ADVANCED SIGNAL PROCESSING TECHNIQUES FOR GLOBAL NAVIGATION SATELLITE SYSTEMS RECEIVERS

A la iaia. This dissertation addresses the synchronization problem using an array of antennas in the gen-eral framework of Global Navigation Satellite Systems (GNSS) receivers. Positioning systems are based on time delay and frequency–shift estimation of the incoming signals in the receiver side, in order to compute the user’s location. Sources of accuracy degradation in satellite–based navigation systems are well–known, and their mitigation has deserved the attention of a number of researchers in latter times. While atmospheric–dependant sources (delays that depend on the ionosphere and troposphere conditions) can be greatly mitigated by differential systems external to the receiver’s operation, the multipath effect is location–dependant and remains as the most important cause of accuracy degradation in time delay estimation, and consequently in position estimation, becoming a signal processing challenge. Traditional approaches to time delay estimation are often embodied in a communication systems framework. Indeed, in DS–CDMA systems many techniques are driven to minimize the probability of error in the symbol detection by taking advantage of several incoming replica