Saturday, September 1, 2012

Comparison of 802.11n and legacy (non 802.11n) beacons

In terms of sheer size the 802.11n beacons are almost 4 times as large at about 225bytes, while the legacy beacons are usually only 62bytes.

This big difference is due to the HT (high throughput) information element (IE) in the new beacon. This contains all the information relating to the HT features supported by this 11n AP. For example it will include information about the max. AMPDU and AMSDUs supported by this AP.

The second HT IE is known as the extended information element. It provides information like whether the secondary channel is above or below the primary channel.

With 802.11ac, the beacon sizes have grown even more. Additional IEs are now supported for different other features which result in the beacon becoming relatively large.

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