Performance analysis of transmit antenna selection in broadcast MISO channels

Time-division multiple access (TDMA) with transmit antenna selection (TAS) is a simple and feasible transmission scheme for broadcast multiple-input single-output (BC-MISO) channels. Compared to other more complex strategies, TAS exhibits two important advantages: 1) The required channel knowledge at the transmitter is relatively low and 2) it only needs a single radio-frequency chain at the transmitter. In this work we analyze the performance of TAS in BC-MISO channels. We derive simple exact closed-form expressions for the achievable sum rate of TDMA-TAS in asymmetric BC-MISO ergodic Rayleigh channels, as well as closed-form expressions for the resulting individual users´ rates. Using these expressions we compare the achievable sum-rate of TAS with two more complex schemes: dirty paper coding and TDMA with transmit beamforming. The performance comparisons reveal that, in some cases, TAS could be and interesting practical alternative to other more complex schemes.