Zte Corporation

Zte (usa) Inc.

Nec Laboratories America, Inc.

Nec Corporation

Zte Corporation (china)

Ztb (usa) Inc.

Jianjun Yu

Hung-Chang Chien

Ting Wang

Zhensheng Jia

Junwen Zhang

Ze Dong

Lei Xu

Dayou Qian

Xinying Li

Philip N Ji

Fan Li

Yuanqiu Luo

Yi Cai

Yuanquan Wang

Junqiang Nochur Hu

Jianyang Shi

Milorad Cvijetic

Bo Huang

Yuan Fang

Xin Xiao

Jianqiang Li

Shaoliang Zhang

Yutaka Yano

Toshihiko Kusano

Lei Zong

Si Yin

Jin Tang

Shu-Hao Fan

Xiao Xin

Phase imbalance between in-phase (I) and quadrature (Q) components of an optical communications signal causes signal degradation that can result in degraded bit-error rate performance, increased power requirements, and reduced transmission distance. The signal degradation can be expressed as a reduced signal to noise and interference ratio. The disclosed system and techniques monitor the phase imbalance between the I and Q channels and provides for adjustment of the phase of one or more of the I and Q channels to improve overall performance.

Monitoring and correcting I/Q imbalance in high-speed optical communications systems

A method of digital communication is described. The method includes generating a first orthogonal frequency division multiplexed (OFDM) signal from a first portion of information bits received at the communication apparatus, generating a second OFDM signal from a second portion of information bits received at the communication apparatus, generating a first input for a modulator using the first OFDM signal and the second OFDM signal, generating a second input for the modulator using the second OFDM signal and the second OFDM signal, and operating the modulator to produce a modulated signal from the first input and the second input.

Reception of twin single sideband signals using a MIMO filter

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

Disclosed systems, methods, and computer program products enable high symbol-rate optical Nyquist signal generation with roll-off factors approaching zero by combining digital and all-optical methods. The combined digital and all-optical methods utilize all-optical sine-shaped pulse generation and orthogonal time-division multiplexing with quadrature amplitude modulation using digital Nyquist signals. Disclosed embodiments exhibit inter-channel-interference penalties that are less than 0.5-dB for both 75-GBaud and 125-GBaud optical Nyquist signals, in contrast to conventional signals generated using rectangular waveform driving signals that exhibit penalties greater than 2.5-dB and 1.5-dB for 75-GBaud and 125-GBaud signals, respectively. The disclosed embodiments, therefore, enable significant improvement over conventional systems by reducing inter-channel-interference penalties caused by excess modulation induced bandwidth.

System and methods for high symbol-rate optical nyquist signal generation with roll-off factor approaching zero

At a transmitter-side in an optical communication network, pulse amplitude modulation optical signals to be transmitted are pre-compensated using a chromatic dispersion pre-compensation stage and a device non-linearity pre-compensation stage. The non-linearity pre-compensation may be achieved by using look-up tables that are built based on messages exchanged between the transmitter and a target receiver using known symbol patterns.

Optical pulse amplitude modulation transmission using digital pre-compensation

A channel estimation technique suitable for implementation at a digital communication receiver such as an optical signal receiver apparatus includes receiving, over a communication channel, a transmission comprising a sequence of modulated symbols, estimating, at multiple frequencies, estimated values of a channel transfer function of the communication channel and selectively revising the estimated values of channel transfer function by reducing glitches in the estimated values of the channel transfer function.

Channel estimation using intra-symbol frequency domain averaging

Blind polarization demultiplexing algorithms based on complex independent component analysis (ICA) by negentropy maximization for quadrature amplitude modulation (QAM) coherent optical systems are disclosed. The polarization demultiplexing is achieved by maximizing the signal's non-Gaussianity measured by the information theoretic quantity of negentropy. An adaptive gradient optimization algorithm and a Quasi-Newton algorithm with accelerated convergence are employed to maximize the negentropy. Certain approximate nonlinear functions can be substitutes for the negentropy which is strictly derived from the probability density function (PDF) of the received noisy QAM signal with phase noise, and this reduces the computational complexity. The numerical simulation and experimental results of polarization division multiplexing (PDM)-quadrature phase shift keying (QPSK) and PDM-16QAM reveal that the ICA demultiplexing algorithms are feasible and effective in coherent systems and the simplified ones can also achieve equivalent performance.

Method and apparatuses for algorithm on QAM coherent optical detection

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

An optical signal transmission can use probabilistically shaped technique to improve performance and increase the transmission capacity. For instance, a 30-Gbit/s/&#x3bb; probabilistically shaped (PS) 1024-QAM DFT-S OFDM was experimentally demonstrated over 40-km SSMF in an intensity modulation-direct detection system. The Achievable Information Rate (AIR) 9.5344-bits/QAM symbol of PS-1024-QAM modulation is first achieved in the experiment and shows feasibility for OFDM.

Probabilistically shaped orthogonal frequency division multiplexing

A digital communication technique, implementable in a digital communication system, includes performing a training phase in which the transmitter sends one or more transmissions of pulse amplitude modulation (PAM) signals wherein the PAM signals are modulated using one or more data-to-PAM-symbol mapping schemes, performing a feedback phase in which the transmitter receives a feedback message from a receiver, the feedback message indicative of a change to be made to data-to-PAM-symbol modulation schemes, and implementing a data transmission phase in which data is transmitted using a current PAM symbol mapping scheme based on the feedback message, wherein at least some symbols of the current PAM symbol modulation scheme are unequally spaced with respect to each other.

Unequally spaced pulse amplitude modulation scheme

Embodiments of the present invention pertain to optical wireless architecture. More particularly, certain embodiments of the invention pertain to a novel method and apparatus to generate millimeter-wave signals with simple and/or low cost architecture. Simple millimeter-wave generation and dispersion-tolerant transmission is based on photonic mixing of two free-running lightwaves and self-mixing down-conversion. More particularly, heterodyne mixing of two free run lightwaves is achieved, wherein one lightwave is modulated by an external modulator driven by electrical data as one of the side-bands of a millimeter-wave signal. Optical to electrical conversion is performed and the millimeter-wave signal is broadcasted by a high-frequency antenna to a receiving side having a local oscillator with self-mixing architecture to down-convert the radio frequency to its baseband form.

Method and apparatus for optical wireless architecture

A scheme for generating, transmitting and receiving dual-polarization 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. Two IQ signals are generated using an integrated dual polarization IQ modulator. The I/Q modulator is driven by a laser source at frequency fc. The resulting signal is transmitter over an optical transmission medium and/or a multi-input, multi-output over the air antenna configuration, upconverted by a single-ended photodiode to a desired radio-frequency (RF) carrier frequency.

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Basking Ridge, NJ, United States of America

Jianjun Yu