On Relay Nodes Deployment for Distributed Detection in Wireless Sensor Networks

In this paper, the problem of deploying relay nodes in wireless sensor networks will be considered. A system consisting of a set of sensor nodes communicating to a fusion center, where decisions are made, is considered. Based on our system model assumptions, some sensor nodes will provide "less- informative" measurements to the fusion center about the state of nature; we consider relay nodes deployment in the sensor network instead of the less-informative sensor nodes to forward the measurements of the other, "more-informative" sensor nodes. This introduces a new tradeoff in the system design between the number of measurements sent to the fusion center and the reliability of the more-informative measurements, which is enhanced by deploying more relay nodes in the network. We will analyze the performance of two protocols over Rayleigh flat-fading channels. In Protocol I, each sensor node directly transmits its measurement to the fusion center. In Protocol II, relay nodes will be used instead of the less-informative sensor nodes to forward the measurements of the more-informative sensor nodes. Hence, in Protocol II, the reliability of the more-informative measurements is enhanced at the expense of having fewer measurements sent to the fusion center and this creates the tradeoff between the number of measurements available at the fusion center and the reliability of the measurements.