AoA and TDoA hybrid solution for transmitter positioning

Accurate positioning has become an active research area in recent years. It has a wide range of applications in many fields such as navigation, asset tracking, health care, proximity marketing/location-based advertising, and sport analytics. Transmitter positioning via radio frequency (RF) signals is the most widely encountered scenario, and it uses a two-step process: first, parameters that depend on the location of the transmitter are extracted from the received signal. Second, the transmitter’s location is estimated by using these parameters. Many parameters can be used; for instance, time of arrival (TOA), time difference of arrival (TDOA), angle of arrival (AOA), and received signal strength (RSS). Localization can use one or multiple of such parameters. In this thesis, a hybrid AOA and TDOA method is studied. Specifically, an array of N co-linear receiving antennas are employed to estimate the transmitter position. In order to use AOA, existing research assumes that the transmitter is far away from the receiving antennas and that the spacing between the receiving antennas is very small (typically a fraction of one wavelength). This ensures that the directions of the incident waves to all receivers are parallel, so that there is a single AOA for all receivers. Such condition cannot be maintained for some scenarios (e.g., when wavelength is very large). Also, in order to use valid TDOAs, the receiving antennas cannot be placed very close to one another, which will result a unique AOA for each of the receiving antennas. This research develop solutions for the cases where the above constraints cannot be maintained. A maximum likelihood (ML) estimator is developed to obtain the AOA of each receiving antenna assuming that the antenna spacing must be sufficiently large. A cross correlation algorithm is used to determine the TDOA between the received signals. Finally, an algorithm that jointly processes the AOAs and the TDOAs to estimate the position of the transmitter is developed.

Major Advisor: Huaping Liu
Committee: Raviv Raich
Committee: Jinsub Kim
GCR: Thomas Schmidt