Outage analysis for hybrid relaying in the parallel relay network

Although cooperation in wireless networks is known to improve communication in many respects, optimal relay selection remains a relatively open problem. We analyze a wireless network which employs multiple parallel relays to assist in communication between a single source-destination pair, demonstrating that gains are achieved when the relays selected form a random set as compared to utilizing a deterministic set of relays. Relays are selected to actively participate in transmission based on their instantaneous channel magnitudes, which implies that the set of relays chosen to participate in a block of time is stochastic. We define a hybrid relaying scheme comprised of two existing protocols and derive thresholds which determine a relay´s forwarding behavior. Numerical results for the network probability of outage are presented.