Transmit antenna selection for two-hop decode-and-forward relaying

Transmit antenna selection schemes for a two-hop decode-and-forward relay system with a source-destination direct link are considered, and the optimal selection scheme and a suboptimal one are proposed. The exact closed-form expressions for the outage probabilities of the two selection schemes are derived. Moreover, the asymptotic expressions at high signal-to-noise ratio for the outage probabilities are presented, and show that both the optimal and the suboptimal transmit antenna selection scheme can achieve the full diversity order.