Power-efficient cooperative relaying with node location information in wireless sensor networks

Cooperative communication with a single relay is a simple and effective technology for wireless sensor networks. However, its gains often come at a price in terms of extra energy consumption for relay selecting and the relaying device running. As such, we contend that it is worthwhile to consider a relaying scheme that satisfies an overall performance requirement constraint such that cooperation is only invoked to save energy when necessary. In this paper, we propose a power-efficient relay selecting (PERS) scheme with node location information to answer the questions, ldquowhen to cooperaterdquoand ldquowhom to cooperate withrdquo, in terms of power-efficiency. Optimal power allocation strategies under both of overall symbol-error-rate (SER) constraint and maximum power limit are derived for both non-cooperative and cooperative schemes. Taking into account extra power, the scheme with minimum overall power is adopted for a source-destination pair. Then we also propose a low-complexity PERS scheme based on local information in wireless sensor nodes. Simulation results show that the proposed schemes are power-efficient than conventional cooperative scheme.