Wireless relay networks with Alamouti space-time code and M-FSK modulation

This paper presents a noncoherent detection scheme for a fixed-gain amplify-and-forward (AF) relay network, in which the source is equipped with two transmit antennas, while the multiple relays and destination are equipped with a single antenna. An Alamouti space-time block code is employed together with M-ary frequency-shift-keying (FSK). Detection at the destination is performed in two steps. First, the destination estimates the overall channels based on the pilot symbol inherent in FSK transmission. Then it performs the maximal ratio combining (MRC) to make a final decision. An upper bound on the error performance is derived in a closed-form expression and it is shown that the investigated scheme achieves the full diversity order. Simulation results are also presented to confirm the analysis in a temporally-correlated fading environment.