Collaborative Code Tracking of Composite GNSS Signals

Modern and modernized global navigation satellite system (GNSS) signals exhibit significant structural innovations such as the use of two channels, namely the data and pilot components, which separately carry the navigation message and ranging information. These innovations have stimulated the development of new techniques that fully exploit the potential of these new signals. This paper analyses two different strategies, noncoherent and coherent channel combining, that enable collaborative tracking of the data and pilot components, thus circumventing the drawback of having the available power split between two channels. Traditional single channel discriminators are modified in order to accommodate the data/pilot structure and the different combining strategies. The performance of each algorithm is analyzed in terms of tracking jitter and a new characterization, based on the sign error rate (SER), is proposed for evaluating the coherent channel combining with sign recovery. This characterization, supported by simulations, is, to the best of the authors´ knowledge, new and represents one of the main contributions of this paper.