Spreading code design for a MC-CDMA based GNSS pilot signal

Multicarrier CDMA (MC-CDMA) can represent an alternative to classical DS-CDMA for the design of GNSS ranging signals. A first requirement MC-CDMA signals must fulfill is that their generation on a satellite payload be feasible. It is well known, indeed, that multicarrier signals have a high Peak-to-Average Power-Ratio (PAPR) and GNSS signals, as well as other signals used in satellite communications, must have PAPR values much lower than values usually considered acceptable in other applications. Therefore, maintaining the PAPR of a MC-CDMA ranging signal within acceptable limits is a fundamental issue in any signal GNSS signal design using a multicarrier technique. The main contribution of this work is to propose a way of designing a MC-CDMA pilot signal based on Huffman codes. Such approach allows to shape the autocorrelation (or equivalently the power spectrum) of the pilot signal according to the specific needs of a GNSS service, guaranteeing arbitrary small PAPR values in all cases.