Abstract: The preferred embodiments of the present invention generally provide improved communications over a subscriber loop that is loaded with at least one and potentially a plurality of load coils. The preferred embodiments of the present invention will work over loaded subscriber loops that also support a native POTS interface as well as over loaded subscriber loops that are not providing a native POTS interface. Furthermore, although the preferred embodiments of the present invention are intended to address the technical and business problems of service providers delivering digital subscriber line service over loaded loops, the preferred embodiments will also work over unloaded loops.

Abstract: Systems and methods for encoding fractional bit rates in a communication system, such as a pulse amplitude modulation (PAM) communication system, are provided. The systems and methods enable a first transceiver to specify to a second transceiver a desired fractional bit rate for transmitting data to the first transceiver. In this manner, the systems and methods of the present invention for the first time enable a single standardized specification of a generalized transmitter that may be used to implement any type of fractional encoding or mapping.

Abstract: Several embodiments of a space diversity trellis interleaver system are provided for communicating data over a plurality of separate communication paths in order to inhibit distortion caused by impulse noise or other correlated noise and enhance the data transmission rate of data communications. The transmitter is designed to receive a plurality of data streams from data terminal equipment (DTE), which can be one or more devices. One or more convolutional encoders, preferably trellis encoders, encode each of the data streams. In an alternative embodiment, more than one trellis encoder is used to trellis encode each data stream. Data segments from the convolutionally encoded data streams are interleaved with a switch. The plurality of interleaved convolutionally-encoded data streams are modulated and transmitted onto a respective plurality of separate communication paths. At the receiver, the plurality of data streams is received from the separate communication paths and demodulated.

Abstract: A communication device for use in a non-self synchronizing scrambling (NS3) communication system and a method for using NS3 in a communication system are disclosed. A digital data stream is scrambled by modifying the digital data stream based on a pseudo-noise sequence (PNS) to produce a scrambled digital data stream. The PNS has a timing reference that is distinct from the digital data stream. The scrambled digital data stream is capable of being descrambled by performing an inverse modification, based on the same PNS and the same timing reference. The scrambled digital data stream may be transmitted over a communication medium and descrambled at the opposing end of the communication medium. Synchronization between the scrambler and the descrambler is maintained by providing a common timing reference to the scrambler and the descrambler. The common timing reference is distinct from the data stream.

Abstract: A digital subscriber line (DSL) driver allows a transmitter to monitor its own transmit spectrum at the subscriber loop and adjust the transmit spectrum based on detected line conditions, affected by the presence of bridged taps or any other impedance variations. The transmit spectrum is preferably equalized so that all carriers, or tones, transmit using the same power and exhibit the same margin. The invention is applicable to DMT and single carrier modulation formats.

Abstract: A discrete multitone interleaver system, including an interleaver and deinterleaver, are provided for efficiently communicating data despite noise affecting a Discrete Multitone modulation (DMT) system. The discrete multitone interleaver includes a convolutional encoder capable of receiving a plurality of bits on tones and capable of outputting a convolutionally encoded plurality of bits and a synchronized dual skipping switch capable of passing the plurality of bits on tones to the convolutional encoder in a non-sequential order and capable of outputting the convolutionally encoded plurality of bits in the same non-sequential order.

Abstract: A tone ordered discrete multitone interleaver system and method, including a tone ordered interleaver and deinterleaver, are provided for efficiently communicating data despite noise affecting a Discrete Multitone modulation (DMT) system. The tone ordered discrete multitone interleaver forces interleaving of trellis encoded information by assigning a different number of bits to adjacent tones or adjacent tone pairs.

Abstract: Fractional bit rate encoding in a discrete multi-tone (DMT) communication environment allows the transmission of fractional bit rates, thus maximizing the use of signal-to-noise ratio (SNR) available on each of the DMT carriers, or tones, while maintaining a constant power density over the entire frequency spectrum.

Abstract: Several embodiments of a space diversity trellis interleaver system are provided for communicating data over a plurality of separate communication paths in order to inhibit distortion caused by impulse noise or other correlated noise and enhance the data transmission rate of data communications. The transmitter is designed to receive a plurality of data streams from data terminal equipment (DTE), which can be one or more devices. One or more convolutional encoders, preferably trellis encoders, encode each of the data streams. In an alternative embodiment, more than one trellis encoder is used to trellis encode each data stream. Data segments from the convolutionally encoded data streams are interleaved with a switch. The plurality of interleaved convolutionally encoded data streams are modulated and transmitted onto a respective plurality of separate communication paths. At the receiver, the plurality of data streams is received from the separate communication paths and demodulated.

Abstract: Several embodiments of an interleaved generalized convolutional encoder system and method are provided for communicating data over a transmission path in order to inhibit distortion caused by impulse noise or other correlated noise and enhance transmission rate of data communications. The encoder system is designed to introduce a variable delay to the convolutional encoder. The variable delay effectively spreads correlated noise over a variable number of symbols in time. Correlated noise that is spread over time allows for better error correction encoding.

Abstract: The present invention provides methods and apparatus for transmitting a data-bearing signal and a non-data-bearing signal. One embodiment comprises communicatively coupling a data-bearing signal during a first time period and communicatively coupling a non-data-bearing signal during a second time period. The data-bearing signal has a first PSD. The non-data-bearing signal has a second PSD substantially the same as the first over a range of frequencies. The non-data-bearing signal has characteristics facilitating echo cancellation. Another embodiment comprises a line interface and a transmitter coupled to the line interface, comprising a data encoder and a periodic signal generator. The encoder is configured to produce a data-bearing signal with a first PSD. The periodic signal generator is configured to produce a non-data-bearing signal with a second PSD. The second PSD is substantially the same as the first PSD over a first range of frequencies.

Abstract: Systems and methods are provided for a trellis interleaver and feedback precoder. One such method includes: producing a series of precoder symbols; interleaving the precoder symbols; producing a trellis state output from the interleaved symbols; and generating a redundant bit based upon the trellis state output. One such system includes: a precoder state element configured to monitor a precoder state and to develop a series of precoder symbols; an interleaver configured to receive and interleave the precoder symbols; a trellis state element configured to receive the interleaved symbols and to develop a trellis state output; and a trellis encoder configured to receive the trellis state output and to generate at least one redundant bit.

Abstract: Fractional bit rate encoding in a pulse amplitude modulation (PAM) communication environment allows the transmission of fractional bit rates, thus maximizing the use of signal-to-noise ratio (SNR) available on a communication channel. The invention allows the transmission of fractional bit rates in a PAM transceiver, thus allowing the encoding and transmission of a fractional number of bits on each PAM transmit symbol. By encoding a non-integer number of bits, a non power-of-two number of PAM levels can be encoded.

Abstract: A digital subscriber line (DSL) driver allows a transmitter to monitor its own transmit spectrum at the subscriber loop and adjust the transmit spectrum based on detected line conditions, affected by the presence of bridged taps or any other impedance variations. The transmit spectrum is preferably equalized so that all carriers, or tones, transmit using the same power and exhibit the same margin. The invention is applicable to DMT and single carrier modulation formats.

Abstract: The invention enables a communication device to efficiently communicate large circular signal constellations by embedding a square signal constellation in each of the circular signal constellation points. By embedding a square signal constellation in the error free slicing region associated with each circular constellation signal point, the beneficial shape of the circular constellation is retained while significantly increasing the amount of information that can be transmitted in each constellation. The invention allows the communication of high bit-per-symbol signal constellations (on the order of 15 or more bits-per-symbol) without the added cost of external memory for large look-up tables or the cost and power consumption of line drivers required to communicate high peak factor square signal constellations.

Abstract: Various embodiments are configured to transform characteristics of a communication signal.

Abstract: A discrete multi-tone (DMT) digital subscriber line (DSL) communication device employs a linear block interleaver for mathematically combining multiple tones into n-tone combinations in order to efficiently suppress or eliminate correlated noise or impulse noise generated in the communication channel. In architecture, the linear block interleaver includes logic configured to combine multiple signaling constellations into n-tone combinations. The multiple constellations are mathematically combined such that noise energy present in at least one of the n-tone combinations is spread among each of the multiple tones, thus reducing the energy of the noise on each of the multiple tones.

Abstract: Systems and methods are provided for a trellis interleaver and feedback precoder. One such method includes: producing a series of precoder symbols; interleaving the precoder symbols; producing a trellis state output from the interleaved symbols; and generating a redundant bit based upon the trellis state output. One such system includes: a precoder state element configured to monitor a precoder state and to develop a series of precoder symbols; an interleaver configured to receive and interleave the precoder symbols; a trellis state element configured to receive the interleaved symbols and to develop a trellis state output; and a trellis encoder configured to receive the trellis state output and to generate at least one redundant bit.

Abstract: A subscriber line driver (SLD) is provided for the continuous and automatic transformation of the characteristics of a communication system signal so that the signal conforms to a power spectral distribution (PSD) standard. The signal is transformed by the SLD which may increase (amplify) portions of the signal to a predefined specification, decrease (attenuate) portions of the signal to a predefined specification, and/or frequency modulate or filter the transmit signal frequencies to fit within the communication channel frequency bandwidth as defined by a predefined frequency band. After modification by the SLD, the transformed communication signal is injected (transmitted) into a communication transmission line. An SLD device can be employed in a variety of communication systems such as a public telephony system, a private branch exchange (PBX), a coaxial cable system, a fiber optic system, a microwave system, a radio communication system or the like.

Abstract: The present invention is directed to unique methods and apparatus for suppressing impulse noise in a multipoint communications environment using a linear block interleaver. One representative embodiment comprises first logic configured to arithmetically combine a time series of input symbols into a block of N-symbol combinations, and second logic configured to transmit, on a separate channel, each N-symbol combination to a receiver. The first logic is located in a transmitter of a first communications device. The time series has size N and N is greater than one, and each of the input symbols is taken from a signaling constellation.