低密度奇偶校验码差分跳频系统的抗干扰性能

基于对无编码差分跳频系统抗干扰性能的研究，将低密度奇偶校验（LDPC）码引入差分跳频系统，研究了其对差分跳频系统抗部分频带干扰性能的改善。当系统有精确干扰状态信息时，针对不同的干扰因子对非规则LDPC码进行了优化，给出了码长趋于无穷大时的抗干扰渐近集合平均比特误码率，并对优化后的LDPC码与规则LDPC码的抗干扰性能进行了仿真。结果表明：当系统有精确干扰状态信息时，优化后的LDPC码差分跳频系统，相对于规则LDPC码差分跳频系统以及无编码差分跳频系统，在抗干扰性能上有明显改善。当系统无干扰状态信息时，提出一种迭代干扰状态估计及译码算法，其仿真结果表明：采用该算法可使编码系统在无精确干扰状态信息的情况下，仍具有极强的抗干扰能力。

Anti-jamming performance of low-density parity-check coded differential frequency hopping systems

Based on the anti-jamming performance study of uncoded differential frequency hopping(DFH)systems, this paper introduces low-density parity-check(LDPC)codes to the DFH systems and investigates the improvements against partial-band jamming.When exact jammer state information(JSI)is available, irregular LDPC codes are optimized with respect to different jamming factors.The cycle-free asymptotic ensemble average bit error rate(BER)is given and the anti-jamming performance of optimized LDPC codes and regular LDPC codes are simulated.Results show that when exact JSI is available, the anti-jamming performance of optimized LDPC coded DFH systems is obviously superior to that of the regular LDPC coded and uncoded DFH systems.When JSI is unavailable, a joint JSI estimation and decoding algorithm is proposed.Simulation results show that this algorithm provides robust anti-jamming performance even without JSI.