In this paper, a low-complexity multi-dimensional architecture for IQ imbalance compensation is proposed, which reduces the effects of in-phase (I) and quadrature (Q) imbalance. The architecture use a transceiver IQ skew estimation structure to compensate for IQ skew, and then use a low-complexity MIMO equalizer to compensate for IQ amplitude/phase imbalance. In the transceiver IQ skew estimation structure, the receiver(RX) IQ skew is estimated by Gardner's phase detector, and the transmitter TX skew is estimated by finding the value that yields the lowest equalizer error. The low-complexity MIMO equalizer consists of a complex-valued MIMO (CV-MIMO) and a two-layer multimodulus algorithm real-valued MIMO (TMMA-RV-MIMO), which employ a butterfly and a non-butterfly structure, respectively. The CV-MIMO is used to perform polarization demultiplexing and the TMMA-RV-MIMO equalizes each of the two polarizations. In addition, the TMMA-RV-MIMO can recovery the carrier phase. A 100 km transmission simulation and experiment with 36 Gbaud dual-polarization 16 quadrature amplitude modulation (DP-16QAM) signals showed that, with the TX/RX IQ skew estimation, the estimation error is less than 0.9/0.25 ps. The low-complexity MIMO equalizer can tolerate 0.1 TX IQ amplitude imbalance and 5 degrees at a 0.3 dB Q-factor penalty. The number of real multiplications is reduced by 55% compared with conventional cases in total.

翻译：本文提出了一种用于IQ失衡补偿的低复杂度多维架构，该架构降低了同相（I）与正交（Q）失衡的影响。该架构采用收发机IQ偏差估计结构来补偿IQ偏差，随后采用低复杂度MIMO均衡器来补偿IQ幅度/相位失衡。在收发机IQ偏差估计结构中，接收机（RX）IQ偏差通过Gardner相位检测器进行估计，发射机（TX）偏差则通过寻找使均衡器误差最小的值进行估计。低复杂度MIMO均衡器由一个复数MIMO（CV-MIMO）和一个两层多模算法实数MIMO（TMMA-RV-MIMO）组成，分别采用蝶形和非蝶形结构。CV-MIMO用于执行偏振解复用，而TMMA-RV-MIMO则对两个偏振态分别进行均衡。此外，TMMA-RV-MIMO能够恢复载波相位。采用36 Gbaud双偏振16正交幅度调制（DP-16QAM）信号进行的100公里传输仿真与实验表明，结合TX/RX IQ偏差估计，估计误差小于0.9/0.25 ps。该低复杂度MIMO均衡器在0.3 dB Q因子代价下，可容忍0.1的TX IQ幅度失衡和5度的相位失衡。与常规方案相比，实数乘法运算总量减少了55%。