JMLA: Joint Monitoring Quality and Network Lifetime for Range-Adjustable Sensors in WRSNs

Area coverage is a critical issue in wireless sensor networks (WSNs). Existing studies mainly used the Boolean sensing model (BSM) and battery-powered sensors with fixed sensing radius, potentially reducing network lifetime and monitoring quality. This article proposes an area coverage algorithm called joint monitoring quality and network lifetime with adjustable sensing radii (JMLA), which employs rechargeable sensors with adjustable sensing radii and utilizes the probabilistic sensing model (PSM) to enhance monitoring quality and perpetuate network lifetime. This will encounter several challenges: 1) more complex sensor scheduling due to the unstable of solar power; 2) more complex energy allocation because of different power consumption rates for different sensing radii; and 3) the cooperative detection between neighboring sensors resulting in different monitoring contribution when applying the PSM. To tackle these challenges, JMLA first estimates the potential solar energy available for the upcoming day. Based on this forecast, it partitions the day into multiple time slots and cycles. Sensors are scheduled to activate in different slots to balance energy consumption with the energy harvested. In addition, JMLA divides the area into several identical grids and forms multiple space-time points with each time slot. Then, sensors are scheduled to cooperatively monitor the bottleneck space-time point with the weakest cooperative detection probability, aiming to maximize the monitoring quality. Performance results show that the proposed JMLA outperforms the existing algorithms in terms of monitoring quality, stability of monitoring quality, and solar energy utilization (SEU).