The distribution of the node in wireless sensor network is stochastic,generally it is randomly distributed in test area. Node positioning technology has become one of the important technologies of wireless sensor networks. Thus,positioning become the foundation of many applications in wireless sensor network. Wireless sensor network localization algorithms can be divided into the localization algorithm of rang-based and the localization algorithm of rang-free.The positioning accuracy of the first one is better, but it requires more on hardware, environment and other factors. The localization algorithm of rang-free does not depend on hardware, environment, energy and other factors, you can achieve more accurate positioning is only based on network connectivity information. In this paper, the work content of the following aspects.Due to this problem that anchor nodes and location nodes of DV-Hop algorithm in wireless sensor networks only when the hop distance approximate calculation will produce relatively large errors, proposing in the original DV-Hop algorithm based on RSSI ranging techniques to determine that if the anchor nodes is one hop distance away from location nodes. Then further determining whether to use the DV-Hop algorithm to approximate the distance between them. The proposed new algorithm is based on ranging and non-combination of two types of algorithms based on ranging. This does not require higher demands on the hardware and also save the cost of ranging, then performance analysis and simulation in terms of positioning accuracy, the storage overhead and energy consumption. The results show that the new algorithm can effectively improve the positioning accuracy of the network nodes.Due to centroid localization algorithm’s coarse-grained rather high errors, shortcomings of the requirements of a large proportion of the anchor node. Chapter III of the DV-Hop algorithm and RSSI Ranging Technology for the problems of the centroid localization algorithm, this paper proposed an improved centric algorithm, this algorithm, the use of a weighted average of the concept makes the new algorithm is estimated the error between the coordinates and the actual coordinates of the unknown node is smaller, and increasingly close to the actual coordinates of the unknown node, thereby positioning accuracy has been improved to some extent.The two proposed improvements after positioning operation all belongs to those that based on positioning of rang-free,meanwhile they they have their own advantage. The first algorithm is based on non-ranged localization algorithm for the number of hops. The smaller the hops value the smaller the error of the cumulative. The former always applied in the cases that don’t demand high in hardware,it can achieve accurate positioning without ranging,which serves the expense of internet and the lose of energy. Applicable to the common hardware, the better node connectivity, the relatively small number of hops between the unknown nodes and anchor nodes. The second algorithm is based entirely on the neighbor relations. It is suitable for those that have more anchor nodes and the calculation is easier,chances of errors is lower too.The two all make better compared with the original one and are able to fix a position more accurately. |