Ikanos Communications, Inc.

Lantiq Deutschland Gmbh

Aware, Inc.

Fernando Ramirez-Mireles

Marcos Tzannes

Sam Heidari

Robert Ayrapetian

Dale Smith

John Gevargiz

Hojat Khelghati

Saman Behtash

Max Chien

Mazen M Shihabi

Avadhani Sridhar

Marcos C Tzannes

A multi-carrier information transceiver that exhibits robustness against radio frequency interference (RFI) signals present in the communications channel. The transceiver includes a RFI mitigation technique that operates not only during the steady state operation of the transceiver but also during the training stage of the transceiver. That requires dynamically modifying the training signals when the presence of RFI is detected. The modification of the training signals facilitates the estimation of RFI, improving the performance of the multi-carrier transceiver.

Systems and methods for a multicarrier transceiver with radio frequency interference reduction

The apparatus for symbol boundary synchronization in one embodiment includes on the receive path of a multi-tone modem a window synchronizer, a converter and a symbol boundary component. The window synchronizer obtains windowed portions of the received datastream which includes symbols each expressed with a corresponding set of tones in a time domain. The windowed portions obtained in the training phase exhibit varying degrees of misalignment with the corresponding symbol boundaries. The window synchronizer is responsive to an alignment signal to obtain succeeding windowed portions of the incoming datastream aligned with the corresponding symbol boundaries therein. The converter couples to the window synchronizer to convert the set of tones from each windowed portion from the time domain to a frequency domain. The symbol boundary module couples to the converter to evaluate a phasor angle characteristic of selected tones from each windowed portion converted by the converter and to convert the phasor angle characteristic of the selected tones from a selected one of the windowed portions to the alignment signal to align the window synchronizer with the symbol boundaries in the received datastream. In an alternate embodiment of the invention the symbol boundary component couples to the window synchronizer to correlate sign values of the selected tones with a reference set and to output the alignment signal identifying the corresponding windowed portion which exhibits maximum correlation with the reference set to align the window synchronizer.

Method and apparatus for symbol boundary synchronization

The present invention provides a method and apparatus for demodulating data received over a communication medium carrying a transmission having multiple pilot tones with pilot data modulated thereon and message tones with message data modulated thereon and with the pilot tones and message tones frequency division multiplexed with respect to one another. In an embodiment of the invention the communication protocol utilized for modulation and demodulation is discrete multi tone (DMT). The invention allows message processing and equalizer training to proceed in parallel before equalizer training tables have been completed thus reducing the time associated with modem initialization. The apparatus in one embodiment of the invention includes on the receive path of a DMT or other multi-tone modem, a fast Fourier transform engine (FFT), a message processor, and a decoder. The FFT converts the received data from a time domain to a frequency domain. The received data in the frequency domain includes successive sets of pilot tones together with message tones. The message processor selects pairs of message and pilot tones proximate to one another in the frequency domain in each set of pilot tones and message tones. The message tone in each pair is then equalized with the pilot tone in the pair to substantially remove frequency dependent phase shifts imparted by the communication medium to the message tone. The equalized message tone is then decoded in the decoder to the corresponding specific set of message data which it represents.

Method and apparatus for initializing modem communications

Systems and methods for a multi-carrier transceiver with radio frequency interference reduction

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Walnut Creek, CA, United States of America

Fernando Ramirez-Mireles