008
Eldad Perahia (Intel)
Slide 10
doc.: IEEE 802.11-08/1132r0
Submission Slide 10
Test Scenario 1 – AFH off
• 802.11 traffic type: TCP
• BT link same as baseline
SCO, AFH off
0.0
1.0
2.0
3.0
4.0
Max TPT 22Mbps 1Mbps
11n offered load
BT
MO
S s
co
re
BT+WiFi2.4/40 11n
BT+WiFi2.4/20 11n
11n 20 MHz: 44 Mbps
11n 40 MHz: 115 Mbps
September 2008
Eldad Perahia (Intel)
Slide 11
doc.: IEEE 802.11-08/1132r0
Submission Slide 11
Test Scenario 1 – AFH on
• 802.11 traffic type: TCP
• BT link same as baseline
SCO, AFH on
0.0
1.0
2.0
3.0
4.0
Max TPT 22Mbps 1Mbps
11n offered load
BT
MO
S s
core
BT+WiFi2.4/40 11n
BT+WiFi2.4/20 11n
11n 20 MHz: 55 Mbps
11n 40 MHz: 136 Mbps
September 2008
Eldad Perahia (Intel)
Slide 12
doc.: IEEE 802.11-08/1132r0
Submission Slide 12
Test Scenario 2
• 802.11 traffic type: TCP
• BT links same as baseline
AFH off AFH on
11n 20 MHz
Max TPT
11n 40 MHz
Max TPT
11n 20 MHz
Max TPT
11n 40 MHz
Max TPT
BT MOS 2.6 2.4 3.9 3.7
802.11n TPT
42 Mbps 90 Mbps 52 Mbps 105 Mbps
• BT MOS are identical to Test Scenario 1• 802.11n throughput results degraded compared to Test
Scenario 2
September 2008
Eldad Perahia (Intel)
Slide 13
doc.: IEEE 802.11-08/1132r0
Submission Slide 13
Analysis of Results
• All BT MOS measurements with AFH-on in the presence of 802.11n 40MHz are comparable to that of the BT baseline for both Test Case 1 and 2
• BT MOS score improves with decreasing 802.11n offered load with AFH-off in Test Case 1
• No measurable impact due to offered load with AFH-on in Test Case 1
• No measurable difference between 802.11n 40 MHz and 802.11n 20 MHz with regards to BT performance
• No change in BT MOS score between Test Case 1 and 2
• 802.11n 20 MHz and 40 MHz max throughput is degraded by BT even with AFH on
September 2008
Eldad Perahia (Intel)
Slide 14
doc.: IEEE 802.11-08/1132r0
Submission Slide 14
Conclusions
• Over-the-air measurements conducted to determine coexistence between 802.11n 40 MHz and Bluetooth SCO voice link
• Measurements demonstrate that neighboring 802.11n 40 MHz link has no difference in impact to quality of nearby Bluetooth SCO voice link as that of 802.11n 20 MHz link
• All BT SCO MOS measurements with AFH-on in the presence of 802.11n 40MHz are comparable to that of the BT SCO baseline