Bluetooth and 802.11b/g interference

Unanswered Question
Jul 17th, 2007

I have a question concerning Bluetooth and 802.11b/g interference. What have you seen concerning this? Our bio-med is looking to purchase some medical devices that have a lot of Bluetooth and I'm concerned since Bluetooth runs in the 2.400-2.4835 band and 802.11b/g runs in the 2.412- 2.462 band.

Thanks

I have this problem too.
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mpatalberta1 Tue, 07/17/2007 - 13:27

1 - Yes you may have a problem. One solution is to use the normal traffic on 802.11a and bluetooth on b/g and you will remove the interefence.

2 - In small network you might get away the bluetooth doing dynamic frequency hoping however you only have 3 primary frequencies on 802.11b/g and if you have busy network you will have nowhere to go.

Good afternoon,

I have conducted two separate research projects into the effects of bluetooth (802.15.1) on data communications (802.11 in the 2.4ghz spectrum).

During my testing, i obtained several bluetooth devices voluntarily from our IS staff. We then conducted several routine tasks which would be commonly used... Talking on your phone, syncing a file with a PDA, and finally attempting to pair/and search for all devices. Note that collecting these devices never turned up a device which was a class 1. This was somewhat expected due to class 1's power requirements.

In my testing utilizing the Cognio Spectrum expert I saw that a reasonable amount of traffic was being seen, however due to bluetooths frequency hopping the duty cycle was extremely low on any given channel.

Utilizing the cisco command 'show dot11 associations all' on an AP which the test laptop was associated to i monitored the signal strength & SNR. At no time did the SNR decrease once the testing began.

Further testing showed that rogue stations communicating in ad-hoc caused more of an issue than bluetooth. Again this was expected as Bluetooth is frequency hopping while the ad-hoc communications are not.

While it is safe to assume that bluetooth devices have the capabilities to cause interference based solely on the fact that they operate in the 2.4ghz frequency. Your attention to other sources of interference will likely yield better results.

Note that the above statements are my own and does not reflect my employer's or its customers thoughts on this subject matter.

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