Design and Reception Method of Code Shift Keying Signals With Power-of-Two Phase Intervals

Precise point positioning (PPP) technology has garnered extensive attention for its ability to deliver real-time centimetre-level accuracy services. When providing PPP services via satellite navigation signals, it is necessary to increase the data rate to over 1000 bps. Code shift keying (CSK) technology has emerged as a key candidate for satellite-based PPP signal design. It can increase the data rate without requiring additional frequency resources and compromising ranging performance. However, CSK technology faces several challenges. Firstly, it is vulnerable to multipath interference, which can lead to intersymbol interference. Secondly, the complexity of demodulation increases exponentially with an increase in the number of bits per symbol. In this paper, a novel approach for the design and reception of CSK signals with a phase interval mapping of power-of-two chips is proposed. Analyses demonstrate that this method is capable of significantly reducing the demodulation complexity while mitigating the intersymbol interference. The CSK (6, 2) modulation with a phase interval mapping of 128 chips is employed for the BDS PPP-B2b signal. The signal is demodulated using the FFT with a phase interval output of 128 points. The computation can be reduced by approximately 85%, compared to the continuous phase mapping CSK signal demodulated by partial-output FFT.