【作者】 李雪松；

【导师】 廉保旺；

【作者基本信息】 西北工业大学 ， 通信与信息系统， 2003， 硕士

【摘要】 正交频分复用(OFDM)技术是当前移动通信领域的一项关键技术，OFDM技术具有很强的抗符号间干扰、抗多径衰落能力，适合在无线信道中传输高速的数据业务，因而倍受关注。OFDM采用了正交多载波技术，频谱利用率很高，目前已被应用于无线局域网、数字音频广播(DAB)、数字视频广播(DVB)系统中，并且有望成为第四代移动通信系统的核心技术。 本文首先研究了OFDM理论，重点分析了在频率选择性衰落信道中OFDM技术解决码间干扰问题的原理，以及如何用基于DFT和IDFT的技术实现OFDM系统。并介绍了基于OFDM的无线局域网标准IEEE802.11a的物理层相关OFDM参数和其基带IFFT实现原理，结合具体的分组结构，给出了其符号定时、载波频率偏移估计和信道估计方法。本论文在MATLAB平台上对OFDM系统进行了仿真，研究了编码，调制映射和信道对OFDM系统的影响。在论文的最后提出了一种基于小波变换的新的OFDM调制方法(W-OFDM)，并且将其与DFT-OFDM进行了仿真比较，取得了一些有意义的仿真结果，对OFDM技术的研究有一定的参考价值。更多还原

【Abstract】 Orthogonal Frequency Division Multiplexing is one of key technologies in mobile communication fields. It is suitable for high rate data transmission in wireless channels because it can combat Inter-Symbol interference and multi-path fading efficiently. Now it has become an attractive technology. OFDM is a multiple carriers technology, supports high rate data transmission with high spectrum efficiency. At present, OFDM technology has been used in many fields, such as wireless local network, digital audio broadcasting (DAB), digital video broadcasting (DVB) systems and so on. It is very promising to be a core technology of the fourth generation mobile communications.In this thesis, we first discuss the basic theory of OFDM, and analyze why OFDM can effectively resolve the FSF and ISI, and how to realize the DFT-based OFDM system. And it is given for the new OFDM based wireless LAN standard IEEE 802. lla. Based on its packet structure, mathematical methods for OFDM symbol timing, carrier Frequency offset and channel estimation are proposed in this paper. In this thesis, we simulate OFDM system in MATLAB platform and analyze the relationship between FER, mapping, channel and OFDM system performance. At the last part we gives a new wavelet transform based OFDM and used to compare with the DFT-OFDM under the same conditions. The results are referential to the research of OFDM technology.更多还原