Transmit Weights Optimization for Wireless Cooperative Communications in Rayleigh Fading Channels

Cooperative communications among the users in the multiple access wireless environments is an efficient way to obtain the powerful benefits of multi-antenna system without the demand for physical arrays. This paper proposes a solution to optimize the weights of partnering user´s signal for the minimum error probability at the output of maximum likelihood (ML) detector. Found weights adapt the propagation environment changes and are obtained by taking advantage of the channel state information (CSI) feedback from the receiver to the transmitter. The closed-form BER expressions were also derived and compared to the simulation results to evaluate the suggested method´s validity. A variety of numerical results demonstrated the cooperation´s superiority over single transmission under flat Rayleigh fading channel plus AWGN (additive white Gaussian noise)