Mitigating the effect of interference in Wireless Sensor Networks

Performance of a deployed Wireless Sensor Network (WSN) is greatly influenced by the interference it is subject to during operation. Degradation happens due to interference resulting in packet drops, retransmissions, link instability and inconsistent protocol behavior. We have conducted experiments that highlight the fact that interference caused by WiFi and co-channel contention significantly degrades the network performance of protocols. These potential sources of interference must therefore be accounted for during the design stage of a WSN in order to achieve acceptable network performance. Based on these observations, we have proposed a multi-hop multi-channel topology control protocol RMMTC for WSN that takes into account interference caused by WiFi networks in operation in the vicinity and uses multiple channels at different frequencies to mitigate the effect of co-channel interference. This paper details the design and performance evaluation of our proposed RMMTC protocol using both simulations and empirical experiments. In addition, we have formulated the multiple channel assignment problem as an Integer linear program (ILP) and compared the performance of our distributed protocol with the centralized ILP solution. The simulation results show that RMMTC performs close to the optimal centralized ILP and achieves a nine-fold reduction in the percentage of dropped packets when a dense network is subjected to interference from WiFi and co-channel contention.