WLAN localization technique using trilateration

This thesis deals with the problem of estimating the position of a client (laptop or a computer) in a Wireless LAN (WLAN) Environment. Our method uses an infrastructure of Reference Points (RPs), whose positions are known, deployed in an area where the client's location is to be estimated. WLAN transmitters (SMTs), placed at the periphery of the WLAN environment, transmit messages (SMs) at multiple power levels into this environment such that each position corresponds to a unique set of messages. The client and the reference points report the received messages to a Localisation Centre (LC), which compares the messages reported by the client and those by each of the RPs to calculate the location of the client.

The effect of interference in WLAN environments is discussed in detail and various remedies are presented to deal with the interference. We have conducted experiments for different values of confidence levels to study the performance of our method. We observe that the proposed method determines the location of the client within 3-7.5 feet of its true location.