Outage performance analysis and optimal power allocation of opportunistic cooperation communications without direct-link

The performance of cooperative communications highly depends on careful resource management, such as power allocation and relay selection. Great deal of works has been done in this field in the past few years. However, the power allocation and relay selection of opportunistic cooperative system without direct-link between source and the destination have not been extensively studied. In this paper, we analysis the outage performance of the opportunistic cooperation without direct-link, and then, using the convex theory, the optimal power allocation expression is given which depend only on partial of channel state information (CSI). It is shown that optimal power allocation can evidently improve the outage performance of opportunistic cooperative system.