在光DD-OFDM背靠背和传输系统中研究IQ不平衡  

IQ Imbalance in Optical DD-OFDM Back-to-back and Transmission Systems

作　　者：李欣颖[1] 侯春宁[1] 张俊文[1] 方武良[1] 黄博[1] 邹书敏[1] 邵宇丰[1] 迟楠[1] 

机构地区：[1]复旦大学通信科学与工程系专用集成电路与系统国家重点实验室,上海200433

出　　处：《光电工程》2010年第3期66-71,共6页Opto-Electronic Engineering

基　　金：国家973资助项目(2010CB328300);国家自然科学基金资助项目(600837004;600777010);国家863资助项目(2009AA01Z253;2007AA01Z260);曙光学者基金资助项目;中国博士后科学基金资助(20090460593);上海市博士后基金资助(10R21411600);北京邮电大学开放基金资助

摘　　要：在直接检测光正交频分复用(DD-OFDM)系统中,同相/正交相(IQ)不平衡造成严重的性能下降。我们搭建了两个分别实现双边带(DSB)和单边带(SSB)调制的背靠背DD-OFDM系统,并依据差错向量幅度(EVM)和符号差错率(SER)分析比较了上述两系统对IQ不平衡的容忍度。结果表明,在背靠背情形下,DSB系统比SSB系统对IQ不平衡的容忍度要大。我们还搭建了两个传输距离均为40km的DD-OFDM系统,分别实现了DSB信号和SSB信号的传输,同样依据EVM和SER分析比较了这两个系统对IQ不平衡的容忍度。结果表明,在传输距离为40km的情况下,SSB调制比DSB调制更能增强DD-OFDM系统在传输信号时对IQ不平衡的容忍度。In-phase/Quadrature-phase （IQ） imbalance can result in severe performance degradation in optical Direct-detection Orthogonal-frequency-division-multiplexing （DD-OFDM） systems. We build two optical back-to-back DD-OFDM systems, which implement Double-sideband （DSB） and Single-sideband （SSB） modulation, respectively. The tolerance to IQ imbalance of these two systems is analyzed and compared by using Error Vector Magnitude （EVM） and Symbol Error Rate （SER）. It is found that, in the back-to-back case, the DSB system has stronger robustness to IQ imbalance than the SSB System. We further build two optical DD-OFDM systems each with 40-km transmission, which respectively implement DSB and SSB transmission. Similarly, the tolerance to IQ imbalance of these two systems are analyzed and compared in terms of EVM and SER. It is found that, however, in the case of 40-km transmission, the SSB system has stronger robustness to IQ imbalance than the DSB system. As a result, it is concluded that, in the case of transmission, SSB modulation can enhance the tolerance to IQ imbalance of DD-OFDM systems.

关 键 词：光通信 直接检测正交频分复用 IQ不平衡 差错向量幅度 符号差错率 

分 类 号：TN929.11[电子电信—通信与信息系统]