Serial Multicode Direct Sequence Spread Spectrum With Applications to Satellite Navigation Pilot Channels

In this letter we introduce Serial Bicode and Serial Multicode Direct Sequence Spread Spectrum (DSSS) and we extend them to Code Division Multiple Access (CDMA). To each user are assigned two or more spreading codes. The information is associated to these codes, which are alternated within a single DSSS signal. The performance of the new techniques for incoherent demodulation is analyzed. Additionally, we present the application to the construction of data-less pilot channels for satellite navigation systems. Alternative codes can be used to embed a pattern or a message that, when recognized, allows to quickly solve time ambiguity and simplify initial synchronization for MEO and LEO scenarios.