  In Wireless Sensor Networks, sensors are used for tracking objects,
monitoring health and observing a region/territory for different environmental
parameters. Coverage problem in sensor network ensures quality of monitoring a
given region. Depending on applications different measures of coverage are
there. Barrier coverage is a type of coverage, which ensures all paths that
cross the boundary of a region intersect at least one sensor's sensing region.
The goal of the sensors is to detect intruders as they cross the boundary or as
they penetrate a protected area. The sensors are dependent on their battery
life. Restoring barrier coverage on sensor failure using mobile sensors with
minimum total displacement is the primary objective of this paper. A
centralized barrier coverage restoring scheme is proposed to increase the
robustness of the network. We formulate restoring barrier coverage as bipartite
matching problem. A distributed restoring of barrier coverage algorithm is also
proposed, which restores it by first finding existing alternate barrier. If
alternate barrier is not found, an alternate barrier is reconstructed by
shifting existing sensors in a cascaded manner. Detailed simulation results are
shown to evaluate the performance of our algorithms.
