Research On Localization Algorithms Of New Heterogeneous Ad Hoc Networks Based On SDN

The rapid development of the Internet of Things technology has made the application of ad hoc network more and more common.However,the accuracy of localization and the power consumption of nodes have been difficult issues in the research of ad hoc networks.The focus of this these is to propose a unmanned aerial vehicle(UAV)assisted ranging method between nodes based on software defined networking(SDN)and to use the UAVs broadcast beacons periodically to get the position of nodes based on range-free algorithm.These nodes are considered as anchors.After obtaining the distance between nodes and locations of anchors,we propose a UAV-assisted distributed collaborative positioning algorithm based on couple information to get the positions of rest agents.The main work of the thesis is summarized as follows.Firstly,a sensor nodes ranging algorithm based on SDN architecture is proposed.With the help of UAV,the method uses UAV broadcasts beacons,and the nodes calculates the corresponding received signal strength indicator(RSSI)vector after receiving the beacon information and sends it back to the UAV,then the UAV sends RSSI information to the computing center of SDN.The SDN computing center calculates the distance between nodes by comparing the similarity of RSSI vector between two nodes.Except for RSSI information,nodes also get the corresponding channel state information(CSI)through beacon information.The SDN computing center gets the distance information by comparing the similarity of CSI information between nodes.Then we use Kalman filter to fuse the multi-channel information to get more accurate distance information.Simulation results show that this method can not only get accurate distance information,but also reduce the power consumption of UAV and nodes.Secondly,a node localization algorithm with UAV broadcast based on SDN is proposed.This method gets the location of unknown nodes through broadcast signals on the premise of knowing the UAV location.And we use the nodes whose positions are obtained by former algorithm as anchor nodes for subsequent localization steps.In this algorithm,the UAV periodically broadcasts beacon signals,and the unknown position nodes will monitor the broadcast signals continuously.When the nodes just enter the sensing range of UAV,the UAV position is taken as the center of the circle,and the communication range is taken as the radius to make the first circle.The UAV flies on the rectangular trajectory and forms the other three circles.Finally,a region can be get by the intersection range of the four circles,which can be used as the location estimation region of unknown nodes.Based on the obtained location estimation area,the estimation error of localization can be analyzed.Simulation results verify that the accuracy of the algorithm can reach the decimeter level accuracy requirements.Finally,we propose a localization method to reduce couple information based on the framework of cooperative positioning.The source of couple information is discussed.The Fisher information matrix(FIM)and Equivalent Fisher Information Matrix(EFIM)are used to analyze the couple information in order to obtain the factors which can affect couple information.Based on this,the topology of network can be changed by adding UAVs so as to change the couple information.Simulation results show that this method can improve the positioning accuracy of distributed cooperative positioning.