Transmit antenna selection/Receive Antenna Selection

Antenna selection can be implemented at both transmit and receive ends.
In Transmit antenna selection (TAS), Source has multiple antennas and receiver has single anenna, with the feedback information from the receiver to source, the single antenna will be selected for tranmission which has highet SNR.

For example
In SC, the receiver selects the largest SNR branch, i.e,
SNR_SC =max[h1, h2,... hk]
In TAS, through the feed back information from receiver to source, the source will select one of its antenna for transmission, which has highest SNR, i.e,
SNR_TAS=max[h1, h2,... hk]