Relaying techniques for cooperative communication systems

Recently, it has been shown that cooperative communication schemes can solve many of the issues faced by future broadband WWAN and WLAN networks. It is a novel communication concept based on resource sharing and coordination among units of wireless network, which enables significant performance improvements in terms of coverage, data rates, capacity, link reliability and spectral efficiency. This paper gives detailed explanations of relay aided communication concept, with the description of techniques applied for the message processing and/or forwarding at the relay stations. A focus of attention is given to: amplify-and-forward with either fixed gain (AF FG) or variable gain (AF VG) and decode-and-forward (DF) relaying techniques. Adequate analytical models, leading towards BER and capacity graphs, are also presented. Further on, assuming a wireless channel with Rayleigh fading, comparisons of the presented relaying techniques are performed, enabling identification of optimal signal transmission scenarios for cooperative communication systems.