Design and Performance Assessment of a Time-Varying Channel Simulator for High-Mobility Satellite Navigation Scenarios

With the development of high-mobility satellite navigation systems such as LEO satellite navigation enhancement system, the ability of traditional fixed channel models to simulate channel characteristics has been widely challenged. This work focuses on the background theory, time-varying emulator design, and performance assessment application for the necessity of a channel simulator to enable the propagation modeling from LEO satellite to mobile receiver in the high-mobility satellite navigation scenario. The concept of satellite Doppler effect, separation of satellite Doppler shift, and local Doppler shift are discussed in this work, along with the sampling criteria for time-varying channel modeling. The time-varying simulator based on the model of the time-varying satellite navigation channel is provided, and it is used to assess the tracking loop performance of the navigation software receiver. The results show that the rapidly updating time-varying channel will subject the receiver to severe fluctuations and may possibly result in the tracking loop losing lock. In general, the rapidly time-varying channel scenario is more challenging to track and produce stable output than the general multipath channel scenario.