Zhou Xian, Long Keping, Li Rui, Yang Xiaolong, Zhang Zhongshan
Institute of Advanced Network Technology and new Services (ANTS), University of Science & Technology Beijing (USTB), No.30 Xue Yuan Road, Haidian, Beijing 100083, China.
Opt Express. 2012 Mar 26;20(7):7350-61. doi: 10.1364/OE.20.007350.
In this paper, we propose a simple frequency offset estimation (FOE) algorithm for high-speed coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems, which avoids the exhaustive search computations on the integer part of FOE by using a merit function. In time domain, the FOE algorithm can estimate all the frequency offset in the range of [-5GHz, +5GHz], for satisfying the practical application requirement, based on only one redesigned training symbol. In addition, we provide the theoretical analysis about the quantitative influences of the residual frequency offset (RFO) on CO-OFDM systems. In order to reduce the final estimation error, a new zero-overhead residual frequency offset estimation (RFOE) algorithm is also proposed in this paper. Finally, the feasibility and effectiveness of the proposed FOE and RFOE algorithms are demonstrated in a 464 Gbit/s polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (QAM) CO-OFDM system by the simulation, and numerical results validate the proposed algorithms.
在本文中，我们为高速相干光正交频分复用（CO-OFDM）系统提出了一种简单的频偏估计（FOE）算法，该算法通过使用一个优值函数避免了对频偏整数部分的穷举搜索计算。在时域中，基于仅一个重新设计的训练符号，该FOE算法能够估计[-5GHz, +5GHz]范围内的所有频偏，以满足实际应用需求。此外，我们给出了残余频偏（RFO）对CO-OFDM系统定量影响的理论分析。为了降低最终估计误差，本文还提出了一种新的零开销残余频偏估计（RFOE）算法。最后，通过仿真在一个464 Gbit/s偏振复用（PDM）16进制正交幅度调制（QAM）CO-OFDM系统中验证了所提FOE和RFOE算法的可行性和有效性，数值结果验证了所提算法。
