Wednesday, July 30, 2008

Beacon interval impacts on battery life

By Jim Geier, Wireless-Nets, Ltd.

I've been experimenting lately with wireless clients having 802.11 power-save mode enabled and different access point beacon intervals. By increasing the beacon interval, clients will sleep longer and save battery power. To get a better idea of the savings, I ran some tests with the beacon interval set to 100 milliseconds (the default) and up to 5 seconds. I found beacon intervals at 1 second provide approximately 14 percent increase in battery life. Beacon intervals set beyond 1 second increased battery very slightly. So, it's probably worth setting the beacon interval out to around 1 second for clients implementing power-save mode. Just be certain that the longer beacon intervals don't negatively impact roaming.

1 comments:

Anonymous said...

What was the DTIM interval during your tests?

I would be curious to see the comparison between two situations.

Beacon Interval = 100ms
DTIM Interval = 10

vs.

Beacon Interval = 1000ms
DTIM Interval = 1


My guess is that the same gain could be seen with a DTIM interval change.

In fact, I would think the fewer Beacons could cause problems with roaming or initial connectivity, but I haven't tested this so I'm guessing.

Thanks for taking the time to do the research!

GTHill