Range-free Localization Algorithms In Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are concerned by a lot of countries in the world and are applied in military, biology and environmental protection, medical and industrial inspection, rescue and relief, etc. If the sensor node in WSN can’t calculate its own position, the observers will be unable to know where the information from and how to process next. Therefore self-localization is very important to WSN.Centroid, APIT and DV-Hop localization algorithms are discussed and simulated by Matlab. The localization errors of these three localization algorithms are varied with the ratio of anchor nodes, communication radius and node density. Based on the DV-Hop localization algorithm, an improved algorithm is proposed. This improved algorithm is called Improved DV-Hop localization algorithm based on the ratio of euclidean distance and hop counts, IDBR localization algorithm for short. Instead of the average size of one hop, the ratio of distance and hop counts of non-collinear anchor nodes groups is calculated in IDBR localization algorithm, thus it decreases the conflict of signals and also cuts down the energy consumption of broadcasting the average size of one hop. In addition, the nodes can only forward the information of anchor nodes whose hop counts to the unknown nodes are less than the threshold of the hop counts. Some of the unknown nodes which can obtain their own positions are upgraded to assisted nodes to help other unknown nodes find their own position. Simulation results show that the performance of the IDBR localization algorithm is better than that of the DV-Hop localization algorithm and it’s more suitable for the WSN with irregular distribution nodes.