Code-Assisted Broadband Jamming Suppression in Multi-Satellite Collaborative Secure Communication

Internet of Remote Things (IoRT), functioning as a supplementary element to terrestrial mobile Internet of Things (IoT) networks, significantly enhances communication for user devices in remote areas with the support of Low-Earth Orbit (LEO) satellites, providing considerable convenience. However, the open nature of satellite-to-ground channels and the predictability of satellite orbits make LEO satellite communications vulnerable to disruptive broadband malicious jamming from external sources. To address this challenge, we propose a broadband jamming suppression methodology that leverages the spatial diversity characteristics of multiple satellites. Moreover, in conditions of unequal power of desired and jamming signals, we derive the theoretical combined Signal-to-Jamming-plus-Noise-Ratio (SJNR). To achieve the maximum combined SJNR, we propose a code-assisted iterative parameter estimation algorithm that is tailored for multi-satellite operations. This algorithm employs Log-Likelihood Ratio (LLR) information feedback from the decoder to refine the estimation of combining weight coefficients, thereby boosting the broadband jamming suppression capacity of the IoRT system. Simulation results demonstrate that Maximum Ratio Combination (MRC) based on the proposed algorithm exhibits minimal combined SJNR loss and outperforms the classical time/frequency-domain anti-jamming algorithm based on Selective Combination (SC), Equal Gain Combination (EGC), and SC itself in Bit Error Rate (BER) performance.