【作者】 赵武生；

【导师】 付永庆；

【作者基本信息】 哈尔滨工程大学 ， 信号与信息处理， 2010， 博士

【摘要】 短波跳频通信系统在现代军事通信领域具有重要的地位和作用,是重要的抗干扰通信手段之一,也是目前西方军事强国重点研究的领域之一。随着现代高科技战争的发展需要,改善和提高短波跳频通信系统的性能对适应现代电子作战具有积极的意义,因此发展更高性能的短波跳频通信系统是重要的研究课题。本论文研究讨论了短波跳频通信系统的编码调制方案,即比特交织编码调制方案,以此来改善和提高短波跳频通信系统的性能。论文在研究短波信道的多径效应、信道衰落、多普勒效应等通信特性的基础上,构建基于比特交织编码调制及其迭代译码技术(BICM-ID)的短波跳频通信系统,分析了影响系统性能的因素,并围绕该通信系统在跳频同步、载波估计、信道估计均衡等关键技术上进行了深入的研究。在跳频同步问题上,基于BICM-ID-FH系统提出一种跳频同步方法。该方法分别将混沌序列和TOD信息序列作为密钥对跳频序列进行加密,从而将复杂系统的跳频序列同步问题转化为了系统的TOD信息序列的同步问题,同时也增强了跳频同步信息的抗截获性。关于BICM-ID-FH系统的载波估计问题,基于Turbo迭代的思想,提出一种系统的调制载波迭代频偏估计算法。该频偏估计算法初始采用Kay算法,迭代时采用L & R算法进行频偏估计,结合了Kay算法范围大和L & R算法精度高的优点,获得了较好的性能。采用该算法,设计了系统的载波迭代频偏估计校正方案。此外,设计了系统的相偏迭代估计校正方案。均衡问题是通信系统的重要问题。在BICM-ID-FH系统中,采用迭代思想对判决反馈均衡进行改进。在BICM-ID-FH系统的Turbo均衡结构中,采用信号的先验概率估计代替传统的假设信号概率均匀分布对SIC算法改进,获得均衡效果的改善。另外,提出MAP算法与SIC算法结合的联合算法。该算法在初始迭代采用MAP算法估计接收信号的先验概率分布以获得较精确的先验概率分布,迭代时采用SIC算法以方便计算和实现,仿真说明该算法有效地提升了系统的均衡效果。最后,探讨了关于短波信道估计的问题。在BICM-ID-FH系统中,基于迭代思想,设计了系统的半盲迭代信道估计均衡方案。该方案初始迭代时采用训练序列来估计信道信息,并结合Turbo均衡迭代过程,充分利用译码器的输出信息,实现了系统的信道估计均衡与译码的统一,仿真结果表明该方案具有良好的短波信道适应性。另外,设计了BICM-ID-FH系统的盲迭代信道估计均衡方案,仿真结果表明该方案在信道衰落不严重时具有收敛性。更多还原

【Abstract】 The High Frequency frequency-hopping communication systems have an important position and role in the modern military communications, and it is an important means of the communication interference, and one of the focus study areas currently in the Western military power. With the development needs of the modern high-tech warfare, it is positive significance to improve and enhance the performance of the HF frequency-hopping communication systems to adapt to the modern electronic warfare, so the development of the more high-performance HF frequency-hopping communication system is an important research topic. This dissertation discusses the coded modulation scheme of the HF frequency-hopping communication systems, called the bit-interleaved coded modulation scheme, to improve and enhance the performance of the HF frequency-hopping communication system.After studying the communication features of the high frequency channels, such as multi-path effects, channel fading, Doppler effects, etc, a frequency hopping communication system based on the bit-interleaved coded modulation and iterative decoding techniques (BICM-ID) is constructed over the high frequency channel. The factors that affect the performance have been analyzed in the system. It is focus on the key technologies in this system, such as the synchronization, carrier estimation, channel equalization, and channel estimation, which have been researched deeply.At the problem of synchronization, a frequency hopping synchronization method is proposed based on the BICM-ID-FH system. The chaotic sequence and the TOD sequence were used as the key to encrypt the frequency hopping sequence. Then the synchronization of the frequency hopping sequences in complexity system was transformed to the synchronization of the TOD sequence. So the anti-interception of the synchronous information was enhanced at the same time.About the estimation of carrier frequency, the carrier frequency offset iterative estimation algorithm is proposed based on the Turbo iteration theory in the BICM-ID-FH system. At the initial iteration of the algorithm, the Kay algorithm was used, and the L&R algorithm was used in the iterative process. So the algorithm has the advantages of the large scope and the high precision, obtained good performance. Using this algorithm, the scheme of the iterative estimation and correction carrier offset was designed in the system. In addition, the scheme of the iterative estimation and correction phase offset was designed in the system.The equalization is the very important problem in the communication systems. The Decision Feedback Equalization has been improved based on the iteration theory in the BICM-ID-FH system. In the Turbo equalization structure of the BICM-ID-FH system, the SIC equalization algorithm has been improved, by using the priori probability estimation of the received signal instead of the traditional assumption that the signal probability was uniformly distribution, which effectively improves the BER performance. Otherwise, a joint algorithm is proposed by combining the MAP algorithm and the SIC algorithm in the Turbo equalization scheme of the system. In the initial iteration of the algorithm, using MAP algorithm to estimate the prior probability distribution of the received signal, it is more accurate than using the SIC algorithm. The SIC algorithm was used in the iterative process, to facilitate the calculation and implementation. The simulation results show that the algorithm effectively improve the system equalizing.Finally, the problem of the channel estimation was discussed. The semi-blind iterative scheme of the channel estimation and equalization was designed based on the iterative theory in the BICM-ID-FH system. At the initial iteration of the scheme, the training sequences was used to estimate the channel information, and then combining with the Turbo equalization iterative process, and the output of the decoder was fully used to achieve the unification of the channel estimation, channel equalization and decoding. The simulation results show that the scheme has good adaptability for the high frequency channel. In addition, the blind iterative scheme of the channel estimation and equalization was designed and implemented in the BICM-ID-FH system, and the simulation results show that the scheme has a convergence when channel fading is not serious.更多还原