Abstract: In one embodiment, a method for communicating data is provided. The method includes, defining a data transmission unit (DTU) to be sent in an xDSL data stream, defining a retransmit container as a time slot that corresponds to the DTU, maintaining a copy of the DTU and an index corresponding to the retransmit container in a retransmission buffer, transmitting the DTU in the xDSL data stream, determining whether the DTU should be retransmitted, and if the DTU should be retransmitted: identifying the DTU by the retransmit container and retransmitting a copy of the DTU as identified by the retransmit container before the DTU leaves the retransmission buffer.

Abstract: Methods, systems, and computer program products for reconfiguring a modem. In an embodiment, fast reconfiguration of a modem occurs when a first modem determines there is a need for fast reconfiguration. The first modem signals its transition from showtime to fast reconfiguration. The first modem waits for acknowledgement from a second modem before transitioning to showtime. Once transitioned from showtime, the first modem estimates a signal to noise ratio and then exchanges parameters with the second modem. The first and second modems then transition to showtime.

Abstract: A method for transmitting data packets of at least two different priority levels via one or more bearer channels is described. The method comprises the steps of fragmenting a data packet into a plurality of corresponding code words, each code word comprising a sync code, with the sync code being adapted for indicating a priority level of the corresponding data packet, and of transmitting the code words via the one or more bearer channels. In case high priority code words corresponding to a high priority data packet arrive during transmission of low priority code words corresponding to a low priority data packet, the following steps are performed: interrupting transmission of low priority code words, transmitting the high priority code words corresponding to the high priority data packet, and resuming the transmission of the low priority code words via the one or more bearer channels.

Abstract: The present invention provides digital subscriber line noise mitigation techniques, and applications thereof. In an embodiment, the present invention provides a toolbox of methods and techniques for mitigating the effects of noise in xDSL systems. These methods and techniques are controllable and locatable at one or both ends of a DSL communication link (e.g., within a central office transceiver unit or a remote transceiver unit). These novel methods and techniques include: (1) per tone noise margin modification, (2) data framer constraints modification, (3) improved noise measurements; (4) more robust on-line reconfiguration processes, (5) worst case noise monitoring, (6) induced bit rate limitations, and (7) distortion noise mitigation. These methods and techniques are particularly useful for mitigating the effects of time-varying noise and impulse noise.

Abstract: Method for transmitting messages in a communications system, wherein the message is segmented into a plurality of message segments, the message segments being of variable length, the plurality of message segments comprising at least one leading message segment and a trailing message segment, and a message segment indication is applied to the at least one leading message segment.

Abstract: A method for transmitting data in an xDSL system is disclosed. In an exemplary embodiment, the method includes defining a data transmission unit (DTU) to be sent in an xDSL data stream, defining a retransmit container as a time slot that corresponds to a sent DTU, maintaining a copy of the sent DTUs and an index of corresponding retransmit containers in retransmission buffer, transmitting the DTUs in the xDSL data stream, determining whether a transmitted DTU should be retransmitted, identifying each corrupted DTU by its corresponding retransmit container, and retransmitting an uncorrupted copy of the DTU as identified by the corresponding retransmit container. The retransmission is deferred until the DTU is at a predefined position in the retransmission buffer.

Abstract: The present invention provides digital subscriber line noise mitigation techniques, and applications thereof. In an embodiment, the present invention provides a toolbox of methods and techniques for mitigating the effects of noise in xDSL systems. These methods and techniques are controllable and locatable at one or both ends of a DSL communication link (e.g., within a central office transceiver unit or a remote transceiver unit). These novel methods and techniques include: (1) per tone noise margin modification, (2) data framer constraints modification, (3) improved noise measurements; (4) more robust on-line reconfiguration processes, (5) worst case noise monitoring, (6) induced bit rate limitations, and (7) distortion noise mitigation. These methods and techniques are particularly useful for mitigating the effects of time-varying noise and impulse noise.

Abstract: An upstream signal power in a communication system is optimized. At least one system parameter is determined and a bits and gains table is modified. For example, a maximum received power parameter for the transmitting device is used by the receiving device to calculate a power backoff parameter. The power backoff parameter is used to calculate the bits and gains table which is then used by the transmitting device. The new SNR may be estimated. This estimation may distinguish between noise sources that vary with the signal level received and those that do not.

Abstract: A technique for determining a symbol erasure threshold for a received communication signal containing symbol information begins by performing a first threshold calculation to produce an initial symbol erasure threshold, then performing a first margin calculation to produce an initial symbol erasure margin and then modifying the initial symbol erasure threshold using the initial symbol erasure margin to produce a modified symbol erasure threshold. By then periodically modifying the modified symbol erasure threshold adaptively via updating the symbol erasure threshold and/or symbol erasure margin based on various error quantities, the technique can compensate for time-variant considerations, such as drifting noise levels.

Abstract: The present invention provides a method for controlling transmission latency in a communications system, wherein the communications system is subject to a noise signal having at least a first noise phase and a second noise phase. The method includes determining a first bit rate for symbols transmitted during the first noise phase, and a second bit rate for symbols transmitted during the second noise phase, the first bit rate and the second bit rate being constrained such that a transmission latency does not exceed a pre-determined maximum allowed transmission latency; and transmitting symbols at the first bit rate during the first noise phase and at the second bit rate during the second noise phase. In other variants, the invention provides an apparatus, a constrained rate reciever, a transmitter and a signal.

Abstract: Provided is a method and system for increasing cyclic prefix and cyclic suffix based upon a fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT). The method includes representing at least one of the one or more DMT symbols in frequency domain to produce a frequency domain representation. The frequency domain representation corresponds to a quadrature amplitude modulation (QAM) constellation. Next the QAM constellation is rotated in the frequency domain by changing a characteristic of the DMT symbol as a function of tone index (k), cyclic extension length (CE), inverse fast fourier transform (IFFT) size (N), and pi. Finally, a number of extended symbols are produced to represent the DMT symbol based upon the rotating.

Abstract: The present invention provides a method for controlling transmission latency in a communications system, wherein the communications system is subject to a noise signal having at least a first noise phase and a second noise phase. The method includes determining a first bit rate for symbols transmitted during the first noise phase, and a second bit rate for symbols transmitted during the second noise phase, the first bit rate and the second bit rate being constrained such that a transmission latency does not exceed a pre-determined maximum allowed transmission latency; and transmitting symbols at the first bit rate during the first noise phase and at the second bit rate during the second noise phase. In other variants, the invention provides an apparatus, a constrained rate receiver, a transmitter and a signal.

Abstract: Discrete multitone transmission assigns bits to tones for transmission. The bits are assigned using permutations of bits and tones that cycle through a sequence of permutations in successive frames.

Abstract: A system and method for changing retransmission and rescheduling queues to support retransmission in a communications system is presented. A method for changing queue size values includes, for an increase in data rate, determining a new retransmission queue size value for a retransmission queue at the transmitting device and a new rescheduling queue size value for a rescheduling queue at the receiving device such that an amount of time for a DTU to enter and exit the retransmission queue is greater than a roundtrip delay. For a decrease in data rate, the method includes determining the new retransmission queue size value and the new rescheduling queue size value such that an amount of time for a DTU to enter and exit the retransmission queue is less than a maximum delay. Systems and methods for changing the retransmission and rescheduling queue sizes are also presented.

Abstract: A method of optimizing a communication system for receiving and processing an input communication signal includes selecting a first noise margin m to be applied against an external noise present on the input communication signal. The method further includes selecting a second noise margin mi to be applied against an internal noise introduced on the communications signal by the communication system. The second noise margin is a predetermined function of the first noise margin. The method also includes calculating a virtual noise to signal ratio that is a combination of an external noise to signal ratio NSRe, an internal noise to signal ratio NSRi, the first noise margin and the second noise margin. The method further includes adjusting one or more system parameters so as to maintain the virtual noise to signal ratio at a predetermined margin above a required noise to signal ratio.

Abstract: A method for transmitting data packets of at least two different priority levels via one or more bearer channels is described. The method comprises the steps of fragmenting a data packet into a plurality of corresponding code words, each code word comprising a sync code, with the sync code being adapted for indicating a priority level of the corresponding data packet, and of transmitting the code words via the one or more bearer channels. In case high priority code words corresponding to a high priority data packet arrive during transmission of low priority code words corresponding to a low priority data packet, the following steps are performed: interrupting transmission of low priority code words, transmitting the high priority code words corresponding to the high priority data packet, and resuming the transmission of the low priority code words via the one or more bearer channels.

Abstract: A method for transmitting data in an xDSL system is disclosed. In an exemplary embodiment, the method includes defining a data transmission unit (DTU) to be sent in an xDSL data stream, defining a retransmit container as a time slot that corresponds to a sent DTU, maintaining a copy of the sent DTUs and an index of corresponding retransmit containers in retransmission buffer, transmitting the DTUs in the xDSL data stream, determining whether a transmitted DTU should be retransmitted, identifying each corrupted DTU by its corresponding retransmit container, and retransmitting an uncorrupted copy of the DTU as identified by the corresponding retransmit container. The retransmission is deferred until the DTU is at a predefined position in the retransmission buffer.

Abstract: The present invention provides systems and methods for pseudo-random signal generation in a multi-carrier communications system. In embodiments, a transmitter includes a pseudo-random bit sequence (PRBS) generator and Medley signal generator. The PRBS generator can operate in at least one of the following modes: a parameter selection mode, a scrambler mode, and/or a combination mode. The Medley signal generator receives an output bit sequence from the PRBS generator. The Medley signal generator then generates a Medley signal which includes a set of Medley tones encoded based on the output bit sequence from the PRBS generator. The Medley signal is then sent over channels of a multi-carrier communication system such as an ADSL system.

Abstract: Methods, systems, and computer program products for reconfiguring a modem. In an embodiment, fast reconfiguration of a modem occurs when a first modem determines there is a need for fast reconfiguration. The first modem signals its transition from showtime to fast reconfiguration. The first modem waits for acknowledgement from a second modem before transitioning to showtime. Once transitioned from showtime, the first modem estimates a signal to noise ratio and then exchanges parameters with the second modem. The first and second modems then transition to showtime.

Abstract: A method of optimizing a communication system for receiving and processing an input communication signal includes selecting a first noise margin m to be applied against an external noise present on the input communication signal. The method further includes selecting a second noise margin mi to be applied against an internal noise introduced on the communications signal by the communication system. The second noise margin is a predetermined function of the first noise margin. The method also includes calculating a virtual noise to signal ratio that is a combination of an external noise to signal ratio NSRe, an internal noise to signal ratio NSRi, the first noise margin and the second noise margin. The method further includes adjusting one or more system parameters so as to maintain the virtual noise to signal ratio at a predetermined margin above a required noise to signal ratio.