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RF technologies [13] are commonly used in location position systems because radio waves can penetrate through obstacles such as building walls and human bodies easily. Moreover, they also enable a larger coverage area than other techniques. Localization solutions in this category estimate the location of a mobile user in the environment by measuring one or more properties of an electromagnetic wave radiated by a transmitter and received by a device carried by the mobile user. These properties typically depend on the distance traveled by the signal and the characteristics of the surrounding environment. RF localization systems can be categorized according to the underlying hardware technology and network type used: (i) personal and local area networks, and (ii) broadcast and wide area networks.