Abstract: With the rapid development of LEO satellite constellations, LEO navigation augmentation has become a research hotspot in the field of satellite navigation. LEO navigation augmentation adopts the "satellite-based monitoring + signal augmentation" system, LEO navigation satellites need to broadcast LEO navigation augmentation signals to the ground while receiving GNSS signals. LEO navigation augmentation signals are usually broadcast in the GNSS frequency band, so the LEO navigation augmentation signal broadcast to the ground is a strong self-interference signal with respect to the received signal, and how to eliminate the effect of the self-interference signal on the received signal is the key to realizing the simultaneous transceiver in the same frequency band. The self-interference cancellation scenario and method of LEO navigation augmentation are studied, and the performance evaluation method applicable to LEO navigation augmentation self-interference cancellation is proposed for the characteristics of LEO navigation augmentation signals, which uses the correlation power difference of the interfering signals before and after self-interference cancellation to characterize the self-interference cancellation capability. The signal power value after interference cancellation is obtained through the correlation power difference, and the equivalent carrier-to-noise ratio loss and the code tracking error evaluation method under the influence of residual self-interference are derived to evaluate the influence of residual self-interference signal on the expected signal reception. A typical navigation signal BPSK(2) and BOC(1,1) are used for simulation verification, and the results show that when the interference-to-noise ratio is 30dB, the self-interference cancellation ability of the existing method is 30.98dB and 33.04dB, and the self-interference cancellation ability of the proposed method is 58.80dB and 58.96dB. Through comparative verification, it can be concluded that the proposed self-interference cancellation performance evaluation method outperforms existing methods. It provides a more accurate assessment of the self-interference cancellation capability in LEO navigation augmentation, serving as a performance evaluation reference for self-interference cancellation methods in this context.

Key words: self-interference cancellation, correlation power, signal to noise ratio, code tracking error, evaluation method