Relaying utilization metrics of diamond cooperative diversity systems

We introduce relaying utilization statistical metrics to quantify the contribution of a relay node to the overall relaying process in cooperative diversity systems. Motivated by the second order statistics of the relay fading channel, the following metrics are defined: i) the average relaying selection rate, ii) the average relaying utilization time, and iii) the average relaying waiting time. These metrics are important for the cooperative systems´ design, especially for applications where power consumption and delay are major concerns. As an application, we present exact analytical expressions of these parameters in an amplify-and-forward relaying system with selection diversity and diamond topology over Rayleigh fading channels.