Capacity of Amplify-and-Forward Selective Relaying With Adaptive Transmission Under Outdated Channel Information

In this paper, we study the impact of outdated channel information on the Shannon capacity of the amplify-and-forward (AF) selective relaying technique in conjunction with specific adaptive transmission over independent and identically distributed (i.i.d.) Rayleigh fading links. We consider three adaptive transmission techniques: 1) optimal power and rate adaptation; 2) constant power with optimal rate adaptation; and 3) channel inversion with fixed rate. We derive closed-form expressions to quantify the degradation for the average channel capacity and outage probability under outdated channel information for AF selective relaying with adaptive transmission. The performances of the considered adaptive transmission techniques are evaluated and compared, showing the impact of outdated channel information on each adaptive transmission technique in an AF cooperative selective relaying.