Adaptive antennas involve manipulating the inherent directionality and polarization of the physical antenna structure itself. This is achieved by electronically switching a subset of a large number of small antenna elements into use with each radio chain for each packet sent. Element selection is optimized client by client, based on achieved throughput, relying on the ACK packet that all clients send as a 100% standard part of the Wi-Fi protocol.

As a result of this unique "layer zero" role in the system, adaptive antennas have none of the operational limitations of TxBF. Specifically, adaptive antennas:

• Require no special client behavior beyond mandatory elements in the 802.11 standards (for b, g, or n).

• Can be used simultaneously with spatial multiplexing and polarization diversity.

• Mitigate interference through highly asymmetric beam patterns.