Cooperative relaying techniques for energy efficient wireless communications

It has been shown that cooperative communication schemes can solve many of the issues faced by future broadband WWAN and WLAN networks. It is about communication concept based on resource sharing and coordination among terminals in wireless network that provides significant performance improvements in terms of increased coverage, data rates, capacity, reliability, spectral and energy efficiency. This paper gives detailed overview of cooperative communication concept based on replacement of direct communication link between source and destination with several shorter links using network terminals called relays. Several, so called fixed relaying techniques, are described: amplify-and-forward fixed gain (AF FG), amplify-and-forward variable gain (AF VG) and decode-and-forward (DF). Appropriate analytical models for bit error rate and system capacity values are presented. Further on, assuming Rayleigh fading channels, comparison of the presented relaying techniques are performed, enabling identification of optimal signal transmission scenarios for cooperative communication systems.