Abstract: Wireless sensor networks are capable of carrying out surveillance
missions for various applications in remote areas without human interventions.
An essential issue of sensor networks is to search for the balance between the
limited battery supply and the desired lifetime of network operations. Beside
data communication between sensors, maintaining sufficient surveillance, or
sensing coverage, over a target region by coordination within the network is
critical for many sensor networks due to the limited supply of energy source
for each sensor. This paper presents a novel sensor network coverage
maintenance protocol, called Coverage-Aware Sensor Engagement (CASE), to
efficiently maintain the required degree of sensing coverage by activating a
small number of sensors while putting the others to sleep mode. Different from
other coverage maintenance protocols, CASE schedules active/inactive sensing
states of a sensor according to the sensor's contribution to the network
sensing coverage, therefore preserving the expected behavior of the sensor
network. Coverage contribution of each sensor is quantitatively measured by a
metric called "coverage merit". By activating sensors with relatively large
coverage merit and deactivating those with small coverage merit, CASE
effectively achieves energy conservation while maintaining sufficient sensor
network coverage. We provide simulation results to show that CASE considerably
improves the energy efficiency of coverage maintenance with low communication
overhead.
