Investigating the Energy Sink-Hole Problem in Connected k-Covered Wireless Sensor Networks

In immobile wireless sensor networks with constant data reporting, the sensors nearer the sink are responsible for forwarding data to it on behalf of all other sensors in the network. Those sensors suffer from a severe batter power depletion problem, also known as the energy sink-hole problem. In this paper, we study the above problem in duty-cycled connected k-covered wireless sensor networks, where each point in a field of interest is k-covered by at least k sensor. In order to change the neighbors of a sink over time, our solutions suggest the use of mobile proxy sinks that collect data from source sensors and drop them off at an immobile sink. Our proposed three-tier architecture has immobile source sensors, immobile sinks, and mobile proxy sinks. First, we present our fundamental results for the design of duty-cycled connected k-covered wireless sensor networks. Second, we provide the first formal analysis of the performance of joint mobility and routing in this type of network. Precisely, we investigate the best mobility strategy of mobile proxy sinks to minimize the total energy consumption for data collection. Third, we propose joint mobility and routing schemes based on the number of immobile sinks and mobile proxy sinks. We provide a thorough analytical model for our schemes. Finally, we evaluate their performance by simulation. Our results show their significant improvement of the network lifetime compared to a solution without mobile proxy sinks.