An ADSL spectral compatibility system provides for computer (200) having a processor (210) in communication with a memory (220) and input/output (I/O) unit (230). I/O unit (230) is adapted to receive data from a broadband test head (BBTH) (240) and/or a database (250) of network configuration data. The ADSL system and a method are for deploying remote-terminal (RT)-based ADSL in a manner that is compatible with central office (CO)-based ADSL so as to maximize both the upstream and downstream data transmission rates while maintaining compliance with spectrum management guidelines.

Method and system for spectrally compatible remote terminal ADSL deployment

Cross-correlation based echo canceller controllers are described herein. By way of example, a system for controlling an echo canceller having one or more adaptive filters can include one or more adaptive filter controllers each corresponding to one of the one or more adaptive filters and each configured to halt adaptation of its corresponding adaptive filter according to the cross-correlation of its corresponding corrupted signal and its corresponding error signal of its corresponding adaptive filter.

Cross-correlation based echo canceller controllers

A hybrid circuit within a full-duplex transceiver transmits an outgoing signal outward on a communication channel at the same time it receives an incoming signal arriving via the communication channel, and the outgoing and incoming signals sum to form a combined signal. The hybrid circuit generates both the outgoing signal and a replica of the outgoing signal in response to an input signal, and then subtracts the replica from the combined signal in producing a received signal. The received signal includes a component derived from the incoming signal and a residual echo component having peaks resulting from a phase difference between the outgoing signal and its replica. The transceiver periodically digitizes the received signal to produce a data sequence representing the incoming signal. The transceiver adjustably delays the input signal so that the residual echo component peaks occur at times other then when the received signal is being digitized, thereby minimizing the influence of the echo component peaks on the data sequence.

Residual echo reduction for a full duplex transceiver

A method and apparatus for reducing crosstalk in a multi-channel communication system is disclosed. In one embodiment, outgoing signals in a multi-channel environment are manipulated into a transform domain, such as the frequency domain. Thereafter, the signals may be combined and modified based on a weighting variable to create a cancellation signal. Combined processing greatly reduces system complexity and increases processing speed. After processing in the transform domain, the cancellation signal undergoes further processing to return the cancellation signal into the time domain. The cancellation signal may then be combined with received signals to cancel crosstalk or echo. A method and apparatus for crosstalk cancellation in the analog domain and digital domain are also disclosed. Cancellation at least partially in the analog domain reduces the dynamic range requirements for digital to analog converters within the front-end processing system of a receiver and thereby reduces clipping and increases operating speed.

Mixed domain cancellation

A power line communication method for realizing data communication between at least one first or sending power line communication partner device and at least one second or receiving power line communication partner device. The method checks transmission conditions of a plurality of possible communication channels, thereby generating transmission condition data descriptive for the communication conditions of the respective possible communication channels. Additionally, communication conditions of the plurality of possible communication channels are selected as actual communication conditions based on the transmission condition data.

Power Line Communication Methods and Devices

The present invention provides methods and systems for providing efficient use of available CPU cycles that may be achieved by reducing the length of the echo canceller filter. An echo canceller's adaptive algorithm may be implemented to reach a lower mean squared error due to the increased training time allowed by cycle reduction. Total power consumption of a processor may be reduced by reducing the number of multiplications (and/or other operations) that may be performed by an echo canceller filter for each time iteration. This may be achieved by not performing multiplications on taps that are not being used. For higher rates, a shorter echo canceller filter may be implemented by transmitting less energy in low frequencies. As a result, the temporal length of the echo channel may be shortened thereby reducing the total number of taps needed to model the channel. The present invention may further enhance performance by reducing CPU cycles and allowing for more echo canceller training time.

Method and system for varying an echo canceller filter length based on data rate

The present invention provides methods and systems for improving the performance of a pair of non discrete multi-tone based digital subscriber line modems by choosing transmitted power spectral densities according to line conditions. The G.SHDSL and HDSL2 standards, for example, may specify the transmitted power to be less than a certain value at any given frequency. The present invention provides a method and system for shaping power spectral density based on line conditions where first line condition data associated with a first modem is determined; second line condition data associated with a second modem is determined; the first and second line condition data are exchanged, and a transmit spectrum is shaped in response thereto.

Method and system for shaping transmitted power spectral density according to line conditions

The present invention is directed to methods and systems for providing an accurate estimate of the channel capacity that may be performed for each symbol rate tested during line probe. In addition, an optimal symbol rate under a set of conditions may be determined using the capacities for each tested symbol rate. In the G.SHDSL (or other) standard, provisions may be made for rate negotiation to take place between two communicating modems after a line probe session. The present invention provides an approach to rate negotiation that implements an approximation of channel capacity using a geometric mean calculation. The capacity for a plurality of M frequency sub-bands may be computed to find an estimate of channel capacity for a rate of interest. The sub-bands may be any segment of a total N frequency bands found with a discrete Fourier transform (DFT) or other method of spectrum estimation.

Method and system for determining data rate using sub-band capacity

The present invention is directed to methods and systems for estimating the log base-2 of a fixed point binary number using a single polynomial for an entire possible range of input numbers. An estimation of the log base-2 of a fixed-point binary number in either hardware or software may be implemented using a minimal number of parameters. In particular, a single 2 nd order or greater polynomial may be sufficient to cover an entire range of input values for any arbitrary input word precision. The present invention provides a method and system for estimating a logarithm of a number where a linear approximation of a fractional part is determined and the linear approximation is implemented in a single polynomial function for estimating the fractional part for a range of input values. A circuit for generating an integer part and an estimate of a fractional part of a logarithm may include a shift register for loading a valid input data and for generating an estimate of a fractional part and a counter for loading a total number of bits in an input data and for generating an integer part, wherein the circuit implements a single polynomial for generating an improved estimate of the fractional part.

Method and system for estimating a base-2 logarithm of a number

The present invention is directed to methods and systems for determining maximum power backoff for modems operating according to G.SHDSL and other standards using frequency domain geometric signal to noise ratio (SNR). In one example, a G.SHDSL standard may specify a minimum power back off (PBO) that may be required for modem implementation. Although the standard specifies the minimum back off, it is desirable to be able to increase the PBO beyond this level. The reasons for this may include reduced power consumption and reduced crosstalk generated by a modem. The present invention discloses a method and system for determining an absolute maximum power PBO that may be tolerated and still meet bit error rate (BER) and/or other requirements. The present invention implements a geometric mean to compute SNR in a frequency domain over a pass-band of a transmit spectrum.

Michael Graziano

Papers

Method and system for varying an echo canceller filter length based on data rate

Method and system for shaping transmitted power spectral density according to line conditions

Method and system for determining data rate using sub-band capacity

Method and system for estimating a base-2 logarithm of a number

Method and system for determining maximum power backoff using frequency domain geometric signal to noise ratio