高码率64QAM调制器的研究

【作者】 唐棣；

【导师】 敬守钊；

【作者基本信息】 电子科技大学 ， 电路与系统， 2008， 硕士

【摘要】 90年代以来,随着电信传输技术的不断发展,同步数字系列(SDH)成为新一代数字传输体制。目前,在数字微波传输网中SDH逐步取代了原来所使用的准同步数字系列(PDH)。SDH体制具有传输容量大、组网灵活、长途传输质量高等优点,因而其应用日益广泛。SDH的广泛应用对基带信号的处理方式、纠错编码在数字微波系统中的应用以及高效率的数字微波调制技术等都提出了新的要求。在调制解调方面,随着中、大容量数字微波通信系统的快速发展,系统的数据传输速率要求越来越高,频谱资源的紧张程度也在不断加剧。传统的移幅键控(ASK)、移相键控(PSK)和移频键控(FSK)这三种数字调制解调方式因其较低的频谱利用率,已经很难满足需要了。M进制正交振幅调制与解调(MQAM)作为一种高效的频谱利用方式,成为了目前国内外研究的热点。在基带信号的处理方面,MQAM调制的基带信号需要经过扰码、串/并转换、差分编码和星座图映射等处理。在纠错编、译码的处理方面,MQAM调制要求纠错码具有相位透明性。LEE氏纠错码具有相位透明性和较低冗余度,在MQAM调制系统中应用较多。本文完成了一个64QAM调制系统的完整设计,包括基带处理部分、差错控制部分和正交调制部分,并通过仿真测试。基带信号的数据速率为75Mbps。纠错码采用能纠单个LEE氏错误的一种LEE氏码——8进制(84,81)SLEC码。基带信号的处理和纠错编码处理采用了FPGA实现。同时,本系统还完全兼容QPSK调制方式以及MQAM(M=8,16,32,…,1024)调制方式。本文还提出了一种易于实现的MQAM调制系统的构造;一种新型的能够克服亚稳态发生的异步FIFO的实现方法;一种新型的适合于FPGA实现的LEE氏纠错编码的硬件实现方法。下面是本文的内容安排:第一章:绪论,介绍了无线通信的发展概况及发展趋势。阐明了本课题的研究意义以及本文的主要工作内容。第二章:无线调制传输方式研究。研究了无线通信中常用的数字调制方式及解调的实现方式,其中包括BPSK调制、QPSK调制、MSK调制、FSK调制和QAM调制等。第三章:基带信号处理的研究。介绍了QAM调制所需的基带信号处理的内容和方法。包括扰码、差分编码和LEE氏纠错码的原理和实现方法。第四章:64QAM调制器方案设计。详细介绍了本课题64QAM调制器的实现方案。将整个系统划分为几个模块,分别介绍其实现方法,并给出仿真数据。第五章:64QAM调制器的电路实现及实验结果。第六章:全文总结。全面总结了本文所完成的工作及意义。更多还原

【Abstract】 Since 90’, with the continuous development of telecommunication transmission technology, synchronous digital series has been gradually becomes the new digital transmission system. Now, SDH has gradually taken place of the quasi-synchronous digital series (PDH) used in old days in digital microwave transmission network. SDH is characteristic with large transmission capacity, network agility, long-haul transmission and high quality. Therefore, it is widely used. The wide application put forward the new demands of handling style, error-correcting codes used in digital microwave system and high-efficiency modulation technique in digital microwave system.In modulation and demodulation area, with the fast development of medium and large capacity digital microwave communication system, the requirement of data transmission rate in a system is higher and higher, also, the intense degree of spectrum resources is much stronger. The three traditional digital modulation and demodulation types, amplitude-shift keying (ASK), frequency-shift keying (PSK) and phase-shift keying (FSK), became hardly satisfied the needs any more, for its low spectrum efficiency. M-ary quadrature amplitude modulation and demodulation (MQAM) became the study focus internationally, as well as nationally.In baseband processing area,base-band signal of MQAM modulation need scrambling code, serial-parallel conversion, differential encoding and constellation mapping processing, etc.In error-correcting encoding and decoding area, MQAM modulation requires error-correcting has the characteristic of phase transparency. LEE error-correcting is both of phase transparency and lower redundancy, used in MQAM modulation system a lot.This article contains a whole design of 64QAM,including the part of baseband processing, error control and quadrature modulation, and passed the simulation test. The data rate of base-band is 75Mbps. error correcting code adopts a LEE error-correcting, which is capable of correcting one of the single LEE error that is 8-ary code (84, 81) SLEC code. The handling of base-band signal and error-correcting encoding has been implicated by FPGA. At the same time, this system is fully compatible of QPSK modulation form and MQAM (M=8,16,32,…,1024) modulation form.This article mentioned an easy realization structure of MQAM modulation system; a new realization method of asynchronous FIFO which is capable of overcoming metastable stateto occur; also a new realization method of LEE error-correcting encoding adapting to FPGA.Below is the arrangement of this paper:Chapter One: Introduction. Introducing the development situation and trend of wireless communication and clarifying the significance of the research subject, as well as the main idea of the paper.Chapter Two: Research of wireless modulation transmission mode. Studying the most used digital modulation types in wireless communication, including PSK modulation, QPSK modulation, MSK modulation, FSK modulation and QAM modulation, etc.Chapter Three: Research of base-band signal processing. Introducing the content and method of base-band signal processing required by QAM modulation; including of the theory and realization method of scrambling code, differential encoding and LEE error-correcting encoding.Chapter Four: Design of 64QAM modulator plan. That is writing specifically the realization plan of the 64QAM modulator. Divides the whole system into a few modules; introduced each realization method, and give the simulation data.Chapter Five: The circuit application and test result of 64QAMmodulator.Chapter Six: Summarize. That is summarizing the whole work and significance in this paper.更多还原