Cooperative Orthogonal Space-Time-Frequency Block Codes over a MIMO-OFDM Frequency Selective Channel

A cooperative algorithm to improve the orthogonal space-time-frequency block codes in frequency selective channels for MIMO-OFDM systems, are presented. This algorithm is composed of three nodes, a source node, a relay node and a destination node are implemented in two stages. During the first stage, the destination and the relay antennas receive the symbols sent by the source antennas. The destination node and the relay node obtain the decision variables employing time-space-frequency decoding process by the received signals. During the second stage, the relay node transmits decision variables to the destination node. In this paper, it is shown that the number of decision variables in the destination node increases and improves system performance. The bit error rate of the proposed algorithm at high SNR is estimated by considering the BPSK modulation. The simulation results show that cooperative orthogonal space-time-frequency block coding, improves system performance and reduces the BER in a frequency selective channel.