40MHz BT Over the Air Demonstration

1. 40MHz BT Over the Air Demonstration Authors: Date: 2009-05-10 Vinko Erceg, Broadcom

2. Introduction • In this presentation we document coexistence demonstration between devices transmitting .11n 20MHz or forced 40MHz frames and BT devices transmitting A2DP traffic (streaming audio) • This demonstration was presented during the two days of IEEE standards meeting in Los Angeles, January 2009. • Approximately 20 IEEE members of different affiliations experienced and/or witnessed the demonstration. Vinko Erceg, Broadcom

3. Description of the setup • WLAN traffic: • Dell laptop (STA) • Belkin (AP) • Fully loaded Bidirectional traffic generated using IPERF • 20MHz and 40MHz transmissions were alternated every 10 seconds • BT A2DP traffic: • Sony stereo headset (slave device) • Broadcom evaluation board with a production chip (master device) • Dell laptop as a music source to the master BT device Vinko Erceg, Broadcom

4. BT Device Parameters • Class II BT Master: +4dBm transmit power • Standard low gain omnidirectional antenna (master) • AFH algorithm enabled • When measured in the laboratory (screen room) BT AFH algorithm masks off 43 MHz in the presence of the WLAN 40 MHz transmissions only • When measured in the laboratory (screen room) BT AFH algorithm mask off 23 MHz in the presence of the WLAN 20 MHz transmissions only Vinko Erceg, Broadcom

5. Demonstration Setup 20/40MHz • Separation between the BT master and Laptop transmitting 20MHz/40MHz was 1.5m, non-line-of-sight • BT master was placed under the table to mimic scenario when a person is sitting with the BT device (streaming music) in a pocket thus creating lower received signal at the BT headset (more susceptibility to WLAN interference) • Separation between the BT headset and Laptop transmitting 20MHz/40MHz was in most cases 0.5m, normal sitting position and laptop usage • Distance was varied by people listening the BT headset music from 0.1m to 10m • Demo participants could monitor on a separate laptop (spectrum analyzer) changing 20MHz/40MHz transmissions every 10 seconds AP BT Headset 5m Distance Music Source 20/40MHz BT Master ISM Band Spectrum Display Vinko Erceg, Broadcom

6. Applications: A2DP connection between phone and stereo headset WLAN connectivity via a laptop connected to an AP with 802.11 (can be simulated with Agilent E4438C along with N7617B WLAN signal studio) 802.11n traffice needs to vary from small to large packets with different repitition rates to analyze AFH impact. Use Case A user is listening to stereo music using mobile phone as source and stereo headset as sink Same user simultaneously accesses a network with a laptop with 802.11n Or, user in same room as another user accesses network with laptop using 802.11n BT link devices separated by 3m to model typical path loss between headset and cell phone or phone in pocket and headset on ear Voice link (SCO) 802.11 link STA separated from AP by 5 m or less (depending on size of test facility) Bluetooth link separated from the 802.11 client STA by 0.5 m to model same individual using both BT and WLAN Bluetooth link separated from 802.11n signal source by 2-0.5 m to model user in room with others using 802.11n Bluetooth Link 802.11 Link Interference Use Case 2 A2DP Setup Documented in 08/984 Frontline Bluetooth Sniffer Agilent Signal Generator OR Very Similar Setup to the live demo setup on the previous slide Vinko Erceg, Broadcom

7. Demonstration Results • Significant difference in A2DP BT audio quality was not observed between 20MHz and forced 40MHz WLAN transmissions • Audio streaming quality was high except for a few short glitches equally common to 20MHz and forced 40MHz transmissions Vinko Erceg, Broadcom