Adaptive Narrow-Band Interference Suppression and Performance Evaluation Based on Code-Aided in GNSS Inter-Satellite Links

In this paper an adaptive narrow-band interference (NBI) suppression scheme based on a code-aided technique in the global navigation satellite system inter-satellite links (ISLs) is proposed. Unlike the commonly used infinte impulse response (IIR) notch filter and frequency domain filtering, the code-aided technique does not require interference detection or fast Fourier transforms, and the adaptive performance is better. We introduce the principle and implementation of code-aided technique, and the concept of interference influence coefficient is proposed to evaluate the influence of residual interference on the carrier-to-noise ratio (CNR) at the receiving end. Through simulation and by combining the tracking CNR after antijamming, the optimal antijamming parameters and scheme are obtained. Meanwhile, we analyze the relationship between the loss of CNR caused by residual interference and the interference influence coefficient. The final results of the bit error rate (BER) and ranging error in ISLs indicate that the adaptive interference suppression scheme based on the code-aided technique can effectively suppress NBI and ensure the reliability of ISL communications. In the case where the pseudo code rate is 10.23 MHz and the BER does not exceed $1 \times {10^{ - 5}}$ , for the NBI with a bandwidth of 2 MHz, the maximum interference-to-signal ratio (ISR) that can be suppressed by the proposed scheme is 40 dB. For the NBI with a bandwidth of 1 MHz, the maximum ISR that can be suppressed is 55 dB, and for single frequency interference, the maximum ISR that can be suppressed is 75 dB.