Cooperative Relaying with Carrier Frequency Uncertainty

We investigate the performance of several suboptimal detectors in a differential space-time coding based cooperative relaying scenario with two relays wherein the carrier frequencies of the relays are not identical due to native oscillator instability. The relays cooperate using a differential Alamouti space-time block code with QPSK symbols transmitted over an unknown quasi-static Rayleigh fading channel. In such a scenario we observe that an optimal detector is prohibitively complex to use and hence we describe various suboptimal detectors and observe that there is no loss in the diversity order which is 2 in the case of using two relays.