Balancing Cooperation and Interference in Wireless Sensor Networks

We study the effect of cooperation in an interference limited, narrow-band wireless sensor network. Cooperation among available sensors can potentially lead to significant capacity increases. However, in an interference limited setting with asynchronous transmissions, exploiting more available sensors to help active sources will cause more interference to other sensors. Therefore, it is crucial to find the optimal trade-off between the amount of cooperation and the amount of interference introduced to the network. In this work we quantify the amount of cooperation using the notion of relay zones for each active sensor. The sensors that lie in such a zone are allowed to cooperate with the source. We then use the physical interference model to determine the probability that a relay node correctly decodes its corresponding source. Through numerical and simulation studies, we investigate the optimization of the relay-zone radius to maximize the network sum-rate based on relay availability and the sink reception capability. We show that the overall system capacity increases significantly under the proposed scheme, compared with cases where relay nodes are not exploited or where the relay zone radius is suboptimal