Including Postcompensation Patents (Class 398/208)
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Patent number: 9467318Abstract: A communication system includes a transmitting device that transmits a signal based on pluralities of symbol coordinates on a constellation and pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates, average coordinates of the pluralities of trajectory coordinates being different coordinates from coordinates of origin, and a receiving device that accumulates pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates on the constellation in the signal received from the transmitting device, and estimates a phase of the signal received from the transmitting device based on a value representing a difference between average coordinates of the pluralities of trajectory coordinates accumulated and the different coordinates.Type: GrantFiled: March 27, 2015Date of Patent: October 11, 2016Assignee: FUJITSU LIMITEDInventors: Daijiro Tanaka, Yohei Koganei
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Patent number: 9425900Abstract: Chromatic dispersion (CD) processing apparatus comprises an equalizer loop comprising: a frequency domain equalizer (FDE) arranged to receive samples of an electrical representation of an optical communications signal having CD and to apply CD compensation to the samples, to form dispersion corrected samples having a residual CD value; a time domain equalizer arranged to receive the corrected samples and to generate a representation of a channel linear transfer function of the signal from the corrected samples, to generate and transmit a monitoring signal comprising said representation; optical performance monitoring apparatus arranged to receive the monitoring signal and to estimate the residual CD value; and a processor arranged to receive the estimated residual value and to compare it to a threshold value and to generate and transmit to the FDE an estimation signal comprising the estimated value unless it is less than the threshold.Type: GrantFiled: March 2, 2012Date of Patent: August 23, 2016Assignee: TELEFONAKTIEBOLAGET L M ERICSSON (PUBL)Inventors: Roberto Magri, Raffaele Corsini, Ernesto Ciaramella, Emma Matarazzo, Andrea Peracchi
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Patent number: 9407473Abstract: A signaling system is described. The signaling system comprises a transmit device, a receive device including a partial response receive circuit, and a signaling path coupling the transmit device and the receive device. The receive device observes an equalized signal from the signaling path, and includes circuitry to use feedback from the most recent previously resolved symbol to sample a currently incoming symbol. The transmit device equalizes transmit data to transmit the equalized signal, by applying weighting based on one or more data values not associated with the most recent previously resolved symbol value.Type: GrantFiled: April 9, 2015Date of Patent: August 2, 2016Inventors: Vladimir M. Stojanovic, Andrew C. Ho, Anthony Bessios, Bruno W. Garlepp, Grace Tsang, Mark A. Horowitz, Jared L. Zerbe, Jason C. Wei
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Patent number: 9401765Abstract: A frequency offset estimation circuit estimates a frequency offset that indicates a difference between a carrier frequency of a received optical signal and a frequency of a local oscillation light used to recover a transmission signal from the received optical signal. The frequency offset estimation circuit includes: a phase difference detector configured to detect a phase difference due to the frequency offset between a first symbol and a second symbol that is transmitted after the first symbol by a specified symbol interval based on a phase of the first symbol and a phase of the second symbol; an estimator configured to estimate the frequency offset based on the phase difference detected by the phase difference detector; and a symbol interval controller configured to specify the symbol interval based on the frequency offset estimated by the estimator.Type: GrantFiled: October 13, 2014Date of Patent: July 26, 2016Assignee: FUJITSU LIMITEDInventors: Nobuaki Kawasoe, Manabu Yamazaki, Kazuhiko Hatae
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Patent number: 9270384Abstract: Presented herein are sub-sampled carrier phase recovery techniques. In accordance with one example, a plurality of consecutive symbols associated with a received optical signal is obtained. Carrier phase recovery of the optical signal is performed using one or more carrier phase estimation stages. At each of the one or more carrier phase estimation stages, a subset of the plurality of consecutive symbols is selected for use in carrier phase estimation. The subset of symbols selected for use in carrier phase estimation at each of the one or more stages comprises symbols that provide the most phase recovery information for each of the one or more stages.Type: GrantFiled: January 14, 2014Date of Patent: February 23, 2016Assignee: Cisco Technology, Inc.Inventors: Andreas Bisplinghoff, Chris Fludger
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Patent number: 9270416Abstract: A transmitter may comprise a symbol mapping circuit that is configurable to operate in at least two configurations, wherein a first of the configurations of the symbol mapping circuit uses a first symbol constellation and a second of the configurations of the symbol mapping circuit uses a second symbol constellation. The transmitter may also comprise a pulse shaping circuit that is configurable to operate in at least two configurations, wherein a first of the configurations of the pulse shaping circuit uses a first set of filter taps and a second of the configurations of the pulse shaping circuit uses a second set of filter taps. The first set of filter taps may correspond to a root raised cosine (RRC) filter and the second set of filter taps corresponds to a partial response filter.Type: GrantFiled: May 30, 2014Date of Patent: February 23, 2016Assignee: MagnaCom Ltd.Inventor: Amir Eliaz
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Patent number: 9240843Abstract: In some embodiments, an apparatus includes a coherent optical receiver that can receive during a first time period a set of in-phase signals and a set of quadrature signals having a skew from the set of in-phase signals. The coherent receiver can blindly determine a delay between the set of in-phase signals and the set of quadrature signals based on the set of in-phase signals and the set of quadrature signals. The delay includes an intersymbol portion and an intrasymbol portion. The coherent optical receiver can apply the delay at a second time after the first time period such that a skew after the second time is less than the skew at the first time period.Type: GrantFiled: December 28, 2012Date of Patent: January 19, 2016Assignee: Juniper Networks, Inc.Inventors: Christian Malouin, Philip A. Thomas, Murat Arabaci, Bo Zhang, Theodore J. Schmidt, Roberto Marcoccia
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Patent number: 9219548Abstract: A modulator with polarization marking comprising two input ports for receiving two optical signals at one wavelength, and exhibiting essentially perpendicular optical polarization states, capable of phase-modulating those signals with data signals and of combining them with polarization, characterized in that it comprises a source of phase overmodulation for overmodulating the phase of one of said two optical signals, said phase overmodulation exhibiting a modulation frequency substantially lower than the modulation frequency of said data signals. A method and a coherent receiver are also disclosed.Type: GrantFiled: September 15, 2010Date of Patent: December 22, 2015Assignee: Alcatel LucentInventors: Massimiliano Salsi, Jeremie Renaudier
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Patent number: 9184854Abstract: An optical communication system includes a digital signal processer coupled to the coherent receiver, said coherent receiver including a nonlinearity compensation module for compensating for nonlinear effects in fiber in the optical link for increasing capacity or transmission distance of the fiber, the nonlinearity compensation module includes a spectral slicing of the signal into bands, computing nonlinear interaction between the bands with parameters opposite to those of the fiber to reverse the non-linear effects in the fiber, and only certain nonlinear interactions between bands are considered thereby reducing complexity of the nonlinearity compensation.Type: GrantFiled: October 2, 2013Date of Patent: November 10, 2015Assignee: NEC Laboratories America, Inc.Inventors: Eduardo F. Mateo, Fatih Yaman, Dayou Qian, Ting Wang
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Patent number: 9178624Abstract: A digital signal processor (DSP) may receive a signal that has an x-polarization (x-pol) and a y-polarization (y-pol). The DSP may equalize the x-pol of the signal and the y-pol of the signal based on filter coefficients determined using a constant modulus algorithm (CMA). The DSP may perform phase correction on the equalized x-pol signal and the equalized y-pol signal. The DSP may identify a first frame header pattern within the phase-corrected x-pol signal, and may identify a second frame header pattern within the phase-corrected y-pol signal. The DSP may determine, based on the first frame header pattern and the second frame header pattern, a quantity of lock-in differential group delay (DGD). The device may adjust one or more of the filter coefficients to remove the quantity of lock-in DGD and to permit an amount of polarization mode dispersion to be determined based on the filter coefficients.Type: GrantFiled: March 31, 2014Date of Patent: November 3, 2015Assignee: Infinera CorporationInventors: Han H. Sun, Kuang-Tsan Wu, Ahmed Awadalla, John D. Mcnicol
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Patent number: 9160448Abstract: An apparatus and method for estimating intra-channel nonlinear damage, including: a first determining unit configured to determine a nonlinear phase shift weighting dispersion distribution function of an optical fiber transmission link according to a parameter of the optical fiber transmission link; a segmenting unit configured to segment the nonlinear phase shift weighting dispersion distribution function of the optical fiber transmission link into at least one rectangle; a calculating unit configured to respectively calculate a nonlinear perturbation coefficient of each rectangle in the at least one rectangle, and perform summation on the nonlinear perturbation coefficients of all the rectangles, so as to obtain a nonlinear perturbation coefficient of the optical fiber transmission link; and a second determining unit configured to determine intra-channel nonlinear damage of the optical fiber transmission link according to the nonlinear perturbation coefficient of the optical fiber transmission link.Type: GrantFiled: June 20, 2014Date of Patent: October 13, 2015Assignee: FUJITSU LIMITEDInventors: Yangyang Fan, Liang Dou, Zhenning Tao
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Patent number: 9100125Abstract: Methods, systems, and devices are described for formatting of data streams to be transmitted over fiber optic channels, and for processing received optical signals. A data transmission device may include a digital coding and modulation module that encodes a digital data stream, inserts unique words into the digital data stream, and modulates the encoded data stream and unique words onto optical channels for transmission over an optical fiber. A demodulation and decoding device may include a unique word identification module that identifies the unique words inserted in each optical channel stream, determines one or more characteristics of the plurality of optical channels based on the unique words, and provides the one or more characteristics to one or more other modules in the demodulator and decoding device.Type: GrantFiled: September 16, 2013Date of Patent: August 4, 2015Assignee: ViaSat, Inc.Inventors: Fan Mo, Sameep Dave
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Patent number: 9088370Abstract: In a coherent optical receiver, sufficient demodulation becomes impossible and consequently receiving performance deteriorates if an inter-channel skew arises, therefore, a coherent optical receiver according to an exemplary aspect of the invention includes a local light source, a 90° hybrid circuit, an optoelectronic converter, an analog to digital converter, and a digital signal processing unit; wherein the 90° hybrid circuit makes multiplexed signal light interfere with local light from the local light source, and outputs a plurality of optical signals separated into a plurality of signal components; the optoelectronic converter detects the optical signals and outputs detected electrical signals; the analog to digital converter quantizes the detected electrical signals and outputs quantized signals; the digital signal processing unit includes a skew compensation unit for compensating a difference in propagation delay between the plurality of signal components, and an FFT operation unit for performing a fasType: GrantFiled: December 19, 2014Date of Patent: July 21, 2015Assignee: NEC CORPORATIONInventors: Junichi Abe, Wakako Yasuda, Kiyoshi Fukuchi
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Patent number: 9042741Abstract: Described herein are systems and methods for accurately estimating and removing a carrier frequency offset. One exemplary embodiment relates to a system comprising a frequency offset detection circuit detecting a carrier frequency offset in an optical signal, and a frequency testing circuit calculating an estimated frequency offset value of the carrier frequency offset, wherein the frequency testing circuit removes a carrier phase based on the estimated frequency offset value and recovers the optical signal. Another exemplary embodiment relates to a method comprising detecting a carrier frequency offset in an optical signal, calculating an estimated frequency offset value of the carrier frequency offset, removing a carrier phase based on the estimated frequency offset value, and recovering the optical signal.Type: GrantFiled: March 15, 2011Date of Patent: May 26, 2015Assignee: AT&T INTELLECTUAL PROPERTY I, L.P.Inventor: Xiang Zhou
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Patent number: 9036999Abstract: One aspect provides an optical communication system. The system includes an optical-to-digital converter, a frequency estimator and a symbol synchronizer. The optical-to-digital converter is configured to receive an optical OFDM bit stream including an OFDM symbol bearing payload data and a symbol header preceding the OFDM payload data. The frequency estimator is configured to determine a carrier frequency offset of the payload data from the symbol header. The symbol synchronizer is configured to determine a starting location of the payload data within the bit stream by cross-correlating a synchronization pattern within the symbol header with a model synchronization pattern stored by the symbol synchronizer.Type: GrantFiled: July 29, 2011Date of Patent: May 19, 2015Assignee: Alcatel LucentInventors: Noriaki Kaneda, Timo Pfau, Qi Yang
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Patent number: 9037005Abstract: In one example, an optical channel monitor includes a tunable filter, a deinterleaver, first and second optical receivers, and a control module. The tunable filter is configured to receive an optical signal having a plurality of channels spaced at a nominal channel spacing. The deinterleaver has an input with an input channel spacing Fi, an even output, and an odd output, the input being connected to an output of the tunable filter. The nominal channel spacing is between about one and two times the input channel spacing Fi. A ?20 dB bandwidth of the tunable filter is between about two and four times the input channel spacing Fi. The first and second optical receivers are coupled to the deinterleaver even and odd outputs, respectively. The control module is coupled to the tunable filter and is configured to tune the tunable filter to a desired center frequency.Type: GrantFiled: December 9, 2013Date of Patent: May 19, 2015Assignee: FINISAR CORPORATIONInventor: John J. DeAndrea
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Patent number: 9031420Abstract: An optical signal is converted into an electric signal by an O/E converter on the reception side, and converted into a digital signal by an analog/digital conversion unit. In a capture unit A at the input stage of the digital signal processing unit at the next stage, the constellation of a signal output from an analog/digital conversion unit is acquired for each polarization. According to the constellation information, the amplitude value of the electric signal input to the analog/digital conversion unit is corrected so that the value is optimum. Also, the capture unit B acquires the constellation on the signal after the demodulation by the digital signal processing. According to the constellation information, the amplitude of the I and Q signals and the skew between the I and Q signals are corrected.Type: GrantFiled: February 5, 2013Date of Patent: May 12, 2015Assignee: Fujitsu LimitedInventor: Yuichirou Sakamoto
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Patent number: 9031421Abstract: Provided is a method of measuring signal transmission time difference of a measuring device. The measuring device according to embodiments, by measuring a skew on two optical paths through signal delays of sufficient sizes for skew measurement on the optical paths, even a skew having a minute size can be measured within a measurable range.Type: GrantFiled: July 3, 2013Date of Patent: May 12, 2015Assignee: Electronics and Telecommunications Research InstituteInventors: Joong-Seon Choe, Chun Ju Youn, Jong-Hoi Kim, Duk Jun Kim, Yong-Hwan Kwon, Kwang-Seong Choi, Eun Soo Nam
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Patent number: 9031403Abstract: A method includes sweeping an optical frequency of an optical signal by an optical transmitter controlling an electric-field information signal corresponding to a transmitted signal, providing different polarization states for individual frequencies of the optical signal by the optical transmitter controlling a mixture of a first electric-field information signal corresponding to a first transmitted signal and a second electric-field information signal corresponding to a second transmitted signal, obtaining, for individual frequencies of the optical signal, polarization dependent characteristics corresponding to different frequencies, when the optical transmitter sweeps the frequency of the optical signal, by an optical receiver calculating a polarization-dependent characteristic of an optical transmission line between the optical transmitter and the optical receiver, based on items of received-electric-field information corresponding to the different polarization states, and obtaining statistical informationType: GrantFiled: June 12, 2013Date of Patent: May 12, 2015Assignee: Fujitsu LimitedInventors: Hisao Nakashima, Takeshi Hoshida
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Publication number: 20150125160Abstract: Methods and apparatus for directly detected optical system based on gapped CAP modulation and DSP Methods for generation and reconstruction of gapped CAP signal are disclosed. An apparatus for direct detection transmission for CAP modulated signal with two unbalanced optical sidebands separated by gaps is disclosed, in which a gapped CAP signal is generated, converted, and passed to an optical filter for unbalanced sidebands generation and wavelength locking before being transmitted over an optical link. Direct detection is performed on the optical signal and passed to gapped matching filters. Channel equalization is performed and the signal information is decoded to binary data.Type: ApplicationFiled: November 7, 2013Publication date: May 7, 2015Applicant: Futurewei Technologies, Inc.Inventors: Yangjing WEN, Xiao SHEN, Yusheng BAI
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Patent number: 9025971Abstract: An optical receiving circuit includes: a first non-feedback amplifier configured to convert a current signal, obtained from a light receiving element in response to an optical signal, into a first voltage signal; a second amplifier configured to convert an input current signal into a second voltage signal, the output signal not being directly fed back to an input side; a differential amplifier configured to perform differential amplification on the first voltage signal and the second voltage signal and to output an in positive signal and a negative signal obtained through the differential amplification; and an offset compensation circuit configured to input, on the basis of the in positive signal and the negative signal output from the differential amplifier, an offset current signal in accordance with an offset of a level of the in positive signal from a level of the negative signal to the second amplifier.Type: GrantFiled: November 27, 2013Date of Patent: May 5, 2015Assignee: Fujitsu LimitedInventor: Satoshi Ide
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Patent number: 9025967Abstract: All-optical phase-modulated data signal regenerator apparatus (10) comprising an optical input (12), an optical signal converter (16), an optical carrier signal source (18), optical signal forming apparatus (20) and an optical output (14). The input (12) is arranged to receive a phase-modulated optical data signal. The signal converter (16) is arranged to receive the data signal and to convert phase modulation of the data signal into a corresponding intensity modulation of an intermediate optical signal. The carrier signal source (18) provides an optical carrier signal.Type: GrantFiled: December 10, 2009Date of Patent: May 5, 2015Assignee: Telefonaktiebolaget L M Ericsson (publ)Inventor: Ernesto Ciaramella
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Patent number: 9025651Abstract: Methods, systems, and devices are described for equalizing data from an optical signal. Samples are filtered with at least one filter to compensate for polarization mode dispersion in an optical path. The filtered samples may be used to determine errors based on a difference between a radius of a recovered symbol and a target radius. A parameter may be assigned to one or more of the errors and properties of the at least one filter may be updated based on the assigned parameters. The parameter may be assigned from a small set of parameters based on at least one threshold value. Outputs generated from the filtered samples may also be assigned a parameter from a different set of parameters. The parameter assigned to the output may be used to update the particular set of taps of the at least one filter from which the output was generated.Type: GrantFiled: March 15, 2013Date of Patent: May 5, 2015Assignee: ViaSat, Inc.Inventors: Sameep Dave, Fan Mo
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Patent number: 9025969Abstract: An optical signal receiver tracks local oscillator frequency offset (LOFO) and compensates for the phase distortion introduced in the received signals as a result of utilizing the local oscillator within a coherent detection scheme. This phase distortion is basically a constant phase rotation caused by the LOFO and implementation of the receiver using coherent detection and a digital interferometer instead of a conventional (yet complex) carrier phase estimation or recovery scheme. With an optical receiver implemented in this manner, the requirement of using a precise local oscillator laser with low frequency offset is less important.Type: GrantFiled: May 24, 2012Date of Patent: May 5, 2015Assignee: Futurewei Technologies, Inc.Inventors: Chuandong Li, Yuanjie Chen, Zhuhong Zhang, Yi Cai, Fei Zhu
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Patent number: 9025970Abstract: A comparator (11) outputs, out of an electrical signal input from a trans impedance amplifier (TIA) via a coupling capacitor, pulses having amplitudes equal to or larger than a reference value as a comparison output signal (Cout). An analog holding circuit (12) charges a holding capacitor with each pulse contained in the comparison output signal (Cout) and also removes a DC voltage obtained by the charging via a discharging resistor, thereby generating a holding output signal (Hout) that changes in accordance with the presence/absence of input of an optical signal. This allows to perform an autonomous operation without any necessity of an external control signal and properly detect the presence/absence of input of an optical signal.Type: GrantFiled: February 14, 2011Date of Patent: May 5, 2015Assignees: Nippon Telegraph and Telephone Corporation, NTT Electronics CorporationInventors: Hiroshi Koizumi, Kazuyoshi Nishimura, Masafumi Nogawa, Yoshikazu Urabe
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Patent number: 9020366Abstract: Provided are a polarization multiplexing optical receiving device and a polarization multiplexing optical receiving method with which a mismatch of optical intensity between polarized signals accumulated in an optical transmission path of an optical receiving system can be compensated with high precision, and a high-quality polarized optical signal can be received.Type: GrantFiled: January 20, 2012Date of Patent: April 28, 2015Assignee: NEC CorporationInventor: Takeshi Okamoto
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Patent number: 9020367Abstract: Optical devices are disclosed consisting of optical chips (planar lightwave circuits) which have optically symmetric or matching designs and properties and optical components which create asymmetry in the optical devices. The devices find application in detection in coherent and non-coherent optical communications systems.Type: GrantFiled: February 17, 2010Date of Patent: April 28, 2015Assignee: Oclaro Technology LimitedInventors: Stephen Jones, Robert Anthony Griffin, Paul Firth, Adrian Perrin Janssen, Colin Smith
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Patent number: 9020337Abstract: A local oscillation light source outputs locally-oscillated light. An light receiving unit phase-separates an input optical signal by making the optical signal interfere with the locally-oscillated light and outputs an analog electric signal corresponding to the phase-separated optical signal. An analog-to-digital converting unit converts the analog electric signal into a digital signal. A processing unit performs digital signal processing by using the digital signal. A failure detection unit determines whether or not the optical signal is being input to the light receiving unit, or detects a failure in the light receiving unit, the analog-to-digital converting unit or the processing unit based on light intensity of the optical signal, whether or not the analog electric signal can be generated in the light receiving unit, and an amplitude of the analog electric signal output from the light receiving unit.Type: GrantFiled: June 14, 2013Date of Patent: April 28, 2015Assignee: NEC CorporationInventor: Takashi Tsubouchi
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Patent number: 9020354Abstract: Remote control signal detection systems and methods are operable to compensate detected infrared energy to identify an infrared energy communication signal emitted by a remote control. An exemplary embodiment detects first infrared energy, wherein the infrared energy communication signal is absent in the first infrared energy; determines compensation based on the first infrared energy; detects second infrared energy, wherein the infrared energy communication signal is present in the second infrared energy; and compensates the second infrared energy based on the determined compensation.Type: GrantFiled: June 17, 2013Date of Patent: April 28, 2015Assignee: EchoStar Technologies L.L.C.Inventors: Samuel Eber, Eric Hieb
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Patent number: 9014573Abstract: A method for processing data in an optical network element are provided, wherein the optical network element comprises a local oscillator operating at a first frequency; wherein an incoming data stream is received at a second frequency; wherein the incoming data steam is processed using the first frequency; wherein a first pattern is searched in the incoming data stream; wherein a second pattern is searched in the incoming data stream; and wherein the first pattern corresponds to the first frequency being in the spectrum on one side of the second frequency and the second pattern corresponds to the first frequency being in the spectrum on the other side of the second frequency. Also, a corresponding optical network element and a communication system comprising at least one such optical network element are suggested.Type: GrantFiled: February 13, 2012Date of Patent: April 21, 2015Assignee: Xieon Networks S.a.r.l.Inventors: Harald Rohde, Thomas Treyer
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Patent number: 9014568Abstract: An optical access network with centralized digital optical line termination OLT including an optical line termination unit having a digital transmitter and a coherent receiver for downstream signal transmitting and upstream signal receiving, and at least one optical network unit ONU with transceiver functions for communicating with the OLT over an optical path, the ONU including intensity modulation and single photodiode detection, wherein the digital transmitter includes digital signal processing DSP, digital-to-analog conversion DAC and analog-to-digital conversion ADC functions that can be shared by all multiple ones of the ONU in the network, the DSP reducing or removing dispersion and non-linearity effects in the network and the coherent receiver enabling performance of the downstream stream signal transmitting to match that of the upstream signal receiving in the OLT.Type: GrantFiled: February 15, 2013Date of Patent: April 21, 2015Assignee: NEC Laboratories America, Inc.Inventors: Dayou Qian, Ting Wang
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Patent number: 9014574Abstract: In order to appropriately demultiplex the polarization multiplexed BPSK signal without using a training sequence and decreasing the resistance to a frequency offset, an optical receiver includes a coherent optical detection unit receiving an optical signal in which BPSK modulated carrier waves are polarization-multiplexed, performing coherent detection by mixing the received optical signal with local light, and outputting first electrical signals corresponding to the carrier waves; a butterfly FIR filter receiving the first electrical signals and extracting second electrical signals corresponding to each of the carrier waves from the first electrical signals; and a coefficient control unit for calculating a sum of respective phases of the second electrical signals output from the butterfly FIR filter, adaptively controlling tap coefficients of the butterfly FIR filter so that the calculated phase sum may become equal to 0 or ?, and outputting tap coefficients after being controlled to the butterfly FIR filterType: GrantFiled: February 28, 2012Date of Patent: April 21, 2015Assignee: NEC CorporationInventors: Manabu Arikawa, Daisaku Ogasahara, Emmanuel Le Taillandier de Gabory, Kiyoshi Fukuchi
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Patent number: 9014575Abstract: In a sampling clock synchronizing apparatus, an A/D converter converts an analog signal to a digital signal based on a sampling clock, and a processor compensates a band limitation due to spectral narrowing by filter characteristics of characteristics opposite to those of the spectral narrowing with respect to a signal produced from the A/D converter subjected to the spectral narrowing, and detects a phase shift in the sampling clock based on a signal after the compensation of the spectral narrowing and synchronizes sampling timing.Type: GrantFiled: January 6, 2012Date of Patent: April 21, 2015Assignee: Fujitsu LimitedInventors: Hisao Nakashima, Takeshi Hoshida
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Patent number: 9008520Abstract: Disclosed is a visible light communication system including a transmission device, including multiple light emitting units emitting light of different colors and mapping transmission data to a chromaticity point, calculating luminescence of each of the light emitting units, generating a preamble signal for channel matrix estimation, and emitting light based on the preamble signal and calculated luminescence amount. A reception device of the visible light communication system includes multiple light receiving units and estimates a channel matrix based on a corresponding optical signal when an optical signal corresponding to the preamble signal is received in each light receiving unit, compensates the optical signal corresponding to the chromaticity point for a propagation path based on the estimated channel matrix, detects a chromaticity point on the chromaticity coordinates based on a signal after the propagation path compensation, and demodulates the transmission data.Type: GrantFiled: April 2, 2013Date of Patent: April 14, 2015Assignee: Samsung Electronics Co., Ltd.Inventor: Atsuya Yokoi
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Publication number: 20150098714Abstract: A receiving device that converts, to a digital signal, a signal in which signal light from an optical transmission path and local oscillation light are mixed, so as to perform digital signal processing, the optical communication receiving device comprising: a frequency offset compensation unit configured to calculate a frequency offset of the digital signal and to, based on the frequency offset, compensate for a phase of the digital signal; a carrier phase recovery unit configured to calculate a carrier phase of the digital signal whose phase is compensated for in the frequency offset compensation unit; and a residual frequency offset detection unit configured to calculate an average of differences in the carrier phase, and to output the average as a residual frequency offset, wherein the frequency offset compensation unit is configured to correct the frequency offset using the residual frequency offset output by the residual frequency offset detection unit.Type: ApplicationFiled: September 24, 2014Publication date: April 9, 2015Applicant: Fujitsu LimitedInventors: Kazuhiko HATAE, Nobukazu KOIZUMI, Koji NAKAMUTA, Manabu YAMAZAKI, Tomoki KATOU, Masashi SATO, Hisao NAKASHIMA
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Publication number: 20150086221Abstract: A transimpedance amplifier (TIA) device. The device includes a photodiode coupled to a differential TIA with a first and second TIA, which is followed by a Level Shifting/Differential Amplifier (LS/DA). The photodiode is coupled between a first and a second input terminal of the first and second TIAs, respectively. The LS/DA can be coupled to a first and second output terminal of the first and second TIAs, respectively. The TIA device includes a semiconductor substrate comprising a plurality of CMOS cells, which can be configured using 28 nm process technology to the first and second TIAs. Each of the CMOS cells can include a deep n-type well region. The second TIA can be configured using a plurality CMOS cells such that the second input terminal is operable at any positive voltage level with respect to an applied voltage to a deep n-well for each of the plurality of second CMOS cells.Type: ApplicationFiled: July 24, 2014Publication date: March 26, 2015Inventors: Rahul SHRINGARPURE, Tom Peter Edward BROEKAERT, Gaurav MAHAJAN
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Patent number: 8989602Abstract: A digital coherent optical receiver includes a processor that is operative to separate electric signals obtained by converting an optical signal into a horizontal signal component and a vertical signal component; to generate a histogram of the horizontal signal component and the vertical signal component as outputs of the equalizing filter; and to determine a presence/absence of local convergence based on distribution of the histogram of the horizontal signal component and the histogram of the vertical signal component.Type: GrantFiled: October 27, 2011Date of Patent: March 24, 2015Assignee: Fujitsu LimitedInventors: Kosuke Komaki, Osamu Takeuchi
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Patent number: 8989599Abstract: Since it is difficult to fast, simply monitor impairments of received signals with higher receiver sensitivity, a monitoring method for an optical communication system according to an exemplary aspect of the invention includes the steps of emitting lightwave signals to be modulated according to a data, forming dips at transitions between temporally consecutive groups of n symbols of the lightwave signals, wherein the dips are formed at each of (n?1) first transitions of the group, no dip is formed at the n-th transition on the lightwave signals, receiving the lightwave signals, extracting frequency components characterized by the numerical value n from received lightwave signals, and monitoring the received lightwave signals by using the frequency components.Type: GrantFiled: February 28, 2011Date of Patent: March 24, 2015Assignee: NEC CorporationInventors: Emmanuel Le Taillandier De Gabory, Kiyoshi Fukuchi, Manabu Arikawa
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Patent number: 8989603Abstract: A coherent optical receiver according to an exemplary aspect of the present invention includes a coherent optical receiving unit, a first waveform equalizing circuit compensating waveform distortion caused by characteristics of the coherent optical receiving unit and compensating chromatic dispersion in a predetermined range to an input signal, a second waveform equalizing circuit compensating chromatic dispersion of the input signal, and a controller monitoring a chromatic dispersion amount of the input signal and controlling a compensation coefficient regarding the chromatic dispersion compensation performed by each of the first waveform equalizing circuit and the second waveform equalizing circuit depending on the chromatic dispersion amount to be compensated.Type: GrantFiled: October 4, 2012Date of Patent: March 24, 2015Assignee: NEC CorporationInventor: Makoto Shibutani
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Publication number: 20150078764Abstract: A method is provided for receiving an optical signal including a step of coherently detecting the optical signal, outputting a multicarrier signal received, and a step of processing the received multicarrier signal, which includes a step of estimating a frequency offset affecting the received multicarrier signal relative to a corresponding multicarrier transmitter signal. The estimation step implements two sub-steps including: a sub-step of determining the entire portion of the frequency offset; and a sub-step of determining the fractional portion of the frequency offset. The sub-step of determining the entire portion implements a measurement, in the spectral range, of an offset between the position of at least one specific carrier of the multicarrier transmitter signal and the position of the corresponding specific carrier or carriers in the received multicarrier signal.Type: ApplicationFiled: March 27, 2013Publication date: March 19, 2015Inventors: Julie Karaki, Erwan Pincemin
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Publication number: 20150078765Abstract: To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus.Type: ApplicationFiled: November 21, 2014Publication date: March 19, 2015Inventors: Koichi Ishihara, Takayuki Kobayashi, Riichi Kudo, Yasushi Takatori, Munehiro Matsui, Masato Mizoguchi, Akihide Sano, Shogo Yamanaka, Etsushi Yamazaki, Yutaka Miyamoto, Eiji Yoshida, Tadao Nakagawa
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Patent number: 8983309Abstract: A transmitter in an optical communications system includes a digital signal processor for processing a data signal to generate a sample stream encoding successive symbols in accordance with a constrained phase modulation scheme having a constellation of at least two symbols and a modulation phase constrained to a phase range spanning less than 4?. A digital-to-analog converter converts the sample stream into a corresponding analog drive signal. A finite range phase modulator modulates a phase of a continuous wavelength channel light in accordance with the analog drive signal, to generate a modulated channel light for transmission through the optical communications system. A receiver in the optical communications system includes an optical stage for detecting phase and amplitude of the modulated channel light and for generating a corresponding sample stream, and a digital signal processor for processing the sample stream to estimate each successive symbol of the modulated channel light.Type: GrantFiled: February 13, 2012Date of Patent: March 17, 2015Assignee: Ciena CorporationInventors: James Harley, Douglas McGhan, Shahab Oveis Gharan, Kim B. Roberts, Mark Rollins
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Patent number: 8983300Abstract: A system and a method are disclosed for receiving an infrared signal on a mobile device. The mobile device receives an infrared signal by creating an intermediate bitstream based on the received infrared signal. The intermediate bitstream is trimmed, downsampled, and demodulated in the time domain. The intermediate bitstream is then converted into a raw infrared code. The received bitstream is processed in a software layer, enabling the mobile device to process infrared signals without the use of additional hardware configured on the mobile device.Type: GrantFiled: May 6, 2014Date of Patent: March 17, 2015Assignee: Peel Technologies, Inc.Inventors: Samyeer Suresh Metrani, Siva Subramanian Muthukumarasamy
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Publication number: 20150071630Abstract: A non-linear distortion compensator includes: a non-linear distortion calculator that calculates non-linear distortion occurred in a received optical signal based on signal information after recovery of a carrier wave in a carrier wave phase recovery which recovers a phase of the carrier wave of the received optical signal; and a non-linear compensator that compensates the non-linear distortion of the received optical signal based on the non-linear distortion obtained by the non-linear distortion calculator.Type: ApplicationFiled: August 15, 2014Publication date: March 12, 2015Inventors: Tomofumi Oyama, Takahito Tanimura, Hisao Nakashima
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Publication number: 20150071652Abstract: Aspects of the present invention provide techniques for compensating nonlinear impairments of a signal traversing an optical communications system. A parallel array of linear convolutional filters are configured to process a selected set of samples of the signal to generate an estimate of a nonlinear interference field. The predetermined set of samples comprises a first sample and a plurality of second samples. A processor applies the estimated nonlinear interference field to the first sample to least partially compensate the nonlinear impairment.Type: ApplicationFiled: September 9, 2014Publication date: March 12, 2015Applicant: CIENA CORPORATIONInventors: Qunbi ZHUGE, Shahab OVEIS GHARAN, Michael Andrew REIMER, Maurice O'SULLIVAN
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Publication number: 20150071653Abstract: An optical communication system, a transmitter, a receiver, and methods of operating the same are provided. In particular, a transmitter is disclosed as being configured to encode optical signals in accordance with a multi-level coding scheme. The receiver is configured to provide skew correction to the optical signals received from the transmitter by dividing a received signal into separate level-specific components and sampling each of the components with distinct sampling blocks.Type: ApplicationFiled: September 6, 2013Publication date: March 12, 2015Applicant: Avago Technologies General IP (Singapore) Pte.Ltd.Inventors: Mike Allen Robinson, David W. Dolfi
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Patent number: 8977141Abstract: A parameter of an adaptive filter is optimized so that inter-symbol interference having an amount corresponding to an inserted fixed filter remains.Type: GrantFiled: February 7, 2012Date of Patent: March 10, 2015Assignee: Nippon Telegraph and Telephone CorporationInventors: Kengo Horikoshi, Etsushi Yamazaki, Takayuki Kobayashi, Eiji Yoshida, Yutaka Miyamoto
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Patent number: 8977139Abstract: A circuit may include a photodiode configured to receive an optical signal and convert the optical signal to a current signal. The circuit may also include a transimpedance amplifier coupled to the photodiode and configured to convert the current signal to a voltage signal. The circuit may also include an equalizer coupled to the transimpedance amplifier and configured to equalize the voltage signal to at least partially compensate for a loss of a high frequency component of the optical signal. The equalizer and the transimpedance amplifier may be housed within a single integrated circuit.Type: GrantFiled: October 29, 2012Date of Patent: March 10, 2015Assignee: Finisar CorporationInventors: Georgios Kalogerakis, Lionel Li, The'linh Nguyen
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Patent number: 8977140Abstract: An optical receiver includes: an interference unit generating a first interference light signal (ILS1) and a second interference light signal (ILS2) with an approximately inverse phase to that of the first interference light signal, by causing a received light signal to interfere with local oscillator light; a first interference light subtraction unit generating a first interference light subtraction signal (ILSS1) representing the difference between signals obtained by photoelectric conversion of ILS1 and a local oscillator light proportional signal having light intensity based on the light intensity of the local oscillator light; a second interference light subtraction unit generating a second interference light subtraction signal (ILSS2) representing the difference between a signal obtained by photoelectric conversion of ILS2 and the signal obtained by photoelectric conversion of the local oscillator light proportional signal; and a difference output unit outputting a signal representing the difference betType: GrantFiled: February 17, 2012Date of Patent: March 10, 2015Assignee: NEC CorporationInventor: Yasuyuki Suzuki
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Patent number: 8977138Abstract: A technique is provided for configuring an optical receiver. A photo detector is connected to a load resistor, and the photo detector includes an internal capacitance. A current source is connected through a switching circuit to the load resistor and to the photo detector. The current source is configured to discharge the internal capacitance of the photo detector. The switching circuit is configured to connect the current source to the internal capacitance based on a previous data bit.Type: GrantFiled: September 12, 2012Date of Patent: March 10, 2015Assignee: International Business Machines CorporationInventors: Jonathan E. Proesel, Alexander V. Rylyakov, Clint L. Schow, Yurii A. Vlasov