Abstract: A transceiver having shared and discrete components forming a transmit path and a receive path configured to couple to a communication medium for establishing a multi-tone modulated communication channel thereon. The transceiver includes a line driver component on the transmit path. The line driver is configured to respond to a protocol determination and by configuring at least one of a transmit power level and a transmit bandwidth of the multi-tone modulated communication channel on the communication medium. The line driver includes a plurality of pre-amplifiers each exhibiting a combination of transmit power and bandwidth for amplification of a transmit signal modulated with a selected multi-tone modulation protocol. The line driver also includes a single output amplifier having an output coupled to the communication medium and an input switchably coupled to an output of a selected one of the plurality of pre-amplifiers in response to the protocol determination.

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: 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: A modem employing feedback control coding to dynamically control signal-to-noise ratios and to identify errored codewords for retransmission. The receive path components of the modem include a signal-to-noise estimator, a feedback controller and a dynamic demapper. The signal-to-noise estimator repeatedly determines a difference between a target signal-to-noise ratio (SNR) and actual SNR in communications received from an opposing modem. A feedback controller responds to each determination by the signal-to-noise controller to send to the opposing modem a set of modified transmit control parameters for reducing the difference between the target and actual SNRs. The dynamic demapper dynamically alters constellation size or power spectral density for demapping communications received from the opposing modem responsive to a change in transmission parameters thereof resulting from the modified set of transmit control parameters.

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 switch for switchably coupling a signal source to a high impedance load. The switch includes a first bipolar transistor and a floating switch driver. The first bipolar transistor is configured to switchably couple the signal source to the high impedance load responsive to a driver signal applied to a base thereof. The floating switch driver has a control input and an output terminal coupled to the base of the first bi-polar transistor to supply the driver signal thereto. The driver signal comprises a limited forward current during the “On” state of the floating switch driver and a voltage “Voff” not less than the reverse breakdown voltage nor greater than the forward voltage drop across a base-emitter connection of the first bipolar transistor during the “Off” state of the floating switch driver.

Abstract: Double-ended line probing (DELP) techniques are described herein that enable a loop configuration to be identified based on mathematically simple error functions, which are both time-efficient and less sensitive to measurement errors. A DELP algorithm uses readily available data about the channel that is generated prior to the modem operation (e.g., theoretical loop models) and other available data (e.g., that provided by loop diagnostic modules) to estimate the loop configuration including the line length and gauge, as well as the number of bridge taps and their gauges, lengths, and locations.

Abstract: A modem configured to couple to a communication medium for establishing a communication channel thereon. The modem includes an interleaver component configurable as to interleaver parameters ‘I, D’ corresponding to block length and depth respectively. An interleaver memory buffers the communication channel. An interleaver controller controls writing to and reading from the memory of successive data elements of the communication channel with a quantity ‘I’ pairs of write and read pointers. Each pair or write and read pointers identifies memory locations corresponding with an input and output respectively of an associated one of ‘I’ virtual first-in-first-out (‘v-FIFO’) buffers in the memory. Control of the pointers required to read out the stored data elements in interleaved fashion is limited to shifting all pointers uniformly by one address block in each interleaver block cycle, which simplifies pointer management.

Abstract: A DSL line interface includes an impedance synthesizer that provides negative feedback to the differential amplifier in the DSL line interface so that the return loss standards for the return signal are met. The DSL line interface unit comprises a differential line driver including a first amplifier and a second amplifier for amplifying the DSL transmit signal, first and second complex termination modules coupled to the outputs of the first and second amplifiers, a transformer including a primary winding coupled to the transmission line and a secondary winding coupled to the first and second complex termination modules, and an impedance synthesizer module coupled between the secondary winding of the transformer and the first and second amplifiers to provide negative feedback to the first and second amplifiers.

Abstract: To reduce the ISDN crosstalk in an incoming DSL signal, a crosstalk canceller observes at least a portion of the crosstalk signal and reproduces an estimate of the crosstalk signal for at least a portion of that signal within the DSL band. The crosstalk canceller applies a canceling signal based on the estimated crosstalk signal to reduce the crosstalk in the received DSL signal.

Abstract: A multi-tone modem supporting multi-tone modulation protocols over multiple bundled transmission lines. The multi-tone modem is configured to transmit and receive communication channels each associated with a corresponding one of a plurality of transmission lines. The modem comprises at least one in-channel forward error correction component and a cross-channel forward error correction component. The at least one in-channel forward error correction component discretely encodes and decodes data from each communication channels transmitted and received over the plurality of transmission lines. The cross-channel forward error correction component encodes data from all communication channels and buffers the corresponding cross-channel redundancy symbols of each cross-channel codeword.

Abstract: Efficient implementation techniques of a low power mode, (i.e. L2 mode for ADSL2) for DSL transceivers are described. The techniques save memory space and reduce implementation complexity. A constellation mapper in a DSL transmitter determines the number of bits to be retrieved for an ith sub-carrier in the low power mode based on the number of bits allocated for this same sub-carrier in a normal transmission mode, (e.g. L0 mode in ADSL2) and a bit allocation threshold T. A constellation demapper in a DSL receiver determines the number of bits used for an ith sub-carrier in the low power mode based on the bit tables for the L0 mode and the bit threshold T.

Abstract: A high efficiency line driver is disclosed. The line driver may be applied with equal advantage in wired and wireless communication media to amplify data signals with a minimum of power consumption. In an embodiment of the invention a line driver is disclosed which includes: at least one amplifier, a delay element, a control signal generator and a generator. The at least one amplifier includes at least one bias supply, a signal input and a signal output. The delay element accepts as an input the data signal and delays delivery of the data signal to the at least one line amplifier for amplification. The generator is responsive to a control signal to generate varying voltage levels corresponding thereto on the at least one bias supply of the at least one amplifier. The control signal generator is responsive to the input data signal to detect peaks therein and to generate the control signal corresponding thereto in advance of delivery of the data signal to the amplifier.

Abstract: An inverse discrete Fourier transform (IDFT) processor processing a lower frequency image of a selected transmit band along with base images of remaining transmit bands called for in a corresponding X-DSL standard. A hybrid upconverter processing the IDFT output by generating a higher frequency replication of the imaged transmit band falling in the standards based frequency range along with the base band images of remaining transmit bands and selectively passing onto the communication medium only images or replications called for by the standards. A hybrid downconverter processing at least one of the received bands at sampling rates below Nyquist thereby creating a lower frequency image within the range of a discrete Fourier transform (DFT) processor. The hybrid downconverter clears the frequency band in which the image processed at sub-Nyquist rates will fold. The DFT then transforms only the images or replications falling within its frequency range.

Abstract: Modem selection of codeword interleaver parameters given standard based, operator based and channel based communication channel performance constraints. A processor implements processes for characterizing the forward error correction codeword and interleaver solution space in terms of expressions from which targeted portions of the solution space may be identified prior to evaluation of the magnitude of the coefficients of the corresponding nodes thereof for compliance with the communication channel performance constraints.

Abstract: A bundler, un-bundler and sequencer for use in controlling and driving opposing sets of logical or physical modems to drive multiple-subscriber lines with multiple communication channels. The sequencer determines subscriber requirements such as maximum and minimum bandwidth and quality of service. The sequencer also determines bandwidth availability and status of multiple subscriber lines from which a bundle may be formed. The bundler couple to the sequencer and implement header or headerless insertion of multiple channels in round robin sequence into the X-DSL frames at data rates which correspond with subscriber requirements. The un-bundler reverses the process of the bundler and passes the appropriate packet data onto the corresponding network.

Abstract: An inverse discrete Fourier transform (IDFT) processor processing a lower frequency image of a selected transmit band along with base images of remaining transmit bands called for in a corresponding X-DSL standard. A hybrid upconverter processing the IDFT output by generating a higher frequency replication of the imaged transmit band falling in the standards based frequency range along with the base band images of remaining transmit bands and selectively passing onto the communication medium only images or replications called for by the standards. A hybrid downconverter processing at least one of the received bands at sampling rates below Nyquist thereby creating a lower frequency image within the range of a discrete Fourier transform (DFT) processor. The hybrid downconverter clears the frequency band in which the image processed at sub-Nyquist rates will fold. The DFT then transforms only the images or replications falling within its frequency range.

Abstract: The present invention advantageously provides a method and apparatus for optimization of channel capacity in multi-line multi-tone communications such as X-DSL among subscriber lines which are bundled with one another. In an embodiment of the invention an apparatus for optimizing channel capacity of multi-tone communications effected by opposing sets of modems coupled to one another by a plurality of subscriber lines is disclosed. The apparatus includes a spectrum manager coupled to at least one of the opposing sets of modems. The spectrum manager includes: a profiler, a demand module and an optimizer. The profiler obtains from the at least one of the opposing sets of modems the spectral characteristics of each of the plurality of subscriber lines. The demand module determines for each of the plurality of subscriber lines the subscriber demand profile.

Abstract: A network modem which interfaces, in an embodiment of the invention, with existing wired media within a home. The network modems couple to an existing shared medium and utilize frequency division multiplexing to create a communication network thereon. Communication channels are established, discrete from one another in frequency space with each of the active modems coupled to the shared communications medium. Each communication channel carries simplex communications between two or more modems, and all simplex communication channels operate simultaneously to provide a network between all the active modems coupled to the shared communications medium.