A Novel Multipath Estimation and Tracking Algorithm for Urban GNSS Navigation Applications

It is recognized that multipath remains as a dominant source of ranging error in CDMA and Global Navigation Satellite Systems (GNSS) positioning. Given the limitations of the traditional multipath code delay estimation techniques, this work considers another class of code tracking algorithm wherein the GNSS receive endeavors to characterize the propagation channel by estimating the relative delay of LOS signal and each individual reflection. Within this class there are two kinds of algorithm, those which require a-priori knowledge of the channel, and those which do not. Without a-priori information, the receiver must perform a full multipath estimation procedure, a process which can be computationally expensive. When provided with an initial estimate of the multipath channel, however, the receiver need only incur a small computational overhead to track changes in the channel. In this work, both of these cases are considered and a receiver design is proposed which adaptively alternates between full channel characterization and recursive channel refinement, depending on the severity of the variations of the channel to provide a robust and efficient multipath mitigating GNSS receiver.