Analysis of outage capacity for DF dual-hop relay and optimal power allocation

The performance of relay is often measured by ergodic capacity and outage capacity. In comparison, Outage capacity is more appropriate measure for channel quality in wireless communication system. Although outage capacity has been mentioned in some literature, but no research has been clearly revealed outage capacity of DF dual-hop relay. In this paper, we obtain a constraint equation of outage capacity for DF dual-hop relay. Otherwise, we take optimal power allocation into account for our analysis. Numerical results compare the performance of uniform power allocation with that of optimal power allocation. It is show that optimal power allocation is required for DF dual-hop relay system. Especially, when the gap of channel gains between the source to relay and the relay to destination increases, the advantage of optimal power allocation become more pronounced.