Broadcom Corporation

Pairgain Technologies, Inc.

Thuji Simon Lin

Robindra B Joshi

Steven T Jaffe

Stephen Edward Krafft

Tian-Min Liu

Jeffrey Scott Putnam

Anders Hebsgaard

L Randall Mote, Jr

Joey Y Chen

Paul T Yang

Thomas J Kolze

Bruce Joseph Currivan

Jonathan S Min

Tak Kwan Lee

Loke Kun Tan

Fang Lu

Kevin Lee Miller

Jeffrey Douglas Carr

Ravi Bhaskaran

David Jones

Gopal Triplicane Venkatesan

James P Cavallo

Igor Djokovic

Hsin-An Liu

A method of compensating for carrier frequency and phase errors of a received multi-carrier modulated signal. The received multi-carrier signal including modulated carriers for transmitting known data and unmodulated carriers for error correction, comprising, time domain down converting the received multi-carrier signal to base-band to provide a down-converted signal, the down-converted signal including a plurality of modulated carriers for transmitting known data and unmodulated carriers for error correction. Sampling an unmodulated carrier of the down-converted signal to provide received data samples. Providing a reference signal derived from the unmodulated carrier of the down-converted signal. And, estimating phase errors from a phase difference between the ummodulated carrier and the reference signal derived from the unmodulated carrier of the down-converted signal to provide a plurality of received sample phase error estimates for each modulated carrier.

System and method for multi-carrier modulation

A device of dynamic communication of information allows, on the average, non-integer bits per symbol transmission, using a compact code set or a partial response decoding receiver. A stream of selectable predetermined integer bits, e.g., k or k+1 data bits, is grouped into a selectable integer number of bit vectors which then are mapped onto corresponding signal constellations forming transmission symbols. Two or more symbols can be grouped and further encoded, so that a symbol is spread across the two or more symbols being communicated. Sequence estimation using, for example, maximum likelihood techniques, as informed by noise estimates relative to the received signal. Each branch metric in computing the path metric of a considered sequence at the receiver is weighted by the inverse of the noise power. It is desirable that the constellation selection, sequence estimation and noise estimation be performed continuously and dynamically.

Constellation-multiplexed transmitter and receiver

A feedforward filter has a plurality of feedforward filter taps, including a feedforward filter reference tap. The reference tap of the feedforward filter is positioned proximate a center position of the feedforward filter. A ramping circuit assembly has an input port configured to receive at least one decision feedback filter tap coefficient from a decision feedback filter. A coefficient ramping circuit is configured to provide a ramped output for at least one of the decision feedback filter tap coefficients. The ramped output is varied over time from a first value to a second value. The second value is dependent upon the value of a decision feedback filter tap coefficient. An output port of the ramping circuit assembly is configured to communicate information representative of the ramped output(s) to a precoder.

Decision feedback equalizer and precoder ramping circuit

A carrier recovery, symbol timing, and carrier phase tracking systems and methods suitable for use in connection with a dual-mode QAM/VSB receiver system. In-phase signals are sampled twice a symbol at the in-phase symbol sampling time and at the quadrature-phase symbol sampling time. The signals are de-multiplexed to generate I and Xdata streams, where I represents the in-phase sampling time signals and Xrepresents mid-symbol point sample times. A similar procedure is carrier out on quadrature-phase signals. When the in-phase signal is de-multiplexed to generate a symbol I, the quadrature-phase signal is de-multiplexed to generate its mid-symbol point X. Both I and Q are decoded to define a symbol error term, which is combined with the opposite mid-symbol signal to define a phase error term Pand Pfor each rail.

Phase detectors in carrier recovery for offset QAM and VSB

All digital reference frequency locking. An all digital approach is provided for operation within one or more CMs within a cable modem communication system to lock the upstream of the one or more CMs to the downstream symbol clock provided from a CMTS. The locking of the CM's upstream may be performed using one of at least three different functions: (1) Locking the upstream symbol clock phase to the downstream symbol clock phase, (2) Locking the downstream symbol clock phase to the headend reference clock phase (typically 10.24 MHz or integer multiple thereof), and (3) Locking the upstream carrier frequency to the downstream symbol clock frequency. The all-digital techniques for supporting all digital reference frequency locking functionality provide high performance to support S-CDMA and other synchronous modulation techniques.

All digital reference frequency locking

A system and method that provides an integrated circuit which includes a small on-chip buffer to store collected data, thereby shifting the burden of storing the majority of the collected data to external system memory, which is typically comprised of commodity memory chips. Since this external system memory is already in use by other system functions, utilizing such unused regions of this external memory increases overall hardware efficiency, while achieving lower ASIC manufacturing cost.

Efficient memory allocation scheme for data collection

Home phone line network devices, conforming to different versions of the standards, are interconnected and interoperable on a UTP transmission medium. Higher order devices support an overlaid dual logical network structure which allows two pairs of higher order devices to communicate simultaneously using two separate frequency bands. A higher order node contains a high speed PHY, a low speed PHY, and either a high and low order MAC or an enhanced MAC capable of supporting dual frequency band transmission, thereby enhancing total system throughput to the sum of the throughputs of each logical network.

Home phone line network architecture

Improved carrier recovery, symbol timing, and carrier phase tracking systems and methods suitable for use in connection with a dual-mode QAM/VSB receiver system are disclosed. Carrier and phase recovery systems operate on complex signals representing symbols having the same time stamp for each phase error term. in-phase signals are sampled twice a symbol at the in-phase symbol sampling time and at the quadrature-phase symbol sampling time. The signals are de-multiplexed to generate I and X data streams, where I represents the in-phase sampling time signals and X represents mid-symbol point sample times. A similar procedure is carrier out on quadrature-phase signals. When the in-phase signal is de-multiplexed to generate a symbol I, the quadrature-phase signal is de-multiplexed to generate its mid-symbol point X . Both I and Q are decoded in a decision device to define a symbol error term, which is combined with the opposite mid-symbol signal to define a phase error term P and P for each rail. In both cases, the symbol (I) decision (&Icirc;), and mid-symbol (X ) in each phase error term (P ) computation will have the same prime index.

A device of dynamic communication of information allows, on the average, non-integer bits per symbol transmission, using a compact code set or a partial response decoding receiver. A stream of k or k&plus;1 data bits is grouped into bit vectors which then are mapped onto corresponding signal constellations forming transmission symbols. Two or more symbols can be grouped and further encoded, so that a symbol is spread across the two or more symbols being communicated. Sequence estimation using, for example, maximum likelihood techniques, as informed by noise estimates relative to the received signal. Each branch metric in computing the path metric of a considered sequence at the receiver is weighted by the inverse of the noise power. It is desirable that the constellation selection, sequence estimation and noise estimation be performed continuously and dynamically.

A improved method for optimally equalizing a multicarrier communications system in the presence of both intersymbol interference (ISI) and colored noise. The method provides a frequency-domain training algorithm to obtain a minimum mean square error (MMSE) equalizer that accounts for both intersymbol interference (ISI) and colored noise, maximizes the signal to noise ratio (SNR) of systems using Discrete Multitone (DMT) modulation, and results in significant performance gains over prior equalization methods.

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Irvine, CA, United States of America

Thuji Simon Lin