Patent application number | Description | Published |
20080199189 | COLORLESS OPTICAL DEMODULATOR FOR DIFFERENTIAL QUADRATURE PHASE SHIFT KEYING DWDM SYSTEMS - A colorless optical DQPSK demodulator and system operating over multiple, equally-spaced DWDM channels with fixed optical delays—capable of demodulating DQPSK within signals within DWDM communications wave bands on ITU grids using delay interferometers having fixed free spectral range at 20 GHz or 25 GHz. | 08-21-2008 |
20080240736 | Inter-Symbol Interference-Suppressed Colorless DPSK Demodulation - An optical device includes an interferometer for a received optical differential phase shift keying DPSK signal, and an equalizer integrated with the interferometer in a manner for reducing from optical filtering effects an interference by signal bits of the DPSK signal with signal bits of a contiguous DPSK signal. The interferometer is a Michelson delay interferometer type, but can also be a Mach-Zehnder delay interferometer type on fiber, waveguide or other optical structure. The equalizer is a Fabry-Perot type equalizer, but can be a ring resonator type or a fiber based equalizer. | 10-02-2008 |
20080253768 | High Bit Rate Packet Generation with High Spectral Efficiency in an Optical Network - Optical packets are generated by generating a first optical beam with a first wavelength and a second optical beam with a second optical beam. The first optical beam is modulated with a payload signal and then filtered to reduce the bandwidth of the signal. The second optical beam is modulated with a label signal. The filtered modulated first optical beam and modulated second optical beam are combined to generate a dual-wavelength optical beam. | 10-16-2008 |
20080267630 | ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS (OFDMA) BASED PASSIVE OPTICAL NETWORK (PON) ARCHITECTURE AND ITS EXTENSION TO LONG DISTANCE - A passive optical network (PON) device, system and method include an optical line terminal (OLT) receiver configured to receive multiple signals at different wavelengths simultaneously and enable multiple transmitters to operate at the same time during one upstream time slot. The optical line terminal employs Orthogonal Frequency Division Multiple Access (OFDMA) to transparently support a plurality of applications and enable dynamic bandwidth allocation among these applications where the bandwidth is allocated in two dimensional frequency and time space. | 10-30-2008 |
20080294968 | Ultra High-Speed Optical Transmission Based on LDPC-Coded Modulation and Coherent Detection for All-Optical Network - An optical communication system includes a bit-interleaved coded modulation (BICM) coder; and a low-density parity-check (LDPC) coder coupled to the BICM coder to generate codes used as component codes and in combination with a coherent detector. | 11-27-2008 |
20090016739 | PATTERN EFFECT REDUCTION OF OPTICAL SIGNALS - A passive optical equalizer and a predistortion technique are employed to reduce pattern effect in optical signals which result from narrow filtering. | 01-15-2009 |
20090052907 | WAVELENGTH TRANSMISSION SYSTEM AND METHOD USING 3-DIMENSIONAL LDPC-CODED MODULATION - A transmitter and method include a LDPC encoder configured to encode source data, and a mapper configured to generate three coordinates in accordance with a | 02-26-2009 |
20090059351 | DEMODULATOR SYSTEM AND METHOD USING MULTILEVEL DIFFERENTIAL PHASE SHIFT KEYING - A demodulator and demodulation method includes an optical coupler configured to receive an input signal. The optical coupler couples the signal to an even number of branches. Each branch including at least one interferometer configured to split, combine and interfere with an optical signal from one of within the branch or from another branch. A common optical delay is disposed on one of every two branches between the optical coupler and the interferometer of the branch. | 03-05-2009 |
20090092393 | Coherent Optical Orthogonal Frequency Division Multiplexing (OFDM) Reception Using Self Optical Carrier Extraction - A method includes producing interference between a received optical OFDM signal and an optical carrier extracted from the received optical OFDM signal to provide optical coherent detection of the received optical OFDM signal. Preferably, producing the interference includes optically splitting the received optical OFDM signal into a first part that is filtered to extract the carrier from the received optical OFDM signal and a second part similar to the received optical OFDM signal. | 04-09-2009 |
20090162066 | Intra-Channel Equalizing Optical Interleaver - An apparatus includes an interleaver configuration for at least one of combining or separating odd and even channel groups to achieve channel density doubling; and an optical equalizer for suppressing inter symbol interference within the channels to provide intra-channel equalizing in the optical path, the equalizer being integrated into the interleaver. Preferably, optical equalizer and interleaver are integrated together as a single monolithic device, the optical equalizer includes a passband that has a dip in the channel center to achieve a raised-cosine filtering profile in the optical signal path to achieve inter-symbol interference ISI suppression, and the equalizer includes integration into the optical path of the interleaver to realize a monolithic device combining or separating odd and even channel groups to achieve channel density doubling. Preferably, also, the optical equalizer includes a first equalizer with half the depth of required ripple dips at both a first output port and an input port and a second equalizer with half the depth of required ripple dips at a second output port. | 06-25-2009 |
20090177945 | POLARIZATION MODE DISPERSION COMPENSATION USING BCJR EQUALIZER AND ITERATIVE LDPC DECODING - A turbo equalizer includes a Bahl-Cocke-Jelinek-Raviv (BCJR) equalizer configured to receive a transmitted signal and partially cancel inter-symbol interference (ISI) due to polarization-mode dispersion (PMD). A low-density parity check (LDPC) decoder is coupled to the BCJR equalizer to receive channel bit reliabilities therefrom. The LDPC decoder iteratively provides extrinsic soft information feedback to the BCJR equalizer to compensate for PMD. | 07-09-2009 |
20090199065 | GLDPC ENCODING WITH REED-MULLER COMPONENT CODES FOR OPTICAL COMMUNICATIONS - A method of encoding for optical transmission of information includes encoding information with a generalized low-density parity-check (GLDPC) code for providing coding gains, and constructing the GLDPC code with a Reed-Muller RM code as a component code, the component code being decodable using a maximum posterior probability (MAP) decoding. In a preferred embodiment, the GLDPC code includes a codeword length of substantially 4096, an information word length of substantially 3201, a lower-bound on minimum distance of substantially greater than or equal to 16, a code rate of substantially 0.78 and the RM component code includes an order of substantially 4 and an r parameter of substantially 6. | 08-06-2009 |
20090202243 | Direct Detection For Receiving Polarization Multiplexing Signals - There is provided a method for detecting optical signals comprising employing a photo diode to both directly detect a received optical signal and convert it into an electrical signal for recovery of data bit stream information in the received optical signal, the received optical signal being derived from a separation of two polarization multiplexed optical signals that were combined before being received. | 08-13-2009 |
20090245810 | Dynamic Signal Equalization in Optical Transmission Systems - In an optical transmission system, data is transmitted via an optical beam modulated with an arbitrary waveform. The optical beam is transmitted through at least one optical element. Transmission through at least one optical element degrades the signal quality of the initial optical beam. The signal characteristics of at least one optical beam at the output of least one optical element are used as feedback to shape the arbitrary waveform to improve signal characteristics. An arbitrary waveform may be used to compensate signal degradation caused by a multiplexer/demultiplexer in a wavelength division multiplex system. | 10-01-2009 |
20090259912 | LDPC CODES AND STOCHASTIC DECODING FOR OPTICAL TRANSMISSION - A method for error correction and a decoder using low density parity check (LDPC) codes includes initializing extrinsic probability information between variable nodes and check nodes in a bipartite graph including generating a Bernoulli sequence according to a probability of a bit having a value one. Parity checking is performed in accordance with a parity check equation. If the parity check equation is not satisfied, then extrinsic information is updated in check nodes from variable nodes using a parity node update logic circuit in a first half iteration, extrinsic information is updated in variable nodes from check nodes using a variable node update logic circuit in a second half iteration, and the variable nodes are updated with a probability based upon the extrinsic information passed between check nodes and variable nodes wherein the probability represents a likelihood that an ith bit is a one. Information bits are passed when the parity check equation is satisfied or a predetermined number of iterations has been reached. | 10-15-2009 |
20090274460 | DIFFERENTIAL DELAY RECEIVER USING CROSS-POLARIZATION INTERFEROMETER FOR POLMUX-DPSK SYSTEM - A differential delay detection system and method includes an optical splitter to split an incoming optical signal between a first path and a second path. The first path includes a cross-polarization interferometer configured to separately generate polarization independent outputs using split paths and to generate cross-polarization interference outputs, and a polarization demultiplexer configured to combine the polarization independent outputs and the cross-polarization interference outputs from the cross-polarization interferometer with updated coefficients received from the second path to remove the cross-polarization mixed signals, The second path includes a training signal receiver configured to compute the updated coefficients and output the updated coefficients to the polarization demultiplexer. | 11-05-2009 |
20090282314 | MULTIDIMENSIONAL TURBO PRODUCT CODES AND GENERALIZED LOW-DENSITY PARITY-CHECK CODES WITH COMPONENT REED-SOLOMON CODES FOR OPTICAL TRANSMISSION - A transmitter, a receiver, and corresponding methods are provided. The transmitter includes encoders configured to encode source bit streams from L information sources into bytes of codewords. Each encoder includes different (n, k) multidimensional turbo-product codes of code rate R=k/n, where k is a number of information bytes, and n is code word length. The encoders operate in at least two phases. A first phase involves operating k | 11-12-2009 |
20090285577 | Optical Frontend for Integration of Optical and Wireless Networks - Data is transmitted by radio over fiber in a wavelength division multiplex optical transmission system. Data is transmitted over a single optical channel by directly modulating a single wavelength laser with a baseband data signal. Multiple single wavelength laser beams are multiplexed into a single multi-wavelength laser beam. All of the single optical channels are up-converted to RF frequencies by modulating the intensity of the multi-wavelength laser beam with an RF carrier. | 11-19-2009 |
20090297144 | POLARIZATION MODE DISPERSION COMPENSATION IN MULTILEVEL CODED-MODULATION SCHEMES USING BLAST ALGORITHM AND ITERATIVE POLARIZATION CANCELLATION - Receivers and methods are provided for polarization mode dispersion compensation in multi-level coded-modulation schemes using a BLAST algorithm and iterative polarization cancellation. A receiver includes a vertical Bell Laboratories Layered Space-Time Architecture (V-BLAST) orthogonal frequency division multiplexing (OFDM) detector configured to receive input sequences and partially cancel polarization interference with respect to the input sequences to output symbol estimates for the input sequences. The receiver further includes one or more low-density parity-check (LDPC) decoders coupled to the V-BLAST OFDM detector configured to receive channel bit reliabilities and output code words. The channel bit reliabilities are indirectly calculated from the symbol estimates. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the V-BLAST OFDM detector to compensate for the polarization interference. | 12-03-2009 |
20100027994 | Phase Modulation Of An Optical Orthogonal Frequency Division Multiplexing Signal - A method includes generating an optical orthogonal frequency division multiplexing OFDM signal with in-phase and quadrature-phase components; varying an RF carrier according to the in-phase and quadrature-phase components; and modulating a phase of a lightwave carrier according to the varied RF carrier to generate an optical OFDM signal with equalized amplitude. | 02-04-2010 |
20100050048 | MITIGATION OF FIBER NONLINEARITIES IN MULTILEVEL CODED-MODULATION SCHEMES - A receiver and method are provided for mitigation of finer non-linearities in multilevel coded-modulation schemes. The receiver includes a multilevel Bahl-Cocke-Jelinek-Raviv (BCJR) equalizer configured to receive channel samples of an input signal, partially mitigate fiber non-linearities, and provide symbol reliabilities. The receiver further includes a bit probabilities module coupled to the BCJR equalizer configured to calculate soft bit reliabilities from the symbol reliabilities. The receiver also includes one or more low-density parity-check (LDPC) decoders coupled to the bit probabilities module and the BCJR equalizer, configured to receive the soft bit reliabilities and output code words. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the BCJR equalizer to compensate for the fiber non-linearities. | 02-25-2010 |
20100215371 | POLARIZATION MODE DISPERSION (PMD) COMPENSATION IN POLARIZATION MULTIPLEXED CODED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (OFDM) SYSTEMS - A receiver and method are provided. The receiver includes a detector configured to receive polarization multiplexed coded orthogonal frequency division multiplexing input sequences and generate estimates of unknown transmitted symbols in the input sequences for x- and y-polarization channels with respect to laser phase noise and PMD. A demapper coupled to the detector is configured to partially cancel polarization mode dispersion (PMD) in the input sequences by computing symbol probabilities for the estimates with respect to the laser phase noise, and averaging the symbol probabilities with respect to the laser phase noise. One or more low-density parity-check (LDPC) decoders coupled to the demapper are configured to receive bit probabilities derived from the averaged symbol probabilities and output code words based at least on the bit probabilities. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the demapper to compensate for the PMD. | 08-26-2010 |
20110085624 | CODED POLARIZATION-MULTIPLEXED ITERATIVE POLAR MODULATION - Systems and methods for optical communication that use a transmitter/receiver. The systems and methods include receiving a modulated, encoded input stream. Channel memory is reduced using coarse digital backpropagation and other channel impairments are removed using turbo equalization. Symbols are detected in the input stream that conform to a non-uniform, polar constellation having a Gaussian source distribution to produce a stream of encoded data. The stream of encoded data is decoded with one or more low density parity check (LDPC) decoders. | 04-14-2011 |
20110182428 | SECURE COMMUNICATION OVER PASSIVE OPTICAL NETWORK (PON) WITH QUANTUM ENCRYPTION - Systems and methods to communicate securely includes communicating quantum encryption data on a first wavelength-division multiplexing passive optical network (WDM-PON); and communicating data over separate classical channels of a second WDM-PON, wherein the second WDM-PON synchronizes with the first WDM-PON while providing data communication over the classical channels. | 07-28-2011 |
20120207470 | SPATIAL DOMAIN BASED MULTI DIMENSIONAL CODED MODULATION FOR MULTI TB PER SECOND SERIAL OPTICAL TRANSPORT NETWORKS - An optical transport network based on multimode/multicore fibers includes a mode-multiplexer to multiplex independent data streams from one or more transmitters; a multimode erbium-doped fiber amplifier (MM EDFA) to compensate for MMF loss; a multimode optical add-drop multiplexer (MM OADM) to add and/or drop multimode channels in multimode networks; a multimode optical cross-connect; and a mode-demultiplexer to separate various mode streams to one or more receivers. | 08-16-2012 |
20120216093 | SOFT-DECISION NON-BINARY LDPC CODING FOR ULTRA-LONG-HAUL OPTICAL TRANSOCEANIC TRANSMISSIONS - Methods and systems for soft-decision non-binary low-density parity-check (LDPC) coding for ultra-long-haul optical transoceanic transmissions are provided. A receiver includes one or more maximum a posteriori (MAP) equalizers configured to decode one or more symbols of an encoded input stream to provide one or more symbol log-likelihood ratios (LLRs). One or more LLR estimators are configured to estimate the log-likelihood ratios of the one or more symbol LLRs to provide one or more bit LLRs. One or more non-binary LDPC decoders are configured to decode the input stream using the one or more bit LLRs to recover an original input stream. | 08-23-2012 |
20120251111 | OPTOELECTRONIC WAVELENGTH CONVERTER FOR POLARIZATION MULTIPLEXED OPTICAL SIGNALS - A wavelength converter that operates on an optical signal having single or multiplexed polarizations and which exhibits any modulation format. | 10-04-2012 |
20120257895 | FOUR-DIMENSIONAL OPTICAL MULTIBAND-OFDM FOR BEYOND 1.4TB/S SERIAL OPTICAL TRANSMISSION - Systems and methods are disclosed to perform four-dimensional optical multiband OFDM communication by organizing an N-dimensional (ND) signal constellation points as a signal matrix; performing 2D-inverse FFT and 2D-FFT to perform modulation and demodulation, respectively; and applying both orthogonal polarizations in the OFDM communication to deal with chromatic dispersion, PMD and PDL effects, and multidimensional signal constellation to improve optical signal-to-noise ratio (OSNR) sensitivity. | 10-11-2012 |
20120257896 | CODED MULTIDIMENSIONAL PULSE AMPLITUDE MODULATION FOR ULTRA-HIGH-SPEED OPTICAL TRANSPORT - Systems and methods are disclosed to provide optical communication by using subcarriers as individual bases functions, obtaining signal constellation points of an N-dimensional pulse amplitude modulation (ND-PAM) constellation diagram as an N-dimensional Cartesian product of a one-dimensional PAM; and transmitting the N-dimensional signal constellation point over all N orthogonal subcarriers serving as individual bases functions. | 10-11-2012 |
20120260142 | FOUR-DIMENSIONAL NON-BINARY LDPC-CODED MODULATION SCHEMES FOR ULTRA HIGH-SPEED OPTICAL FIBER COMMUNICATION - Systems and methods are disclosed for communicating signals, by receiving a K-symbol-long input block from a 2 | 10-11-2012 |
20120263251 | GENERALIZED OFDM (GOFDM) FOR ULTRA-HIGH-SPEED SERIAL OPTICAL TRANSPORT NETWORKS - A coded multidimensional modulation system called generalized OFDM (GOFDM) uses orthogonal subcarriers as bases functions, and the signal constellation points of corresponding multidimensional constellation diagram are obtained as N-dimensional Cartesian product of one-dimensional PAM/two-dimensional QAM. In GOFDM, the N-dimensional/2N-dimensional signal constellation point is transmitted over all N subcarriers/2N-subcarriers, which serve as individual bases functions. Even if some of the subcarriers are severely affected by channel distortion, the overall signal constellation point will face only small distortion, when strong channel capacity achieving channel codes are used. In addition, because the channel capacity is a linear function of number of dimensions, the spectral efficiency of optical transmission systems is significantly improved. Finally, since Euclidean distance of multidimensional signal constellation is much larger that that of two-dimensional signal constellations, OSNR sensitivity is dramatically improved. | 10-18-2012 |
20120263466 | MULTIDIMENSIONAL HYBRID MODULATIONS FOR ULTRA-HIGH-SPEED OPTICAL TRANSPORT - Systems and methods are disclosed with a spatial-domain-based multi-dimensional coded-modulation scheme that improves dramatically OSNR sensitivity and tolerance to fiber nonlinearities by using D-dimensional signal constellations, where D=2(2+M)N. The factor 2 originates from two polarizations, 2+M electrical basis functions are selected (2 in-phase/quadrature channels and M pulse-position like basis functions), and N represents the number of orbital angular momentum (OAM) states used in FMFs/MMFs. For single mode fiber applications N is 1. | 10-18-2012 |
20120307933 | ENERGY EFFICIENT CONSTELLATION METHOD AND SYSTEM - A method and apparatus employing statistical physics energy minimization methods to signal constellation design. By using statistical physics concepts, an energy-efficient signal constellation design algorithm (EE-SCDA) is described. In the presence of amplified spontaneous emission (ASE) noise and channel impairments, we use EE-SCDA to determine a source distribution, and represent the signal constellation design as a center of mass problem. Furthermore a discrete-time implementation of D-dimensional transceiver as well as corresponding EE polarization-division multiplexed (PDM) system is described. | 12-06-2012 |
20120321318 | CARRIER AND SUBCARRIER HOPPING FOR OPTICAL OFDM SECURITY - Methods and systems for secure communication include assigning data streams to respective orthogonal sub-carriers according to random number information at a transmitter. The data streams are modulated onto the respective orthogonal sub-carriers before the orthogonal sub-carriers are transmitted. The random number information is transmitted on a second medium, separate from the transmission medium. The orthogonal sub-carriers are received from the transmission medium at a receiver, while the random number information is received from the second medium at the receiver. The orthogonal sub-carriers are associated with data streams using the random number information and demodulated to produce data for the associated data stream. | 12-20-2012 |
20130091399 | HIGH-SPEED LONG CODEWORD QC-LDPC SOFT DECISION DECODER - A Quasi-Cyclic, LDPC, large girth, soft-decision decoder and accompanying methods. | 04-11-2013 |
20130108270 | VARIABLE BIT-RATE QPSK TRANSMITTER AND METHOD EMPLOYING POLARIZATION MANIPULATION | 05-02-2013 |