基于频率子集的相干快跳频通信系统关键技术研究

发布时间：2017-12-27 04:18

本文关键词：基于频率子集的相干快跳频通信系统关键技术研究　出处：《电子科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：快跳频(Fast Frequency Hopping,FFH)是指在每个调制码元时间内存在多个宽间隔的频率跳变的技术。作为无线通信的主流技术,快跳频通信因其在抗干扰、抗多径衰落、抗侦察截获等方面具有的优势,从一诞生就得到了大量应用。正是快跳频的上述特性,导致其难以实现信道估计。非相干的FFH系统由于不需要信道估计,实现简单,在FFH系统中得到了广泛的应用,但是由于其存在非相干合并损失,频谱效率低且拓展性有限等局限,因此就迫切需要把相干的调制解调技术应用到快跳频系统中。本论文重点研究了基于频率子集的相干快跳频(Subset Based Coherent Fast Frequency Hopping,S-CFFH)通信系统的关键技术,主要包括:S-CFFH系统的方案设计和帧格式设计,无干扰环境下的接收处理技术,干扰环境下的抗干扰合并技术和干扰抑制技术。论文主要工作体现在以下几个部分:首先,给出了S-CFFH的系统方案设计。S-CFFH实现了快跳频系统中的信道估计,在保留FFH系统抗干扰和抗截获能力的同时提高了系统的频谱效率,大大增加了系统的可拓展性。其次,研究了无干扰环境下S-CFFH系统的接收处理技术,包括信道估计、插值算法和相干合并,并仿真分析了上述不同算法在AWGN信道、单径瑞利衰落信道、典型郊区信道和典型丘陵信道下的性能。仿真结果表明,S-CFFH/QPSK系统相对于FFH/4FSK系统在误码率(Bit Error Ratio,BER)和频谱效率两方面都展现出了显著的优势。再次,研究了S-CFFH系统的抗干扰合并技术。在理论分析的基础上,仿真分析了S-CFFH系统在AWGN信道和典型郊区瑞利衰落信道中,在部分频带噪声干扰和多音干扰环境下的理想信道估计和非理想信道估计ML(Maximum Likelihood)抗干扰合并性能。仿真结果表明,无论理想信道估计还是非理想信道估计,ML合并均优于MRC(Maximum Ratio Combining)的抗干扰性能。最后,研究了S-CFFH系统中的干扰抑制技术。重点分析了基于分组检测的脉冲干扰抑制技术和基于最大似然的频域干扰抑制技术,并进行了仿真验证。仿真结果表明,这两种干扰抑制技术能够有效地抑制脉冲干扰、多音干扰(Multitone Jamming,MTJ)和部分频带噪声干扰(Partial band noise jamming,PBNJ)。在有编码情况下,干扰抑制的两种方法中,ML限幅的性能优于置零的性能,同时相比于ML的抗干扰合并技术,S-CFFH系统的干扰抑制技术在不提升复杂度的同时,大大提升了其抗干扰性能。
[Abstract]:Fast frequency hopping (Fast Frequency Hopping, FFH) refers to the technique of frequency hopping at a number of wide intervals in each modulation symbol time. As the mainstream technology of wireless communication, fast frequency hopping communication has been widely applied in many fields, such as anti-jamming, anti multipath fading, anti reconnaissance and interception. It is the above characteristics of fast frequency hopping, which makes it difficult to realize channel estimation. Non coherent FFH system without channel estimation, simple implementation, has been widely used in the FFH system, but because of the existence of non coherent spectrum with loss, low efficiency and development limited, so there is an urgent need to apply to the coherent demodulation technology of fast frequency hopping system. This paper focuses on the study of coherent fast frequency hopping based on frequency subset (Subset Based Coherent Fast Frequency Hopping, S-CFFH) key technology, communication system mainly includes: the design and frame format of S-CFFH system, without receiving technology under interference environment, anti-jamming technology and combined with interference suppression technology environment. The main work of this paper is embodied in the following parts: first, the system scheme design of S-CFFH is given. S-CFFH implements channel estimation in fast frequency hopping system, while retaining the ability of FFH system to resist interference and intercept. Meanwhile, it improves the spectrum efficiency of the system, and greatly increases the expansibility of the system. Secondly, on the receiving and processing technology of S-CFFH system without interference environment, including channel estimation, interpolation algorithm and coherent combination, and simulation analysis of the different algorithms in the AWGN channel, the performance of single path Rayleigh channel, channel and typical hilly suburbs typical fading channel. The simulation results show that the S-CFFH/QPSK system shows significant advantages over the FFH/4FSK system in the two aspects of the bit error rate (Bit Error Ratio, BER) and spectrum efficiency. Thirdly, the anti-jamming technology of S-CFFH system is studied. Based on the theoretical analysis, the performance of the S-CFFH system in the AWGN channel and the typical suburban Rayleigh fading channel under the partial band noise and multi tone jamming environment is simulated and analyzed, and the performance of the ideal channel estimation and the imperfect channel estimation ML (Maximum Likelihood) is analyzed. The simulation results show that both the ideal channel estimation and the non ideal channel estimation are better than the MRC (Maximum Ratio Combining) anti-interference performance of the ML. Finally, the interference suppression technology in the S-CFFH system is studied. The pulse jamming suppression technology based on packet detection and the frequency domain interference suppression technology based on maximum likelihood are emphatically analyzed, and the simulation verification is carried out. The simulation results show that these two kinds of interference suppression technologies can effectively suppress pulse jamming, Multitone Jamming (MTJ) and partial band noise Partial band noise jamming. In the two ways of interference suppression with coding, the performance of ML limiter is better than that of zeroing. Meanwhile, compared with the ML's anti-jamming merging technology, the interference suppression technology of S-CFFH system greatly improves its anti-jamming performance without enhancing the complexity.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN914.41

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