Path Planning For Data Collection Of Mobile Sinks In Wireless Sensor Networks Deployed In Complicated Areas

Wireless sensor networks(WSNs),which are one of the key technologies of Internet of Things(IoT),are critically limited by restricted energy of sensor nodes.The “energy hole” problem in WSNs with static sinks due to the many-to-one transmission pattern leads to premature death of them.The introduction of mobile sinks effectively reduces the energy consumption and balances the load of WSNs;however,the limited moving speed of mobile sinks also causes high latency in network data transmission.On the other hand,since WSNs are usually deployed in complicated areas with severe surrounding and various of obstacles in actual applications,building an optimal obstacle avoidance path for mobile sinks is a burning issue which has not been solved.In this dissertation,we present two obstacle avoidance methods and one path planning method to solve the problem of obstacle avoidance and path planning for WSNs deployed in complicated areas with mobile sinks,which are summarized as follows:1)We present Visible Point-based Obstacle Avoidance(VPOA),which models the obstacles to simple polygons and transforms them into convex hulls for the convenience of computation.An obstacle list is obtained after checking all obstacles which the sink needs to bypass in VPOA.After that,All mutually visible points are checked out for VPOA to generate a weighted graph for A* algorithm to find the path.The simulation result shows the advantage of VPOA in running time and path quality.2)We put forward Navigation Mesh-based Obstacle Avoidance(NMOA)for the mobile sinks.To the best of our knowledge,this is the first time that navigation mesh(NavMesh)is introduced into the field of WSNs with mobile sinks.NMOA utilizes NavMesh to represent the accessible zone of the map.An optimal NavMesh cell order is computed by NavMesh-based A* and then a Simple Stupid Funnel algorithm(SSF)is used to make an optimal path for the sink.The simulation result illustrates that NMOA greatly advances the obstacle avoidance performance for mobile sinks.3)We propose Path Planning in Complicated Area(PPCA)to plan tours for mobile sinks in WSNs deployed in complicated areas,which is based on the support of the obstacle avoidance methods mentioned above.A number of candidate rendezvous points(CRPs)are generated by PPCA firstly.The CRP with densest sensor nodes surrounds is chosen as the first rendezvous point(RP).Then,PPCA tries to expand the tour by adding new RPs from CRPs,with both considerations of two factors of CRPs: sensor node densities and minimum distances to existing RPs.The simulation result proves that PPCA could solve the path planning problem for mobile sinks in WSNs deployed in complicated areas effectively.