Distributed space-time processing in sensor networks

Given the power limitations of sensor networks, it is of interest to determine cooperative communication schemes for such networks which can exploit the inherent spatial diversity of nodes. This paper proposes a simple scheme based on maximal ratio combining and a distributed transmission protocol to effectively exploit temporal and spatial diversity in a sensor network. In contrast to cooperative communication schemes based on distributed space-time codes, the proposed distributed space-time processing (DSTP) method exploits diversity in a greedy manner and does not require the overhead of setting up clusters. DSTP is a suite of cross-layer (physical, media access control and network) distributed protocols designed for ease of implementation, robustness and scalability in large sensor networks. Two modes of DSTP are proposed to allow one-to-one or many-to-one distributed communication. The efficacy of the proposed scheme is evaluated by a diversity analysis as well as simulation results. The frame-error rate performance of DSTP is observed to be superior to simple relaying and a cluster-based distributed space-time method.