Node Switching Rates of Opportunistic Relaying and Switch-and-Examine Relaying in Rician and Nakagami-m Fading

Abstract

In opportunistic relaying systems, only the relay with best channel condition among K relays is selected to take part in cooperation. This setup efficiently achieves diversity gain. However, the high switching rate of such systems may be undesirable due to practical implementation issues, for example, the corruption of the data signal by receiver switching transients, channel estimation and synchronization failures due to excessive switching as well as network control switching overheads which increase with increased switching. Recently, switch-and-examine relaying whose main advantage is its low switching rate, was proposed as a low complexity suboptimal alternative to opportunistic relaying. Meanwhile, comparisons of the switching rates of opportunistic and switch-and-examine schemes have been undertaken only for the case of Rayleigh fading. The switching rates of opportunistic relaying and switch-and-examine relaying systems with two or more relays operating under Rician and Nakagami-m fading are obtained in closed-form or single integral expressions. Results for independent and identically distributed fading links are obtained for the case of multiple relays and additionally for independent but not identically distributed fading links for the two relays case. The closed-form solutions explicitly depend on the Doppler frequency of the fading.