偏振复用CO-OFDM-OQAM系统的高频谱效率频域信道估计方法  

Frequency-Domain Channel Estimation for Polarization-Division-Multiplexed CO-OFDM-OQAM Systems with High Spectrum Efficiency

作　　者：张硕 王道斌[1] 赵航宇 黄全盛 宋婷婷 元丽华[1] Zhang Shuo;Wang Daobin;Zhao Hangyu;Huang Quansheng;Song Tingting;Yuan Lihua(School of Science,Lanzhou University of Technology,Lanzhou 730050,Gansu,China)

机构地区：[1]兰州理工大学理学院,甘肃兰州730050

出　　处：《光学学报》2023年第13期44-52,共9页Acta Optica Sinica

基　　金：国家自然科学基金(62141505,61367007);甘肃省自然科学基金(20JR10RA154)。

摘　　要：研究对象是偏移正交幅度调制的相干光正交频分复用通信(CO-OFDM-OQAM)系统的信道估计方法。为了减少训练序列所占用的频谱资源,进一步提升频谱效率,为偏振复用CO-OFDM-OQAM系统提出了一种新的频域信道估计方法。该方法利用偏振复用系统的解调原理和固有虚部干扰系数的对称性规律设计全负载型实值导频方案,结合插值法,将每个偏振态上训练序列需要占用的频域符号个数降低为4。此外,该方法的另一个优势是具有更好的功率峰均比。搭建了偏振复用CO-OFDM-OQAM系统的数值仿真平台,在背靠背(BtB)、100 km和200 km光纤传输3种场景下对所提方法的频谱效率、功率峰均比和信道估计性能进行了验证。获得的结果证实所提方法能够提高频谱效率,而且功率峰均比更加优良。Objective OFDM-OQAM involves special modulation and demodulation methods,owing to which offers several advantages,including flexible time-frequency lattice,very low out-of-band spectral leakage,and excellent spectral efficiency.Presently,it is widely applied in fields such as wireless communication and optic-fiber communication.In the past,several frequency-domain channel estimation methods have been proposed for CO-OFDM-OQAM.However,these methods are associated with various drawbacks.For instance,more guard intervals need to be inserted between the training sequence and payload to reduce the influence of inherent imaginary part interference(IMI),which can lead to excessive spectrum resources.Thus,this work proposes and studies an improved frequency-domain channel estimation method for PDM CO-OFDM-OQAM systems.The proposed method remarkably enhances the spectrum efficiency and does not severely degrade the power peak-to-average ratio(PAPR)of the signal.Methods A fully-loaded training sequence was designed using real-valued pilots based on the demodulation principle of a polarization multiplexing system and the symmetry rules of an inherent imaginary interference.This method was combined with the interpolation method to ensure that number of frequency-domain symbols to be occupied by the training sequence on each polarization state was reduced to four.The training sequence and the payload at the transmitter's end form a data frame,which assist in generating a baseband transmission signal.The training sequences of x-polarized and y-polarized states occupied four frequency-domain symbols and the real-valued pilots were placed in the 2nd and 3rd frequency-domain symbols.All the odd-numbered subcarriers of the x-polarized state were zero,while the even-numbered subcarriers were not zero.In contrast,the odd-numbered subcarriers of the y-polarized state were not zero,while all the even-numbered subcarriers were zero.For convenience,we denoted the transmission training sequences in the x-and y-polarized directions as[z,p

关 键 词：正交频分复用 偏振复用 信道估计 光通信系统 

分 类 号：TN913.7[电子电信—通信与信息系统]