Energy Constraints of Localization Techniques in Wireless Sensor Networks (WSN): A Survey <s> INTRODUCTION <s> Wireless sensor network localization is an important area that attracted significant research interest. This interest is expected to grow further with the proliferation of wireless sensor network applications. This paper provides an overview of the measurement techniques in sensor network localization and the one-hop localization algorithms based on these measurements. A detailed investigation on multi-hop connectivity-based and distance-based localization algorithms are presented. A list of open research problems in the area of distance-based sensor network localization is provided with discussion on possible approaches to them. <s> BIB001 </s> Energy Constraints of Localization Techniques in Wireless Sensor Networks (WSN): A Survey <s> INTRODUCTION <s> Localization is an active field of research in wireless sensor networks WSNs. The information of exact physical location of the sensor nodes in WSNs is useful for various application e.g. intrusion detection, target tracking, environmental monitoring and network services etc. In this paper we present the classification and comparative study of localization algorithms. The goal of our consideration is to analyze, how these localization algorithms work in order to increase the life span of network nodes in harsh environments like oil fields, gas fields, forests, chemical factories and underground mines etc. and how to find the position of mobile node with Distributed, Range-based and Beacon-based Localization technique in harsh environments. Furthermore this paper also highlights some issues experienced by these localization techniques. <s> BIB002
Wireless sensor networks consist of dispersed autonomous sensors that monitor physical conditions such as air pollution, water quality, heat, pressure, temperature, etc. in an environment (outdoor or in-door). Recent advancements (Micro-Electro-Mechanical Systems (MEMS) and VLSI technology) in manufacturing of small and low cost sensor nodes has led to the large scale deployment of disposable sensor nodes, especially in many applications that require unattended operations and in harsh environments. The data collected from these autonomous sensor nodes are processed into meaningful information, in the case where each sensor node is equipped with processing capabilities (Distributed Processing) or the data is transmitted to a Base Station (BS) for processing, in which case the BS has all the processing capabilities on the network (Centralized Processing). In most Wireless Sensor Network applications (WSN), based on the mode of deployment the exact locations of the sensor nodes may be unknown. Wireless sensor network localization is an active research area and has attracted significant research interest. This will grow further with the spread of diverse wireless sensor network applications. Finding the positional coordinates of these sensor nodes manually or automatically is the process of localization  BIB001 . Location information plays an important role in making sensed data geographically meaningful and a lot more network functions can be improved based on our understanding of sensed data and location information. Sensed data and location information will help in improving network routing, topology control, congestion control, coverage, boundary detection, clustering, etc. Sensor location information can be used for tagging sensory data, which is important for application such as smart grid, environmental monitoring, etc. Determining the location (manually or automatically) of sensor nodes requires considering factors (cost, power, memory, communication cost, etc.) that directly affect the overall performance of the network. Future data dependent applications of wireless sensor network (WSN) will heavily depend on the location information provided by the network. WSN localization is an active research area that has seen a lot proposal in terms of algorithms and techniques. Localization can be done in two ways: Centralized and Distributed BIB002 . Centralized localization techniques estimates the location of each sensor node on a network from a central Base Station (BS) or Server, while in the distributed localization techniques each sensor node is equipped with capabilities to estimate its own location on the network. Localization may involves determining the distance (ranging) between nodes and/or finding absolute or relative coordinates (positioning) with or without a reference node usually called the anchor (beacon) node BIB002 .