Huawei Technologies Co., Limited

Future Wei Technologies, Inc.

Chuandong Li

Zhuhong Zhang

Mahdi Zamani

Zhiping Jiang

Chen Chen

Fei Zhu

Jianhong Ke

Xuefeng Tang

Jeebak Mitra

Yu Sheng Bai

Hossein Najafi

Syed Faisal Ali Shah

Yuanjie Chen

Jin Wang

Mehdi Torbatian

YuSheng Bai

Demin Yao

Jun Chen

Xiao Andy Shen

Dominic John Goodwill

Yi Cai

Lutz Hans-Joachim Lampe

Ahikam Aharony

Hongyan Fu

Wing Chau Ng

Mrinmoy Jana

Lewei Zhang

Ahmed Mohamed Medra

Weikun Hou

Ali Bakhshali

Yanming Li

Nash'at Abughalieh

Sung Chung

Mohsen Nader Tehrani

Jin Wan

Zhikui Yong

Hongliang Li

Zilong He

Shengyu Bai

Pre-compensation for linear and non-linear distortion in data symbols comprises generating a set of data symbols to be transmitted and converting the set into a set of frequency-domain samples, which are then pre-processed. Linear distortion compensation is provided, prior to compensating for non-linear distortions, to the pre-processed set of frequency-domain samples. The linear distortion compensated set of frequency-domain samples is converted into a linear distortion compensated set of time domain samples. Non-linear distortion compensation is provided to the linear distortion compensated set of time domain samples. A Pattern Dependent Lookup Table (PDLUT) is generated by receiving consecutive sequences of samples included in a set of time domain samples, quantizing the consecutive sequences of samples into integer-valued consecutive sequences of samples, computing error correction values corresponding to the integer-valued consecutive sequences of samples, and storing the indexes of integer-valued consecutive sequences of samples and the corresponding error correction values in the PDLUT.

Method and system for pre-compensating non-linear distortion in data samples

A digital signal processor (DSP) for a receiver and a method for processing signals in a receiver are provided. The DSP comprises a processor configured to: receive a digital signal at a symbol rate in a frequency domain; and compensate an impairment of the digital signal in the frequency domain.

Method and apparatus for low-complexity symbol-rate receiver digital signal processing

The disclosed systems, and methods are directed to compressing a Pattern Dependent Look-up Table (PDLUT) including distortion correction values corresponding to data symbol sequences, including: i) symmetrically rearranging the data symbol sequences and the associated distortion correction values; ii) folding and amplitude reversing a second half of the rearranged data symbol sequences and the associated distortion correction values; iii) determining approximate distortion correction values for a first half of the rearranged data symbol sequences based on the distortion correction values associated with the first half of the rearranged data symbol sequences and the folded and amplitude reversed distortion correction values associated with the second half of the data symbol sequences; and iv) updating the PDLUT based on the approximate distortion values corresponding to the first half of the rearranged data symbol sequences.

Method and system for compressing and employing pattern dependent look-up table

A clock synchronization apparatus, an optical transmitter, an optical receiver, and a clock synchronization method are provided. In the clock synchronization apparatus, a digital interpolator adjusts a sampling clock frequency of a digital signal under sampling clock control of a clock control circuit.

Clock synchronization apparatus, optical transmitter, optical receiver, and clock synchronization method

The disclosed systems and methods for compensating the polarization dependent loss (PDL) in communication networks comprising: i) filtering, by a first feed-forward filter, a current set of symbols in an equalized X-Pol signal; ii) filtering, by a second feed-forward filter, a current set of symbols in an equalized Y-Pol signal; iii) filtering, by a first feed-backward filter, a previously decided set of symbols associated with the equalized X-Pol signal; iv) filtering, by a second feed-backward filter a previously decided set of symbols associated with the equalized Y-Pol signal; v) adding, by a first adder, the outputs from the first feed-forward filter and the second feed-forward filter; and vi) subtracting, by the first adder, the outputs from the first feed-backward filter and the second feed-backward filter from the addition of outputs from the first feed-forward filter and the second feed-forward filter to determine the symbols in the equalized X-Pol signal.

Systems and methods for compensating polarization dependent loss (PDL) in dual polarized communication network

The disclosed systems and methods for processing a subcarrier-multiplexed signal comprising: i) mixing the subcarrier-multiplexed signal with a local oscillator (LO) signal; ii) extracting a respective subcarrier signal from the subcarrier-multiplexed signal; iii) sampling the respective subcarrier signal; iv) extracting timing recovery information from the respective subcarrier signal; and v) processing the respective sampled subcarrier signal to extract data from the respective sampled subcarrier signal.

Systems and methods for processing a subcarrier-multiplexed signal

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).

Apparatuses and methods of far-end transmitter skew monitoring in digital subcarrier multiplexing systems

Methods and systems for low complexity interference cancellation in multichannel optical transmission. Local or self-iteration is performed one or more times between an expected propagation decision feedback equalizer and a soft demapper. Following local iteration, a soft decision forward error correction decoder determines bit log-likelihood ratios, which are fed back to the expected propagation decision feedback equalizer and soft demapper for further self-iteration. Global iteration involving the decoder can also be performed one or more times before a bitstream is decoded.

System and method for interference cancellation in optical transmission

The disclosed systems, structures, and methods are directed to a single-stage frequency-domain equalization (FDEQ) structure implemented on a processor, comprising a data preprocessing unit configured to concatenate received data samples in time-domain digital signals, transform the concatenated data samples in the time-domain digital signals to frequency-domain digital signals, and an adaptive equalizer comprising 2&#xd7;2 multiple-input multiple output (MIMO) configured to compensate for non-time-varying fixed impairments and time-varying adaptive impairments in the frequency-domain digital signals.

System and method for single-stage frequency-domain equalization

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.

Method and apparatus of low-complexity pattern dependent lookup table pre-compensation

Methods and devices are described for frequency domain equalization with low complexity and loop delay. A transmitter inserts pilot symbols into a data signal at intervals of every n data bits. These pilot symbols are used by a receiver-side frequency-domain equalizer to calculate error levels and equalize the received data signal to effect impairment compensation such as SOP tracking. QPSK or BPSK symbols may be used for the pilot symbols, simplifying error calculation into an addition operation instead of the conventional multiplication operation required by conventional FDEQs. Equalizers are described that may operate in a pilot-assisted mode, a conventional decision-directed mode, or both.

Method and apparatus for frequency domain equalization with low complexity and loop delay

Aspects of the present application provide methods and devices for compensating crosstalk in in the digital domain, the crosstalk occurring in the analog domain, for an optical coherent transceiver on a photonic integrated circuit (PIC).

Method and apparatus for transmit/receive radio frequency crosstalk compensation in a photonic integrated circuit

A method includes distributing payload data among a master sub-band and a plurality of slave sub-bands. The master sub-band and the plurality of slave sub-bands collectively extend over an allocated frequency spectrum; the master sub-band and the plurality of slave sub-bands are associated with different carrier frequencies; and the master sub-band has a center frequency that corresponds to a center frequency of the allocated frequency spectrum. The method includes generating modulated data for the master sub-band and the plurality of slave sub-bands based on the distributed payload data; and transmitting an optical signal to an optical medium representing the modulated data.

Hybrid digital multi-band optical receiver and transmitter

Aspects of the present disclosure are directed in part to a receiver DSP unit including an equalization module. The equalization module includes a trellis-based equalization module that may utilize multiple trellis-based processors (TBP), which can each be individually adaptively configured for performing a trellis-based equalization. The design of the TBPs allows them to be configured for compensating a residual Inter-Symbol Interference (ISI) as well as compensating a residual Phase Noise (PN). ISI is an example of an additive impairment and PN is an example of a multiplicative impairment that communication systems, particularly high speed transmission systems such as coherent optical systems, can suffer from.

Trellis based processing for robust digital multiband transmission

The disclosed systems, apparatuses and methods are directed to controlling optical channel signal and an optical network equipment in optical networks. The methods comprise adjusting an optical channel spectrum based on bit error rates (BER) measured for a dithered optical channel signal. The optical channel spectrum is dithered such that a signal reference frequency is alternated between a first second signal reference frequency and a second signal reference frequency. BER is measured and analysed separately for the dithered signal reference frequency being detuned to the first and to the second signal reference frequencies. Based on a BER difference between BER at the first signal reference frequency and BER at the second signal reference frequency, the optical channel spectrum is shifted with regards to frequency in order to improve optical network performance.

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Ottawa, Canada

Chuandong Li