基于镜像映射的载波间干扰自消除机制  

Mirror-Mapping-Based ICI Self-Cancellation Schemes

作　　者：段俊奇[1] 刘磊[1] 王兆伟[1] 刘志鹏[1] 

机构地区：[1]中国电子科学研究院,北京100041

出　　处：《中国电子科学研究院学报》2017年第2期137-142,共6页Journal of China Academy of Electronics and Information Technology

摘　　要：正交频分复用(OFDM)对于某些非理想因素十分敏感,例如接收机前端的载波频率偏移(CFO)以及同相/正交(IQ)不平衡等,这些因素会导致子载波的正交性损失和载波间干扰(ICI)问题。采用相邻或对称映射的ICI自消除机制是一种应对ICI问题的常见方法。然而,虽然该机制可以有效减少由CFO引起的ICI问题,但仍然不能保证在IQ不平衡条件下获得令人满意的系统性能。为了解决上述问题,本文提出了一种新的采用镜像映射的ICI自消除方法。基于提出的方法,我们通过采用两种被广泛应用的映射操作和一种额外的相位旋转操作,推导获取了三种不同的镜像映射机制。理论分析和仿真结果验证了本文提出的镜像映射方案,该方案不仅继承了现有ICI自消除机制的效率,抑制了由CFO引起的ICI,还具备减少甚至消除IQ不平衡影响的能力。Orthogonal Frequency Division Multiplexing （OFDM） is sensitive to non-idealities such as carrier frequency offset （CFO） and in-phase/quadrature （IQ） imbalance at the receiver front end, which result in loss of subcarriers orthogonality and inter-carrier interference （ICI）. As a simple ICI countermeasure, ICI self-cancellation methods, which originally apply adjacent or symmetric mapping, are effective in reducing ICI caused by CFO, yet still cannot guarantee a satisfactory performance in the presence of IQ imbalance. To solve this problem, in this paper a novel type of ICI self-cancellation method using mirror mapping is proposed to combat both impairments, namely, CFO and IQ imbalance. Based on the proposed method, we altogether derive three different mirror mapping schemes by adopting two widely used mapping operations and an additional phase rotation. Analyses and simulation results verify that the proposed mirror mapping schemes not only inherit the efficiency of the existing ICI self-cancellation schemes in suppressing ICI caused by CFO, but also have the ability of compressing or even eliminating IQ imbalance effect.

关 键 词：载波间干扰 自消除 镜像映射 载波频率偏移 IQ不平衡 

分 类 号：TN929.5[电子电信—通信与信息系统]