Abstract: A base station initializes pseudo-random sequence generators on which wireless devices base generation of uplink reference signals. The base station determines a first sequence from a first subset of possible initialization sequences for a sequence generator of a first device, and determines a second sequence from a second subset of possible initialization sequences for a sequence generator of a second device. The range of this second subset spans at least the range of the first subset. The base station further encodes the first sequence as a first set of two or more parameters, and encodes the second sequence as a second set of one or more parameters. This second set includes at least one parameter not included in the first set, and comprises fewer bits than the first set. The base station initializes the sequence generators by transmitting the first and second sets of parameters to the devices.

Abstract: Method, arrangement and devices for calibration of a line driving device, such as a DSLAM, having a line port. The method comprises deriving of a first parameter vector, PVinf, for example Hinf. The parameter vector PVinf is derived by performing, at a first site, an echo measurement on the line driving device while the line port on said line driving device is open. The method further comprises calibrating the line driving device based on the first parameter vector PVinf and a second parameter vector PVref, which second parameter vector is based on information on echo measurements performed on at least one reference line driving device.

Abstract: Method, arrangement and network node/device for estimating a quantity related to impedance in a first frequency interval, D1, of a telecommunication transmission line where the transmission line has a length d. The method involves determining a quantity related to impedance of the telecommunication transmission line for at least two frequencies, f1D2 and f2D2, in a second frequency interval D2. The frequencies f1D2 and f2D2 should fulfil the condition that the line length d times the absolute value of the difference between a line propagation constant ?(f1)D2 and a line propagation constant, ?(f2)D2, is less than ?, i.e. abs(d*?(f1)D2?d*?(f2)D2)<?. The method further involves estimating a quantity related to impedance in the first frequency interval D1 based on the determined quantity related to impedance in the second frequency interval D2, where the estimating involves the fitting of a Puiseux series to the determined quantity related to impedance in frequency interval D2.

Abstract: In a method of mitigating interference for received signals in a communication system, receiving S10 a transmitted signal via at least two antenna elements, estimating S20 a channel for the received signals, and estimating S30 a disturbance covariance matrix based on the channel estimate, which estimated disturbance covariance matrix represents received interference plus noise of the received signals. Subsequently, adapting S40 the estimated covariance matrix by enhancing the diagonal elements of the covariance matrix to provide an enhanced covariance matrix, to reduce the spread in eigenvalues of the covariance matrix, and thereby improve the robustness of the covariance matrix. Finally, selectively S50 using IRC and/or MRC to mitigate interference of the received signals, based on at least the channel estimate and on the enhanced covariance matrix, to provide a received signal with improved quality on channels with Doppler frequency.

Abstract: A method and device for estimating one or more transmission properties of a telecommunication transmission line. At least one signal is sent on the line, the at least one signal including at least two frequencies for which the absolute value of the line propagation constant times the line length is less than ?, and a resulting signal is received. An estimate of at least one transmission line property is then determined by examining the relationship between the sent and resulting signal or signals. The process may be repeated, if necessary. The estimate determination may also be repeated one or more times, with each successive estimate preferably using for the determination only those frequencies for which, as previously estimated, the absolute value of the line propagation constant times the line length is less than ?.

Abstract: In a method of interference rejection combining (IRC) for mitigating interference in received signals in the frequency domain for a telecommunication system, selecting (S 10) a sub-group of frequencies of a received signal, determining (S20) a joint representation of a covariance matrix for the interference plus noise for at least one time slot of the received signal for the selected sub-group of frequencies, determining (S30) a channel estimate based on at least one pilot symbol of said at least one time slot. Finally, determining (S40) IRC coefficients in the frequency domain for each symbol of said at least one time slot based on said determined joint representation of the covariance matrix and said determined channel estimate.

Abstract: A method of automatically determining a far-end crosstalk (FEXT) and near-end crosstalk (NEXT) transfer function in communication lines such as Digital Subscriber Lines (DSL). In a first phase, an input test signal with a known power density spectrum (PSD) covering a frequency range of interest is transmitted at the near end of line A while a received signal or noise-related quantity or PSD is measured at both the near end and far end of line B. In a second phase, transmission of the test signal is stopped, and a received signal or noise-related quantity or PSD is again measured at both ends of line B. In a third phase, the FEXT/NEXT transfer function is determined based on the measurements of the first and second phases.

Abstract: A method and arrangement for estimating line insertion loss of a customer transmission line at a frequency (f1) or a plurality of frequencies. Values of line insertion loss for at least two reference transmission lines are pre-measured at each frequency and stored in a memory. A calibration quantity representing an amplitude of a far-end Time Domain Reflectometer (TDR) reflection is also measured for each of the reference transmission lines. The pre-measured line insertion loss of each reference transmission line is then calibrated by the calibration quantities of the reference transmission lines. The calibration quantity for the customer transmission line is then measured, and an estimate of the line insertion loss at each frequency for the customer transmission line is generated based on the calibrated line insertion losses of the reference transmission lines and the measured calibration quantity of the customer transmission line.

Abstract: A method and loop qualification unit for determining loop parameters of a topology of a twisted pair loop for a digital subscriber line system. The parameters are represented by a vector that receives a measurement of a SELT parameter measured at one end of the loop and a measurement of a DELT loop transfer function measured at both ends of the loop. A first model generator generates a first model for the SELT parameter and a second model generator generates a second model for the DELT function based on the loop parameters represented by the vector. A processor then determines the parameters by minimizing the differences between the first model and the SELT parameter, and the second model and the DELT function. The determined parameters are represented by the vector that provides the minimization.

Abstract: Embodiments of the present invention relate to an arrangement for analyzing transmission line properties. Measurement data providing means provide data of a first frequency dependent line property, line property calculation arrangement with model handling means, a Hubert transform handler and line property determination means calculate said first property based on model parameters, line resistance at 0 frequency, roc r cut-off frequency, v, line capacitance C?r and line inductance ??. The line model handling means calculates the line inductance L(J) via a Hubert transform of Q(f/v)r relating line resistance R(J) to roc such as formula (I). The Hilbert transform values are calculated using a parameterized closed form expression for the Hubert transform or they are tabulated.

Abstract: In a method of mitigating interference for received signals in a communication system, receiving S10 a transmitted signal via at least two antenna elements, estimating S20 a channel for the received signals, and estimating S30 a disturbance covariance matrix based on the channel estimate, which estimated disturbance covariance matrix represents received interference plus noise of the received signals. Subsequently, adapting S40 the estimated covariance matrix by enhancing the diagonal elements of the covariance matrix to provide an enhanced covariance matrix, to reduce the spread in eigenvalues of the covariance matrix, and thereby improve the robustness of the covariance matrix. Finally, selectively S50 using IRC and/or MRC to mitigate interference of the received signals, based on at least the channel estimate and on the enhanced covariance matrix, to provide a received signal with improved quality on channels with Doppler frequency.

Abstract: A system, method, and transceiver unit for determining one or more properties of a digital subscriber line (DSL) utilizing a time-variable finite impulse response (FIR) filter. The transceiver unit sends a loop test signal to the line and calculates an impulse response of a reflection of the loop test signal from the line. The calculated impulse response is filtered utilizing the time-variable FIR filter and properties of the line are determined. Characteristics of the FIR filter may be controlled by a set of parameters that vary as a function of time according to a predetermined formula. As a result, the FIR filter provides both high time resolution of closely separated pulses and amplification of far-end pulse reflections.

Abstract: A system and method for using loop topology identification to investigate a transmission line having a plurality of cable segments. At a measurement plane for each segment, a probing signal is transmitted into the cable. A reflected signal is detected, and an equivalent total input impedance is calculated. The system iteratively calculates the distance between the measurement planes as well as the length, characteristic impedance, and the propagation constant of each segment. A model is used to calculate the respective equivalent input impedance of each segment using the calculated characteristic impedance, propagation constant, and length of the preceding segment. The equivalent total input impedance is then calculated from the iteratively calculated segment values.

Abstract: The present invention relates to a method for managing transmission resources in a digital communication system comprising an access network, such as a DSL system, implementing resource management for minimization of cross-talk interference in a cable or cable binder of the access network comprising a number, N of lines. It comprises the steps of: determining, by means of calculating means, for a respective of said lines, a relevant line set, comprising interference relevant lines, for said respective line, and applying, for the respective line, an algorithm for resource management using the determined relevant line set, thus reducing computational complexity of the resource management algorithm.

Abstract: A method and localization unit for localizing load coils within a transmission line. The load coil localization is achieved using a measurement of a Single-Ended Line Testing (SELT) parameter for the transmission line and an approximation of the SELT parameter obtained from a model of the transmission line. The model is based on a parameter vector ? including parameters describing the transmission properties of each load coil and cable section and the length of a plurality of individual cable sections as unknown independent parameters. The location of at least one load coil is determined by substantially minimizing a criterion function that represents a deviation between the measurement of the SELT parameter and the approximation of the SELT parameter obtained from the model. The load coil localization method and unit can be used for both symmetric and asymmetric transmission lines.

Abstract: A method and loop qualification unit for determining loop parameters of a topology of a twisted pair loop for a digital subscriber line system. The parameters are represented by a vector that receives a measurement of a SELT parameter measured at one end of the loop and a measurement of a DELT loop transfer function measured at both ends of the loop. A first model generator generates a first model for the SELT parameter and a second model generator generates a second model for the DELT function based on the loop parameters represented by the vector. A processor then determines the parameters by minimizing the differences between the first model and the SELT parameter, and the second model and the DELT function. The determined parameters are represented by the vector that provides the minimization.

Abstract: A method of automatically determining a far-end crosstalk (FEXT) and near-end crosstalk (NEXT) transfer function in communication lines such as Digital Subscriber Lines (DSL). In a first phase, an input test signal with a known power density spectrum (PSD) covering a frequency range of interest is transmitted at the near end of line A while a received signal or noise-related quantity or PSD is measured at both the near end and far end of line B. In a second phase, transmission of the test signal is stopped, and a received signal or noise-related quantity or PSD is again measured at both ends of line B. In a third phase, the FEXT/NEXT transfer function is determined based on the measurements of the first and second phases.

Abstract: A method and localization unit for localizing load coils within a transmission line. The load coil localization is achieved using a measurement of a Single-Ended Line Testing (SELT) parameter for the transmission line and an approximation of the SELT parameter obtained from a model of the transmission line. The model is based on a parameter vector ? including parameters describing the transmission properties of each load coil and cable section and the length of a plurality of individual cable sections as unknown independent parameters. The location of at least one load coil is determined by substantially minimizing a criterion function that represents a deviation between the measurement of the SELT parameter and the approximation of the SELT parameter obtained from the model. The load coil localization method and unit can be used for both symmetric and asymmetric transmission lines.

Abstract: An echo canceller reduces an echo signal produced when the transmitted signal leaks back into the receiver via a hybrid. The echo canceller estimates the echo signal from the transmitted signal, and then subtracting the estimated echo signal from the received signal. In practice, the echo path channel in a DMT-modem is much longer than the cyclic prefix, and therefore, the received echo signal will be subjected to both ISI (inter-symbol-interference) and ICI (inter-carrier-interference). A traditional echo canceller, designed for a xDSL-modem, uses either a time domain adaptive FIR-filter or a combined echo canceller implemented in both time and frequency domain. A matrix-based adaptive echo canceller is implemented in the frequency domain. Various example embodiments are disclosed.

Abstract: A system, method, and transceiver unit for determining one or more properties of a digital subscriber line (DSL) utilizing a time-variable finite impulse response (FIR) filter. The transceiver unit sends a loop test signal to the line and calculates an impulse response of a reflection of the loop test signal from the line. The calculated impulse response is filtered utilizing the time-variable FIR filter and properties of the line are determined. Characteristics of the FIR filter may be controlled by a set of parameters that vary as a function of time according to a predetermined formula. As a result, the FIR filter provides both high time resolution of closely separated pulses and amplification of far-end pulse reflections.