Rake接收中信号幅度估计算法及误差影响分析

Algorithm for signal amplitude estimation and error impact analysis in Rake reception

摘要:

对于受多径影响的扩频通信系统,通常采用Rake接收技术来提高系统传输的性能；多径合并是Rake接收技术研究的一个重要板块,其中最大比合并的性能最优；推导得出参与最大比合并的两路信号的权值归一化方差近似等于两路径信号幅度归一化方差之和；分析了幅度估计误差对信号信噪比恶化的影响,得出归一化幅度估计方差与信噪比恶化的关系公式；对典型的信号幅度估计算法进行分析,提出了一种基于辅助通道的幅度估计算法,可以在低信噪比且无数据辅助的情况下获得更好的性能；对于QPSK调制,两路信号信噪比分别为和,且,,的条件下,取观测长度为2048,采用基于辅助通道的幅度估计算法,实验结果表明,幅度估计误差导致的性能恶化小于0.01dB,达到了抑制多径干扰、提高通信系统性能的效果。

Abstract:

For the spread spectrum communication system affected by multipath, Rake receiving technology is usually adopted to improve the performance of the system transmission; Multipath merging is an important part of the research on Rake receiving technology, in which the maximum ratio merging has the best performance; It is deduced that the normalized variance of the weights of the two signals participating in the maximum ratio merger is approximately equal to the sum of the normalized variances of the amplitudes of the signals of the two paths; By analyzing the effect of the amplitude estimation error on the deterioration of the signal-to-noise ratio of the signals, the formula for the relationship between the variance of the normalized amplitude estimation and the deterioration of signal-to-noise ratio is derived; By analyzing typical amplitude estimation algorithms of the signals, an amplitude estimation algorithm based on the auxiliary channels is proposed to obtain better performance in the case of low signal-to-noise ratio and without data assistance to obtain better performance; For the QPSK modulation, the signal-to-noise ratios of the two signals are and and under the condition of , , , taking the observation length as 2048 and adopting the amplitude estimation algorithm based on the auxiliary channel; The experimental results show that the deterioration of the performance caused by the amplitude estimation error is less than 0.01dB, suppressing the multipath interference and improving the performance of the communication system.