Abstract: An improved Tomlinson Harashima Precoding (THP) communication system through special configuration of its feedback coefficients is disclosed. Improvement, in terms of THP system robustness against analog-to-digital (ADC) sampling phase variation, is achieved either by deriving feedback coefficients of the Decision Feedback Equalizer at worst ADC sampling phase or by inserting a Zero Edge Filter (ZEF) at the receiver. The ZEF modifies the communication system such that the feedback filter coefficients derived in the Decision Feedback Equalizer (DFE) mode and later used in the THP mode is capable to compensate the zero at Nyquist Frequency due to a non-optimum sampling, phase of the ADC. The THP communication system, modified and improved with the insertion of ZEF, is operable to switch from an adaptive Decision Feedback Equalizer (DFE) mode to a THP mode having an adaptive Linear Equalizer (LE) at the receiver.

Abstract: The invention relates to a method and apparatus of an improved Tomlinson Harashima Precoding (THP) communication system through special configuration of its feedback coefficients. Improvement, in terms of THP system robustness against analog-to-digital (ADC) sampling phase variation, is achieved either by deriving feedback coefficients of the Decision Feedback Equalizer at worst ADC sampling phase or by inserting a Zero Edge Filter (ZEF) at the receiver. The ZEF modifies the communication system such that the feedback filter coefficients derived in the Decision Feedback Equalizer (DFE) mode and later used in the THP mode is capable to compensate the zero at Nyquist Frequency due to a non-optimum sampling phase of the ADC. The THP communication system, modified and improved with the insertion of ZEF, is operable to switch from an adaptive Decision Feedback Equalizer (DFE) mode to a THP mode having an adaptive Linear Equalizer (LE) at the receiver.

Abstract: A method for trellis constellation shaping is disclosed. In one embodiment, this method comprises receiving two or more input bits and filtering at least one of the two or more input bits to create two or more filtered output bits. The step of filtering at least one input bit introduces at least one extra bit. The method then encodes the input bits which are not filtered to create encoded bits and stores the encoded bits and the filtered bits in a buffer. A processing element may be configured to perform Viterbi type processing on the filtered bits to create processed bits. The method combines at least one of the processed bits with at least one of the buffered bits to create a combined bit set from the buffered bits and then performs mapping on the combined bet set to thereby map the combined bit set into a constellation.

Abstract: A method and apparatus is disclosed for use in a communication system for encoding data to achieve more efficient coding rates and high data transmit rate, or a lower bit error rate. An encoder may receive a portion of the data to be encoded and process the portion of the data to create encoded data. The encoded data and the portion of the data not sent to the encoder are presented to a transform module configured to perform matrix multiplication on the inputs with a transform matrix. The resulting transformed data is mapped, using a mapper, either via an algorithmic approach or a manual mapping approach to generating a constellation mapped output. 2-dimensional encoding may occur.

Abstract: The present invention is generally directed to a system and method for encoding a DSL information bit stream and decoding a corresponding encoded DSL symbol. In accordance with one embodiment, an apparatus for encoding a DSL information bit stream is provided having a switch with an input configured to receive a DSL information bit stream and at least two outputs. An encoder is provided and coupled to a first output of the switch. A serial to parallel converter is provided and coupled to both an output of the encoder and a second output of the switch. Finally, a mapper is provided and coupled to an output of the serial to parallel converter through multiple paths. Preferably, a first coupling path between the serial to parallel converter and the mapper is a direct path and a second coupling path includes a second encoder.

Abstract: A method and apparatus is disclosed for processing two or more encoded signals received over a multi-channel communication system to cancel or mitigate coupling and the effects of the channel on the two or more encoded signals. In one embodiment a multi-channel communication system utilizes DMT processing and some form of encoding, such as block coding or convolutional coding. To recover the transmitted signal, processing in the receiver may comprise MIMO processing in conjunction with decoding. The MIMO processing may be configured with decision directed processing to thereby generate one or more cancellation signals based on isolated error terms. Decoding occurs on encoded signals after MIMO processing. Memory may be interspersed or available throughout the system to store incoming symbols that have not yet undergone decoding and MIMO processing. Decoding and MIMO processing may occur sequentially through the channels.

Abstract: A method for combining trellis-coded modulation with one-bit constellations to make more efficient use of available channel capacity in discrete multitone (DMT) asymmetric digital subscriber line (ADSL) systems. Through fine transmit gain adjustment, in individual tones, DMT systems are able to compensate for truncation effects in bits-per-tone loading. However, the allowed fine gain adjustment range is insufficient to compensate for the DMT requirement that data modulated tones carry at least two bits. Therefore, by allowing data-modulated tones to carry a single bit, the available channel capacity can be more efficiently utilized. Additionally, one-bit constellations may be combined with trellis coded modulation. A pair of one-bit sub-carrier may be considered as a virtual two-bit sub-carrier in the trellis encoder with the resulting encoded bit pair transmitted on the original sub-carriers using one-bit constellations.

Abstract: A method for combining trellis-coded modulation with one-bit constellations to make more efficient use of available channel capacity in discrete multitone (DMT) asymmetric digital subscriber line (ADSL) systems. Through fine transmit gain adjustment, in individual tones, DMT systems are able to compensate for truncation effects in bits-per-tone loading. However, the allowed fine gain adjustment range is insufficient to compensate for the DMT requirement that data modulated tones carry at least two bits. Therefore, by allowing data-modulated tones to carry a single bit, the available channel capacity can be more efficiently utilized. Additionally, one-bit constellations may be combined with trellis coded modulation. A pair of one-bit sub-carrier may be considered as a virtual two-bit sub-carrier in the trellis encoder with the resulting encoded bit pair transmitted on the original sub-carriers using one-bit constellations.

Abstract: 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.