A distributed transmit antenna selection scheme for fixed-gain multi-antenna AF relaying systems

Antenna selection has arisen as an attractive strategy in multi-antenna systems due to its reduced complexity and cost. In this paper, the outage performance of a distributed transmit antenna selection scheme for dual-hop fixed-gain amplify-and-forward relaying systems is investigated. Our analysis considers a multi-antenna source, a multi-antenna relay, and a single-antenna destination, in which selection combining and maximal-ratio combining are employed at the relay and destination receptions, respectively. Lower and upper bounds for the outage probability of the proposed scheme are derived as the sum of two terms, one term given in closed form and the other term given in single integral form. Moreover, asymptotic expressions for these bounds at high signal-to-noise ratio are obtained in closed form. The results show that our scheme presents full diversity order. More importantly, the underlying distributed strategy is shown to perform closely to the costly optimal centralized antenna selection.