Abstract: Methods and systems for DVB-C2 are disclosed and may include receiving data encoded utilizing variable encoding, variable modulation and outer codes via a physical layer matched to a desired quality of service. An error probability may be determined for said received data and retransmission of portions of said data with error probability above an error threshold may be requested. The variable modulation may include single carrier modulation, orthogonal frequency division modulation, synchronous code division multiple access, and/or from 256 QAM to 2048 QAM or greater. The variable encoding may include forward error correction code, which may include low density parity check code.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: A method and apparatus is disclosed to map a sequence of data to Quadrature Amplitude Modulation (QAM) constellation symbols. The method and apparatus encodes only a portion of the sequence of data and leaves a remaining portion of the sequence of data unencoded. The encoded portion of the sequence of data and the remaining unencoded portion of the sequence of data are then mapped into modulation symbols of the QAM constellation. The encoded portion of the sequence of data selects subsets of the QAM constellation, and the remaining unencoded portion of the sequence of data determines a specific modulation symbol within each subset of the QAM constellation.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: Digital to analog converter (DAC) with ternary or tri-state current source. A DAC including a number of ternary or tri-state devices operates based upon codewords provided thereto. Generally, each respective codeword bit directs operation of one of the respective ternary or tri-state devices within the DAC. Each ternary or tri-state device operates in at least three respective operational states (e.g., based upon the respective values of +1, ?1, or 0 being provided thereto). In a current source implementation, each respective current source is implemented to deliver current, draw current, or neither delivered or draw current. In a voltage source implementation, each respective voltage source is implemented to provide a positive voltage, a negative voltage, or provide no voltage. A DAC coding table may be designed based upon characterization of codewords provided to one or more DACs (e.g., based upon a distribution, a probability density function (PDF), etc. of such codewords).

Abstract: Signal processing under attenuated transmission conditions. Within an orthogonal signal space, the number of orthogonal signals that are used to transmit information from a transmitter to a receiver is reduced and the transmitted power of each of the now remaining orthogonal signals is modified; this may involve increasing the power of all of the remaining orthogonal signals equally or alternatively modifying them individually. The same modulation used before the reduction may also be used afterwards; within communication systems having multiple transmitter-receiver paths, this will ensure that the communication system's throughput and efficiency will remain unchanged even when one (or more) transmitter-receiver paths are highly attenuated. In addition, robust mode operation is provided for ranging and registering of transmitter devices when entering the communication system.

Abstract: A communication system includes a supervisory node (e.g., a headend) and one or more remote nodes (e.g., cable modems). The supervisory node or a remote node monitors a characteristic associated with the communication system. Remote node transmits an upstream communication among a plurality of physical upstream channels based on the characteristic. The average transmit power used to transmit the upstream communication among the plurality of physical upstream channels is no greater than the average transmit power that would be necessary to transmit the upstream communication using a single physical upstream channel at a lower data rate.

Abstract: A system for mitigating impairment in a communication system includes a delay block, a signal level block, a moving average window block, an impulse noise detection block, and a combiner. The delay block receives and delays each chip of a plurality of chips in a spreading interval. The signal level block determines a signal level of each chip of the plurality of chips in the spreading interval. The moving average window block determines a composite signal level for a chip window corresponding to the chip. The impulse noise detection block receives the signal level, receives the composite signal level, and produces an erasure indication for each chip of the plurality of chips of the corresponding chip window. The combiner erases chips of the plurality of chips of the spreading interval based upon the erasure indication.

Abstract: Provided is a method and system for estimating distortion in a communications channel including an adaptive equalizer. The method includes determining one or more adaptive filter coefficients associated with a signal passed through the equalizer. The method also includes estimating un-equalized channel distortion based upon the determined adaptive filter coefficients.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: A communication system performs burst noise cancellation. A transmitter produces and transmits a spread signal that comprises at least one known-value symbol spread by a plurality of non data-carrying orthogonal codes and data symbols spread by at least one data-carrying orthogonal code. The transmitter transmits the spread signal across a communication link that introduces burst noise. A burst noise detector determines burst noise affected chips of the orthogonal codes. A weight computation functional block calculates a plurality of complex-valued combining weights based upon the burst noise affected chips. A vector de-spreader and a linear combiner operate in combination to use the plurality of non data-carrying orthogonal codes, the at least one data-carrying orthogonal code, and the plurality of complex-valued combining weights to de-spread the received spread signal to produce the data symbols with the burst noise substantially removed.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: A method of transmitting data in a cable modem system includes the steps of encoding the data using forward error correction. The data is then encoded with Turbo encoding. The data is then sent to a modulation scheme. The data is then transmitted over a cable channel. The data is then demodulated. The data is then decoded using a Turbo decoder. An inverse of the forward error correction is then applied to the data.

Abstract: A method and apparatus is disclosed to map a sequence of data to Quadrature Amplitude Modulation (QAM) constellation symbols. The method and apparatus encodes only a portion of the sequence of data and leaves a remaining portion of the sequence of data unencoded. The encoded portion of the sequence of data and the remaining unencoded portion of the sequence of data are then mapped into modulation symbols of the QAM constellation. The encoded portion of the sequence of data selects subsets of the QAM constellation, and the remaining unencoded portion of the sequence of data determines a specific modulation symbol within each subset of the QAM constellation.

Abstract: A communication system includes a supervisory node (e.g., a headend) and one or more remote nodes (e.g., cable modems). The supervisory node or a remote node monitors a characteristic associated with the communication system. Remote node transmits an upstream communication among a plurality of physical upstream channels based on the characteristic. The average transmit power used to transmit the upstream communication among the plurality of physical upstream channels is no greater than the average transmit power that would be necessary to transmit the upstream communication using a single physical upstream channel at a lower data rate.

Abstract: Handling burst error events with interleaved Reed-Solomon (RS) codes. A received signal, that has undergone convolutional interleaving sometime before, is received from a burst noise affected communication channel. The signal undergoes convolutional deinterleaving and the codewords generated there from undergo appropriate successive cyclic shifting to arrange burst noise affected symbols of various codewords into at least some common symbol locations. For example, at least two codewords have burst noise affected symbols in common symbol locations. An ensemble decoder jointly decodes multiple codewords during a same time period (i.e., processes multiple codewords simultaneously). By processing multiple codewords simultaneously, the ensemble decoder has greater error correction capability than a decoder that processes a single codeword at a time.

Abstract: In addition, to pilot tones which may be existent within an orthogonal frequency division multiplexing (OFDM) signal, one or more data tones within that same signal may be employed to assist with channel estimation (alternatively, detection). Once a data tone qualifies as a pseudo-pilot tone, it may be used with the pilot tones for channel estimation. A qualifier considers slicer error associated with hard decisions for a data tone to determine if it is a candidate for assistance within channel estimation. A frame within an OFDM signal may, in one situation, include no pilot tones at all, and a previously calculated channel estimate may be used to process that frame. In addition, fewer pilot tones than needed to perform accurate channel estimation (based on the channel delay spread) may be employed by using one or more pseudo-pilot tones (e.g., qualified data tones).

Abstract: A method of transmitting data in a cable modem system includes the steps of encoding the data using forward error correction. The data is then encoded with Turbo encoding. The data is then sent to a modulation scheme. The data is then transmitted over a cable channel. The data is then demodulated. The data is then decoded using a Turbo decoder. An inverse of the forward error correction is then applied to the data.

Abstract: A filter settings generation operation includes sampling a communication channel to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characterization. Finally, the communication channel is filtered using the filter settings when the signal of interest is present on the communication channel. In modifying the spectral characterization, pluralities of spectral characteristics of the spectral characterization are independently modified to produce the modified spectral characterization. Modifications to the spectral characterization may be performed in the frequency domain and/or the time domain.

Abstract: Upstream frequency response measurement and characterization. Signaling is provided between respective communication devices within a communication system. Based upon at least one of these signals, one of the communication devices captures a number of sample sets corresponding thereto at different respective frequencies (e.g., a different respective center frequencies, frequency bands, etc.). Then, spectral analysis is performed with respect to each of the sample sets to generate a respective and corresponding channel response estimate there from. After this number of channel response estimates is determined, they are combined or splice together to generate a full channel response estimate. In implementations including an equalizer, different respective sample sets may correspond to those that have undergone equalization processing and those that have not.