Zte Corporation

Zte (usa) Inc.

Zte Corporation (china)

Ztb (usa) Inc.

Hung-Chang Chien

Jianjun Yu

Zhensheng Jia

Ze Dong

Junwen Zhang

Yi Cai

Jianqiang Li

Xinying Li

Fan Li

Xiao Xin

An optical signal transmitter system in an optical communication network includes a digital pre-emphasis device structured to generate a pre-emphasized digital data signal by pre-emphasizing at least a portion of a digital data signal to be transmitted, a digital-to-analog converter coupled to the digital pre-emphasis device to convert the pre-emphasized digital data signal into an analog data signal, an analog pre-emphasis device coupled to the digital-to-analog converter to generate a pre-emphasized analog data signal by pre-emphasizing at least a portion of the analog data signal, an electrical-to-optical converter to convert the pre-emphasized analog signal into an optical signal, and a processor configured to determine a pre-emphasis assignment distribution between the digital pre-emphasis device and the analog pre-emphasis device.

Mixed signal pre-emphasis technique for optical transceivers

An optical transmitter apparatus is disclosed. The apparatus includes a processor, a memory coupled to the processor, and one or more programs configured to be executed by the processor. The programs include instructions for nonlinearity estimation that characterizes nonlinearity in an optical communication and estimates an amount of symbol distortion caused by the nonlinearity, instructions for selecting and mapping symbols to provide, for the nonlinearity estimation, only symbols that meet predetermined nonlinearity criteria, and instructions for storing, in the memory, the amount of symbol distortion to be used for a nonlinearity pre-compensation.

Nonlinearity pre-compensation of high order modulation transmissions

An optical receiver apparatus includes a photo detector that detects amplitude modified optical signals transmitted through an optical transmission channel and mapped to constellation points and converts the optical signal into electrical signals, a sampling circuit that samples the electrical signals and generates digital signals, and a signal processing circuit that has a two-step equalization algorithm converging actual constellation points into desired constellation points. The two-step equalization algorithm includes a first equalization algorithm that uses multiple modulus in performing an error signal calculation, and a second equalization algorithm that includes a filtering procedure that compares actual constellation points with desired constellation points and an adjustment procedure that iteratively adjusts parameters of the filtering procedure in accordance with the comparison result.

Using multi-level pulse amplitude modulation with probabilistic shaping

A method of generating a probabilistically shaped (PS), multi-level modulation signals includes encoding information bits into coded bits to which probability values are assigned according to a probability mass function, and mapping, based on a Gray coding scheme, the coded bits into symbols to which the probability values are assigned. The probability mass function is implemented by determining probabilities of the coded bits so that the probabilities of the coded bits in ascending or descending order have a Gaussian distribution, and performing a probability distribution pre-adjustment by redistributing probabilities of the coded bits corresponding to symbols probabilities of which are outside Gaussian distribution so that the symbols mapped based on the Gray coding scheme have the Gaussian distribution.

Probabilistically shaped multi-level pulse modulation with gray code mapping

A technique for optical signal transmission includes generating a plurality of double sideband modulated optical signals by modulating a plurality of source data signals using a plurality of direct modulation laser (DML) optical sources, wherein the plurality of double sideband modulated optical signals occupy non-overlapping neighboring optical frequency bands, generating a chirp-managed laser (CML) output signal by multiplexing the plurality of double sideband modulated optical signals using a wavelength-selective multiplexer, and transmitting the CML output signal over an optical transport medium.

Chirp managed laser generation for next generation passive optical networks

Methods and apparatus to realize high spectral efficiency in optical signals transmitted over long distances.

System and method for coherent detection with digital signal procession

A scheme for generating asymmetric single sideband photonic vector signal at millimeter wave spectral region is described. At a transmitter, information bits to be transmitted are modulated using a vector modulation technique to generate a baseband signal. The baseband signal is converted into its single sideband (SSB) version using a complex frequency source having a first frequency. The real part of the upconverted signal is added to the real part of a second frequency source and is input as I component to an I/Q modulator. The imaginary part of the upconverted signal is added to the imaginary part of the second frequency source and is used as the Q component. The I/Q modulator is driven by a laser source at frequency fc. The resulting signal is transmitter over an optical transmission medium and upconverted by a single-ended photodiode to a desired radio-frequency (RF) carrier frequency.

Optical mm-wave signal generation using a single IQ modulator

A method of optical communication, implemented at a receiver in an optical communication network, includes receiving an optical signal carrying modulated information bits, processing the optical signal through a receiver subsystem to generate a stream of digitized modulation symbols from the optical signal, and producing, using the digitized modulation symbols as input symbols to an iterative process, estimates of information bits. Each iteration includes: generating estimated output symbols from input symbols by filtering by an estimate of inverse of the optical channel, updating, using the estimated output symbols, the estimate of the inverse of the optical channel to minimize a measure of error, and compensating the estimated output symbols by using pre-distortion values from a look-up table (LUT) to generate compensated output symbols that are used as input to a next iteration.

Iterative nonlinear compensation

Throughput between a transmitter and a receiver is increased by performing a three-stage joint channel optimization in which training sequences are used for calculating a pre-equalization estimate in the first stage, a look up table for pre-distortion in the second stage and a further updating the pre-equalization estimate and the look up table based on a third stage in which the training sequence used for the updating is pre-equalized and pre-distorted using previously calculated values prior to transmitting from the transmitter to the receiver.

Training assisted joint equalization

In an optical communication system, an optical transmitter changes operational physical layer parameters to meet future target throughput for the optical communication system. The optical transmitter communicates the upcoming change to the optical receiver in a message that used current physical layer parameters. The optical transmitter provides sufficient time to the optical receiver to adjust reception functions of the receiver, including polarization based demodulation scheme. In some implementations, the optical transmitter performs the transition to a new physical layer transmission format without waiting for an acknowledgement from the optical receiver.

In-band signaling for reconfiguring software defined optics

A method and apparatus for generating sub-carriers is disclosed. Coherent optical sub-carriers with sub-carrier spacing are generated for carrying an orthogonal frequency division multiplexed (OFDM) signal. Multiple peaks are generated by cascading multiple phase modulators driven by different radio frequency sources.

Method and apparatus for generation of coherent and frequency-lock optical subcarriers

The filter estimate produced by post-equalization processing of an optical signal at a receiver is used to generate pre-equalizer filter coefficients that are communicated back to the source of the optical signal for performing pre-equalization. In one advantageous aspect, the already existing post-equalization modules of an optical receive equipment can thus be used to produce, in addition, a pre-equalizer filter for use by the source side.

Adaptive pre-equalization in optical communications

Duo-binary encoding is used for encoding I and Q data prior to performing orthogonal frequency division multiplexing based transmission using discrete Fourier transform spreading (DFT-S). Advantageously, duo-binary encoding improves robustness of the encoded signal to inter symbol interference, making the degradation caused by the subsequent DFT-S stage less susceptible to reduction in bit error rate performance.

Optical communication that achieves baud rate greater than sample rate

The present invention relates to optical transmitters, transceivers, and transponders used for transmission of information or data in any form through a physical medium dependent (PMD) network. The speed of such networks depends, in part, on the density of information that can be transmitted through the physical medium. Optical transmitters or transceivers can be used to transmit multiple independent signals simultaneously through the same medium using different directions or axes of polarization, where the difference in the directions or axes of polarization can be used to distinguish the multiple signals at the receiver. In this invention, we use a master laser (l) to synchronize two slave lasers (land l) by its x-polarization and y-polarization components of carrier, respectively, so that two slave lasers can be enforced to lock on exactly the same wavelength lwith perpendicular polarization directions.

Directly-modulated multi-polarization optical transmitters

Aspects of the present invention include apparatus and methods for transmitting and receiving signals in communication systems. A multicarrier generator generates a multicarrier signal. An optical demultiplexer separates the multicarrier signal into separate multicarrier signals. At least one QPSK modulator modulates signals from the separate multicarrier signals. An optical multiplexer combines the QPSK modulated signals into a multiplexed signal. The multiplexed signal is then transmitted.

Growing community of inventors

Bridgewater, NJ, United States of America

Hung-Chang Chien