Trajectory Design Of Mobile Sink In Wireless Sensor Networks

As an important part of IoT(Internet of Things),Wireless Sensor Networks(WSNs)has revolutionized the way that we interact with the physical world,and greatly extend the depth and range of how we perceive the physical world.So far,WSNs has been wildly used for its low cost,powerful sense ability and easy deployment.However,in most traditional static WSNs,we often gathering data from every sensor node in a multi-hop manner which implies that sensor node needs to relay the data of the other nodes.Therefore,the sensor nodes that distribute near the sink must help plenty of sensor nodes to forward the data to the sink,and these sensor nodes would deplete their energy much faster than the sensor nodes which are far away from the sink.This unbalance energy consumption will cause the energy hole phenomenon around the sink.We can respond to this problem by introducing the mobile sink into WSNs.Mobile sink could collect the data in a single-hop or limited-hop manner while moves through the sensing field.With dynamic change of the location of the sink i.e.the location of the energy hole,mobile sink can balance the traffic load of the sensor nodes,increase energy efficiency and extend the network lifetime.In addition,mobile sink can also help with the sparse WSNs architecture,strengthen the connectivity.For the power of the mobile sink is also limited,so the most important challenge is how to collect more data with this limited energy.In addition,the core solution is plan the shortest travelling path for the mobile sink.This path must make sure the entire sensor nodes could be covered,and the length of the path should be the shortest in order to save the energy of the mobile sink and shorten the time delay of the data collection.In order to resolve these problems,this dissertation has done some research on the routing algorithm design for the mobile sink and some relevant issues.The main innovations of this dissertation are summarized as follows:1?As the distribution of sensor nodes in WSNs is the most important premises for the routing algorithm design of the mobile sink,a Range-Free self-localization algorithm has been proposed.This algorithm does not rely on the distance measurement,so the architecture of the networks does not have to be changed and the sensor nodes do not need any additional devices.The algorithm filters the anchors base on the distribution characteristic of the non-uniform network with the grid method.While in some similar research,the authors suppose the distribution of the sensor nodes is even.However,in practice the sensor nodes are often being deployed randomly or even just been spread by plane,so it is very difficult to have a uniform network.The simulation results show that,with these grid and filter methods the proposed algorithm can work well no matter the distribution of the network is uniform or not.And with the partition combination design,the algorithm can greatly enhance the localization accuracy of the anonymous nodes and just impose small computation burden.2?A routing algorithm of mobile sink base on rendezvous points(RP)selection scheme is proposed.This algorithm differs from some exist routing algorithms which work base on cluster theory.That is still required to forward the data with multi-hop manner,and this would affect energy efficiency of the network.This algorithm make every sensor node send its data to sink with only one hop,it means that the sensor nodes do not need to construct the cluster structure or forward data any more,so the energy consumption will be minimized.The algorithm proposed will first select the right positions of the RPs for the mobile sink base on covering theory,and this method could deduce the dimension of the path solutions.Then the algorithm calculates the path for the mobile sink base on variable-length Partheno-genetic Algorithm.The simulation results show that the satisfactory and accurate path can be acquired only with a little computation,and no matter how the network distributed.3?This dissertation proposed a routing algorithm for mobile sink with no RP position constrained in order to lower the limitation to the solve process of the travelling path,and try to find the optimize path in a much larger space.But in this free condition,there are an infinite number of possible positions and numbers of the RP,so it will be more difficult to find the best path for the mobile sink.The proposed algorithm is a great solution for this problem.It expressed every feasible path solution of mobile sink as a particle.And each dimension of the particle is the coordinates of a RP.Then the dimensionality of the particle is the number of the RPs in the path.This algorithm can derive the optimal path of the mobile sink with the evolutionary method of the particles.However,for the positions and the number of RPs is unlimited,then the dimension of every particle could be different,so the algorithm is called VD-PSO: Variable Dimension Particle Swarm Optimization.Simulation results show that the proposed algorithm can derive the travelling path for the mobile sink throughout the entire network with no RP constrained.4?With no RP constrain,for the solutions space is very large,the routing algorithm for the mobile sink may need more execution time to evolute.To solve this problem,an optimization algorithm for VD-PSO was proposed.The algorithm uses the partition similarity between the particles i.e.the solution of the shortest path,to merge the nearest dimensions of the particles.This process can increase the evolutionary efficiency of the algorithm and the quality of the solution.And with introducing the simulated annealing algorithm into this routing algorithm,it can avoid trapping in local optimum.The simulation results show that with these optimization method,VD-PSO can find the shortest path effectively and perform efficiently,and the result is quite approximate to the optimal solution.