Sensing Coverage for Randomly Distributed Wireless Sensor Networks in Shadowed Environments

Sensing coverage is an important issue for sensor networks and is viewed as one of the critical measures of the performance offered by a sensor network. In previous studies, the sensing range of a node is generally assumed to be a deterministic value in all directions. For most types of sensing signals emitted from a far field, the obstructions in the propagation path will induce an extra loss in the received signal power and cause a large variation in the received signal strength. This variation is classified as the shadowing effects similar to the phenomenon in radio wave propagation. The objective of this paper is to examine the impact of the shadowing effects on the sensing coverage. The analytical results of the sensing coverage for a large-scale randomly distributed sensor network in shadowed environments are provided. It was found that the increase in standard deviation of the shadowing effects severely degrades the sensing coverage. For an increase of 2 dB in the standard deviation, the sensing coverage degrades by about 10%.