公开(公告)号：US11451329B2

公开(公告)日：2022-09-20

申请号：US17157691

申请日：2021-01-25

申请人： Jianhong Ke ,  Chuandong Li ,  Xuefeng Tang

发明人： Jianhong Ke ,  Chuandong Li ,  Xuefeng Tang

IPC分类号： H04L1/00

摘要： Methods and systems for performing signal pre-correction of a transmission signal comprising a sequence of symbols using a Pattern Dependent Look-up Table (PDLUT) containing one or more distortion correction values. Upon accessing a distortion correction value from the PDLUT for a symbol of the sequence of symbols, the accessed distortion correction value is quantized into one or more quantized values according to one or more quantizations, thereby reducing the bit-width of the distortion correction value. The transmission signal and the distortion correction value with reduced bit-width may undergo linear correction compensation, such as through a finite impulse response (FIR) filter, independent of one another, where the one or more quantized correction values with reduced bit-width reduce a number of calculation steps performed during linear correction compensation resulting in power savings. The linearly compensated quantized values and the linearly compensated signal are combined to form a pre-corrected signal.

公开(公告)号：US11581951B1

公开(公告)日：2023-02-14

申请号：US17589284

申请日：2022-01-31

申请人： Wing Chau Ng ,  Xuefeng Tang ,  Chuandong Li

发明人： Wing Chau Ng ,  Xuefeng Tang ,  Chuandong Li

IPC分类号： H04B10/61 ,  H04J14/02 ,  H04B10/516

摘要： Apparatuses and methods for far-end monitoring of transmitter IQ skew in a DSCM system are described. Soft symbols for a given subchannel and a corresponding mirror subchannel are used as joint inputs to a MIMO equalizer. The hard decision symbols for the given subchannel and mirror subchannel are used as references to compute the equalizer coefficients. An estimated phase or estimated transmitter IQ skew is computed for at least the given subchannel using the equalizer coefficients. The computation is repeated to obtain estimated phase or estimated transmitter skew for all subchannels. The transmitter IQ skew is computed using the estimates from all subchannels. The computation is performed for each polarization. The computed transmitter IQ skew is communicated back to the transmitter via optical path (for correcting the skew).

公开(公告)号：US09735883B2

公开(公告)日：2017-08-15

申请号：US15060318

申请日：2016-03-03

申请人： Sung Chung ,  Xuefeng Tang ,  Chuandong Li ,  Zhuhong Zhang

发明人： Sung Chung ,  Xuefeng Tang ,  Chuandong Li ,  Zhuhong Zhang

IPC分类号： H04B10/564 ,  H04B10/54 ,  H04B10/2513 ,  H04B10/61

CPC分类号： H04B10/541 ,  H04B10/25133 ,  H04B10/588 ,  H04B10/6161

摘要： An optical transceiver using a modulator biased to a non-linear region of the modulator's power transfer function can extend the possible transmission distance of intensity modulated direct detection (IMDD) n-level pulse amplitude modulated (PAM-n) signals. A non-linear look-up-table may compensate for non-linear characteristics of the modulator. An adaptive decision threshold look-up-table may be used to provide adaptive decision levels at the receiver.

公开(公告)号：US20170104544A1

公开(公告)日：2017-04-13

申请号：US15060318

申请日：2016-03-03

申请人： Sung CHUNG ,  Xuefeng Tang ,  Chuandong Li ,  Zhuhong Zhang

发明人： Sung CHUNG ,  Xuefeng Tang ,  Chuandong Li ,  Zhuhong Zhang

IPC分类号： H04B10/54 ,  H04B10/61 ,  H04B10/2513

CPC分类号： H04B10/541 ,  H04B10/25133 ,  H04B10/588 ,  H04B10/6161

摘要： An optical transceiver using a modulator biased to a non-linear region of the modulator's power transfer function can extend the possible transmission distance of intensity modulated direct detection (IMDD) n-level pulse amplitude modulated (PAM-n) signals. A non-linear look-up-table may compensate for non-linear characteristics of the modulator. An adaptive decision threshold look-up-table may be used to provide adaptive decision levels at the receiver.

公开(公告)号：US10187155B2

公开(公告)日：2019-01-22

申请号：US15352040

申请日：2016-11-15

申请人： Zhiping Jiang ,  Chuandong Li ,  Zhuhong Zhang ,  Xuefeng Tang

发明人： Zhiping Jiang ,  Chuandong Li ,  Zhuhong Zhang ,  Xuefeng Tang

IPC分类号： H04B10/00 ,  H04B10/40 ,  H04B3/32 ,  H04B10/556 ,  H04Q11/00 ,  H04B10/572 ,  H04B10/61 ,  H04J14/02

摘要： An optical transceiver is provided with an optical front end for receiving signal light comprising an optical sub-channel, and for providing an electrical signal based on the signal light; a light source optically coupled to the optical front end for providing local oscillator light thereto for mixing with the signal light; an electro-optical modulator coupled to the light source for receiving output light therefrom and for modulating the output light with digital information to obtain modulated light; and a signal processor operably coupled to the optical front end. The signal processor is configured for processing the electrical signal to obtain a frequency offset of the sub-channel; and adjusting an optical frequency of the modulated light based on the frequency offset. When applied to a multiple-access environment, this may allow access nodes to generate optical sub-channels in the uplink direction using the downlink optical signal as an optical frequency reference.

公开(公告)号：US11277207B1

公开(公告)日：2022-03-15

申请号：US17008402

申请日：2020-08-31

申请人： Wing Chau Ng ,  Xuefeng Tang ,  Zhuhong Zhang

发明人： Wing Chau Ng ,  Xuefeng Tang ,  Zhuhong Zhang

IPC分类号： H04L25/03 ,  H04B10/61 ,  H04B7/0413

摘要： Methods and apparatuses for IQ time skew calibration in a coherent transceiver are described. A four-channel signal is received. A set of inputs is constructed for a 4×8 MIMO equalizer by converting the four-channel signal into four complex inputs that each have a phase shift corresponding to an estimated carrier frequency offset. The set of inputs further includes conjugate replicas of the four complex inputs. Using output from the 4×8 MIMO equalizer, equalizer coefficients are calculated by minimizing error between the MIMO output and a reference signal. Receiver and transmitter IQ skew are estimated using the equalizer coefficients, by converting the equalizer coefficients form the time domain to the frequency domain to determine receiver and transmitter IQ differential phase responses, which are indicative of respective receiver and transmitter IQ skew in the time domain. Skew compensation is then performed.

公开(公告)号：US09473263B2

公开(公告)日：2016-10-18

申请号：US14598581

申请日：2015-01-16

申请人： Zhiping Jiang ,  Zhuhong Zhang ,  Xuefeng Tang

发明人： Zhiping Jiang ,  Zhuhong Zhang ,  Xuefeng Tang

IPC分类号： H04B10/00 ,  H04J14/02 ,  H04B10/077

CPC分类号： H04J14/0276 ,  H04B10/077 ,  H04B10/0775 ,  H04B10/2504 ,  H04B10/516 ,  H04B2210/075 ,  H04J14/06

摘要： The present applies to digital wavelength converters that convert, independently of the format in which optical data may be encoded, an input waveform at a first wavelength to an output waveform at a second wavelength. When operating in an environment where an input waveform has a pilot tone associated thereto, the method and system of the present disclosure allows for the removal of the pilot tone from the input waveform, and also allows for the addition of another pilot to the output waveform.

摘要翻译： 本发明适用于与光学数据可被编码的格式独立地将第一波长的输入波形转换为第二波长的输出波形的数字波长转换器。 当在输入波形具有与其相关联的导频音的环境中操作时，本公开的方法和系统允许从输入波形中去除导频音，并且还允许将另外的导频添加到输出波形 。

公开(公告)号：US08787754B1

公开(公告)日：2014-07-22

申请号：US13665318

申请日：2012-10-31

申请人： Douglas James Beckett ,  Nourhan Eid ,  Michael Reimer ,  Xuefeng Tang ,  Maurice O'Sullivan

发明人： Douglas James Beckett ,  Nourhan Eid ,  Michael Reimer ,  Xuefeng Tang ,  Maurice O'Sullivan

IPC分类号： H04B10/25

CPC分类号： H04B10/2543 ,  H04B10/0793 ,  H04B10/0795

摘要： A method of estimating nonlinear transmission impairments of an Optical Channel (OCh) trail in an optical communications network. A per-span nonlinear field variance is calculated for each span of the trail. The per-span nonlinear field variance represents nonlinearly induced noise due to the transmission impairments of that span. The nonlinearly induced noise being imparted to a signal transmitted through the trail and detected by the receiver. A respective covariance between the nonlinear fields contributed by each span pair of the OCh trail is computed. The covariance represents the correlation of the nonlinearly induced noise imparted to the signal within the first span of a span pair with the nonlinearly induced noise imparted to the signal within the second span of the pair. A covariance matrix is populated using the computed per-span variance values and covariance values. A total nonlinear field variance is computed by summing over the covariance matrix elements.

摘要翻译： 一种估计光通信网络中的光信道（OCh）路径的非线性传输损伤的方法。 对于每个跨度的跨度计算每跨跨度的非线性场方差。 由于该跨度的传输损伤，每跨度非线性场方差代表非线性感应噪声。 非线性感应噪声被赋予通过踪迹传输并由接收器检测的信号。 计算由OCh轨迹的每个跨距对贡献的非线性场之间的相应协方差。 协方差表示施加到跨距对的第一跨度内的信号的非线性感应噪声与施加到该对的第二跨度内的信号的非线性感应噪声的相关性。 使用计算的每跨度方差值和协方差值来填充协方差矩阵。 通过对协方差矩阵元素求和来计算总非线性场方差。

公开(公告)号：US11381444B2

公开(公告)日：2022-07-05

申请号：US17037840

申请日：2020-09-30

申请人： Wing Chau Ng ,  Xuefeng Tang ,  Zhuhong Zhang

发明人： Wing Chau Ng ,  Xuefeng Tang ,  Zhuhong Zhang

IPC分类号： H04B10/50 ,  H04B10/077 ,  H04L27/36 ,  H04L27/227 ,  H04L27/04

摘要： Methods and apparatus for coherent transmitter calibration are provided that employ direct detection (DD) using one single photodetector (PD). The provided method and apparatus do not require hardware for coherent reception, or additional ADCs for quality control. An additional optical tone is added to a QAM optical signal that is outside the band of the QAM optical signal. The result of this is that after direct detection, there is a correlation between the real and imaginary parts, and the imaginary part can be recovered with a Hilbert transform. The estimated QAM optical signal obtained by direct detection is used to perform a transmitter factory calibration method to calibrate for one or more transmitter impairments and/or to perform in-line self-calibration.

公开(公告)号：US11153012B1

公开(公告)日：2021-10-19

申请号：US17000068

申请日：2020-08-21

申请人： Zhiping Jiang ,  Xuefeng Tang ,  Junho Chang

发明人： Zhiping Jiang ,  Xuefeng Tang ,  Junho Chang

IPC分类号： H04B10/04 ,  H04B10/516 ,  H04B10/50

摘要： Optical transmitters, receivers, and methods are described in an optical network. An optical transmitter comprises an encoder configured to receive an input data stream and to encode the input data stream into a signal. The signal is defined as a sequence of regular units, and a rotator is configured to receive each unit of the signal and to output, for each given input unit with an input state of polarization (SOP), a respective given output unit associated with an output SOP. The output SOP of the given output unit is different from a corresponding output SOP of each other output unit that is immediately adjacent to the given output unit. The output SOPs of the units in a transmitted signal may form an alternating pattern (or other repeating pattern), which may help to lower the average BER, in particular, due to forward error correction (FEC).