Selective cooperation based on overall power minimization in wireless networks

In this paper, we propose a selective cooperative scheme based on overall power minimization in wireless networks. While cooperation can potentially improve communication quality, this improvement often comes at a price in terms of extra power consumption for protocol overhead and the relaying device running. As such, we contend that it is worthwhile to consider a scheme that satisfies an overall symbol error rate (SER) constraint such that cooperation is only invoked to save power when necessary. We study that issue by looking at the overall power consumptions of cooperative and non-cooperative schemes in a 3-node model. Optimal power allocation strategies under an overall SER constraint are derived for both non-cooperative scheme and DF cooperative scheme. Taking into account overhead power, the scheme with minimum overall consumed power is adopted for a source-destination pair. When cooperative scheme is used, the potential relay leading to minimum overall power is also selected as the best relay. To reduce the complexity of the selective scheme, three geographical parameters, which are used to make decisions in proposed selective scheme, are evaluated. Numerical results show that the selective cooperative scheme is more power-efficient than both non-cooperative scheme and conventional cooperative scheme.