Conexant Systems, Inc.

Mindspeed Technologies, Inc.

Silicon Laboratories Inc.

Pctel, Inc.

Hi-trend Technology (shanghai) Co., Ltd.

Xuming Zhang

Zhenyu Zhou

Sverrir Olafsson

Yuanjie Chen

Markos G Troulis

Evangelos Petsalis

The present invention relates to communication field, disclosing a data block interleaving and deinterleaving method and apparatus for communication equipments. In the present invention, a recursive method for calculating interleaver or deinterleaver addresses for existing power line communication standards is proposed. The complex modulo operation is simplified to a series of Add-Compare-Subtract operations. Therefore, the hardware implementation complexity is significantly reduced.

Data block interleaving and deinterleaving method and apparatus for communication equipments

In one embodiment, a device includes but is not limited to: a precoder having a precoder input and a precoder output; a spectral shaper, having a spectral-shaper transfer function and being operably coupled internal to said precoder; and a precoder filter, internal to the precoder, the precoder filter having a transfer function which provides substantially the inverse of the spectral-shaper transfer function.

Combining precoding with spectral shaping

Systems compensate for the presence of digital impairments using adaptive constellation techniques. Sample magnitudes are estimated from received samples transmitted during a training period using an algorithm based on minimizing the sum of squares of the estimated errors, afterwhich a suitable constellation is derived. In one embodiment, an optimum least-squares algorithm is employed. In an alternate embodiment, a least mean squares (LMS) or normalized LMS algorithm is performed.

Methods and apparatus for adaptive PCM level estimation and constellation training

A method and for optimizing bit rate throughput in a digital communication system is provided. The method includes establishing a relationship between signal to noise ratio and plural symbol rates for a particular constellation size. The method also includes determining noise power spectral density (N(f)), wherein N(f) is determined during a silent period of line probing; determining X(f), wherein X(f) is determined by turning on a remote station transmit signal, after N(f) has been measured and determining residual echo E(f), wherein E(f) is determined by turning on a central station echo canceller.

Method and system for data rate optimization in a digital communication system

A technique for identifying the encoding law utilized by a central office codec may be implemented in a receive modem. The encoding law, which is typically dictated by the country in which the central office is located, is employed to generate a plurality of transmission levels during an initialization period associated with the modem system. The receive modem analyzes a number of these transmission levels to determine whether the levels have certain characteristics associated with the particular encoding law followed by the central office codec. When the receive modem detects the codec type, it may transmit a suitable identifier back to the transmit modem.

Method and apparatus for identifying the encoding type of a central office codec

The time domain equalizer filter of the present invention increases the data rate of a communications system while shortening a channel. Such a time domain equalizer filter is spectrally flat and the central tap is constrained to a non-zero real number. The error between the data filtered by the time domain equalizer filter and the data filtered by a target filter is reduced by adapting the time domain equalizer filter and the target filter. Adaptation of the time domain equalizer filter and the target filter may be accomplished by calculating new tap values for each filter while constraining the central tap of the time domain equalizer filter. In this way, the error between the data filtered by the time domain equalizer filter and the data filtered by the target filter may be reduced, so that a shortened channel may be provided. Accordingly, by shortening the channel and balancing the use of a spectrally flat time domain equalizer filter, the data rate of the communications system may be increased.

Spectrally flat time domain equalizer and methods

A convolutional interleaver includes an interleaver memory partitioned into a plurality of circular buffers, wherein each of the circular buffers has associated write pointers and read pointers, and wherein the interleaver is configured to selectively read symbols from an input vector and store the input symbols in the interleaver memory in accordance with the write pointers, and to selectively read symbols from the interleaver memory to form an output vector in accordance with the read pointers. In one aspect, symbols are written to the interleaver prior to reading; in another, the position of the write pointer corresponds to the position of the read pointer within the circular buffer, and symbols are read from said interleaver memory prior to writing. In another aspect, a de-interleaver applies the concepts and algorithms described above in an inverse manner.

Convolutional interleaver employing an efficient memory scheme

Systems compensate for the presence of digital impairments using adaptive constellation techniques. Sample magnitudes are estimated from received samples transmitted during a training period using an algorithm based on minimizing the sum of squares of the estimated errors, after which a suitable constellation is derived. In one embodiment, an optimum least-squares algorithm is employed. In an alternate embodiment, a least mean squares (LMS) or normalized LMS algorithm is performed.

Method and apparatus for adaptive PCM level estimation and constellation training

The present invention relates to multiple modulus conversion (MMC) techniques for mapping data in a pulse code modulation (PCM) modem system. In accordance with the present invention, signal point constellations are arranged to receive the output indices generated by the MMC procedure such that the probability of transmission of higher power codewords is relatively low compared to the probability of transmission of lower power codewords, while maintaining the same or larger minimum distance between signal points. In addition, the present invention provides techniques for obtaining the probability of occurrence for each constellation or signal point associated with a given data communication session and for determining the theoretical average transmit power associated with a given set of signal point constellations and MMC parameters. In addition, the present invention provides a method for estimating a reasonable upper bound for the average transmit power associated with a given set of signal point constellations and MMC parameters. The present invention is also capable of transmitting the codewords defined by an MMC procedure in a specific order that may be optimized in accordance with a particular cost function associated with the modem system.

Method and apparatus for implementing enhanced multiple modulus conversion techniques in a signal point mapping context

An improved two-point equalizer training technique for use with V.90 modem systems utilizes a number of scaling parameters to enable the compensation of robbed bit signaling (RBS) effects in a manner that is decoupled from the compensation of analog impairments in the data communication channel. The preferred technique employs six scaling parameters corresponding to the six RBS phases typically associated with practical V.90 systems. One of the scaling parameters is fixed at a value of one to simplify the computational load associated with the adaptive training algorithms. The decision error is utilized to adaptively adjust the equalizer filter taps and the scaling parameters. The techniques of the present invention may be used to initially train the equalizer resident at the analog client modem and/or to initially train the echo canceler resident at the digital server modem.

Method and apparatus for training equalizer structures in a digital communication system having periodic digital impairments

A method and apparatus for controlling and shaping the spectrum of transmitted signal samples having predetermined frequency characteristics and allowable transmit signal levels. A running measure of unwanted components is measured and, for each block of the transmitted samples, an objective function based on the previously calculated running measure is computed. Depending upon the measurements, redundancy is determined and selected for each block of the transmitted samples. Accordingly, at least one redundant sample may be added or, the sign of the sample modified, at structured or randomized locations within the block to optimize the objective function.

System for controlling and shaping the spectrum and redundancy of signal-point limited transmission

A method and apparatus for performing spectral shaping transmitted samples with a set of predetermined frequency characteristics and a predetermined set of allowable transmitted signal levels are disclosed. The method first calculates, for each of the transmitted samples, a running measure of unwanted components upto the current sample. It then computes, for each block of the transmitted samples, an objective function based on the running measure previously calculated. It then selects, for each block of the transmitted samples, at least one redundant sample to be added or at least one transmitted sample to be modified, at structured or randomized location within the block to optimize the objective function. The location of the dependent sample can further be fixed, scrambled (pseudo random) or randomized. The method of computing can be any one of the following: a Running Filter Sum, a Running Fourier Transform (&ldquo;RFT&rdquo;) or Fast FT (&ldquo;RFFT&rdquo;), or an RDS, for each transmitted sample.

Method and apparatus for spectral shaping in signal-point limited transmission systems

An improved multiple modulus conversion (MMC) procedure is provided that employs an alternate scheme for obtaining the MMC outputs in response to a binary input of a number of bits. The alternate MMC procedure utilizes short-word division operations such that a practical digital processor may efficiently perform the required binary divisions. An exemplary short-word division process partitions the original long-word binary input into a plurality of short binary words, each having an equal number of bits. Individual short words or a combination of two short words are then divided by the appropriate modulus in a systematic manner to obtain the quotient and remainder associated with the particular division operation. The short-word divisions technique may be employed throughout the entire MMC procedure to suitably obtain the output values associated with each modulus.

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Mission Viejo, CA, United States of America

Xuming Zhang