Voronoi-based coverage improvement approach for wireless directional sensor networks

Review Over Hole Healing Techniques in Wireless Sensor Networks

“…Change in working direction to avoid common vertex and coverage overlap. [1] In fig 15, we can see that sensor s j changes its working direction from v1 to v2 but still there is some overlap. To avoid this a new set of vertices U`s is defined as Here s v is the other node which has selected vertex v as working direction.…”

“…Hence, voronoi diagram is also used to detect coverage holes. In [1][2], the redeployment strategy for homogeneous directional sensor nodes using voronoi diagram, to improve the coverage ratio is proposed. The sensing model of directional sensors is shown in fig 11. Figure 11.…”

“…This means the directional sensors can rotate 360 o and their working direction θ can be changed. In [1], three algorithms are proposed to adjust the working direction of the sensors such that the overall coverage ratio of the network is improved. Initially the sensor nodes are deployed randomly as shown in fig 12, then each node starts constructing its voronoi cell with the information of its neighbor nodes.…”

“…After getting the vertices for triangles, length of the three sides of each triangle is obtained and area of each triangle is calculated as [1]:…”

“…The vertex with maximum value of intra-cell coverage area is selected as the working direction of the sensor. This can be written mathematically as [1]:…”