The Research On CTP Protocol And APIT Location Algorithm In Wireless Sensor Networks

In recent years,wireless sensor networks(WSNs),which characterized by low cost and low power,have been widely used in scientific research,disaster early warning,environmental monitoring,battlefield surveillance,intelligent transportation,industrial and agricultural production and other fields.Therefore WSNs cause much academic and industry's concern.As key technology of wireless sensor networks,node localization and routing protocol have been the focus of research.This thesis consists of two parts:In the first part,an improved CTP protocol is proposed,which based on heterogeneous network for the load imbalance of CTP(Collection Tree Protocol)and the problem of heterogeneous network(H-CTP).This protocol adds node energy to the original ETX computation factor and node flow factor,and designs the RFD-specific routing to transmit data.Simulation results show that the proposed protocol can improve the load imbalance of the original CTP protocol and can achieve better network performance under heterogeneous networks.In the second part,this thesis proposes an improved APIT protocol.First of all,contrary to the incorrect location of this algorithm,a joint APIT algorithm named J-APIT is proposed.In order to locate unknown nodes,this algorithm joints APIT location technology,ranging technology which based on connectivity,RSSI ranging technology and centroid positioning technology.Simulation results show that the proposed algorithm can reduce more the positioning error than APIT algorithm.Second,in order to solve the problem that the J-APIT algorithm locates the uneven distribution of anchor nodes,mobile anchor nodes are used to form the J-APIT positioning algorithm(MJ-APIT).This part makes use of the mobile anchor nodes to adjust the network topology,which further improves the coverage of the node and reduce the positioning error effectively.At last,to improve the positioning accuracy of the nodes,a concept of MJ-3D-APIT algorithm is proposed,which combines 3D-APIT with MJ-APIT.According to the character of 3D-APIT algorithm,the miscarriage of justice which caused by the edge effect is reduced.Through the result of the simulation and comparison,the positioning accuracy and coverage of the MJ-3D-APIT are better.