Patents by Inventor Kim B. Roberts
Kim B. Roberts has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8023402Abstract: 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 1<N<2, to generate a corresponding sample stream, and filtered using a low-pass filter characteristic having a cut-off frequency corresponding to 1/2T. Phase distortions due to the filtering are compensated by digitally processing the sample stream.Type: GrantFiled: December 21, 2009Date of Patent: September 20, 2011Assignee: Ciena CorporationInventors: Kim B. Roberts, Kuang Tsan Wu, Maurice O'Sullivan, Han Sun
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Publication number: 20110222854Abstract: 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.Type: ApplicationFiled: March 14, 2011Publication date: September 15, 2011Applicant: CIENA CORPORATIONInventors: Kim B. ROBERTS, James HARLEY
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Publication number: 20110222850Abstract: 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.Type: ApplicationFiled: March 11, 2010Publication date: September 15, 2011Applicant: NORTEL NETWORKS LIMITEDInventors: Kim B. ROBERTS, Maurice O'SULLIVAN, Ian BETTY
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Patent number: 8009985Abstract: 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 relation), 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.Type: GrantFiled: May 13, 2003Date of Patent: August 30, 2011Assignee: Ciena CorporationInventors: Kim B. Roberts, Jerome Chiabaut
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Publication number: 20110150505Abstract: 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 ?f between a transmit laser and a Local Oscillator (LO) of the receiver. A phase rotation ?(n) is computed based on the estimate of the frequency offset ?f, 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.Type: ApplicationFiled: December 22, 2009Publication date: June 23, 2011Applicant: NORTEL NETWORKS LIMITEDInventors: Kim B. ROBERTS, Ahmed AWADALLA
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Publication number: 20110142457Abstract: 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.Type: ApplicationFiled: March 11, 2010Publication date: June 16, 2011Applicant: NORTEL NETWORKS LIMITEDInventors: Ian BETTY, Kim B. ROBERTS, Christopher KUROWSKI
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Patent number: 7957641Abstract: Provided is an optical apparatus and method wherein power transfer coefficients arising from SRS are measured at a designated co-location point and the power of dithers, which are impressed on the channels of a multiplexed optical signal propagating through the optical apparatus, is measured at each co-location point. Within the optical apparatus distances between co-location points are short and the power transfer coefficients are effectively constant. Consequently, the power of each channel of the multiplexed optical signal at the co-location points is obtained from the power of the dithers at a respective one of the co-location points and the power transfer coefficients measured at the designated co-location point. In some embodiments, information on the channel power at the co-location points is used to provide instructions for compensating for fluctuations in channel power and/or channel count at an input and/or channel count within the optical apparatus.Type: GrantFiled: February 8, 2002Date of Patent: June 7, 2011Assignee: Ciena CorporationInventors: David W. Boertjes, Kim B. Roberts
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Publication number: 20110103795Abstract: 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.Type: ApplicationFiled: October 29, 2009Publication date: May 5, 2011Applicant: NORTEL NETWORKS LIMITEDInventors: Amir Keyvan KHANDANI, Han SUN, Kim B. ROBERTS
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Patent number: 7936999Abstract: In a coherent optical receiver, a method of at least partially compensating Polarization Dependent Loss (PDL) of an optical signal received through an optical communications system. A respective multi-bit sample stream of each one of a pair of orthogonal received polarizations of the optical signal is tapped, and used to derive a respective metric value indicative of a quality of each multi-bit sample stream. A gain of an analog front end of the coherent optical receiver is adjusted based on the derived metric values.Type: GrantFiled: September 20, 2006Date of Patent: May 3, 2011Assignee: Ciena CorporationInventors: Mark Hawryluck, Kim B. Roberts, Kuang Tsan Wu
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Patent number: 7930435Abstract: 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.Type: GrantFiled: May 2, 2008Date of Patent: April 19, 2011Assignee: Ciena CorporationInventor: Kim B. Roberts
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Patent number: 7899340Abstract: Methods and systems for compensating a frequency mismatch ?f between a local Oscillator (LO) of a coherent optical receiver and a carrier of a received optical signal. An average frequency of the LO is controlled to compensate at least long-period variations of the frequency mismatch. An electrical carrier recovery circuit for compensating short period variations of the frequency mismatch.Type: GrantFiled: April 7, 2006Date of Patent: March 1, 2011Assignee: Ciena CorporationInventors: Chandra Bontu, Han Sun, Kim B Roberts, Kuang Tsan Wu
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Patent number: 7894721Abstract: An optical network system having a global controller capable of controlling all the elements of the network. The controller receives performance data from each optical network element and calculates a performance value for each channel transmitting through the system. The controller then isolates the channel with the minimum performance value and tests possible changes in network element parameters to find a change which would increase this performance value. Once such a change is found, it is implemented and the system is reoptimized.Type: GrantFiled: September 19, 2006Date of Patent: February 22, 2011Assignee: Ciena CorporationInventors: Kim B. Roberts, Genzao G. Zhang, James Harley, Feng Shi, Leo Strawczynski
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Patent number: 7894728Abstract: A method of compensating phase error between parallel digital signals of a received optical signal, in a coherent optical receiver. A phase differential between the digital signals is determined. A digital skew is imposed between the digital signals, an amount of skew imposed being an integer number of sample periods calculated to most nearly compensate the phase differential. The skewed digital signals are then digitally processed, in the frequency domain, to compensate a residual portion of the phase differential.Type: GrantFiled: October 17, 2006Date of Patent: February 22, 2011Assignee: Ciena CorporationInventors: Han Sun, Chandra Bontu, Kim B. Roberts, John Sitch, John Wolczanski
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Publication number: 20100254702Abstract: 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.Type: ApplicationFiled: April 7, 2009Publication date: October 7, 2010Applicant: NORTEL NETWORKS LIMITEDInventors: Han SUN, Kuang Tsan WU, Kim B. ROBERTS
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Patent number: 7787713Abstract: A method of modulating an optical carrier. A target carrier modulation is computed based on an input data signal. An effective length of an optical modulator is then controlled based on the target carrier modulation.Type: GrantFiled: March 23, 2007Date of Patent: August 31, 2010Assignee: Ciena CorporationInventors: Kim B. Roberts, Michel Belanger
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Patent number: 7769305Abstract: In a coherent optical receiver, a frequency domain engine digitally processes at least two multi-bit sample streams of a received optical signal. The frequency domain engine includes a Fast Fourier Transform (FFT) filter for computing a complex vector representative of a frequency-domain spectrum of the received optical signal. A transpose and add block computes a vector sum of the complex vector and a transposed version of the complex vector, and an Inverse Fast Fourier Transform (IFFT) filter computes a complex output vector from the addition result. With this arrangement, parallel real filter operations are efficiently performed on each of the multi-bit sample streams, using a single back-to-back FFT-IFFT filter structure.Type: GrantFiled: September 21, 2006Date of Patent: August 3, 2010Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Han Sun, Chandra Bontu, Kuang Tsan Wu
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Publication number: 20100189443Abstract: 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.Type: ApplicationFiled: January 22, 2010Publication date: July 29, 2010Applicant: NORTEL NETWORKS LIMITEDInventors: David KRAUSE, Charles LAPERLE, Kim B. ROBERTS
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Patent number: 7756421Abstract: Nonlinearity-induced signal distortions are compensated by processing an input communications signal, in the electrical domain prior to Electrical-to-optical conversion and transmission through an optical link of a communications system. According to the invention, a compensation operator is determined that substantially mitigates the nonlinearity-induced signal distortions imparted to an optical signal traversing the communications system. The input communications signal is then input to the compensation operator to generate a predistorted electrical signal. This predistorted electrical signal is then used to modulate an optical source to generate a corresponding predistorted optical signal for transmission through the optical communications system. With this arrangement, arbitrary nonlinearity-induced signal distortions imparted by the optical link can be compensated in such a manner that a comparatively undistorted optical signal is obtained at the receiving end of the optical link.Type: GrantFiled: April 3, 2003Date of Patent: July 13, 2010Assignee: Ciena CorporationInventors: Kim B. Roberts, Leo Strawczynski, Maurice S. O'Sullivan
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Publication number: 20100138722Abstract: 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.Type: ApplicationFiled: December 3, 2008Publication date: June 3, 2010Applicant: NORTEL NETWORKS LIMITEDInventors: James HARLEY, Kim B. ROBERTS, Han SUN
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Patent number: 7701842Abstract: 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 1<N<2, to generate a corresponding sample stream, and filtered using a low-pass filter characteristic having a cut-off frequency corresponding to 1/2T. Phase distortions due to the filtering are compensated by digitally processing the sample stream.Type: GrantFiled: February 13, 2008Date of Patent: April 20, 2010Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Kuang Tsan Wu, Maurice O'Sullivan, Han Sun