Survey on half- and full-duplex relay based cooperative communications and its potential challenges and open issues using Markov chains

In this study, the authors address a brief survey on the half-duplex (HD) and full duplex (FD) relay based cooperative communications. Some nodes in wireless communication acting as relays can share their resource with other nodes by exploiting relaying technologies to achieve cooperative communications. Generally, the buffer-less HD relaying (HDR) limits the performance of a wireless system when the worst condition of transmitting and receiving channels of the relay occurs. The HDR is affected by pre-log factor one-half that reduces the spectral-efficiency of the wireless system. Significantly, advanced technologies in self-interference cancellation enable the FD relaying (FDR) in the cooperative wireless system to achieve high spectral efficiency. Recently, the buffer-aided FDR provides significant performance gains by exploring the concepts of Markov chain of queuing theory at relay as compared to either buffer-aided or buffer-less HDR. Finally, they outline several research challenges associated with small size, interference management, and fading channel for FDR. In addition, some research challenges remain for further investigation that is related to physical-layer security, FDR with a cross-layer approach and two-way buffer-aided FDR.