Detection Techniques for Two-Relays Decode and Forward Cooperative Systems

In this paper, we propose maximum likelihood (ML) detectors to mitigate the influence of the interference signal for the two-relays full- rate cooperative systems. At the relays, the proposed ML detector is employed by averaging out the interference signal. Furthermore, at the destination, we exploit the interference signal to develop the ML detector. It is shown that the optimal detector is implemented by parallel Viterbi algorithms. The major drawback of the proposed optimal detector is the delay, i.e a destination has to receive and store the whole received packets before performing data detection. Due to the inevitable delay restriction, sub-optimal detector is developed. In contrast with the optimal detector, the sub-optimal detector exploits two consecutive received packets to decode one packet. It turns out that the sub-optimal detector outperforms the optimal detector in terms of the required delay, memory size, bandwidth loss, and computational complexity. Extensive simulation results have been presented to demonstrate the effectiveness of the proposed detectors. Results indicate that the proposed detectors outperform conventional relaying detectors in terms of their bit error rate and packet error rate.