Outage performance of orthogonal space–time block coded amplify-and-forward two-way relay networks

The outage probability of two-way relaying network with orthogonal space-time block coded (STBC) transmission is analysed. Two sources equipped with different numbers of antennas send orthogonal STBC coded signals with different parameters. The channel gain between two antenna elements is assumed to be Rayleigh faded. The amplify-and-forward (AaF) relay with a single antenna repeats the received signal after power scaling. Exact expressions for the outage probabilities are provided, where the authors integrate out the outage probability over one of the three different regions on the plane defined by the inverses of channel gains. According to the orthogonal STBC code rates and the source and relay powers, one integration region is selected among the three. The closed-form expression is verified via a set of comparisons with the simulation results. The authors also show that the maximum diversity is attained when the orthogonal STBC is applied at both sides of the two-way channel.