earticle

영어

Recent advancements in MEMSs technology, VLSI and wireless private area networks have contributed in developing enormous interest in wireless sensor networks by both academia and research community. WSN is formed by large number of small, cheap and low energy sensors that work together in monitoring region. These sensors sense, collect and forward data within the network through wireless medium. WSN find its application in many areas such as object tracking, disaster relief and smart environments etc. Most of these applications need location awareness of sensor nodes to estimate the place of origin of events. The task of determining physical coordinates of sensor nodes within the network is known as localization. Localization has always remained a challenge in successful implementation of WSN and so, it is a hotspot of research. Localization techniques are broadly categorized as Range based techniques and Range-free techniques based on their dependency on range measurements. Because of constraints on cost, energy, computation complexity and infrastructure requirements, range free localization techniques are given importance in recent research works. Considering the latest trends in localization, a thorough analysis for major range free techniques is done in this paper and accordingly their pros and cons are highlighted. As the existing range free techniques are not fully efficient so, open issues are also raised to give directions to future research.