Algoritmo para localização em redes de sensores sem fio

Abstract

The knowledge of the geographical location of sensor nodes in Wireless Sensor Networks is an essential feature, because the information collected by a node is only significant if we know the node's location. The Wireless Sensor Network Localization Problem is defined as determine the location off all sensor nodes in a network without need the use infrastructure, such as GPSs, for them. Among the various existing approaches to the problem, this work addresses the problem based on the existence of anchors (some network nodes that know their positions) and estimates distance between the other nodes of the network and among these nodes and anchors. The problem is NP-Hard, therefore we designed a heuristic for it.This thesis proposes a specific heuristic to the problem, using a centralized approach based on trilaterations and intersections between two circles. The control of these methods through the process of choosing reference nodes, the order of choice for the reference nodes, and the fault tolerance control make it possible to find solutions better than are usually found by algorithms based on these methods. Experiments carried out compared the proposed algorithm with other four algorithms. We analyzed several sets of instances by varying the network size, the number of anchor nodes, the radio range and the noise factor. The results show that the proposed algorithm is competitive, achieving the best results in several of the instances tested, evenwhen noise is considered.