一种用于自适应跳频的卫星通信信道质量评估方法

A Channel Quality Evaluation Method for Adaptive Frequency Hopping Satellite Communication

摘要:

针对现有自适应跳频卫星通信信道质量评估方法的不足,提出了一种基于虚拟解调的评估方法；该方法核心在于对实际接收跳频信号功率进行估计,以精确构建可能受到干扰影响的虚拟接收信号；其中,虚拟接收信号由实时采集的信道噪声和可能存在的干扰,以及由接收机按不同编码调制方案生成且与实际接收信号功率大小几乎相同的虚拟测试信号混合而成；通过对虚拟解调结果的连续统计得到信道质量评估结果,以指示各个频段和接收机适用的编码调制方案；为实现干扰环境下信号功率的精确估计,采用引入平滑处理的改进FCME算法估计噪声功率,并通过前向排序、加权补偿的方法实现信号与噪声总功率快速估计,进而完成实际接收信号功率估计；仿真结果表明,在不同干扰带宽占比和干扰与噪声功率谱比值的条件下,归一化信号功率估计偏差小于±0.2 dB；估计偏差通常小于实际跳频信号在单次调整周期内的自然波动,可满足虚拟接收信号构建的精度要求。

Abstract:

To address the limitations of existing channel quality evaluation (CQE) methods for adaptive frequency hopping satellite communication, a CQE method based on virtual demodulation is proposed, with emphasis on the actual received signal power estimation for construction of virtual received signal with the disturbance of possibly existing interference; Specifically, the virtual received signal is designed to be the mixture of noise and possibly existing interference from the satellite channel, and the virtual test signal generated by the receiver with candidate modulation and coding schemes (ModCod), with its power closely matched to that of the actual received signal; The CQE results are obtained by continuous statistics on the virtual demodulation results to indicate which ModCod is suitable for each frequency band and each receiver; To achieve precise estimation of signal power, an improved FCME algorithm with smoothing processing is adopted to estimate noise power. Meanwhile, the total power of signal and noise is rapidly estimated through a forward-sorting and weighted-compensation method, from which the actual received signal power is obtained; Simulation results show that, under different interference bandwidth ratios and interference-to-noise power spectral density ratios, the normalized signal power estimation deviation is less than ±0.2 dB; The estimation deviation is generally less than the natural fluctuation of actual signal within a single adjustment period, meeting the accuracy requirements for virtual received signal construction.