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Top1. Introduction
Wireless sensor network is a broad area in wireless networking, which is explicitly designed to measure small amounts of information, typically sensed information and transmit the little information to a principal server or an aggregation point. Recently, mobility became prevalent and forced WSN to make the MWSN to be a part of it. Figure 1 illustrates a typical moveable wireless sensor network. The use of off-the-shelf materials and low power sensor devices was made possible because of the progressions in communication protocols. Initially location identification of moveable devices was considered to be more difficult; whereas (Hu, L., & Evans, D., 2004) exploited mobility to achieve exact and accurate location identification. Although mobility has few limitations, the introduction of mobility has benefited the network performance in terms of packet delay, coverage, and scalability (Munir, S. A, et al., 2007).
Figure 1. Typical moveable wireless sensor network
Whenever a sensor device transmits the sensed information to the principal server, the latter identifies the packet origin with the help of the location coordinates sent by the device. Location information is the heart of various solicitations like routing, surveillance and monitoring, fault identification, and defence. Location-based routing (Füßler, H, et al., 2003) and location-aided routing (Ko, Y. B., & Vaidya, N. H., 2000) avail location information of devices to increase the performance of routing in an ad hoc surrounding. Ubiquitous computing and smart surroundings (Baldauf, M, et al., 2007) necessitate location information to satisfy the involvement of individuals from every surrounding. This paper reviews the diverse location identification techniques used to detect the location coordinates of moveable sensor devices. In this paper, the device that does not know its location coordinates are termed as ‘anonymous devices’.
During installation every sensor device is made available with its location information with the help of physical or involuntary configuration. Physical configuration involves a lot of physical work and is not encouraged for a colossal network, and installing a GPS receiver for every sensor device would surge the installation cost of the network. This engendered the sensor devices to detect its location without any affluent approaches, like using GPS receiver. Several location identification and ranging techniques such as lateration, angulation, Angle of Arrival (AoA) (Kuriakose, J, et al., 2014), (Peng, R., & Sichitiu, M. L., 2006), Time of Arrival (ToA) (Schau, H. C., & Robinson, A. Z., 1987), Time Difference of Arrival (TDoA) (Gustafsson, F., & Gunnarsson, F., 2003), Received Signal Strength Indicator (RSSI) (Luo, X, 2011), DV hop based location identification (Niculescu, D., & Nath, B., 2003), and proximity based location identification (Patwari, N., & Hero III, A. O., 2003) are used by the moveable sensor devices to detect its location coordinates.