Patents by Inventor Jianjun Yu

Jianjun Yu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • OPTICAL COMMUNICATION USING SUPER-NYQUIST SIGNALS
    Publication number: 20160211939
    Abstract: An optical transmitter multiplexes multiple optical channels for transmission over an optical communication medium. The spectrum of modulated signal in each optical channel is lowpass filtered in the electrical (digital) domain at half the channel baud rate such that super Nyquist signal multiplexing can be achieved in the optical domain without having to perform optical filtering. An optical coupler may be used to multiplex the multiple optical channels.
    Type: Application
    Filed: August 26, 2014
    Publication date: July 21, 2016
    Applicant: ZTE Corporation
    Inventors: Jianjun Yu, Junwen Zhang
  • TIME DIVISION MULTIPLEXED ORBITAL ANGULAR MOMENTUM BASED COMMUNICATION
    Publication number: 20160204896
    Abstract: Optical signals with different orbital angular momentum (OAM) modes are used to multiplex data directed to different receiver together using time division multiplexing. The OAM based multiplexing may be used in addition to other multiplexing schemes such as time division multiplexing, polarization multiplexing and so on. Capacity of existing optical network infrastructure can be increased significantly using OAM modulation, and data communication can be secured at the same time.
    Type: Application
    Filed: January 13, 2016
    Publication date: July 14, 2016
    Inventors: Jianjun Yu, Yuan Fang
  • Nyquist wavelength division multiplexing system
    Patent number: 9391731
    Abstract: Aspects of the present invention include apparatus and methods for transmitting and receiving signals in communication systems. A beam splitter splits an optical signal into a plurality of signals. At least one QPSK modulator generates a plurality of QPSK modulated signals from the plurality of signals. An optical multiplexer combines the plurality of QPSK modulated signals into a multiplexed signal. The multiplexed signal is then transmitted.
    Type: Grant
    Filed: February 27, 2013
    Date of Patent: July 12, 2016
    Assignee: ZTE (USA) Inc.
    Inventors: Zhensheng Jia, Jianjun Yu, Hung-Chang Chien
  • Method and apparatus for heterodyne coherent detection
    Patent number: 9369228
    Abstract: A simplified coherent receiver based on heterodyne detection with only two balanced photo detectors (PD) and two analog-to-digital converters (ADC) is disclosed. The polarization diversity hybrid can be simplified relative to the conventional one. The detected intermediate frequency signals are first down converted to baseband with I/Q separation.
    Type: Grant
    Filed: August 14, 2013
    Date of Patent: June 14, 2016
    Assignee: ZTE (USA) Inc.
    Inventors: Jianjun Yu, Ze Dong, Hung-Chang Chien
  • Method and apparatus of algorithm for coherent receivers with M-QAM modulation format
    Patent number: 9369264
    Abstract: An improved Eighth-Order Statistics (EOS) blind phase recovery method is proposed for high-order coherent modulation formats. The method combining EOS blind phase estimate with maximum-likelihood (ML) carrier phase estimate uses multi-stage feed-forward carrier phase recovery algorithm. Experimental results show that the proposed new algorithm can reduce the required computational effort by more than a factor of 3 for 16-QAM system.
    Type: Grant
    Filed: April 26, 2013
    Date of Patent: June 14, 2016
    Assignee: ZTE (USA) Inc.
    Inventor: Jianjun Yu
  • Flattened optical frequency-locked multi-carrier generation by one DML and one phase modulator
    Patent number: 9356702
    Abstract: The disclosure relates to a method for optical frequency-locked multi-carrier generation based on one directly-modulated laser (DML) and one phase modulator (PM) in cascade driven by sinusoidal waveform (at the same or different frequency). When the DML and PM is driven by the same frequency RF signal at 12.5 GHz, adopting this method, 16 optical subcarriers with 12.5-GHz frequency spacing are generated with power difference less than 3 dB. When the DML and PM is driven by the different frequency with DML at 12.5 Ghz and PM at 25 GHz, over 24 optical subcarriers are generated with 12.5-GHz frequency spacing and amplitude fluctuation less than 3 dB. The number of the generated optical subcarriers can be further increased when the driving power for the DML is increased.
    Type: Grant
    Filed: May 15, 2014
    Date of Patent: May 31, 2016
    Assignee: ZTE (USA) Inc.
    Inventors: Jianjun Yu, Ze Dong
  • SIGNAL TO NOISE RATIO ESTIMATION IN OPTICAL COMMUNICATION NETWORKS
    Publication number: 20160112122
    Abstract: Optical signal to noise ratio within a band of interest (in-band OSNR) is calculated by using a reference signal for noise estimation. In-band noise at a node along the optical communication path is estimated by subtracting the reference signal contribution from the received in-band signal energy. Contribution from the reference signal is calculated using an effective transfer function of the optical communication path using either a direct method in which measurements are made a priori on an equivalent optical system or an indirect method in which the effective transfer function is calculated using computerized simulations. The selection of which method to use may be based on the desired resolution bandwidth for the estimation of transfer function.
    Type: Application
    Filed: October 14, 2015
    Publication date: April 21, 2016
    Inventors: Hung-Chang Chien, Zhensheng Jia, Jianjun Yu
  • BLIND EQUALIZATION OF DUAL SUBCARRIER OFDM SIGNALS
    Publication number: 20160112143
    Abstract: A dual-polarization, 2-subcarriers code orthogonal, orthogonal frequency division multiplexed signal carrying information bits is transmitted in an optical communication network without transmitting a corresponding pilot tone or training sequence. A receiver receives the transmitted signal and recovers information bits using a blind equalization technique and by equalizing the 2-subcarriers OFDM signal as a 9-QAM signal in time domain with a CMMA (constant multi modulus algorithm) equalization method.
    Type: Application
    Filed: August 18, 2015
    Publication date: April 21, 2016
    Inventors: Jianjun Yu, Fan Li
  • MAXIMUM LIKELIHOOD SEQUENCE ESTIMATION OF QUADRATURE AMPLITUDE MODULATED SIGNALS
    Publication number: 20160105245
    Abstract: In a receiver of Quadrature Amplitude Modulation (QAM) signal, the received QAM signal is divided into multiple Quadrature Phase Shift Keying (QPSK) symbol streams. A Maximum Likelihood Symbol Estimation (MLSE) is performed on each QPSK symbol stream to recover information bits in the received QAM signal. In one advantageous aspect, complexity of implementation can be reduced by performing MLSE on QPSK signals instead of QAM signals.
    Type: Application
    Filed: October 7, 2015
    Publication date: April 14, 2016
    Inventors: Yi Cai, Zhensheng Jia, Jianjun Yu
  • Channel estimation in optical communication based on orthogonal frequency division multiplexing
    Patent number: 9312979
    Abstract: Techniques for optical communications using optical orthogonal frequency division multiplexing (OFDM) include operating a signal transmitter to modulate laser light to produce modulated light that carries, in optical domain, OFDM subcarriers for carrying communication information, without a frequency guard band between the OFDM subcarriers, and pilot subcarriers for channel estimation at a signal receiver, each pilot subcarrier being free of communication information, and controlling optical power of the pilot subcarriers to vary with optical frequencies of the pilot subcarriers so that optical power of a pilot subcarrier at a high optical frequency is different from optical power of another pilot subcarrier at a low optical frequency.
    Type: Grant
    Filed: August 10, 2012
    Date of Patent: April 12, 2016
    Assignee: ZTE (USA) Inc.
    Inventor: Jianjun Yu
  • HALF-CYCLED ORTHOGONAL FREQUENCY DIVISIONAL MULTIPLEXING TRANSMISSION AND RECEPTION
    Publication number: 20160087740
    Abstract: An optical transmitter transmits an orthogonal frequency division multiplexing symbol in which only one-half of available subcarriers are modulated with data and the remaining subcarriers are suppressed by not modulating with data. The transmission is of duration equal to half the symbol period of the OFDM symbol, resulting in a half-cycle transmission. An optical receiver receives the half-cycle transmission OFDM symbol, regenerates the full time domain representation and recovers data modulated on the one-half of available subcarriers. The modulated subcarriers and the suppressed subcarriers alternate in the frequency domain.
    Type: Application
    Filed: May 15, 2014
    Publication date: March 24, 2016
    Inventors: Jianjun Yu, Fan Li
  • Method for generating an optimized return-to-zero pulse shape against aggressive optical filtering and an optical transmitter implementing the method
    Patent number: 9294199
    Abstract: An optical transmitter comprises: first and second sets of optical in-phase and quadrature modulators; an integrable tunable laser assembly; a first polarization beam splitter that is configured to divide the continuous-waveform optical signal into a x-polarized tributary and a y-polarized tributary, each of the x-polarized tributary and the y-polarized tributary is modulated by one of the first and second sets of optical in-phase and quadrature modulators in accordance with the two respective input signals; a second polarization beam splitter that is configured to combine the modulated x-polarized tributary and the modulated y-polarized tributary into one optical signal; and an optical modulator that is configured to modulate the combined optical signal using a driving voltage, wherein the driving voltage has a bias point that is reduced by a predefined offset from a predefined reference voltage level.
    Type: Grant
    Filed: September 13, 2012
    Date of Patent: March 22, 2016
    Assignee: ZTE (USA) INC.
    Inventors: Hung-Chang Chien, Jianjun Yu, Ze Dong
  • RECOVERING DATA FROM QUADRATURE PHASE SHIFT KEYING MODULATED OPTICAL SIGNALS
    Publication number: 20160065313
    Abstract: Systems, devices and techniques for processing received QPSK modulated optical signals include sampling the received signal at twice the baud rate, thereby producing samples that are then processed as 9-QAM symbols using a decision directed least squares optimization method. A third stage of channel equalization is filtering performs channel equalization to mitigate linear filtering effects along the transmission link. Data bits are then recovered from the resulting symbol estimates. The received optical signal may also include dual polarized signals for increased bandwidth capacity.
    Type: Application
    Filed: March 28, 2014
    Publication date: March 3, 2016
    Inventors: Jianjun Yu, Junwen Zhang
  • Method and apparatus for algorithm on flexible square-QAM coherent detection
    Patent number: 9270513
    Abstract: In Software defined elastic optical networks, modulation format and constellation size may be flexibly modified. As a result, digital signal processing (DSP) algorithm should be compatible with different modulation schemes or readily reconfigurable at the optical coherent receiver. Therefore we propose a novel cascaded adaptive blind equalizers based on decision-directed modified least mean square (DD-MLMS) algorithm for polarization separation and carrier phase recovery. The algorithm is square quadrature amplitude modulation (QAM) independent so that it could be applied in the elastic optical systems. The 28 Gbaud polarization multiplexing quadrature phase shift keying (PM-QPSK) and PM-16QAM back-to-back transmission is demonstrated. The results show that the performance is very close to the general algorithm but with a benefit of the reduced operation complexity.
    Type: Grant
    Filed: January 27, 2014
    Date of Patent: February 23, 2016
    Assignee: ZTE (USA) Inc.
    Inventors: Jianjun Yu, Bo Huang
  • Transmission and reception of quad-subcarrier orthogonal frequency division multiplexed signals
    Patent number: 9264144
    Abstract: A dual-polarization, 4-subcarriers orthogonal frequency division multiplexed signal carrying information bits is transmitted in an optical communication network without transmitting a corresponding pilot tone or training sequence. A receiver receives the transmitted signal and recovers information bits using a blind equalization technique and by equalizing the 4-subcarriers OFDM signal as a 25-QAM signal in time domain with a CMMA (constant multi modulus algorithm) equalization method.
    Type: Grant
    Filed: October 22, 2014
    Date of Patent: February 16, 2016
    Assignee: ZTE Corporation
    Inventors: Jianjun Yu, Fan Li
  • RECEPTION OF 2-SUBCARRIERS COHERENT ORTHOGONAL FREQUENCY DIVISION MULTIPLEXED SIGNALS
    Publication number: 20160028577
    Abstract: A dual-polarization, 2-subcarriers code orthogonal, orthogonal frequency division multiplexed signal carrying information bits is transmitted in an optical communication network without transmitting a corresponding pilot tone or training sequence. A receiver receives the transmitted signal and recovers information bits using a blind equalization technique and by equalizing the 2-subcarriers OFDM signal as a 9-QAM signal in time domain with a CMMA (constant multi modulus algorithm) equalization method.
    Type: Application
    Filed: August 6, 2014
    Publication date: January 28, 2016
    Inventors: Jianjun Yu, Fan Li
  • ADAPTIVE POST DIGITAL FILTER AND INTER-SYMBOL INTERFERENCE EQUALIZER FOR OPTICAL COMMUNICATION
    Publication number: 20160020857
    Abstract: Modulated optical signals are received in a coherent optical receiver employing both post digital filter and inter-symbol-interference (ISI) equalizer such as a maximum likelihood sequence estimation (MLSE) or Bahl-Cocke-Jelinek-Raviv (BCJR) algorithms. Some disclosed techniques are directed to adaptively adjusting the impulse response in time domain (or equivalently the frequency response in frequency domain) of the post digital filter and the corresponding structure of ISI equalizer in different spectrum-narrowing operation scenarios.
    Type: Application
    Filed: July 15, 2015
    Publication date: January 21, 2016
    Inventors: Zhensheng Jia, Yi Cai, Jianjun Yu
  • Digital non-linear compensation in optical communication systems
    Patent number: 9225455
    Abstract: Systems, devices and techniques for processing an optical signal transmitted from a source over a transmission medium having a length L and performing compensation of non-linear distortions include formulating the compensation as a digital back propagation algorithm by logically dividing the length L into N steps and compensating non-linear distortions for each step as a function of an attenuation adjusting constant parameter that can be selected from a range between 0.3 and 0.7.
    Type: Grant
    Filed: January 14, 2014
    Date of Patent: December 29, 2015
    Assignee: ZTE (USA) Inc.
    Inventors: Jianjun Yu, Junwen Zhang
  • Recovering data from quadrature phase shift keying modulated optical signals
    Patent number: 9225429
    Abstract: Systems, devices and techniques for processing received QPSK modulated optical signals include sampling the received signal at twice the baud rate, thereby producing samples that are then processed as 9-QAM symbols using a decision directed least squares optimization method. Data bits are then recovered from the resulting symbol estimates. The received optical signal may also include dual polarized signals for increased bandwidth capacity.
    Type: Grant
    Filed: December 22, 2013
    Date of Patent: December 29, 2015
    Assignee: ZTE Corporation
    Inventors: Jianjun Yu, Bo Huang
  • Method and apparatus for generation of frequency- and phase-locked subcarrier
    Patent number: 9209927
    Abstract: We describe and demonstrate a novel and simple scheme to generate flattened optical subcarriers using only phase modulators driven by single frequency fundamental sinusoidal sources. 160.8 Gb/s PM-QPSK experiment over a single subcarrier has been demonstrated.
    Type: Grant
    Filed: October 16, 2013
    Date of Patent: December 8, 2015
    Assignees: ZTE Corporation, ZTE (USA) Inc.
    Inventor: Jianjun Yu