Energy efficient workforce selection in special-purpose wireless sensor networks

Sensors are typically powered by non-renewable energy sources (e.g. batteries). This fact makes sensors energy very precious resource that must be saved and used wisely. Many protocols have been proposed to optimize energy consumption in different areas of WSNs (e.g. MAC, routing, data aggregation, etc). However, literature has paid less attention to energy efficient workforce management, namely the way sensors are being recruited. In this work, we show that tasking sensors improperly may result in severely uneven consumption of sensors energy. This can negatively impact network performance through reducing network density, creating energy holes or reducing network lifetime. For the limited communication capabilities of sensors, communication in WSNs deployed in large areas is multihop by nature. However for some special WSN applications (e.g firefighting and handicapped assistance) where the central Aggregating Node (AN) (mounted on the firefighter helmet or the handicapped stick) has low mobility, the monitored area of interest is temporarily limited to a small disk that is centered at the AN. Sensors that reside on that moving disk and the AN form a dynamic WSN where a single hop communication model is appropriate and beneficial. For such scenarios, we propose and evaluate a new protocol that provides an energy efficient workforce management for single and multihop WSNs. Analytical and simulation results demonstrate that the proposed approach significantly increases network lifetime by evenly consuming sensors energy. We also propose an algorithm to extend the single hop version of the protocol to a multihop environment.