沈阳建筑大学毕业设计说明书毕业设计题目基于OFDM系统信道估计的设计与仿真学院专业班级信息与控制学院通信10-1班学生姓名范晓峰性别男指导教师王鑫职称讲师2014年6月9日1摘要正交频分复用(OFDM)是一项关于高速无线传输的十分有吸引力的技术。这项技术通过把整个频带分成许多并行传输的窄子频带的方法来把多径迟延效应降至最小。这项技术已经在数字声音广播、数字陆地电视广播、无线局域网和高速蜂窝数据通讯等方面提出或采纳。信道估计是无线通信传输领域的一项关键技术，直接影响无线通信传输系统的性能所谓信道估计，就是从接收数据中将假定的某个信道模型的模型参数估计出来的过程。通过信道估计，接收机可以得到信道的冲激响应，从而为后续的相干解调提供所需的CSI。在OFDM系统的相干检测中需要对信道进行估计，信道估计的精度将直接影响整个系统的性能。本文首先简单介绍了OFDM系统的基本原理，发展历史以及实际应用。随后讲述了无线通信的一般特性，着重分析了时延和多普勒频移对系统的影响。最后针对OFDM系统的信道估计这一关键技术，介绍了基于导频序列的信道响应的频域估计和时域估计的法。关键词：OFDM；信道估计；导频符号；接收机2AbstractOrthogonalFrequencyDivisionMultiplexing(OFDM)isaveryattractivetechnologyonhigh-speedwirelesstransmission.Thetechnologythroughthewholefrequencybandisdividedintomanynarrowsub-bandmethodbasedonparalleltransmissiontominimizetheeffectofmultipathdelay.Thetechnologyhasbeenproposedoradoptedinthedigitalvoicebroadcast,digitalterrestrialtelevisionbroadcast,high-speedwirelesslocalareanetwork(LAN),cellulardatacommunicationsandotheraspects.Channelestimationisakeytechniqueinthefieldofwirelesscommunicationtransmission,whichimpactontheperformanceofwirelesscommunicationtransmissionsystemdirectly.Theso-calledchannelestimationisassumedinthemodelreceivingdatafromachannelmodelparametersestimatedfromtheprocess.Throughthechannelestimation,thereceivercangetthechannelimpulseresponse,whichprovidetheCSIforsubsequentcoherentdemodulation.IncoherentdetectionofOFDMsystemsneedtochannelestimation,channelestimationaccuracywilldirectlyaffecttheperformanceofthewholesystem.First,thispaperintroducesthebasicprincipleofOFDMsystem,thedevelopmenthistoryandthepracticalapplication.Thenthepapertellsthegeneralcharacteristicsofwirelesscommunication,andthenanalyzesthetimedelayanddopplershifteffectofthesystem.Atlast,inviewofthekeytechnologyofchannelestimationinOFDMsystem,thepaperdescribesthefrequency-domainandtime-domainresponsewhichisestimatedbasedonchannelestimationpilotsequenceslaw.Keywords:OFDM；channelestimation；pilotsymbols；receiverI目录第一章绪论...............................................................11.1OFDM系统的发展历史....................................................21.2OFDM技术的优缺点......................................................21.3OFDM的应用............................................................31.4本文主要工作及章节安排.................................................4第二章OFDM系统的基本原理和参数选择.......................................62.1OFDM系统的调制和解调原理.............................................62.2保护间隔和循环前缀....................................................72.3本章小结..............................................................8第三章OFDM在无线信道中的传输.............................................93.1无线多径信道的分析....................................................93.1.1移动多径信道的参数.................................................103.1.2多径衰落类型..............................
