Research On Range-free Node Localization Algorithms For Wireless Sensor Networks

Node localization is the key technology for Wireless Sensor Networks(WSN). Sensors’ accurate position information is necessary in many WSN applications, such as environment data collection, wild animal monitoring and target tracking. According to the different localization mechanisms, the WSN localization algorithms can be classified into two categories: range-free and range-based. Range-free localization algorithms have more advantages in cost and power consumption. This paper mainly studies the range-free localization algorithms and the main contents include:Based on position limitation and distance estimation, this paper focuses on seven typical range-free localization algorithms. Firstly, the basic idea and implementation of typical algorithms are studied, and then briefly analyzing the advantages and disadvantages. Lastly, the improved schemes are introduced.To solve the problem that the localization accuracy of centroid algorithm need to be enhanced, an improved centroid algorithm based on possible position set is proposed. By analyzing the error sources of centroid algorithm, the proposed algorithm introduces the concept of possible position set, fully utilizes the position information of anchors and uses the position search strategy which takes localization accuracy and computational overhead into consideration. The proposed algorithm basically maintains the advantages of easy implementation and the simulation results represent that the algorithm can effectively improve the localization accuracy of centroid algorithm.For node localization in irregular network, a range-free localization algorithm using anchor power-control and neighbor information is proposed. The proposed algorithm can be divided into distance estimation phase and position calculation phase. In the first phase, unknown node gets the approximate distances between itself and anchors by anchor power-control and deployment information of neighbor nodes. In the second phase, unknown node uses different approaches to calculate its estimated coordinates according to the number of approximate distances. Simulation experiments show that the proposed algorithm can provide higher localization accuracy in both regular network and irregular network.