Method and performance of QoS-based adaptive hybrid cooperative transmission

In an ideal hybrid cooperative transmission system, all relay nodes are involved in decoding the received signals from the source, which will result in an increase in computational complexity, resource consumption and transmission delay. In this paper, a novel quality of service (QoS)-based adaptive hybrid cooperative transmission method is proposed in a multi-relay assisted wireless transmission network. The symbol error rate (SER) and outage probability performance of the proposed method are analyzed and their analytical expressions are given. This method can adjust the transmission mode of the relay nodes adaptively according to the QoS requirement at the destination and the threshold of signal-to-noise ratio (SNR) at the relay nodes. Therefore, the resource consumption of the system can be reduced and the life-span of the relay nodes can be extended. Numerical and simulation results show that the performance of the SNR threshold based hybrid cooperative transmission is close to that of the ideal hybrid cooperative transmission while the former has lower implementation complexity. The theoretical performance analysis is consistent with the results of actual Monte Carlo simulation.