| Space-time coding has demonstrated that the deployment of multiple antennas at the transmitter allows for simultaneous increase in throughput and reliability. However, the use of antenna arrays is impractical for deployment in some practical scenarios. Therefore, cooperative diversity has been recently introduced for realizing transmit diversity.;Most of the literature in cooperative diversity assume perfect channel state information (CSI). However, in practice, imperfect CSI should be considered. In this thesis, we first investigate the performance of cooperative communications with imperfect CSI, where the channel estimates are obtained by pilot symbols. We present an exact bit error probability expression in the presence of channel estimation errors.;We also study the effect of imperfect CSI in two-way multi-relay cooperative networks when the max-min relay selection is used. We derive an exact expression for the outage probability based on which a novel optimum power allocation scheme is proposed.;Keywords: Cooperative communications, Diversity, Imperfect channel state information, Outage probability, Relay selection, Two-way relaying networks. |
