导　　师： 余小游

学科专业： 0810

授予学位： 硕士

作　　者： ;

机构地区： 湖南大学

摘　　要： 正交频分复用/(OFDM/)技术是一种多载波调制技术,它具有频谱利用率高、抗多径干扰能力强等优点,已经被数字音频广播系统/(DAB/)、地面数字视频广播系统/(DVB-T/)、无线局域网/(IEEE802.11/)、无线城域网/(IEEE802.16/)、3GPP LTE等国际标准采用。OFDM技术容易与分集技术、智能天线技术以及空时编码技术等相结合,以进一步提高信息传输的可靠性,OFDM技术已被公认为下一代无线移动通信系统的关键技术之一 OFDM系统优势明显,但面临的问题也很突出,同步、高峰均功率比和信道估计是严重限制OFDM系统应用的关键问题,高峰均功率比抑制一般在数字中频部分实现,而同步和信道估计等关键技术都在数字基带部分实现。本文主要研究OFDM基带系统关键技术及其基于System Generator的FPGA设计与实现。 论文的主要工作包括以下几个方面： 首先,建立了适合于高层综合的OFDM系统框架模型,用于关键技术的理论仿真研究和FPGA的设计与实现研究。 其次,对基于循环前缀的最大似然时频联合估计算法、基于训练序列的时频同步算法进行了同步性能分析和仿真研究,结果表明基于训练序列的时频同步算法更适合于突发OFDM系统；对最小平方/(LS/)和最小均方误差/(MMSE/)信道估计算法性能进行了比较分析和仿真研究,实验结果表明MMSE算法较LS算法性能更好,但算法实现复杂度较高。 然后,建立了基于System Generator的OFDM基带发射机高层综合模型,该模型采用支持BPSK、QPSK、16QAM和64QAM等多种映射模式的数字调制方案,并提供外部配置接口以满足下一代无线移动通信系统对多工作模式的需求。建立了基于System Generator的OFDM基带接收机高层综合模型,采用了改进的基于训练序列定时同步算法设计方案,在不影响定时同步精度的情况下能较大程度地减小硬件实现的复杂度。 最后,基� Orthogonal Frequency Division Multiplexing/(OFDM/) is a special multi-carrier modulation technology, and because of its high spectrum efficiency and good performance in resisting to multipath interference, it has been widely adopted in many wireless communication systems, such as Digital Audio Broadcasting System/(DAB/), Terrestrial Digital Video Broadcasting System/(DVB-T/), WLAN/(IEEE802.11/), WMAN/(IEEE802.16/),3GPP LTE and so on. OFDM can be easily put into application to further improve the reliability of transmission system combined with some other new-emerging technology, such as diversity techniques, smart antenna technology, space-time coding techniques and so on. OFDM has been recognized as one of the key technologies for the next generation of wireless communication systems. The advantage of OFDM system is obvious, but it also faces some serious problems. Synchronization, high peak to average power ratio and channel estimation are the key issues which are limiting OFDM'application very badly. High peak to average power ratio reducing should be implemented in Intermediate Frequency part of OFDM system, and synchronization system and channel estimator should be implemented in digital baseband system. In this paper, the research on the key technologies of OFDM system and the FPGA design of OFDM baseband system based on System Generator is introduced. The main work of this thesis is as following: First of all, a framework of high level synthesizable OFDM system model is designed, and the model can be used for research on key technologies of OFDM and the FPGA design of OFDM baseband system. Secondly, analysis and simulation result of synchronization performance on the joint time-frequency synchronization algorithm based on cyclic prefix with the maximum likelihood method and synchronization algorithm based on training sequence are given, and the result shows that the synchronization algorithm based on training sequence is better than that based on cyclic prefix when they are applied to burst

关 键 词： 正交频分复用 同步 信道估计 现场可编程逻辑门阵列

领　　域： [电子电信] [电子电信]