OFDM下多音干扰技术.doc

摘 要 正交频分复用技术(OFDM)利用相互正交的多个子载波束传送信息，具有高的频谱利用率和良好的抗多径干扰能力，已被应用于数字音频广播、高清晰度电视和无线局域网等方面，并且被看作是第四代移动通信的核心技术之一。介绍了OFDM 的基本原理并在分析了这一技术的优缺点后。 基于对OFDM信号产生和信道中频谱规律的分析，选择一种干扰方式在小功率情况下对OFDM信号进行强有力的影响，主要针对军通方面的应用，在战争期间对敌方使用OFDM进行通信的原信号进行干扰。系统论述了多音信号的产生、在OFDM系统下加入多音信号的原理以及此多音信号对OFDM系统的干扰效果。通过仿真证明了理论分析的正确性，并可根据仿真结果进一步应用于实践中。 本文的创新点在于，在OFDM系统中给出了一种行之有效的干扰方式——多音干扰，并且理论分析和仿真了多音干扰相比于三种传统干扰(部分频带干扰、宽带干扰和脉冲干扰)方式，在OFDM系统中具有高效性的特点，即在相同干扰功率的情况下使OFDM系统产生最大的误码率。 关键词：正交频分复用；OFDM；多音干扰；IFFT；FFT ABSTRACT OFDM transmits informationthrough orthogonal multiple subcarriers．It has high spectrum utilization and good capability to prevent from multipath interference． It has beenused in digital voice broadcast, HDTV and W LAN and is regarded as one of the core technologies in 4G mobile communication system.Basic principles of OFDM are introduced．And then analysis the advantages and disadvantages of this technology． Based on the OFDM signal generation and channel spectrum analysis of the law，the OFDM signal is given a strong interference by selecting a small disturbance in power，mainly for military applications during the war to the enemy who using OFDM to communicate to interfere the original signal．Discussing the principle of multi—tone signals generated in the OFDM system by adding multi—tone signals to OFDM system，as well as interference effects of the multi-tone signals on the OFDM system．The simulation proves the correctness of theoretical analysis and it is applied to practice based on the results of simulation further． The innovation of this article is to give an effective way of interference-the multitone interference in the OFDM system，and theoretical analysis and simulation of a multi-tone interference with the characteristics of high-performance contrast to three traditional interfering ways which are broadband interference，some of the band interference and pulse interference，that is the same as interference in the power in the OFDM system so that having the maximum error rate． Key Words：o