【作者】 张天放；

【导师】 胡爱群；

【作者基本信息】 东南大学 ， 信号与信息处理， 2005， 硕士

【摘要】 IEEE802旗下的无线网络协议引领了无线网络领域的新革命,其不断提升的速度优势满足了人们对于高速无线接入的迫切要求,在这其中,OFDM技术所起的作用不可小觑。随着FPGA、信号处理和通信技术的发展,OFDM的应用得到了长足的进步。在此情况下,以OFDM技术为核心实现数据传输的原型机系统显得应情应景而且必要。本课题在深入理解OFDM技术的同时,结合相应的EDA工具对系统进行建模并基于IEEE802.11a物理层标准给出了一种OFDM基带传输的系统实现方案。整个设计采用目前主流的自顶向下的设计方法,由总体设计至详细设计逐步细化。在系统功能模块的FPGA实现过程中,针对Xilinx Virtex-II芯片对各个模块进行了详细设计,通过采用双端口RAM、流水、乒乓结构等处理实现高速的同步的信道编码的功能模块;通过比较符号定时的不同算法,给出了基于MultiplierlessCorrelator的实现结构并给出了仿真波形图,验证了采用该算法后符号定时模块的资源耗费大大降低而功能却依然和基于乘法器的符号定时模块相当;通过对Viterbi算法进行简化,给出了(2,1,6)卷积码的4比特软判决Viterbi解码器的设计和实现。最后根据系统所选芯片XC2V3000给出了具有较高配置灵活性的基于System ACE配置方案的FPGA的硬件原理图设计和PCB设计。本文首先以无线局域网和IEEE802无线网络家族引出OFDM技术发展、研究价值及OFDM的优缺点,接下来从OFDM原理入手,简要说明了OFDM的基本要素以及目前的研究热点,之后在介绍完IEEE802.11a物理层标准的同时给出了本原型机系统的总体设计方案,并从硬件语言设计和FPGA硬件原理设计两方面给出了该系统的详细设计。随着OFDM技术的普及以及未来通信技术对OFDM的青睐,相信本论文的工作对OFDM基带传输系统的原型设计和实现具有一定的参考价值。更多还原

【Abstract】 OFDM (Orthogonal Frequency Division Multiplexing) technology, due to its longersymbol duration which is resistant to multipath e?ects, has been widely used in many ad-vanced digital communication systems such as IEEE802 wireless family, which has broughthuge impacts and great convenients on human’s life and now reaches or is capable of reach-ing virtually every location on the face of the earth. In this case, how to realize e?cientOFDM system has been a very important issue for either academic or industrial fields.Meanwhile, the development of the VLSI and EDA has also made the implementation ofthe OFDM system become possible and feasible.In this thesis, a prototype design for the Physical Layer of IEEE 802.11a standard,which is based on OFDM technique, is presented. Implementation aspects of parts of thefunctional modules of the OFDM system on Xilinx Virtex-II field programmable gate array(FPGA) are addressed. The whole design is accompanied with the top-down strategy, whichhas been the proposed“solution”in FPGA design.The design ?ow starts with ?oating-point modeling with parameters specified by IEEE802.11a for the physical layer. After that, the designs of function models including scram-bler, convolutioner, interleaver, symbol mapper, and pilot insertion are given, which aremainly implemented through ping-pong architecture, Dual-Port RAM and pipelining. Con-sequently, di?erent symbol timing schemes are examined and as the result of the comparison,a modified algorithm based on the multiplierless correlation of received long preamble sym-bols is selected for hardware implementation. Furthermore, the (2,1,6) 4-bit soft-decisionViterbi decoder for QPSK is discussed according to the IEEE802.11a standard. Finally,the hardware scheme and PCB of the FPGA kernel board based on System ACE strategyis given, which makes the FPGA configuration more ?exible.As the OFDM technology becomes more and more widely applied and prevalent, thisthesis demonstrates good reference value in some extent.更多还原