College:- Veer Surendra Sai University of Technology Burla, Odisha, India
Abstract:- Wireless sensor network is a type of sensor network which consist of a large number of sensor nodes, which are low cost small in size. When sensor nodes send the data to the user it must be localized itself. Here basically we focus on cooperative and distributed localization. Here we use cooperative positioning algorithm which is a hybrid positioning method used for the improvement of coverage network positioning and accuracy which is based on ultra-wide band technique, normally in harsh environment. In cooperative localization nodes are work together to make measurements and after that it form a map of network. There is a method for selection of neighbors for the distributed localization. Basically distributed algorithms are simple, have asynchronous operations that are there is no global coordination between nodes is required, and have the capability to operate in a disconnected network. Here also describe a Distributed algorithm in which whole network can be divided into cluster, after the initial cluster localized, by stitching together into other cluster whole network can be localized. The graph rigidity theory is define here for the new structure and their relationship. So the algorithm can provide relative location to maximum number of nodes. A hybrid scheme of AOA/TOA explained here. This hybrid scheme employ in multiple seeds in the line of sight scenario. Here we have to find the position of target sensor which not changes its moving direction.
Keywords: WSN, cooperative localization, AOA/TOA hybrid scheme, Distributed localization
A wireless sensor network consists of a large number of sensor nodes which can sense or monitor the environment. The node must be localized itself i.e. to find out the exact location, before sending the data to the neighbors, which is called as “localization”. By localization estimation we can find the absolute position of a sensor node. This can be done by “anchor node”, the node who knows its own position. Previously localization can be done through GPS. But due to some limitation i.e. by installing GPS its antenna increases the sensor node size factor, whereas sensor nodes are required to be small. It reduces the battery life of the sensor nodes due to high power consumption.
Sensor nodes can be used in Military applications, Battlefield Surveillance, target tracking, Nuclear, biological and chemical attack detection. The process of estimating unknown node position in the network is referred to node localization. We can apply localization algorithm not only 2D plane but also 3D. In 2d localization require less energy and time as compare to 3d plane. In 2D provides high accuracy on flat terrains but difficult to estimate in harsh terrains or hilly area. So by using 3D localization positioning error is improved in harsh terrain as well as in flat terrains.
For 3D localization we use some algorithms :
- New 3-dimensional DV-Hop localization Algorithm.
- Novel Centroid Algorithm for 3D.
- The 3-dimensional accurate positioning algorithm.
- Unitary Matrix pencil Algorithm for ranged-Based 3D Localization.
In WSN localization we can locate the node by some techniques :
A. Ranged Based Technique
this technique relay on the distance and angle measurement of nodes. This technique employ on point to point distance to identify the location among neighboring nodes. Ranged based techniques are Angle-Of-Arrival (AOA), TOA (Time-Of-Arrival), RSS (Receive Signal Strength).