Patent application number | Description | Published |
20080281984 | HUB AND SPOKE COMPRESSION - A method of compressing data traffic for transmission through a network, the method comprises computing, for each one of a plurality of contexts of data traffic within the network, a respective optimal dictionary for encoding data traffic; For each block of data to be transmitted through the network: identifying a block context of the block of data; and encoding the block of data using the respective dictionary computed for the context corresponding to the identified block context. | 11-13-2008 |
20090201796 | LOW CONVERSION RATE DIGITAL DISPERSION COMPENSATION - A method of suppressing effects of aliasing in a system for digitally processing a high speed signal having a symbol rate of 1/T. The high speed signal is sampled at a fractional multiple (N) of the symbol rate, wherein 108-13-2009 | |
20090245799 | PROTECTED LIGHT SOURCE FOR MULTIPLE WAVELENGTH DIVISION MULTIPLEXED PASSIVE OPTICAL NETWORKS (WDM-PONS) - A protected light source for generating seed light for at least two wavelength division multiplexed passive optical networks (WDM-PONs). The protected light source includes an optical coupler having N≧2 input ports and M≧2 output ports, each output port being optically connected to supply seed light to a respective set of one or more WDM-PONs. A respective multi-wavelength light source (MWLS) is optically coupled to supply seed light to each input port of the optical coupler. A controller unit controls operation of each multi-wavelength light source (MWLS). | 10-01-2009 |
20090256622 | SOFT THERMAL FAILURE IN A HIGH CAPACITY TRANSMISSION SYSTEM - A method of managing operation of an Integrated Circuit (IC) designed to process a signal A temperature of the IC is detected, and signal processing performed by the IC adjusted based on the detected temperature. | 10-15-2009 |
20100031114 | LOW DENSITY PARITY CHECK (LDPC) DECODER USING BROADCAST MESSAGING - In a decoder implementing a belief propagation algorithm for iteratively decoding a Low Density Parity Check (LDPC) encoded data block, a method of computing messages to be sent by a first node of the decoder to at least one neighbour node of the decoder. The method comprises: processing messages received by the first node to remove an echo of a previous message sent by the first node to the at least one neighbour node in a previous iteration, to yield corresponding modified messages; computing a message for a current iteration using the modified messages; and broadcasting the computed message for the current iteration to each of the at least one neighbour nodes. | 02-04-2010 |
20100067902 | OPTICAL TRANSMITTER ERROR REDUCTION USING RECEIVER FEEDBACK - Described is a method of reducing transmitter error in an optical communications channel. An optical signal transmitted from an optical transmitter that has impairment due to transmitter error is processed to generate a digitally-equalized signal. A nonlinear characteristic of the digitally-equalized signal that relates to the transmitter error is determined. An optical control signal comprising data that are based on the nonlinear characteristic is transmitted to the optical transmitter. The optical transmitter modifies a transmitter parameter in response to the optical control signal to change the nonlinear characteristic and thereby reduce the impairment. | 03-18-2010 |
20100092181 | LOW CONVERSION RATE DIGITAL DISPERSION COMPENSATION - A method of suppressing effects of aliasing in a system for digitally processing a high speed signal having a symbol rate of 1/T. The high speed signal is sampled at a fractional multiple (N) of the symbol rate, wherein 104-15-2010 | |
20100138722 | CYCLE SLIP LOCATION AND CORRECTION - Methods and techniques are disclosed for correcting the effect of cycle slips in a coherent communications system. A signal comprising SYNC bursts having a predetermined periodicity and a plurality of known symbols at predetermined locations between successive SYNC bursts is received. The received signal is partitioned into data blocks. Each data block encompasses at least data symbols and a set of check symbols corresponding to the plurality of known symbols at predetermined locations between a respective pair of successive SYNC bursts in the signal. Each data block is processed to detect a cycle slip. When a cycle slip is detected, the set of check symbols of the data block are examined to identify a first slipped check symbol, and a phase correction applied to data symbols of the data block lying between the first slipped check symbol and an end of the data block. | 06-03-2010 |
20100189443 | HIGH SPEED SIGNAL GENERATOR - A high-speed signal generator. A digital signal processing (DSP) block generates a set of N (where N is an integer and N≧2) parallel digital sub-band signals, each digital sub-band signal having frequency components within a spectral range between 0 Hz and ±Fs/2, where Fs is a sample rate of the digital sub-band signals. A respective Digital-to-Analog Converter (DAC) processes each digital sub-band signal to generate a corresponding analog sub-band signal, each DAC having a sample rate of Fs/2. A combiner combines the analog sub-band signals to generate an output analog signal having frequency components within a spectral range between 0 Hz and ±NFs/2. | 07-29-2010 |
20100254702 | CLOCK RECOVERY WITH CHANNEL COEFFICIENTS - In a coherent optical receiver of an optical communications network, a method of recovering a clock signal from a high speed optical signal received through an optical link. A set of compensation vectors are adaptively computed for compensating Inter-symbol Interference (ISI) due to at least polarization impairments of the optical signal. A channel delay is estimated based on the computed compensation vectors. The estimated channel delay is subtracted from the computed compensation vectors to generate corresponding modified compensation vectors. Finally, the modified compensation vectors are used to derive a recovered clock signal. | 10-07-2010 |
20110103795 | SOFT DECODING OF DATA IN A COHERENT OPTICAL RECEIVER - In a coherent optical receiver receiving a polarization multiplexed optical signal through an optical communications network, a method of compensating noise due to polarization dependent loss (PDL). A Least Mean Squares (LMS) compensation block processes sample streams of the received optical signal to generate symbol estimates of symbols modulated onto each transmitted polarization of the optical signal. A decorrelation block de-correlates noise in the respective symbol estimates of each transmitted polarization and generating a set of decorrelated coordinate signals. A maximum likelihood estimator soft decodes the de-correlated coordinate signals generated by the decorrelation block. | 05-05-2011 |
20110142457 | INTEGRATED TRANSMIT AND RECEIVE MODULES FOR A COHERENT OPTICAL TRANSMISSION SYSTEM - An integrated optical package includes a package mount including a plurality of electrical connectors. A digital electronic integrated circuit (IC) is electrically connected to the electrical connectors of the package mount via a first set of solder balls or bumps. An optical IC includes optical waveguide traces and one or more electrical contact points for electrically coupling the optical IC to the digital electronic IC via a second set of solder balls or bumps. One or more optical fibre pig-tails optically coupled to the optical waveguide traces of the optical IC. | 06-16-2011 |
20110150505 | ZERO MEAN CARRIER RECOVERY - A method of data symbol recovery in a coherent receiver of an optical communications system. Two or more SYNC bursts, having a known symbol sequence and periodicity, are processed to derive an estimate of a frequency offset Δf between a transmit laser and a Local Oscillator (LO) of the receiver. A phase rotation κ(n) is computed based on the estimate of the frequency offset Δf, and applied to a plurality of data symbol estimates to generate corresponding rotated symbol estimates. The rotated symbol estimates are then filtered to generate corresponding decision values of each data symbol. | 06-23-2011 |
20110222850 | SELF TEST OF A DUAL POLARIZATION TRANSMITTER - A method of testing a dual-polarization optical transmitter comprising a pair of polarization transmitters for respectively generating first and second polarization signals, and a polarization combiner for generating an optical signal composed of the first and second polarization signals with respective orthogonal polarization vectors. Each of the polarization transmitters is controlled to transmit respective polarization optical signals having predetermined characteristics. An output of the dual-polarization optical transmitter is tapped to obtain a first tap signal representative of the first polarization signal, and a second tap signal representative of the second polarization signal. A relative angle between respective polarization vectors of the tap signals is controlled, and the first and second tap signals combined to generate a combined light. A power level of the combined light is detected, and processed to obtain information about the performance of the dual polarization transmitter. | 09-15-2011 |
20110222854 | COHERENT OPTICAL HUBBING - An optical communications system includes a hub modem and a set of two or more remote modems. Each remote modem includes a transmitter stage for transmitting a respective uplink data stream within a selected one of a set of two or more sub-channels. The hub modem optically communicates with the set of remote modems. The hub modem includes a receiver stage having an optical front-end for receiving an uplink optical channel signal within a spectral range that encompasses the set of two or more spectral sub-bands; a photodetector for detecting modulation components of the received uplink optical channel signal and for generating a corresponding high bandwidth analog signal; and a digital signal processor for processing the high bandwidth analog signal to recover the respective uplink data stream transmitted by each remote modem. | 09-15-2011 |
20110268442 | COHERENT AUGMENTED OPTICAL ADD-DROP MULTIPLEXER - In an Optical Add-Drop Multiplexer, a drop section comprises a Wavelength Selective Switch (WSS) having at least one drop-port, the WSS being operative to couple a respective set of w (where w> | 11-03-2011 |
20120063786 | CLOCK RECOVERY WITH CHANNEL COEFFICIENTS - In a coherent optical receiver of an optical communications network, a method of recovering a clock signal from a high speed optical signal received through an optical link. A set of compensation vectors are adaptively computed for compensating Inter-symbol Interference (ISI) due to at least polarization impairments of the optical signal. A channel delay is estimated based on the computed compensation vectors. The estimated channel delay is subtracted from the computed compensation vectors to generate corresponding modified compensation vectors. Finally, the modified compensation vectors are used to derive a recovered clock signal. | 03-15-2012 |
20120076507 | SINGLE PIN COHERENT RECEIVER - In a coherent optical receiver of an optical communications system, methods and systems for receiving a data signal x(t) modulated on an optical signal. A linearly polarized LO light is generated, which has a frequency of f | 03-29-2012 |
20120189309 | PROTECTED LIGHT SOURCE FOR MULTIPLE WAVELENGTH DIVISION MULTIPLEXED PASSIVE OPTICAL NETWORKS (WDM-PONS) - A protected light source for generating seed light for at least two wavelength division multiplexed passive optical networks (WDM-PONs). The protected light source includes an optical coupler having N≧2 input ports and M≧2 output ports, each output port being optically connected to supply seed light to a respective set of one or more WDM-PONs. A respective multi-wavelength light source (MWLS) is optically coupled to supply seed light to each input port of the optical coupler. A controller unit controls operation of each multi-wavelength light source (MWLS). | 07-26-2012 |
20120219288 | TRAFFIC DRIVEN VARIABLE BANDWIDTH OPTICAL TRANSMISSION - Link bandwidth is varied based on the subscriber traffic load. Varying the link bandwidth has the effect of varying the actual noise margin of the link (in an inverse elation), so that the noise margin will vary inversely with the traffic load. A beneficial result is that, because the noise margin is increased during “off-peak” traffic periods, rapidly varying and burst impairments can be absorbed without causing data loss. In effect, the respective probability distributions of error bursts and traffic load are separated. Data loss only becomes a significant risk when peaks in both distributions coincide. However, the probability of that event occurring is comparatively low. This enables a lower noise margin allocation during design of the link, which dramatically reduces the link cost. | 08-30-2012 |
20120321325 | PARALLEL CONVERSION BETWEEN OPTICAL AND DIGITAL - A coherent optical receiver Includes an electro-optic module coupled to an electronic signal processing Integrated circuit (IC) via a parallel analog transmission line bus. The electro-optic module receives and detects an optical channel light including a high-bandwidth signal modulated thereon. The electro-optic module includes: a single optical hybrid for mixing the optical channel light with a corresponding continuous wave local oscillator light to generate a mixed light containing the high-bandwidth data signal, at least one photodetector; and an analog frequency decimator for generating a set of parallel analog signals, each analog signal representing a respective portion of the high-bandwidth signal. The electronic signal processing IC includes a respective Analog-to-digital (A/D) converter for sampling each one of the set of parallel analog signals, and for generating corresponding parallel digital sample streams; and a digital signal processor (DSP) for processing the parallel digital sample streams to extract the high-bandwidth signal. | 12-20-2012 |
20130136450 | SIGNAL EQUALIZER IN A COHERENT OPTICAL RECEIVER - A signal equaliser for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments. | 05-30-2013 |
20130191696 | PARITY FRAME - A method of forward error correction in an optical communications system. A signal to be transmitted is logically defined as a super-frame comprising a plurality of frames including a parity frame and a predetermined set of data frames. Each frame of the super-frame is processed in accordance with a first FEC scheme having a known error correlation characteristic. At least the set of data frames is processed in accordance with a second FEC scheme which is selected based on the error correlation characteristic of the first FEC scheme. | 07-25-2013 |
20130209089 | CONSTRAINED CONTINUOUS PHASE MODULATION AND DEMODULATION IN AN OPTICAL COMMUNICATIONS SYSTEM - 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 4π. 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. | 08-15-2013 |
20140161469 | HIGH SPEED SIGNAL GENERATOR - A high-speed signal generator. A digital signal processing (DSP) block generates a set of N (where N is an integer and N≧2) parallel digital sub-band signals, each digital sub-band signal having frequency components within a spectral range between 0 Hz and ±Fs/2, where Fs is a sample rate of the digital sub-band signals. A respective Digital-to-Analog Converter (DAC) processes each digital sub-band signal to generate a corresponding analog sub-band signal, each DAC having a sample rate of Fs/2. A combiner combines the analog sub-band signals to generate an output analog signal having frequency components within a spectral range between 0 Hz and ±NFs/2. | 06-12-2014 |
20140212149 | SOFT DECODING OF DATA IN A COHERENT OPTICAL RECEIVER - In a coherent optical receiver receiving a polarization multiplexed optical signal through an optical communications network, a method of compensating noise due to polarization dependent loss (PDL). A Least Mean Squares (LMS) compensation block processes sample streams of the received optical signal to generate symbol estimates of symbols modulated onto each transmitted polarization of the optical signal. A decorrelation block de-correlates noise in the respective symbol estimates of each transmitted polarization and generating a set of decorrelated coordinate signals. A maximum likelihood estimator soft decodes the de-correlated coordinate signals generated by the decorrelation block. | 07-31-2014 |