Relay Selection in Dual-Hop Transmission Systems: Selection Strategies and Performance Results

We address the problem of selecting an appropriate relay station for forwarding data from a source to a destination node in dual-hop communication systems. In this regard, we focus on regenerative relays, which try to fully decode the messages received from the source before forwarding them to the actual destination. Several different scenarios are considered with different kinds of channel state information (CSI) available at the selecting entity. For all cases, we present the optimal selection strategies aiming at either maximizing the mean mutual information or minimizing the outage probability. The performance of all schemes is evaluated by means of numerical and simulation results and it turns out that with minimal CSI often almost the same performance as with perfect CSI can be achieved.