Outage Probability Study of Multiuser Diversity in MIMO Transmit Antenna Selection Systems

This letter develops a framework to analyze the multiuser diversity (MUD) gain in multiple-input multiple-output (MIMO) transmit antenna selection with a maximal-ratio combining (TAS/MRC) system, through which the transmitter selects the optimal antenna out of the total transmit antennas based on the channel state information (CSI) feedbacks. Over a flat-fading Rayleigh channel, a tight analytical closed-form expression of the MUD gain in terms of outage probability is derived. The analytical results show that 1) the MUD system can achieve an order of diversity equal to the product of the number of users, number of transmit antenna, and number of receive antennas; 2) users can be viewed as equivalent "virtual" transmit antennas, and the number of users has a great impact on the system outage probability