Distributed Facility Location for Sensor Network Maintenance

The continuous growth of wireless sensor networks demands new approaches to efficiently manage and service them. We present an approximation solution to the facility location problem for sensor network maintenance based on static sensors and mobile facilities. The main goal is to increase the network lifetime by recharging or redeploying sensors with the help of mobile multi-purpose maintenance facilities. Our problem is a variant of the facility location problem (FLP). In our case, we need to find a suitable deployment of the facilities where their workload is balanced and the movement of the facilities in their areas is minimized. This should be accomplished keeping the number of sensor communications at minimum. While finding the optimal placement of the maintenance facilities is a NP-hard problem, we show a simple and efficient solution, totally distributed and localized, which starting with a balanced deployment, progresses to a final partition of remarkable quality. Such final partition satisfies the load balancing requirement and minimizes the facility travel times. The experimental analysis of our distributed and localized solution shows that sensor message cost remains low as the size of the network increases. The experiments also show a load distribution similar and sometimes better than centralized deployment solutions.