基于软件无线电的DQPSK调制解调算法研究与实现

【作者】 王晨；

【导师】 潘建国；

【作者基本信息】 上海师范大学 ， 工程硕士（专业学位）， 2019， 硕士

【摘要】 软件无线电技术是近年来伴随着移动通信和微电子发展起来的新技术,它的主要思想是构建一个灵活、开放、模块化的硬件平台,在这个硬件平台上用软件来实现数字通信系统中各个模块的功能。软件无线电作为一种指导思想和发展方向,在如今的移动通信领域大放异彩。FPGA就是软件无线电技术中发展较快的一种。数字调制解调技术在高速数据通信中起着至关重要的作用,而DQPSK因其频带利用率高和抗干扰能力强的特点,广泛应用于现代通信系统中。因此,用FPGA来实现DQPSK调制解调具有重要意义。本课题对DQPSK调制解调算法在FPGA的实现进行了较为全面的研究,实现了DQPSK全数字调制解调,输入信号码速为1Mbps,调制器与解调器的设计都分别达到了预期要求。论文首先介绍了软件无线电和数字调制解调技术的发展及研究现状,分析了FPGA在数字频带通信中的应用前景。深入研究了DQPSK调制解调的相关理论,为具体电路设计提供了坚实的理论基础。其中,调制部分由码型变换器、成型滤波器、NCO、相乘器等模块组成,解调部分由极性Costas环、位同步环、码型变换等模块组成。本文重点对差分编解码、极性Costas环、位同步环进行了深入的原理分析,详细介绍了各模块的FPGA设计与仿真过程和结果。在MATLAB建模仿真验证设计正确性的基础上,利用Altera公司的Quartus II平台,用Verilog HDL语言实现了DQPSK调制解调算法中的各个模块功能设计,并用ModelSim进行功能仿真,分析仿真波形以验证算法的正确性。文中还对极性Costas环的跟踪策略做了进一步调整,使之在环路收敛后的频差抖动减小,提高解调性能。最后在DQPSK调制解调系统中集成信道校验算法用以提高系统的传输性能,对Hamming编译码进行了FPGA设计与实现。更多还原

【Abstract】 Software radio technology is a new technology that has been developed along with mobile communication and microelectronics in recent years.Its main idea is to build a flexible,open and modular hardware platform on which software is used to implement the function of each module in various digital communication systems.As a guiding ideology and development direction,software radio is used a lot in the field of mobile communications nowadays.FPGA is one of the fastest developing software radio technologies.Digital modulation and demodulation technology plays a vital role in high-speed data communication,and DQPSK is widely used in modern communication systems due to its high frequency band utilization and strong anti-interference ability.Therefore,it is important to implement DQPSK modulation and demodulation with FPGA.This topic has carried out a comprehensive research on DQPSK modulation and demodulation algorithm in FPGA implementation,realized DQPSK full digital modulation and demodulation,the input signal code rate is 1Mbps,the modulator and demodulator design have reached the expected requirements.The paper first introduces the development and research status of software radio and digital modulation and demodulation technology,and analyzes the application prospect of FPGA in digital frequency band communication.In-depth study of the relevant theory of DQPSK modulation and demodulation provides a solid theoretical basis for specific circuit design.The modulation part is composed of a module such as a code converter,a shaping filter,an NCO and a multiplier,and the demodulation part is composed of a module such as a polar Costas loop,a bit synchronization loop,and a code converter.This paper focuses on the in-depth principle analysis of differential codec,polar Costas loop and bit synchronization loop,and introduces the FPGA design and simulation process and results of each module in detail.Based on the correctness of MATLAB modeling and verification design,using the Quartus II platform of Altera Corporation,the function design of each module in DQPSK modulation and demodulation algorithm is realized by Verilog HDL language.The function simulation is performed by ModelSim,and the simulation waveform is analyzed to verify the correctness of the algorithm.The tracking strategy of the polar Costas loop is further adjusted to reduce the frequency jitter after loop convergence and improve the demodulation performance.Finally,the channel check function is integrated in the DQPSK modulation and demodulation algorithm to improve the transmission performance of the system.The FPGA design and implementation of Hamming coding code are also carried out.更多还原