OFDM在短波通信中的应用研究
发布时间：2019-01-11 11:04
【摘要】：短波通信在现代通信中一直占据着重要地位,是远距离无线通信的重要手段之一,其通信的速率和效率长期以来都是广受人们关注的问题。但是,由于受到其带宽较小和信道复杂多变的限制,尽管出现了各种各样的新型调制和传输技术,短波通信速率提高的问题仍然没有从根本上得到改变。OFDM是一种新型的多载波调制技术,它可以有效地利用有限的频段,在提高频谱利用率的同时增加系统的信息传输速率;它同时也大大降低了系统对均衡的要求。OFDM的出现促进了各种通信技术的发展,也使短波通信面临新的机遇和挑战。将OFDM应用于短波通信,可以减少带宽对短波通信速率的限制、降低多径等信道特性对系统的影响、提高信息的传输速率。因此,OFDM在短波通信中的应用具有相当大的吸引力。本文主要对使用大规模数字信号处理器实现短波OFDM基带部分的理论和方法进行研究。文中首先简要介绍了短波OFDM通信系统的研究背景、研究短波OFDM系统的理论与实践\,重点分析了短波OFDM系统主要的技术细节,包括短波信道模型的构建、发射机/接收机/射频部分的实现等。随后,通过理论与仿真相接合的方式,重点分析了短波OFDM系统实现过程中的两个关键技术:同步技术和峰平比消减技术。在同步技术方面,针对分组检测判决变量大小不确定的问题,我们对延时相关算法进行了部分改进;同时,通过完全的时域方法完成OFDM符号检测和频率误差估计,降低了实现的复杂度。在峰平比消减方面,我们对几种常用的方法进行了比较,并采用便于实现的削波滤波方法对其效果进行了仿真说明。最后,重点介绍了短波OFDM基带部分的DSP实现细节。从短波信道的参数设定开始,我们逐步分析了短波OFDM基带部分实现过程中需要考虑的纠错编码、IFFT/FFT的实现、同步方法和削波滤波方法等的具体实现过程,并对它们的性能进行了仿真。
[Abstract]:Shortwave communication has been playing an important role in modern communication and is one of the important means of long-distance wireless communication. The rate and efficiency of HF communication have long been concerned by people. However, due to its small bandwidth and complex channel constraints, despite the emergence of a variety of new modulation and transmission technologies, OFDM is a new type of multi-carrier modulation technology, which can effectively utilize limited frequency band and increase the rate of information transmission while improving the efficiency of spectrum. The emergence of OFDM promotes the development of various communication technologies and makes shortwave communication face new opportunities and challenges. The application of OFDM in shortwave communication can reduce the limitation of bandwidth on the rate of shortwave communication, reduce the influence of channel characteristics such as multipath on the system, and improve the transmission rate of information. Therefore, the application of OFDM in HF communication has considerable attraction. In this paper, the theory and method of using large-scale digital signal processor to realize the base band of short-wave OFDM are studied. This paper first introduces the research background of shortwave OFDM communication system, studies the theory and practice of shortwave OFDM system, and analyzes the main technical details of shortwave OFDM system, including the construction of shortwave channel model. Implementation of transmitter / receiver / RF part etc. Then, through the combination of theory and simulation, two key technologies in the implementation of shortwave OFDM system are analyzed: synchronization technology and peak-to-average ratio reduction technology. In the aspect of synchronization, we partially improve the delay correlation algorithm for the uncertain size of decision variables in packet detection. At the same time, the OFDM symbol detection and frequency error estimation are completed by using a complete time domain method, which reduces the complexity of the implementation. In the aspect of peak-to-average ratio reduction, several common methods are compared, and the simulation results are illustrated by using the easily realized clipping filtering method. At last, the implementation of DSP in the base band of short wave OFDM is introduced in detail. Starting with the parameter setting of shortwave channel, we analyze the realization process of error correction coding, IFFT/FFT realization, synchronization method and clipping filtering method, which need to be considered in the realization of HF OFDM baseband. Their performance is simulated.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN925
[Abstract]:Shortwave communication has been playing an important role in modern communication and is one of the important means of long-distance wireless communication. The rate and efficiency of HF communication have long been concerned by people. However, due to its small bandwidth and complex channel constraints, despite the emergence of a variety of new modulation and transmission technologies, OFDM is a new type of multi-carrier modulation technology, which can effectively utilize limited frequency band and increase the rate of information transmission while improving the efficiency of spectrum. The emergence of OFDM promotes the development of various communication technologies and makes shortwave communication face new opportunities and challenges. The application of OFDM in shortwave communication can reduce the limitation of bandwidth on the rate of shortwave communication, reduce the influence of channel characteristics such as multipath on the system, and improve the transmission rate of information. Therefore, the application of OFDM in HF communication has considerable attraction. In this paper, the theory and method of using large-scale digital signal processor to realize the base band of short-wave OFDM are studied. This paper first introduces the research background of shortwave OFDM communication system, studies the theory and practice of shortwave OFDM system, and analyzes the main technical details of shortwave OFDM system, including the construction of shortwave channel model. Implementation of transmitter / receiver / RF part etc. Then, through the combination of theory and simulation, two key technologies in the implementation of shortwave OFDM system are analyzed: synchronization technology and peak-to-average ratio reduction technology. In the aspect of synchronization, we partially improve the delay correlation algorithm for the uncertain size of decision variables in packet detection. At the same time, the OFDM symbol detection and frequency error estimation are completed by using a complete time domain method, which reduces the complexity of the implementation. In the aspect of peak-to-average ratio reduction, several common methods are compared, and the simulation results are illustrated by using the easily realized clipping filtering method. At last, the implementation of DSP in the base band of short wave OFDM is introduced in detail. Starting with the parameter setting of shortwave channel, we analyze the realization process of error correction coding, IFFT/FFT realization, synchronization method and clipping filtering method, which need to be considered in the realization of HF OFDM baseband. Their performance is simulated.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN925
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