OTFS-Based Communication and Navigation Integrated Signal Transmission for LEO Satellites

To get higher utilization efficiency of spectrum and orbits in low earth orbit (LEO) satellite system, satellite communication and navigation integration has become a search hotspot recently. Because orthogonal time frequency space (OTFS) modulation can reduce the effect of time-frequency doubly selective channels between the LEO satellite and earth, an OTFS-based communication and navigation integrated scheme is studied in this paper. First, a hybrid modulation constellation by superimposing quadrature amplitude modulation (QAM) and dual-code alternating binary offset carrier (AltBOC) modulation is proposed to realize signal integration of two systems. Second, a serial interference cancellation (SIC) detector is designed to separate two signals. In addition, a direct path time delay estimator based on pseudo-range code measurement is designed. What's more, the BER performance of the integrated signal is derived. Simulation results demonstrates that the proposed scheme has the lower BER and the higher localization accuracy than the baseline method under a LEO scenario with doubly selective channel.