【作者】 葛永明；

【导师】 张凤元；

【作者基本信息】 北京化工大学 ， 计算机应用技术， 2007， 硕士

【摘要】 随着多媒体移动通信等新业务的发展,频谱资源日益紧张。人们持续增长的需求与有限频谱资源之间的矛盾成为研究高频谱利用率技术的动力和挑战。众多新技术中,基于多天线的多输入多输出无线通信结构已显示出无尽的潜力,成为充分利用空间资源的必然途径。它可以不需增加带宽和发射功率,大幅度地提高无线通信系统的信息容量和传输速率,从而提供远高于传统单天线系统的频带利用率。室内多输入多输出系统,即MIMO（Multiple-Input Multiple-Output）系统,如使用无指向性天线作为基站天线,由于存在大量墙壁散射,送信电力损失比较大。本文提出应用指向性天线作为室内MIMO系统的基站天线,从而改善系统的信道容量。通过EEM-RTM软件仿真与Matlab软件计算信道容量,接收端采用最小均方差算法,即MMSE（Minimum MeanSquare Error）算法,与最大似然检测算法,即MLD（Maximum LikelihoodDetection）算法,进行信号处理。计算结果表明指向性天线作为基站天线时,较之无指向性天线相比,系统信道容量能够得到很大提高,从而系统的性能得到改善。本文还进一步研究了如何通过合理地配置基站天线系数,改善系统的信道容量。仿真与计算结果表明在从四根终端天线中选择两根作为接收器的情况下,基站天线参数设置为波瓣角度差φ_B∶90°,方向系数φ_HP=60°时,系统信道容量最佳。此外,为了提高系统的通信性能,降低系统的成本,本文探讨了MIMO系统终端天线的选择方式,仿真结果表明依据最大信道容量选择接收天线时,使用多根终端天线并从中选择两根作为接收天线是最有效的。更多还原

【Abstract】 MIMO （Multiple-Input Multiple-Output） system attracts much attention and has been put into a practical use. It makes high-speed wireless communications possible by using plural antennas for each station without extending frequency bandwidth.As well know, the channel capacity is low using omni antennas as the base station antennas because of useless radiation. As to improve the channel capacity, this paper proposes that channel capacity of the indoor MIMO system can be improved using directional antennas rather than omni antennas. Using EEM-RTM software to simulate, Matlab software to calculate the channel capacity, and signal processing algorithms of terminal: MMSE（Minimum Mean Square Error） and MLD（Maximum Likelihood Detection） algorithms to process signal, the results prove that channel capacity of the indoor MIMO system can be improved using directional antennas rather than omni antennas. Moreover, the effects of directivity and beam direction of base station antennas on the system capacity are evaluated, it is proved that whenφ_B = 90°andφ_HP = 60°, we can achieve the maximum channel capacity. As to improve the performance of MIMO system and reduce the cost of system, this paper also discusses the way of selecting the terminal antennas with good characters. Selecting terminal antennas is according to the maximum channel capacity, it can be said that using two receivers with many terminal antennas is very effective.更多还原