知识与财富的链接
在高速移动环境下,基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的长期演进(longterm evolution,LTE)移动通信系统受信道快速时变引起的多普勒频偏影响,产生子载波间干扰(inter-carrier-interfer-ence,ICI),严重破坏系统性能。ICI成为LTE技术在高速移动场景下应用的一个难点。在分析多普勒频偏及ICI成因的基础上,总结国内外通过编码自消除、均衡、迭代判决反馈消除、时域快变信道估计等方法消除高速移动引起的OFDM系统ICI的主要方法,分析并指出现有方法存在的问题。在此基础上,介绍了最新提出的OFDM频域快变信道估计的思想。报道了LTE上、下行链路正交频分多址接入系统中相关问题的研究情况,并对后续的研究工作提出了展望。
Under highly mobile environments,the performance of long term evolution (LTE) based on orthogonal frequency division multiplexing (OFDM) can be destroyed by inter-carrier-interference (ICI) caused by the time varying channels''Doppler shifts. ICI is a difficult point of LTE in highly mobile environments. The cause of Doppler shifts and ICI are introduced firstly. ICI mitigation techniques of OFDM over highly mobile environments are reviewed such as data encoding self ICI cancellation,equalization techniques,iterative interference cancellation and time domain time-varying channel estimation etc. Existing problems of such methods are analyzed and the new proposed frequency domain time-varying channel estimation is introduced. Finally,related work for LTE uplink/downlink systems were reported and directions for following research is pointed out.