A Hybrid TDoA-ToA Localization Method

One of the main advantages when comparing time over signal strength localization methods, is that the former do not require the creation of fingerprint databases. On the other hand, the majority of time based methods require some sort of clock synchronization due to the drifting of the local clocks. This paper presents an innovative time-based localization method which utilizes the information provided by 802.11 Beacon packet data. The advantage of this method over other time based methods is that the Mobile Terminal (MT) does not require to establish a connection to an Access Point (AP), or to send and receive packets as other time based methods do. Also, the proposed method does not require any clock synchronization. The method works by analyzing Beacon timestamp and MAC timestamp. By using Beacon Interval, Beacon timestamp and Service Set Identifier (SSID) of a packet, it has been made possible to optimally process the collected MAC timestamps to provide a hybrid TDoA-ToA localization method with an average error of less than 2.5 meters.