Effective relay selection for lifetime maximization in decode-and-forward networks when only mean channel gain is available at transmitter side

In this paper, for an energy-constrained two-stage selective decode-and-forward (DF) relaying network which employs a Best-Select form of cooperation, we focus on maximizing the minimum node lifetime when only the mean channel state information (CSI) toward the destination is available at each relay node. If only the mean CSI can be exploited, an optimal relay selection strategy for lifetime maximization in an energy-constrained network is not readily available. In this paper, a simple but effective relay-selection strategy is proposed by exploiting only the mean CSI and the residual energy information (REI) at relay nodes. For any given transmit power at each node, the proposed strategy can maximize the minimum node lifetime while achieving fairly stable end-to-end outage performance. A decentralized implementation with minimal overhead is also designed, so that only the local mean CSI and REI is required at each relay node. Both asymptotic performance analyses and realistic simulations verify the advantages of the proposed relay-selection strategy.