公开(公告)号：US10826605B2

公开(公告)日：2020-11-03

申请号：US16605324

申请日：2019-09-02

Applicant: Ciena Corporation

Inventor： Shahab Oveis Gharan ,  Michael Andrew Reimer ,  Andrew D. Shiner ,  Hamid Ebrahimzad ,  Maurice O'Sullivan ,  Kim B. Roberts

IPC: H04B10/00 ,  H04B10/079 ,  H04B10/66 ,  H04B10/50 ,  H04J14/00

Abstract: An optical transmitter (102,200) is operable to generate an optical signal (260) by modulating a number N of frequency divisional multiplexing (FDM) subcarriers using transformed digital signals which are determined by applying a pseudo FDM (pFDM) transformation to preliminary digital signals representative of multi-bit symbols. Rather than experiencing the effects of the number N of FDM channels, the optical signal experiences the effects of a different number M of pFDM channels, where M≠N. In some examples, the number M of pFDM channels is less than the number N of FDM channels, and frequency-dependent degradations may be averaged across different symbol streams. In other examples, the number M of pFDM channels is greater than the number N of FDM channels, and different symbol streams may experience different frequency-dependent degradations. An optical receiver (102,300) is operable to apply an inverse pFDM transformation to recover estimates of the multi-bit symbols.

公开(公告)号：US10396902B2

公开(公告)日：2019-08-27

申请号：US15268746

申请日：2016-09-19

Applicant: Ciena Corporation

Inventor： Shahab Oveis Gharan ,  Kim B. Roberts ,  Mahmoud Taherzadehboroujeni ,  Amir Khandani ,  Akbar Ghasemi

IPC: H04B10/61

Abstract: A method of data symbol recovery in a coherent receiver of an optical communications system includes processing data symbol estimates detected from a received optical signal, and determining recovered symbol values from the processed data symbol estimates. The recovered symbol values belong to a symbol constellation having a predetermined asymmetry. Processing the data symbol estimates compensates phase noise that is greater than one decision region of the symbol constellation. A coherent receiver of an optical communications system includes a module configured to process data symbol estimates detected from a received optical signal and a decision circuit configured to determine recovered symbol values from the processed data symbol estimates. The recovered symbol values belong to a symbol constellation having a predetermined asymmetry. Processing the data symbol estimates compensates phase noise that is greater than one decision region of the symbol constellation.