Research On The Three-dimensional Localization Algorithm For WSN Based On RSSI

Wireless sensor network(WSN), which consists of a large number of simple and inexpensive sensor device, equipped with wireless communication interface, has been proposed for various applications such as environment monitoring, disaster relief, target tracking, medical care, and so on. In these applications, it is important for the sensor nodes to be aware of their own locations, because sensed data is always meaningless without relating to its physical position. Furthermore, many protocols of WSN, for example, the location aided routing protocols, will likely depend on the location aware sensors. Therefore, localization has become a critical problem in WSN and also attracted massive attentions from both industry and academy.The location technology for WSN can be divided into two categories:range-based methods and range-free methods. The former provides better accuracy, but requires additional hardware at the sensor nodes. The range-free algorithm makes no assumption about the availability or validity of range information. Acknowledging that the cost of hardware required by range-based solutions may be inappropriate in relation to the required location precision, researchers have sought alternate range-free solutions to the localization problem on WSN. Because of the advantages on power and cost on sensor node, solutions in range-free and range-based have aroused extensive concern by the scientific researcher. Therefore, the thesis focuses on investigation of range-free algorithm for WSN.Many localization algorithms for wireless sensor networks have been proposed to provide per-node location information. Among the numerous proposals for range-free localization, the most representative includes Centroid algorithm, Convex optimization, APS, APIT, which, specially designed for two-dimensional (2D) applications, are difficult to be expanded to three-dimensional(3D) application. However, sensor networks may often be deployed over 3D terrains in real applications. For example, an environmental monitoring network deployed in the sea to detect the temperature and salinity of sea water, the ocean currents and tide, and so forth. These 3D applications bring more than just one extra dimension to the localization problem. In a sensor network deployed over complex 3D terrains, network topologies could be much more complex than 2D cases, which require the localization schemes to be more robust to network irregularities. However, there are no effective solutions to 3D localization up to now. Thus, the research of 3D localization has considerably practical significance.In this paper, we present a novel range-based 3D localization algorithm, and the performance is presented through computer simulation using OpenCV. The simulation results demonstrate that the scheme eliminates the requirement for specific positioning hardware, avoids any interaction between the unknown nodes and is independent of network densities; and the accuracy provided by the proposed scheme is sufficient to support various applications in WSN.