【作者】 赵民建；

【导师】 仇佩亮；

【作者基本信息】 浙江大学 ， 通信与信息系统， 2003， 博士

【摘要】 随着无线通信技术和服务需求的飞速发展，无论在军用还是民用无线通信领域，各个系统的兼容性、可升级性、自适应性问题突出。针对这些问题，J. Mitola提出了的射频信号数字化、软件化处理的思想，即软件无线电技术，成为解决上述问题的有效途径。软件无线电思想经过几年的发展，目前研究者认为，不仅要对调制解调进行数字化、软件化处理，还需要从系统的角度来重新构建整个无线通信系统。一般来说，软件无线电系统应该具有很强的灵活性，通过软件的更新、加载可以增加新的功能、适应新的通信模式；同时具有很强的开放性和可扩展性，采用标准化、模块化软硬件体系结构。为了达到通用性、可升级性和兼容性的目的，软件无线电需要解决三类关键技术：第一，需要研究一个开放式、可扩展、标准化的软件、硬件平台结构。第二，需要研究实现适合于软件无线电系统的高性能射频、数字信号处理器件。第三，需要研究适合于软件无线电的多波段、多速率、多模式信号接收理论和实现方法。 尽管软件无线电技术受到了广泛关注，但深入而细致的研究工作并不多，特别是对上述第三个问题。本文基于作者在调制解调技术研究方面的积累，深入研究了多波段、多速率、多模式软件无线电接收技术，并结合软件无线电开放式、通用性软件、硬件系统结构的思想，提出和实现了一个多波段、多速率、多模式软件无线电的验证系统。 本文在阐述软件无线电的开放式、标准化软件结构和硬件平台，以及关键器件及其特性的基础上，针对多波段射频(或者高中频)信号数字化问题，深入分析了采样理论在软件无线电接收机中的应用，提出了实现多波段(全波段)采样的方法。从理论上分析了软件接收机以正交带通采样、一阶均匀带通采样、高阶采样等方法为基础，如何计算、选择合理的采样频率。 其次，研究了软件无线电系统中十分重要的多速率处理问题。多速率处理本质上就是采样率变换的实现问题。文中分析了整数倍、分数倍和NCO控制的正实数倍的采样率变换方法。从节省资源的角度出发，从理论上分析了一般化的采样率变换高效实现结构。同时把NCO控制的插值变换(从高速到低速)方法应用到软件无线电接收机中，阐明了其控制原理，指出了控制环路中内插滤器的实现方法。另外，结合多速率多相信号处理和NCO内插控制思想，分析了时变CIC内插滤波器的采样率变换实现。 再次，深入研究了软件无线电多模式接收实现问题。多模式调制解调是软件无线电的核心技术之一。本文在软件无线电通用硬件平台结构下，分析了线性调制方式、非线性连续相位调制方式和多载波调制的软件接收机实现问题，分别以突发模式MPSK调制、GMSK调制、OFDM调制模式为对象，给出了具体的多模式接收实现方法和仿真结果。深入研究了上述三种突发调制模式全软件接收的突发信号检测，载波频率、相位、定时误差估计，同步实现结构，以及同步跟踪方法、特点和性能。大多研究结果已在实际的演示系统上得到验证。该项工作的深入进行对软件无线电技术从理论模型走向实际应用具有重要的现实意义。 最后，结合前文对软件、硬件模型结构、带通采样技术、多模式接收方法的研究分析结果，和目前最新的信号处理器件水平，提出并实现了一个软件无线电实验硬件平台和软件系统构架。更多还原

【Abstract】 With wireless communication technologies progressing and communication services expanding, problems on compatibility, scalability, and adaptability of various communication systems are arising, either in civil or in military field. J. Mitola proposed Software Radio (or Software Defined Radio, SDR) technology to deal with those problems, i.e., digitizing waveforms as near as possible to RF, and modulating / demodulating signals by software. It is considered the most promising way to resolve the problems. After several years’ investigation, it is convinced that not only wireless modems should be implemented via software, but also the architecture of wireless systems should be reconstructed. Generally, software radio systems should be greatly flexible, and new communication modes can be provided by the system only through software update, or download. Furthermore, a software radio system is an open structured, standardized, modularized and extendable system. To achieve compatibility, scalability, and adaptability, the key technologies of software radio may be divided into three classes. Firstly, to construct an open, standardized and extendable hardware & software architecture. Secondly, to produce very powerful RF & DSP devices. Thirdly, to investigate multi-band, multi-rate, and multi-mode (MMM) signal processing methods and theories for software receivers.Though software radio technology is widely discussed, lucubrated and meticulous work on the subject is not so much, especially on the third point noted above. Based on much pre-work on modem technology, the author investigated the MMM technology for software receiver and build a SDR testbed.Firstly, with a description of open and standardized hardware & software architecture and RF/ADC/DSP devices, we discussed the bypass sampling theory and applied it in software radio receivers. Two multi-band (all band) sampling schemes are also proposed for software radio. Based on the quadrature sampling, uniform sampling and high order sampling techniques, we investigated how to compute and choose a reasonable sampling frequency.Secondly, another important technique, multi-rate signal processing for software receivers, is investigated. In fact, multi-rate processing is corresponding to sampling rate conversion. Sampling rate conversion methods of integral ratio, fractional ratio, and NCO controlled positive real ratio are investigated. In consideration of resource consuming, high efficient universal rate conversion structures are discussed. And sampling rate conversion with timing variable interpolator controlled by NCO (from high rate to low rate) is applied to software radio receivers. The controlling principle and implementation of interpolator are presented. Moreover, based on poly-phase signal processing and interpolation, a timing variable CIC (Cascaded- Integrator -Comb) filter based method for sampling rate conversion is analyzed.Thirdly, multi-mode signal receiving is investigated. Multi-mode demodulation is one of the essential techniques of software radio. Under the same restriction of a universal SDR hardwareplatform, the demodulation of linear modulated waveform, continuous phase (no-linear) modulated waveform, and multi-carrier modulated waveform, are investigated. Corresponding to those three modulation schemes, bust mode MPSK, OMSK, and OFDM signals are taken as the examples to implement a multi-mode SDR receiver, and results are presented. Most of the work is focused on frame detection, carrier and symbol timing offset estimation, and their implementation structures. Tracking loops and performances of three demodulation modes are also discussed respectively. Most of the work has been demonstrated on our self-built software radio, testbed.At last, based on the universal software & hardware architecture, COST devices, bypass sampling techniques, and multimode demodulation methods, a SDR testbed for software radio is described.更多还原