MIL-STD-188-110C高阶QAM信号解调关键技术研究

发布时间：2018-06-08 11:02

本文选题：短波通信标准 + 高阶QAM信号　；参考：《解放军信息工程大学》2014年硕士论文

【摘要】：正交幅度调制(Quadrature Amplitude Modulation,QAM)由于具有高频谱利用率,在高速短波通信中的应用日渐广泛。2011年公布的MIL-STD-188-110C协议首次将高阶QAM引入美军短波通信标准中,对非合作接收端的解调技术提出了更高的要求。本文研究了MIL-STD-188-110C协议高阶QAM信号的盲解调关键技术,包括盲均衡、盲定时同步以及盲载波同步技术。论文工作为作者所在实验室承担的某大型工程项目的一部分。论文的主要工作和创新点可概括如下:1、分析了110C协议信号和短波信道的特点,结合实际条件和任务规划明确了本文课题背景下协议高阶QAM信号解调的关键技术步骤。2、在盲均衡方面,首先针对协议信号星座的特点,给出了一种适用于圆形星座高阶QAM信号的基于区域判决的符号间隔混合多模盲均衡算法,通过改进区域划分方式,构造新的误差函数及引入数据重用技术,降低了稳态误差,减少了收敛所需符号个数。然后针对符号间隔均衡器在多径深衰落信道下性能恶化的问题,将分数间隔预测判决反馈均衡结构与误差判决双模式多模算法相结合,给出了一种收敛性能稳健的盲均衡算法,有效实现多径深衰落信道下的协议高阶QAM信号盲均衡。3、在协议高阶QAM信号盲定时同步方面,针对基于最大似然的定时误差估计算法在短波信道下性能不佳的问题,研究了基于循环统计量的定时误差估计算法,在此基础上结合实际情况与载波同步相结合,给出了适用于频率选择性衰落信道的基于高阶循环累积量的定时与载波同步参数联合估计算法,实现了信号的定时误差、载波频偏及相偏的联合盲估计。仿真实验表明,在低信噪比和恶劣短波信道下,所提算法对协议高阶QAM信号相较于二阶循环统计量定时误差估计算法具有更低的均方误差,相较于遍历搜索循环频率估计频偏的算法提高了频偏估计精度,且对相位误差具有良好的估计性能。4、在协议高阶QAM信号盲载波同步方面,针对实际短波通信环境,将时变频偏列入考虑范围,给出了一种基于二次相位函数的载波同步参数联合估计算法,将多普勒频率变化率、频偏和相偏进行联合估计,较传统频偏估计算法更适用于时变频偏环境;在反馈结构算法方面,给出了多状态自适应扩展卡尔曼滤波载波同步算法,通过分析滤波器环路带宽的动态特性,细化滤波器的工作状态,相较于现有同类算法提高了频偏捕获速度,扩大了捕获范围,增强了对时变频偏的跟踪能力。最后将所提卡尔曼同步算法与盲均衡算法相结合,实现了多径衰落信道下盲均衡与载波同步的联合结构,增强了算法的实用性。
[Abstract]:Quadrature Amplitude Modulation QAM (Quadrature Amplitude Modulation) has been widely used in high speed HF communication due to its high spectral efficiency. MIL-STD-188-110C protocol published in 2011 first introduced high-order QAM into the U.S.Army shortwave communication standard. A higher demand is put forward for the demodulation technology of the non-cooperative receiver. In this paper, the key techniques of high order QAM signal demodulation based on MIL-STD-188-110C protocol are studied, including blind equalization, blind timing synchronization and blind carrier synchronization. The work of the thesis is part of a large project undertaken by the author in the laboratory. The main work and innovation of this paper can be summarized as follows: 1. The characteristics of 110C protocol signal and shortwave channel are analyzed. Combined with practical conditions and task planning, the key technical steps of high order QAM signal demodulation under the background of this thesis are defined. In blind equalization, firstly, the characteristics of protocol signal constellation are pointed out. This paper presents a region decision based mixed multimode blind equalization algorithm for high order QAM signals of circular constellations. By improving the region division, constructing a new error function and introducing data reuse techniques, the steady-state error is reduced. The number of symbols required for convergence is reduced. Then, aiming at the problem of the performance deterioration of symbol interval equalizer in multipath deep fading channel, a robust blind equalization algorithm with convergence performance is proposed by combining the fractional interval predictive decision feedback equalization structure with the error decision double mode multimode equalization algorithm. Blind equalization of high order QAM signals in multipath deep fading channels is realized effectively. In the aspect of blind timing synchronization of high order QAM signals, the performance of timing error estimation algorithm based on maximum likelihood is poor in short wave channels. In this paper, the timing error estimation algorithm based on cyclic statistics is studied. Based on this algorithm, the carrier synchronization is combined with the actual situation. A joint estimation algorithm of timing and carrier synchronization parameters based on high order cyclic cumulants is proposed for frequency selective fading channels. The joint blind estimation of timing error carrier frequency offset and phase offset is realized. Simulation results show that the proposed algorithm has lower mean square error than the second order cyclic statistic timing error estimation algorithm for high order QAM signals in low SNR and bad HF channels. Compared with the ergodic search algorithm for frequency offset estimation, the frequency offset estimation accuracy is improved, and the phase error is estimated. 4. In the aspect of blind carrier synchronization of high order QAM signals, we aim at the actual shortwave communication environment. A joint estimation algorithm of carrier synchronization parameters based on quadratic phase function is presented, in which Doppler frequency change rate, frequency offset and phase offset are jointly estimated. Compared with the traditional frequency offset estimation algorithm, it is more suitable for time-conversion bias environment. In the aspect of feedback structure algorithm, a multi-state adaptive extended Kalman filter carrier synchronization algorithm is presented, and the dynamic characteristics of the filter loop bandwidth are analyzed. Compared with the existing algorithms, the filter can improve the frequency offset acquisition speed, enlarge the acquisition range, and enhance the tracking ability of time-conversion offset. Finally, the proposed Kalman synchronization algorithm is combined with the blind equalization algorithm to realize the joint structure of blind equalization and carrier synchronization in multipath fading channels, which enhances the practicability of the algorithm.
【学位授予单位】：解放军信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.3

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