摘要：Wireless Sensor Network (WSN) has been a source of attraction for manyresearchers as well as common people for the past few years. The use of WSN invarious environmental applications like monitoring of weather, temperature,humidity, military surveillance etc. is not limited. WSN is built on hundreds tothousands of nodes where each node is a sensor whose main role is to sense data.These nodes are restricted to various constraints like power, energy, efficiency anddeployment. The location of deployment influences the efficiency of datatransmission. In this paper we briefly discuss on localization process in WSN and theclassification of localization methodologies, namely centralized localization anddistributed localization. The various techniques like ToA, TDoA, AoA and RSSI thatare used to estimate the distance among the nodes are studied in detail. Thelocalization issues categorized under proximity-based, range-based and range-freelocalization are discussed in detail. This paper also focuses on how the nodes withGPS can contribute to the localization process. The merits and demerits of using GPShave also been looked into. The various approaches of range-based techniques likeBounding box, SumDistMinMax, geometric methods, general techniques have beendiscussed briefly. We will also discuss on how the factors like path loss, noise,propagation, device measurements, connectivity, power control and tracking caninfluence the measurements in localization. In the tracking process we have brieflydiscussed about the variants of Kalman filter that can be used in detecting the directpath, strongest path and undirected path. This paper as a whole is just a brush up ofthe localization methodologies used in wireless sensor networks. This paper may giveidea to the researchers to develop efficient algorithms to localize nodes with accuracyadapting to different techniques with respect to the environment and applications tobe designed.
