Novel LDPC Code-Aided Modified CME-Based Anti-Jamming Strategy

Direct sequence spread spectrum (DSSS) system is extensively utilized in modern satellite communication systems owing to its inherent anti-interception and anti-jamming capabilities. However, the anti-jamming performance of the system is constrained by its spreading ration. While a larger spreading ration increases the jamming margin, it also leads to an expansion in signal bandwidth, thereby resulting in reduced communication efficiency and wastage of spectrum resources. The consecutive mean excision (CME) algorithm shows the potential to enhance the system's resistance to jamming for a fixed spreading ratio. Nonetheless, it is limited in effectively addressing residual burst errors in the channel. In this paper, an LDPC code-aided anti-jamming strategy based on modified CME is proposed. By introducing overlap windowing and overlap addition operations, the CME algorithm is optimized to achieve jamming detection and suppression in the frequency domain. Moreover, the logarithmic likelihood ratio (LLR) of the despread signal is modified, along with decoding based on the belief propagation (BP) algorithm to further improve the error-correcting capability of the DSSS system. Simulation results compared with the traditional algorithm demonstrate that the proposed method has significantly improved communication performance against narrowband jamming.