Abstract: In a multi-carrier system, the carriers (f0 . . . f511, f512 . . . f1023, . . . , f3584 . . . f4095) are grouped in subsets (SUBSET1; SUBSET2; . . . ; SUBSET8). A constellation information transmitting arrangement (BiGi_TA), for instance located in the multi-carrier receiver (RX), produces for each carrier subset (SUBSET1; SUBSET2; . . . ; SUBSET8) a limited set of parameter values (B1, G1; B2, G2; . . . ; B8, G8) and transmits these sets of parameter values (B1, G1; B2, G2; . . . ; B8, G8) to a constellation information receiving arrangement (BiGi_RA), for instance located in the multi-carrier transmitter (TX). Through interpolation of the limited set of parameter values (B1, G1; B2, G2; . . . ; B8, G8) the latter constellation information receiving arrangement (BiGi_RA) determines the constellation where each carrier (f0 . . . f511, f512 . . . f1023, . . . , f3584 . . . f4095) of a carrier subset (SUBSET1; SUBSET2; . . . ; SUBSET8) will be modulated with.

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 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 and system for communicating data in an xDSL data retransmission mode is disclosed. A data transmission unit (DTU) is defined. The DTU is sent in an xDSL data stream. A retransmit container is further defined a as a time slot that corresponds to a sent DTU. A copy of the sent DTUs and an index of corresponding retransmit containers is maintained. The DTUs are transmitted the in the xDSL data stream. A determination is made on whether a transmitted DTU was corrupted during transmission. Each corrupted DTU is identified by its corresponding retransmit container. An uncorrupted copy of the DTU is then retransmitted as identified by the corresponding retransmit container.

Abstract: An apparatus for transmitting data in an xDSL system is disclosed. In an exemplary embodiment, the apparatus comprises a transmitter that sends data over an xDSL system in the form of a data transmission unit (DTU), the transmitter having physical media specific—transmission convergence (PMS-TC) communication sublayer. The apparatus may further include a retransmission unit that is implemented in the PMS-TC sublayer. The retransmission unit may include a retransmission buffer that stores and indexes transmitted DTUs in retransmit containers. The retransmit container may be defined as a time slot corresponding to a sent DTU, wherein the retransmission unit is configured to respond to a retransmission request indicating which stored DTU should be retransmitted. The stored DTU to be retransmitted may be identified by its corresponding retransmit container.

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: 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 modem receiver 10 receives a multitone signal with a cyclic extension of M samples on a channel 20. The receiver includes a time domain equalizer 14 that includes a finite impulse response (FIR) filter. The FIR filter targets the combined response of the channel and filter to a target impulse response having N taps, where N is less than M+1.

Abstract: A technique for determining a symbol erasure threshold for a received communication signal containing symbol information is disclosed. The technique 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 adaptive 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: 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: A technique for determining a symbol erasure threshold for a received communication signal containing symbol information is disclosed. The technique 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 adaptive 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: A method for determining differential delay of at least two bonded links is described. The method comprises a step of providing, on the part of a transmitting entity, at least some of the data packets transmitted from the transmitting entity to a receiving entity with time stamps, the time stamps indicating a point of time when a respective data packet has been generated, and a step of deriving a propagation delay from a time stamp of a data packet and a time of arrival of the data packet at a receiving entity. The method further comprises a step of determining a differential delay of a link from the propagation delay of the link and a propagation delay of a reference link.

Abstract: A system and method for optimizing the power level in the upstream direction in an ADSL communication system are disclosed. The system and method optimize the upstream signal power level by determining at least one system parameter related to the transmission of the input communications signal and modifying the bit and gain tables in response to the system parameter to optimize the upstream power level. More specifically, in one embodiment, the present invention selects a maximum received power configuration parameter for a receiving device, measures the received signal power at the receiving device, determinines a power backoff parameter for the transmitting device, uses the power backoff to modify the bit and gain tables and communicates the modified bit and gain tables to the transmitting device.

Abstract: There is disclosed a technique in which any peaks above a threshold level are reduced, but not clipped, such that the effects of such peaks is reduced. Although the implementation of the technique preferably includes a clipping step, it is performed on the front-end rather than as the last step in the technique, such that the output signal is not a clipped signal. Any noise introduced by the clipping step, so-called clipping noise, is preferably filtered out of the useful frequency band of the signal.

Abstract: To determine the channel characteristic of a channel (CHANNEL) between a transmitter (TX) and a receiver (RX), a predetermined periodic signal of pulse amplitude modulated symbols is modulated on waveforms by a cosine modulated filter bank (DWMT MOD) in the transmitter (TX), and the waveforms are transmitted over the channel (CHANNEL). In the receiver (RX), the received pulse amplitude modulated symbols are demodulated from the waveforms by a cosine modulated filter bank (DWMT DEMOD), pairs of the received pulse amplitude modulated symbols are combined to form received quadrature amplitude modulated symbols, and the received quadrature amplitude modulated symbols are divided by the transmitted predetermined pulse amplitude modulated symbols considered pairwise as transmit quadrature amplitude modulated symbols. So, samples of the channel characteristic are generated.

Abstract: In a multi-carrier communication system wherein data are transferred bi-directionally in a time division duplexed way, a first pilot carrier is used to transfer a sample rate between two transceivers (VDSL_LT, VDSL_NT) and a second pilot carrier is used to transfer a time division duplexing frame rate between the two transceivers (VDSL_LT, VDSL_NT). The first pilot carrier has an instantaneous frequency that is a fraction of the sample rate of the first transceiver (VDSL_LT) and is orthogonal to other carriers used in the multi-carrier communication system. The second pilot carrier has a mean frequency that is a fraction of the time division duplexing frame rate and is also orthogonal to the other carriers used in the multi-carrier communication system. The second pilot carrier is different from the first pilot carrier.

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 relates to a method and a system for transmitting data in a xDSL communication system increasing the range of the communication link. The communication system may consist of any two communication devices that are connected together by a band limited communication line.

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: 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.