TRaVarSeL-Transmission Range Variation based Secure Localization

Location based services (LBS) enable the wireless network operators to provide specific services to wireless users, based on their current locations. In a wireless network, users can connect from various physical locations, but their current location information is required to enable LBSs. Several localization schemes have been proposed earlier to estimate the location of a wireless user. However these schemes assume that none of the users in the system is malicious which might not always be true. This chapter presents a Secure Localiza-tion Algorithm (SLA) that can be implemented on current 802.11 infrastructure based wireless networks without the need for any additional specialized hardware. The scheme is based on the transmission of unique messages at different power levels from the access points. The user device receives a certain set of messages which it will have to transmit back to the access point. The location of the user device can be estimated securely based on this set of messages. We have investigated the properties of SLA using simulations.