Energy-Conserving Coverage Configuration for Dependable Wireless Sensor Networks

Wireless sensor networks consist of a large number of low-power, short-lived, unreliable sensors. Developing a configuration for sensor sleeping is an effective approach for obtaining a long network lifetime without sacrificing crucial aspects of quality of service (sensing coverage and sensing reliability). In this report, two sensing models are investigated: boolean sensing model (BSM) and general sensing model (GSM). For the BSM, we present “minimum partial arc-coverage” (MPAC) to exploit sensing arc coverage information provided by the one-hop neighborhood. The MPAC algorithm can deal with the case in which each sensor has different sensing radii while the deployed area preserves its k-coverage requirement, where k is a user defined coverage degree. With the proposed MPAC, three fault-tolerant approaches, adaptive sleeping, (k + 1)-coverage round-based configuration, and configuration with reduced communication radius, are developed. For the GSM, we present “sensibility-based sleeping configuration protocol” (SSCP) by evaluating the proposed neighboringsensor field sensibility and exploiting the cooperation between neighboring sensors. Pessimistic and optimistic sleeping eligibility conditions are constructed; both are based on the responsible sensing region formed by a Voronoi diagram. With the MPAC and SSCP, redundant sensors are optionally identified and scheduled to sleep in order to extend the system lifetime while maintaining adequate sensor redundancy in order to tolerate sensor failures and energy depletions. The proposed MPAC and SSCP are exploited and simulated with ns-2. Simulation results show that there are three effective approaches to build dependable wireless sensor networks: increasing the required degree of coverage or reducing the communication radius, configuring sensor sleeping adaptively, and utilizing the cooperation between neighboring sensors.