Abstract: Included are embodiments for reducing interference in a communications network. At least one embodiment of a method includes receiving data related to an updated Power Spectral Density (PSD) mask and processing a first Seamless Rate Adaptation (SRA) request. Some embodiments include processing a second Seamless Rate Adaptation request and implementing the updated Power Spectral Density mask.

Abstract: Included are embodiments for subframe interleaving. At least one embodiment of a method includes receiving at least one subframe, the at least one subframe being derived from a plurality of frames of data and interspersing at least a portion of the at least one subframe according to a predetermined subframe interleaving strategy.

Abstract: In accordance with one embodiment, a method is implemented in a vectored system for improving a signal-to-noise ratio (SNR) of a far end transmitted signal on a victim line in the system. The method comprises mitigating, by the vectored system, self-induced far-end crosstalk (self-FEXT) on the victim line based on self-FEXT mitigation coefficients and receiving, by a second sensor, information relating to at least one of: self-FEXT of the vectored system, external noise, and the far end transmitted signal. The method further comprises learning, at the second sensor, coefficients relating to self-FEXT coupling into the second sensor and removing self-FEXT from the second sensor based on the learned coefficients. Upon removal of self-FEXT from the second sensor, a linear combiner configured to combine information relating to the victim line and the second line is learned.

Abstract: One embodiment is a method for precoding data for transmission in a discrete multi-tone (DMT) system to cancel self-induced far end crosstalk (self-FEXT). The method comprises learning, by the system, characteristics associated with a plurality of N users within a digital subscriber line (xDSL) system to determine an initial off-diagonal multiple input multiple output (MIMO) precoder (ODMP) for a given tone frequency and converging towards an ODMP from the initial ODMP to cancel self-FEXT for the plurality of N users, wherein the ODMP is represented as a zero diagonal matrix containing only off-diagonal terms.

Abstract: Systems and methods for monitoring impulse noise are described. At least one embodiment is a method, which comprises detecting whether impulse noise is present and in response to detecting the presence of impulse noise, performing time domain analysis to determine whether one or more impulse noise sources are present based on minimum interarrival time and maximum impulse length. The method further includes performing frequency domain analysis to estimate frequencies associated with the one or more impulse noise sources and based on the time domain analysis and frequency domain analysis, providing a total number of impulse noise sources and frequencies associated with the impulse noise sources. In this regard, the embodiments described herein provide dual-speed monitoring of impulse noise in the form of short-term and long-term monitoring.

Abstract: Various embodiments are described for back channel communication. One embodiment is a method that comprises receiving data at customer premises equipment (CPE), determining at least one error in the received data, formatting the determined error for communication to a central office (CO), and sending the formatted error to the CO via a back channel, wherein the formatted error is sent between sync frames of a discrete multitone (DMT) superframe.

Abstract: Systems and methods for reducing the peak-to-average power ratio (PAR) at the transmitter can reduce the dynamic range required in various analog components. PAR can be reduced by applying a time-domain compensation signal in the oversampled regime, using tones reserved for PAR reduction. A set of vectors corresponding to PAR tones is generated by processing out-of-phase symbols for each PAR tone to form a span matrix. The span matrix is used to find a best fit of a desired target signal to a time-domain compensation signal comprising only PAR tones.

Abstract: A technique for real-time formation of optimal power spectral density masks is disclosed. In one particular exemplary embodiment, the technique may be realized as a method for real-time formation of optimal power spectral density masks. The method may comprise sensing line conditions in a communication medium, wherein the communication medium is capable of carrying signals in a plurality of tones. The method may also comprise determining, in real-time, one or more power spectral density masks that substantially optimize transmissions of the signals in the plurality of tones. The method may further comprise transmitting the signals in the plurality of tones based on the one or more power spectral masks.

Abstract: A method implemented in a multi-user communication system is described for performing far-end crosstalk (FEXT) cancellation for each victim user. The method comprises performing dynamic programming to allocate resources according to (N?1) normalized disturber coupling values and difference rate function values associated with N total users in the system involved in partial FEXT cancellation. In accordance with some embodiments, dynamic programming comprises selecting a tone and one or more disturbers to be cancelled for the tone.

Abstract: Systems and methods for off-diagonal MIMO precoders are described. At least one embodiment includes a method for precoding data for transmission in a discrete multi-tone (DMT) xDSL system to cancel self-induced far end crosstalk (self-FEXT) comprising: learning characteristics associated with a plurality of N users within the xDSL system to determine an initial off-diagonal multiple input multiple output (MIMO) precoder (ODMP) for a given tone frequency; and converging towards an optimum ODMP from the initial ODMP in order to cancel downstream self-FEXT for the plurality of N users, wherein the ODMP is represented as a zero diagonal matrix with only off-diagonal terms, and wherein the converging towards the optimum ODMP comprises: maximizing the channel capacity for the plurality of N users for the given tone frequency; and minimizing an increase in transmit power of the xDSL system relative to an original transmit power where a precoder is not active.

Abstract: A system is described that comprises a frequency domain impulse noise detector configured to monitor received discrete multi-tone (DMT) symbols for impulse noise, a Reed Solomon (RS) decoder with erasure and erasure correction capability for performing error correction on received DMT symbols, and an optimization module configured to adjust parameters associated with the impulse noise detector, the optimization module configured to adjust values for ?pivot, ?c, and a ratio (m/M), wherein M is a number of monitored tones, m is a number of slicer error samples that must exceed a decision threshold for a symbol to be flagged as corrupted, and ?pivot and ?c are values associated with a monotonic function of a ratio of a statistical parameter of disruptive noise to a statistical parameter of nominal noise.

Abstract: An amplifier including complementary push and pull components, a bias component and a quiescent current balancer. The complementary push and pull components are serially coupled to one another between an electrical source and sink to generate an output signal at a common output terminal responsive to the input signal source. The bias component is coupled between the input signal source and the complementary push-pull components to bias the input signal to the push component and the input signal to the pull component by discrete amounts which reduce cross-over clipping exhibited in the output signal. The quiescent current balancer is coupled to the output terminal to balance quiescent currents in the push and the pull component at discrete levels which equilibrate amplification levels of the input signal generated by the push component and the pull component in the output signal at the output terminal.

Abstract: A transceiver having shared and discrete components forming a transmit path and a receive path configured to couple to a subscriber line for establishing a communication channel with a remote transceiver. The transceiver comprises a pseudo link manager coupled between the transmit and receive path components to manage pseudo links on the subscriber line prior to entry into a session with the remote transceiver. The pseudo link manager includes: a line monitor and a disruptor. The line monitor monitors the subscriber line, prior to initiating a session, for a received communication signal indicative of a pre-existing session on the remote transceiver. The disruptor transmits a disruptor signal over the subscriber line to the remote transceiver responsive to the detection by the monitor of the received communication signal; thereby disrupting the remote transmitter's pre-existing session and allowing a new session to be established with the remote transceiver.

Abstract: Included are embodiments for back channel communication. At least one embodiment of a method includes receiving data at customer premises equipment and determining at least one error in the received data. Some embodiments include formatting the determined error for communication to a central office and sending the formatted error to the central office via a back channel.

Abstract: Systems and methods for resolving signal-to-noise ratio margin difference n dual latency discrete multi-tone (DMT)-based xDSL systems under colored noise conditions. Rather than assuming a constant power spectral density (PSD) for noise over fast and interleaved data paths of a dual latency system, band edges vulnerable to colored noise are determined and data on the fast data path is allocated away from these band edges. Also, receive windowing may be used to further enhance performance.

Abstract: An adaptive hybrid system is coupled to a loop for adjusting trans-hybrid loss. The system comprises a fixed portion comprising a first receiver transfer function block and a first hybrid transfer function block. The fixed portion is configured to receive a far-end signal and mitigate frequency dependent attenuation experienced by the far-end signal. The system also comprises a variable portion comprising a second receiver transfer function block and a second hybrid transfer function block configured to subtract a transmit echo from the received far-end signal.

Abstract: A multi-tone transceiver including: a channel controller and a plurality of components forming a transmit path and a receive path. The channel controller configured to determine bit-loading for each successive symbol or tone set based on a 1st noise margin target for a first subset of tones in each tone set dedicated to transport of a robust communications channel (RCC) and based on a 2nd noise margin target less than the 1st noise margin target for remaining tones in each tone set dedicated to a standard communications channel (SCC). The plurality of components forming the transmit and receive paths are responsive to the channel controller to select for data modulated on a given tone at least one of smaller constellations and higher gain scaling levels when the given tone corresponds to an RCC tone as compared to an SCC tone, whereby the first set of tones dedicated to the RCC exhibit greater immunity to noise variations than the remaining tones dedicated to the SCC.

Abstract: An xDSL modem having an adaptive hybrid termination impedance. The modem has a transformer with two cores, one connected to the modem's receiver and the other connected to the modem's transmitter. The two cores share an adjustable termination impedance. The modem determines which impedance setting to use, based on one or more measurements of channel loss, local echo power and received power from the far end transmitter, and the like.

Abstract: A multi-tone transceiver including: a transform component, a tone selector, an error detector, an aggregator and an oscillator. The transform component transforms received communications from the time domain to the frequency domain. The tone selector selects a sub-set of the received tones which exhibit an elevated signal-to-noise ratio (SNR) as a clock recovery tone set (CRTS) and drops and add tones to the CRTS as required by changes in the SNR of the individual tones. The error detector detects phase errors in each received tone of the CRTS. The aggregator calculates an average aggregate phase error from all tones in the CRTS. The oscillator controls clocking of the transceiver. The oscillator is responsive to the average aggregate phase error to adjust a clock phase in a direction which reduces a phase error with a clock on the opposing transceiver.

Abstract: A method is described for reducing self-induced far end crosstalk (self-FEXT) in a multiple input multiple output (MIMO) digital subscriber line (xDSL) system. An initial value for an off-diagonal multiple input multiple output canceller (ODMC) is derived while the ODMC is inactive and while in data mode. The method includes activating the initial ODMC and converging towards an steady-state value for the ODMC by performing an adaptive algorithm to maximize the Shannon's capacity of the system and to reduce upstream self-FEXT. Bit loading is performed and a frequency domain equalizer (FEQ) is updated.