Research On 3D Node Localization Algorithms For Wireless Sensor Networks

Wireless Sensor Networks (WSN) are comprehensive intelligent information processing platform integrated functions with sensor technology, Micro Electro-Mechanical Systems (MEMS), the modern network and the wireless communication technology. They have broad application prospects, and have already attracted more and more attention. WSN refer to the self-organizing multi-hop networks, in which the monitoring area is composed of many micro-sensor nodes and are formed by wireless communication, aiming to collaboratively perceive, collect and dispose the information from the perceived objects in the network overlay area, and then send to the observer. Wireless sensor networks can be widely used in public safety, national defense and military, health care, environmental monitoring, smart home, disaster relief and many other fields.In WSN, sensor nodes are deployed randomly and densely in the area to be monitored. The precise positions of the most nodes may be unknown in advance; but in order to obtain the exact position where events occur and the process information, it is important to know the nodes location. Therefore, determining the positions of the nodes is the prerequisite and basis for a variety of applications. In practical application, sensor networks are often randomly deployed over three-dimensional (3D) terrain, which requires location algorithm can be achieved within three-dimensional space. Nowadays, many kinds of localization algorithms have been proposed for two-dimensional (2D) wireless sensor networks, yet there is still not an effective method to solve the problem of the nodes positioning in 3D wireless sensor networks. Therefore, the 3D positioning of distributed, low computational complexity, high-precision has greater development potential and prospect than the 2D positioning. This thesis focuses on the nodes positioning in 3D wireless sensor networks. First the thesis reviews the localization technology of unknown nodes in wireless sensor networks, introduces the fundamental concept and the basic approach of the node localization, and mainly discusses several classification methods and evaluation indicator of the node location in wireless sensor networks.Then, a novel distributed and range-free positioning algorithm is proposed for three-dimensional wireless sensor networks (DRFP-3D) after in-depth analyzing and researching several typical three-dimensional positioning. DRFP-3D does not need to measure the distance between nodes, which only needs anchor nodes to broadcast their location information step by step, the unknown nodes which are in the one-hop communication range of the anchor node receive and store the beacon information, and then estimate their own position according to the information.Compared with the existing three-dimensional positioning based on range-free algorithm, DRFP-3D has less computation cost and does not need extra hardware support. The communication cost and positioning error of the algorithm are relatively small, and it is more robust to the network topology. This algorithm makes up for some deficiencies of many other algorithms, and is very suitable for the application of low-power wireless sensor networks. The simulation results demonstrate that in 500m×500m×50m three-dimensional space,20 anchor nodes are placed randomly with ANR=4,97% of the unknown nodes will be located, and the average location error is only about 20%.