Application of network coding in Wireless Sensor Networks for bridge monitoring

Wireless Sensor Networks (WSNs) have been deployed for the purpose of structural health monitoring (SHM) of bridges. SHM applications can potentially produce a very high volume of sensing data, which consumes much transmission power and thus decreases the lifetime of battery-run networks. We employ the network-coding technique to improve network efficiency and prolong its lifetime. By increasing the transmission power, we change the node connectivity and control the number of nodes that can overhear transmitted messages so as to hopefully realize the capacity gain by use of network coding. We propose here to control transmission power as a means to adjust the number of nodes that can overhear a message transmission by a neighboring node. However, too much overhearing by high power transmission consumes too much limited battery energy. We investigate the interplay between transmission power and network coding operations. We show that our solution reduces the overall volume of data transfer, thus leading to significant energy savings and prolonged network lifetime. We present the mathematical analysis of our proposed algorithm. By simulation, we study the tradeoffs between overhearing and power consumption for the network-coding scheme. Specifically, we consider a bridge with fixed length and sensor nodes are deployed at a uniform distance along one or both sides of the bridge. Our numerical results reveal that appropriate choices of transmission power can achieve the optimal extent of overhearing for network coding gain, while minimizing the overall power consumption for the WSN.