On the performance of sensor node repositioning under realistic terrain constraints

Node mobility has been exploited in many context of Mobile Sensor Networks (MSNs) and Wireless Sensor and Actor Networks (WSANs) to improve network performance. In particular, network partitioning due to node failures has been addressed via repositioning of some of the mobile nodes. In all of these studies, the application terrain is assumed to be obstacle free and the movements are performed by following the direct path from the source to destination. However, in reality, this is not the case since the terrains would not be obstacle free and the nodes cannot move freely and smoothly to every requested location. The terrain type, elevation as well as the obstacles should be taken into account before the nodes start moving. In this paper, we claim that most of the existing approaches would either not work or produce wrong results if realistic assumptions regarding the terrain are not considered. To demonstrate our claims regarding the mobility issues, we consider two of the existing heuristics on the connectivity restoration problem in disjoint MSNs. Rather than following the direct path for movement as done in these works, we propose to use a path planning algorithm for determining the least-cost path in terms of energy consumption. In the experiments, we simulate several varieties of terrain types, obstacles and elevations in the region. Simulation results indicate that the movement cost is significantly higher and this should be taken into account to redesign the existing approaches.