【作者】 陈娟；

【导师】 李平安；

【作者基本信息】 武汉理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 无线局域网是计算机网络技术和无线通信技术相结合的产物,是利用无续媒介传输信息的计算机网络。在无线通信信道中,由于多径时延不可避免地存在符号间干扰,正交频分复用(OFDM)作为一种可以有效对抗符号间干扰(ISI)和提高频谱利用率的高速传输技术,引起了广泛关注。在无线局域网(WLAN)系统中,OFDM调制技术已经被采用作为其物理层标准,并且公认为是下一代无线通信系统中的核心技术。基于IEEE802.11a的无线局域网标准的物理层采用了OFDM技术,能有效的对抗多径信道衰落,达到54Mbps的速度,而未来而的IEEE802.11n将达到100Mbps的高速。因此,研发以OFDM为核心的原型机研究非常有必要。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基带发射机系统的FPGA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一款160万门的Spartan-3E XCS1600E芯片,依照IEEE802.11a帧格式,对发射机系统各个模块进行了详细设计和仿真:(1)训练序列生成模块,包括长,短训练序列;(2)信令模块,包括卷积编码,交织,BPSK调制映射;(3)数据模块,包括加扰,卷积编码,删余,交织,BPSK/QPSK/16QAM/64QAM调制映射;(4)OFDM处理部分,包括导频插入,加循环前缀,IFFT处理;(5)对整个发射处理部分联调,并给出仿真结果另外,还完成了接收机部分模块的FPGA设计,并给出了相应的顶层结构与仿真波形。最后提出了改进和进一步开发的方向。更多还原

【Abstract】 Orthogonal Frequency Division Multiplexing (OFDM) has been widely regarded as an effective technique for increased spectral efficiency and for combating the detrimental effects of Inter-symbol interference (ISI) that inevitably occurs due to multipath propagation in wireless communication channels. OFDM has been applied to worldwide standards of WLAN and has been considered to be a promising technique for high data-rate wireless transmission in next-generation mobile communications. In this case, how to realize efficient OFDM system has been a very important issue.This thesis aims to explore the implementation of an OFDM baesband process targeted on its application in IEEE802.11a systems. A design and hardware implementation of the transmitter processor has been accomplished on Xilinx Sparten-3E field programmable gate array(FPGA) . The whole design is accompanied with the top-down strategy.The detailed design and simulation of the transmit functional models are as follows:(1) Training sequence generator module , including both long and short training sequence;(2) Signal symbol generator module , as well as convolutioner, interleaver, BPSK mapper;(3) Data symbol generator module,which contain scrambler, convolutioner, interleaver, BPSK/ QPSK/ 16QAM/ 64QAM mapper;(4) OFDM modulate module , including pilot insert module, cycle prefix added modlue and IFFT/FFT module;(5) Complete the joint-debug of transmitter module successfully;In addition, part of receiver modules have also been designed based on FPGA.更多还原