天基测控通信系统中CPM信号低复杂度解调及同步技术研究

发布时间：2019-04-08 13:16

【摘要】：连续相位调制(CPM)是一种高功率和带宽利用率的先进调制方式,与网格编码调制(TCM)相类似,发射信号中引入的记忆效应可以提高功率利用率,而不同符号之间的平滑效应可以提高带宽利用率。除此之外,CPM信号恒包络的特点还可以进一步提高非线性功率放大器的效率。CPM信号的诸多优良特性使得其非常适合发射功率和信道带宽都受限的天基测控系统。随着天基测控技术的快速发展,各种CPM信号不断被引入各类标准,然而解调复杂度高、同步获取难等问题却一直制约其得到广泛应用。本文对天基测控系统中CPM信号低复杂度的传输技术进行了深入研究,主要研究内容包括分析不同场景下最佳CPM信号设计,低复杂度解调和同步技术三方面内容。取得的主要研究成果如下:1.总结了CPM信号在各类测控标准及数据链中的应用现状;归纳了CPM信号低复杂度解调和同步技术的研究现状,分析了各类算法的优势和缺陷,为后续分析打下了基础。2.研究了CPM信号的常见数学表示方式,分析了不同参数对CPM信号带宽和功率效率的影响;对比了CPM信号和常规线性调制信号在卫星非线性信道的差异,得出了CPM信号在天基测控通信中具有突出的优势和巨大的应用潜力。3.通过分析和仿真得出了高速测控通信链路场景下最佳CPM信号体制;根据SOQPSK-A信号特点,在有无信道编码的情况下分别提出、改进了几种低复杂度解调算法,相比传统算法在保证解调性能的同时显著降低了实现复杂度。4.通过改进有记忆信道容量的计算方法,得出了多址测控通信场景下信道容量的计算方法;利用简化因子图的方法,提出了一种低复杂度的干扰抑制检测算法,该算法在有限性能损失的情况下可以极大降低实现复杂度;通过非线性相位恢复的方法,利用单脉冲检测器,设计了一种低复杂度的解调器,很好的规避了多址测控场景下临道干扰的问题。5.针对高速测控和多址测控场景,分别提出了基于反馈环路的同步算法和基于导频的同步方法,并分别给出了两种同步方法的性能仿真结果。
[Abstract]:Continuous phase modulation (CPM) is an advanced modulation method with high power and bandwidth utilization, which is similar to trellis coded modulation (TCM). The memory effect introduced in the transmitted signal can improve the power utilization ratio. The smoothing effect between different symbols can improve the bandwidth utilization. In addition, the constant envelope of the CPM signal can further improve the efficiency of the nonlinear power amplifier. Many excellent characteristics of the CPM signal make it very suitable for space-based measurement and control system with limited transmission power and channel bandwidth. With the rapid development of space-based measurement and control technology, a variety of CPM signals have been introduced into various standards. However, the high complexity of demodulation and the difficulty of synchronous acquisition have always restricted its wide application. In this paper, the low complexity transmission technology of CPM signal in space-based measurement and control system is deeply studied. The main contents include analyzing the best design of CPM signal in different scenarios, low complexity demodulation and synchronization technology. The main results obtained are as follows: 1. This paper summarizes the application status of CPM signal in all kinds of measurement and control standards and data link, summarizes the research status of low complexity demodulation and synchronization technology of CPM signal, analyzes the advantages and disadvantages of various algorithms, and lays a foundation for the follow-up analysis. 2. The common mathematical representation of CPM signal is studied, and the influence of different parameters on the bandwidth and power efficiency of CPM signal is analyzed. The difference between CPM signal and conventional linear modulation signal in satellite nonlinear channel is compared. It is concluded that CPM signal has outstanding advantages and huge application potential in space-based TT & C communication. Based on the analysis and simulation, the optimal CPM signal system in the high-speed TT & C communication link scenario is obtained. According to the characteristics of SOQPSK-A signal, several low-complexity demodulation algorithms are proposed in the presence or absence of channel coding. Compared with the traditional algorithms, the implementation complexity is reduced significantly while ensuring the demodulation performance. 4. By improving the calculation method of the channel capacity with memory, the calculation method of the channel capacity in the multi-access measurement and control communication scenario is obtained. In this paper, a low complexity interference suppression detection algorithm is proposed by using the simplified factor graph method. The algorithm can greatly reduce the implementation complexity in the case of limited performance loss. By using the method of nonlinear phase recovery, a low complexity demodulator is designed by using monopulse detector, which avoids the problem of near channel interference in multiple access measurement and control scenario. 5. The synchronization algorithm based on feedback loop and the synchronization method based on pilot are proposed for high-speed measurement and control and multi-access measurement and control scenarios, and the performance simulation results of the two synchronization methods are given respectively.
【学位授予单位】：国防科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN911.3

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