Abstract: A process transmits digital data to an A/D converter via an analog channel. The process includes generating a sequence of output signals by precoding a sequence of input signal points to precompensate for ISI in the analog channel. In the precoding is matched to the ISI, at least one of the output signals would be distorted by the ISI to a signal representative of a signal point lying between quantization levels of the A/D converter. If the precoding is matched to the ISI, others of the output signals would be distorted by the ISI to signals representative of signal points that are quantization levels of the A/D converter. A majority of the input signal points are quantization levels of the A/D converter.

Abstract: A process transmits digital data to an A/D converter via an analog channel. The process includes generating a sequence of output signals by preceding a sequence of input signal points to precompensate for ISI in the analog channel. In the preceding is matched to the ISI, at least one of the output signals would be distorted by the ISI to a signal representative of a signal point lying between quantization levels of the A/D converter. If the precoding is matched to the ISI, others of the output signals would be distorted by the ISI to signals representative of signal points that are quantization levels of the A/D converter. A majority of the input signal points are quantization levels of the A/D converter.

Abstract: An approach for decoding a substantially orthogonal code, such as a CCK code, based on its trellis diagram is provided. Compared to the conventional decoder based on codeword correlation, the unconventional decoder here has the advantage that it can work together with a decision feedback equalizer without suffering from the error propagation effect of the equalizer. In other words, the unconventional decoder makes joint decision feedback equalizer and decoder workable, which in turn enables reliable transmission of a signal encoded by a substantially orthogonal code over a multi-path channel.

Abstract: A transmitter of digital data includes a modulator with an input for a carrier signal and an input for a first stream of control symbols. The modulator modulates the carrier signal with a second stream of symbols produced by the modulator. Each symbol of the second stream has a value that corresponds to a sum of the present control symbol and the last K first symbols of the first stream. The integer K is greater than one.

Abstract: A transmitter of digital data includes a modulator with an input for a carrier signal and an input for a first stream of control symbols. The modulator modulates the carrier signal with a second stream of symbols produced by the modulator. Each symbol of the second stream has a value that corresponds to a sum of the present control symbol and the last K first symbols of the first stream. The integer K is greater than one.

Abstract: An approach for using multi-dimensional trellis codes in a communication system over a multi-path channel, such as a wireless local area network, is provided. In this approach, the received signal is equalized and decoded by a joint decision feedback equalizer and multi-dimensional trellis decoder that is based on a multi-stage trellis diagram. The multi-stage trellis diagram used by the decoder comprises at least two stages of state transitions for each stage of state transitions in the encoder. The multi-stage trellis diagram makes the joint decision feedback equalizer and multi-dimensional trellis decoder possible, which in turn makes the use of multi-dimensional trellis codes in such a communication system advantageous.

Abstract: A process transmits digital data to an A/D converter via an analog channel. The process includes generating a sequence of output signals by preceding a sequence of input signal points to precompensate for ISI in the analog channel. In the preceding is matched to the ISI, at least one of the output signals would be distorted by the ISI to a signal representative of a signal point lying between quantization levels of the A/D converter. If the precoding is matched to the ISI, others of the output signals would be distorted by the ISI to signals representative of signal points that are quantization levels of the A/D converter. A majority of the input signal points are quantization levels of the A/D converter.

Abstract: A process transmits digital data to an A/D converter via an analog channel. The process includes generating a sequence of output signals by precoding a sequence of input signal points to precompensate for ISI in the analog channel. In the precoding is matched to the ISI, at least one of the output signals would be distorted by the ISI to a signal representative of a signal point lying between quantization levels of the A/D converter. If the precoding is matched to the ISI, others of the output signals would be distorted by the ISI to signals representative of signal points that are quantization levels of the A/D converter. A majority of the input signal points are quantization levels of the A/D converter.

Abstract: A transmitter of digital data includes a modulator with an input for a carrier signal and an input for a first stream of control symbols. The modulator modulates the carrier signal with a second stream of symbols produced by the modulator. Each symbol of the second stream has a value that corresponds to a sum of the present control symbol and the last K first symbols of the first stream. The integer K is greater than one.

Abstract: A process transmits digital data to an A/D converter via an analog channel. The process includes generating a sequence of output signals by precoding a sequence of input signal points to precompensate for ISI in the analog channel. In the precoding is matched to the ISI, at least one of the output signals would be distorted by the ISI to a signal representative of a signal point lying between quantization levels of the A/D converter. If the precoding is matched to the ISI, others of the output signals would be distorted by the ISI to signals representative of signal points that are quantization levels of the A/D converter. A majority of the input signal points are quantization levels of the A/D converter.

Abstract: A transmitter of digital data includes a modulator with an input for a carrier signal and an input for a first stream of control symbols. The modulator modulates the carrier signal with a second stream of symbols produced by the modulator. Each symbol of the second stream has a value that corresponds to a sum of the present control symbol and the last K first symbols of the first stream. The integer K is greater than one.

Abstract: An approach for decoding a substantially orthogonal code, such as a CCK code, based on its trellis diagram is provided. Compared to the conventional decoder based on codeword correlation, the unconventional decoder here has the advantage that it can work together with a decision feedback equalizer without suffering from the error propagation effect of the equalizer. In other words, the unconventional decoder makes joint decision feedback equalizer and decoder workable, which in turn enables reliable transmission of a signal encoded by a substantially orthogonal code over a multi-path channel.

Abstract: An approach for using multi-dimensional trellis codes in a communication system over a multi-path channel, such as a wireless local area network, is provided. In this approach, the received signal is equalized and decoded by a joint decision feedback equalizer and multi-dimensional trellis decoder that is based on a multi-stage trellis diagram. The multi-stage trellis diagram used by the decoder comprises at least two stages of state transitions for each stage of state transitions in the encoder. The multi-stage trellis diagram makes the joint decision feedback equalizer and multi-dimensional trellis decoder possible, which in turn makes the use of multi-dimensional trellis codes in such a communication system advantageous.

Abstract: Signal points from a PCM-derived constellation are selected for transmission via a modulation technique which employs different levels of redundancy coding—including the possibility of no redundancy coding—for respective different sub-constellations of the overall PCM-derived constellation. The coding that is employed for at least one of the sub-constellations is carried out independently from any coding that is employed for any of the other sub-constellations. The PCM-derived constellation and the overall modulation technique are designed so as to accommodate the possibility that the telecommunications system in which the modulation technique is implemented may include so-called bit robbing and so-called digital attenuation.

Abstract: A multilevel coded modulation scheme is provided in which a first portion of input data is encoded by a first-level code and a second portion of input data is encoded by an second-level code, the second-level code being such that the overall multilevel code exhibits a desired level of time diversity of at least 2 and the minimum distance of the overall code is not increased by virtue of the presence of the second-level code.

Abstract: Advantageous error rate performance, high bandwidth efficiency, low delay and reduced error floor are achieved at an acceptable level of decoding complexity via the use of serial concatenated turbo codes. These are codes for which at least some of the output bits, including at least one redundant bit, provided by a first, outer encoder are, after interleaving, further processed by a second, inner encoder. The resulting data and redundant bits then select a symbol from a predetermined constellation for transmission. In the receiver, the turbo code is decoded using a corresponding number of soft output decoders which operates iteratively in such a way that improved performance as compared to a single encoding can be achieved. The turbo codes can be of various dimensionalities and can be used as a component of a multilevel code to achieve a desired level of bandwidth efficiency.

Abstract: A portion of signal points that appear at predetermined positions in a signal point stream and that benefit less from a particular form of error immunity—e.g., conversion gain—are transmitted in such a way that their robustness against errors is at least as great as that of the signal points that benefit more therefrom. In preferred packet transmission embodiments of the invention, the ending signal points of a packet are transmitted using a signal point constellation that has fewer signal points than the constellation that is used for the other signal points in the packet.

Abstract: Advantageous error rate performance, high bandwidth efficiency, low delay and reduced error floor are achieved at an acceptable level of decoding complexity via the use of serial concatenated turbo codes. These are codes for which at least some of the output bits, including at least one redundant bit, provided by a first, outer encoder are, after interleaving, further processed by a second, inner encoder. The interleaver uses as its interleaved elements the bits associated with a particular symbol interval. The resulting data and redundant bits then select a symbol from a predetermined constellation for transmission. In the receiver, the turbo code is decoded using a corresponding number of soft output decoders which operates iteratively in such a way that improved performance as compared to a single encoding can be achieved. The turbo codes can be of various dimensionalities and can be used as a component of a multilevel code to achieve a desired level of bandwidth efficiency.

Abstract: A process transmits digital data to an A/D converter via an analog channel. The process includes generating a sequence of output signals by precoding a sequence of input signal points to precompensate for ISI in the analog channel. In the precoding is matched to the ISI, at least one of the output signals would be distorted by the ISI to a signal representative of a signal point lying between quantization levels of the A/D converter. If the precoding is matched to the ISI, others of the output signals would be distorted by the ISI to signals representative of signal points that are quantization levels of the A/D converter. A majority of the input signal points are quantization levels of the A/D converter.

Abstract: Advantageous error rate performance, high bandwidth efficiency, low delay and reduced error floor are achieved at an acceptable level of decoding complexity via the use of serial concatenated turbo codes. These are codes for which at least some of the output bits, including at least one redundant bit, provided by a first, outer encoder are, after interleaving, further processed by a second, inner encoder. The resulting data and redundant bits then select a symbol from a predetermined constellation for transmission. In the receiver, the turbo code is decoded using a corresponding number of soft output decoders which operates iteratively in such a way that improved performance as compared to a single encoding can be achieved. The turbo codes can be of various dimensionalities and can be used as a component of a multilevel code to achieve a desired level of bandwidth efficiency.