Abstract: Various embodiments for addressing the performance objectives of LDSL and examples of smart systems for LDSL are disclosed. An evaluation of the spectral compatibility of two LDSL modes based on two different downstream masks, identified herein as LDSL Wide and Narrow, is disclosed. Spectral compatibility is evaluated in accordance with existing rules. Other embodiments may further comprise determining features of upstream transmission.

Abstract: A system and method for multiple inputs, multiple outputs (MIMO) PSD allocation in a DSL system is disclosed. In some embodiments, the method may comprise monitoring system performance by performing a multi-ended line test (MELT), processing the MELT and allocating PSD based on at least one of system coupling power and system traffic.

Abstract: A method and system for reducing the power to average ratio (PAR) at the transmitter and after the up sampling and interpolation filter. In the time domain, Fractional Local Peak Detection and Mitigation (FLPDM) locally (i.e. in the neighborhood where the high peak occur) detects the high peaks at a sampling rate of T/K and combines an optimal binary and a PAR-lowering sequence at the scale of one extended symbol for multi-carrier modulation and at the scale M of symbols for single-carrier modulation. Since the technique acts locally, FLPDM does not require peaks search and processing at the scale of many time samples, does not require iterative Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) processing and it assures tunable millions of instruction per second (MIPS) performance.

Abstract: In an asynchronous digital subscriber line (ADSL) system comprising a central office High Speed ADSL Terminating Unit (HSTU-C) in bi-directional discrete multitone (DMT) communication with a remote High Speed ADSL Terminating Unit (HSTU-R), a method for improving handshake detection is provided by the present invention. The method comprises transmitting handshake signaling from the HSTU-C to the HSTU-R via a first subset of carrier sets at a first symbol rate and transmitting handshake signaling from the HSTU-C to the HSTU-R via a second subset of carrier sets at a second symbol rate, the second symbol rate being less than the first symbol rate.

Abstract: Systems and methods for performing single-end line testing (SELT) are described. At least one embodiment includes a method for SELT to determine loop characteristics for a loop. The method for performing SELT comprises generating a test signal through a loop to be tested and receiving an echo response. The method further comprises subtracting predetermined near end echo response from the received echo to derive a far end echo response, performing time-dependent scaling on the far end echo response to compensate for loop attenuation, comparing the time-scaled far end echo response to a set of predefined templates, and providing an estimate of loop characteristics by identifying a matching template within the set of predefined templates, wherein the matching template contains information relating to loop characteristics comprising loop length and loop termination.

Abstract: The present invention overcomes various problems by defining two upstream masks (UI, U2) and two downstream masks (DI, D2) and using a mask selectable system for the long reach digital subscriber line (LDSL), in which a unique modem feature is activated during handshake to automatically check for physical layer status in terms of spectral compatibility and, thus, automatically optimize the boosted mode with the use of the mask selectable system choose the best combination of upstream/downstream masks in any physical layer noise scenario.

Abstract: Systems and methods for off-diagonal MIMO precoders are described. At least one embodiment includes a method for precoding data for transmission in a discrete multi-tone (DMT) xDSL system to cancel self-induced far end crosstalk (self-FEXT) comprising: learning characteristics associated with a plurality of N users within the xDSL system to determine an initial off-diagonal multiple input multiple output (MIMO) precoder (ODMP) for a given tone frequency; and converging towards an optimum ODMP from the initial ODMP in order to cancel downstream self-FEXT for the plurality of N users, wherein the ODMP is represented as a zero diagonal matrix with only off-diagonal terms, and wherein the converging towards the optimum ODMP comprises: maximizing the channel capacity for the plurality of N users for the given tone frequency; and minimizing an increase in transmit power of the xDSL system relative to an original transmit power where a precoder is not active.

Abstract: A method and apparatus implements a Virtual Exchange Reference Impact (VERI) technique to define a pattern to shape the spectrum of a cabinet deployed system to minimize its impact, e.g., FEXT, into an exchange deployed system while achieving effective cabinet system performance, e.g., in terms of data transmission rate. The invention shapes the cabinet system to replicate a self-impact of the exchange system on itself based on the known distance of the cabinet from the exchange. The shaping is required when both exchange and cabinet systems share the same bundle and exhibit overlapped bandwidths. A particular example consists of VDSL deployed from remote cabinet impacting ADSL2/ADSL2+ deployed from the exchange.

Abstract: There is provided a method of shaping PSD (Power Spectrum Density) of an FTTN (Fiber-To-The-Node) downstream signal from a disturber source to achieve spectral compatibility at an FTTN downstream victim with a downstream PSD from a reference source. The method includes receiving the downstream PSD from the reference source. The method further includes receiving an unshaped downstream PSD from the disturber source. The method further includes shaping the PSD of the FTTN downstream signal to have a substantially equivalent FEXT (Far-End Cross-Talk) into the FTTN downstream victim as the downstream PSD from the reference source.

Abstract: The present invention overcomes various problems by defining two upstream masks (U1, U2) and two downstream masks (D1, D2) and using a mask selectable system for the long reach digital subscriber line (LDSL), in which a unique modem feature is activated during handshake to automatically check for physical layer status in terms of spectral compatibility and, thus, automatically optimize the boosted mode with the use of the mask selectable system choose the best combination of upstream/downstream masks in any physical layer noise scenario.

Abstract: Included are embodiments for subframe interleaving. At least one embodiment of a method includes receiving at least one subframe, the at least one subframe being derived from a plurality of frames of data and interspersing at least a portion of the at least one subframe according to a predetermined subframe interleaving strategy.

Abstract: Included are embodiments for self protection. At least one embodiment includes Self-protection Unit for protecting a signal that includes a first receiving component configured to receive data, the received data being received as at least one frame and a subframing component configured to subframe at least a portion of the received data, wherein subframing includes converting the at least one into a plurality of subframes. Some embodiments include a subframe interleaver component configured to interleave at least a portion of the subframes.

Abstract: Systems and methods for multi-stage signal detection in MIMO transmission including Bernoulli-Gaussian detection are provided. A multistage iterative signal decoder is provided that exploits the property that in a relatively simply decoding scheme such as mean square error (MSE) or zero-forcing (ZF) only a small portion of the total symbols are mis-detected. Therefore, an optimality test is performed on the output of a relatively low complexity decoder unit. If the symbol passes the optimality test, it is presumed to be correctly decoded. Otherwise, the symbol is sent for further processing to a relatively higher complexity decoding unit such as a sphere decoder. In this way, processing efficiency is increased, because only those symbols requiring additional processing are processed by the high complexity processing unit.

Abstract: A communications system may be characterized by a system error variance because the error variance provides an indication of signal corruption in the system. By strategically adding a secondary sensor to the communications system, system characteristics may be altered so that the system error variance is reduced. A system and method are presented, wherein a secondary sensor is configured to receive a disturbance effect and produce a filtered slave signal as a function of the disturbance effect. The filtered slave signal is configured to alter the characteristics of the communications system and thereby reduce system error variance.

Abstract: A method and system for reducing the power to average ratio (PAR) at the transmitter after the up sampling and interpolation filter. In the time domain, Side Tone Packets Injection (STPI) system and method detects the optimal peaks that will result in having a low PAR at a sampling rate of T/K and combines an optimal binary and a PAR-lowering sequence and an upsampled, interpolated original discrete time signal at the scale of one extended symbol for multi-carrier modulation and at the scale M of symbols for single-carrier modulation. STPI does not require peaks search and processing at the scale of many time samples, does not require iterative Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) processing thus, allowing the receiver not to perform extra demodulation.

Abstract: Disclosed herein are various mechanisms for the adaptive cancellation of radio frequency interference (RFI) in Discrete Multitone (DMT)-based signal transmissions systems. various mechanisms for the adaptive cancellation of radio frequency interference (RFI) in Discrete Multitone (DMT) modulated signal transmissions systems. In at least one embodiment of the present invention, RFI introduced by one or more RFI disturbers (e.g., ham radios) into a DMT modulated signal may be detected by calculating an RFI canceller coefficient for some or all of the DMT bins of the signal, where the RFI canceller coefficient represents the correlation between the noise at the corrupted bin and the reference RFI noise. The RFI canceller coefficients for the corrupted bins may be calculated using an LMS adaptation process. Those bins where the magnitude of the corresponding RFI canceller coefficient is greater than a certain threshold may be marked as corrupted by RFI.

Abstract: A system and method for reducing peak-to-average ratio (PAR) values in signal transmission systems is presented. The presented approach divides a plurality of symbols into a number of non-overlapping subsets of symbols, and manipulates each of the non-overlapping subsets of symbols to produce a plurality of sub-sequences. A strategic manipulation of the subsets of symbols results in the reduction of PAR values.

Abstract: A system and method for increasing payload in a data transmission system. In architecture, the system comprises a modulation device configured to modulate data bins to produce bin-clusters, a mechanism to load the bin-clusters with data, a transmitter configured to transmit the loaded bin-clusters, a receiver configured to receive the transmitted bin-clusters, and a demodulation device configured to extract data from the received bin-clusters. The method steps comprise the steps of modulating data bins to produce bin-clusters, loading the bin-clusters with data, transmitting the loaded bin-clusters, receiving the transmitted bin-clusters, and extracting data from the received bin-clusters.

Abstract: A method and apparatus implements a Virtual Exchange Reference Impact (VERI) technique to define a pattern to shape the spectrum of a cabinet deployed system to minimize its impact, e.g., FEXT, into an exchange deployed system while achieving effective cabinet system performance, e.g., in terms of data transmission rate. The invention shapes the cabinet system to replicate a self-impact of the exchange system on itself based on the known distance of the cabinet from the exchange. The shaping is required when both exchange and cabinet systems share the same bundle and exhibit overlapped bandwidths. A particular example consists of VDSL deployed from remote cabinet impacting ADSL2/ADSL2+ deployed from the exchange.

Abstract: Method and System for evaluating a turbo-coding scheme suitable for VDSL2 systems. The scheme is a Turbo-Trellis Coded Modulation TTCM that makes use of a Parallel Concatenated Convolutional Code (PCCC) including an inner Latin square/rectangular matrix of Random sequence pattern Interleaver (LRI) of approximately 2044 bits. In the presence of the outer Reed Solomon Code but without an outer interleaver (fast mode), the method and system provides 7.1 dB of average net coding gain, i.e., 2.6 dB of coding gain improvement relative to the standard 16 states 4-dimensional (4-D) trellis code used in current ADSL2 systems. The substantial coding gain achieved through the method and system, leads to an increase in the VDSL2 rate by 38% at 6 kft against local exchange carriers, such as ILEC (SBC) conditions with approximately 1.5 ms of latency. By encoding only two bits per tone (i.e., 1 bit per dimension), the turbo code implementation complexity is kept reasonable.