Telefonaktiebolaget Lm Ericsson (publ)

Antoni Fertner

Pål Frenger

Per Ola Börjesson

Fredrik Lindqvist

Miguel Berg

Klas Ericson

Daniel Cederholm

Mattias Hyll

Per Ödling

Anders Orling

Torkel Cj Solve

Ioanna Pappa

Jaume Rius I Riu

Henrik Almeida

Henrik Back

Stefan Höst

Axel Frank Jensen

Adam Wiå

Stefan Allevad

Jonas Gustafsson Rosenberg

Per Mikael Ödling

Henrik Daniel Back

Stefan Alf Allevad

The present disclosure relates to methods and devices for communication systems comprising an electrically conductive line. The disclosure proposes a method in a line estimation device for determining termination characteristics of an electrically conductive line in a communication system. The method comprises outputting a test signal to the line, wherein the test signal is a wideband test signal with a bandwidth arranged to provide an adequate measurement time-resolution. The method further comprises receiving reflections from impedance discontinuities of the line in response to the test signal. The method also comprises forming a trace of the reflections. The method additionally comprises identifying at least one anomaly in the trace of reflections. The method yet further comprises determining termination characteristics of the line based on characteristics of the trace before and after the identified at least one anomaly. The disclosure also relates to corresponding line estimation devices and computer programs.

Methods and devices for determining termination characteristics of an electrically conductive line

The present disclosure relates to wireline communication systems, and in particular to aspects of a method and a line estimation device for estimating a characteristic impedance of a section of a transmission medium. The method comprises determining, by a test equipment having a test port with known impedance Z, an Sscattering parameter vector S[f] of the transmission medium, indexed by frequency f. The method also comprises generating, based on Zand S[f], a model of reflection in the transmission medium corresponding to an observation of the transmission medium via a test port having a test impedance Z, and also estimating the characteristic impedance of the section as a value of Zwhich minimizes a difference between a reflection value of the model of reflection and a respective target reflection value of the section.

Estimation of impedances in a transmission medium

The present disclosure relates to determining parameters in a model of a transmission line. For determining the parameters, reflection coefficient defining data and the total capacitance of the transmission line are obtained. Further, true reflection coefficients obtained through the reflection coefficient defining data are applied in an objective function for the line. The objective function for the line is a sum of error signals and each error signal is the difference between a model value of a reflection coefficient and a corresponding true reflection coefficient. Further, the objective function is minimized by utilizing gradients of the objective function with respect to the transmission line parameters to be determined. A capacitive length is employed and at least two further transmission line parameters are determined as combinations of a basic resistive transmission line parameter, a basic capacitive transmission line parameter and a basic inductive transmission line parameter of the transmission line model.

Transmission line parameter determination

A method and a test device for determining communication characteristics of a metal cable suitable for use in a communication system are provided. The method comprises transmitting a wideband test signal on the metal cable; receiving a reflected signal as a result of the wideband test signal; and determining an interval of the reflected signal to be analyzed, the interval corresponding to a part of the cable length. The method further comprises approximating the reflected signal within the interval by a regression model; and determining characteristics of the metal cable based on the regression model.

Test device and a method for determining communication characteristics of a metal cable

The invention relates to a multi-carrier method in a measurement device for improving reach of a measurement, said method comprising: transmitting a first signal in a sequence, measuring a response to said first signal, calculating a first transfer function for frequency of each modulated subcarrier in the first signal, transmitting a second signal of the sequence, wherein at least one subcarrier in the second signal has modulation different from that of the subcarriers in the first signal, measuring a response to said second signal, calculating a second transfer function for frequency of each modulated subcarrier in the second signal, said second transfer function comprising for each frequency a thereto associated second distortion component, calculating a mean value of all first and second transfer functions. The invention further relates to a measurement device for performing said method.

Multi-carrier method in a measurement device

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, r, a cut-off frequency, v, a line capacitance Cand a line inductance L. The line model handling means calculates the line inductance L(f) via a Hubert transform of a function of Q(f/v), wherein the function Q(f/v) relates the line resistance R(f) to ras R(f)=r&#xb7;Q(f/v). The Hilbert transform values are calculated using a parameterized closed form expression for the Hubert transform or they are tabulated. The line property determination means calculates the first property and criteria function application means uses the measured first property and the calculated first property for model parameters to find optimized numerical model parameter values.

Arrangement and method relating to analysis of transmission lines

Transmission properties of a telecommunications transmission line may be estimated with improved accuracy by numerical solution for &#x393; of Z&#xb7;j&#x3c9;^C=&#x393;coth(&#x393;). At least one curve is adapted to &#x393; solutions already obtained and a starting point for numerical solution is selected in dependence of the at least one curve and in dependence of an already obtained solution close in frequency. In a first frequency range, starting points for numerical solution may be calculated from a biquadratic equation. In a second frequency range, a line in the complex plane may be adapted to solutions already obtained and new starting points selected in dependence of the line and in dependence of the previous solution. In a third frequency range, two lines in the frequency plane may be adapted to solutions already obtained and new starting points selected in dependence of the lines.

Method for estimating transmission properties of a telecommunications transmission line

The present invention relates to a method for estimating properties of a transmission line by means of features of a noise spectrum generated by noise entering said transmission line at an intermediate location between the ends of the line. The invention provides possibility to estimate a number of properties, e.g. length of a portion of the transmission line, line attenuation of said line portion and even line termination.

Passive single-ended line test

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.

Calibration of a line driving device

The present invention concerns methods for estimating one or more transmission properties of a telecommunications transmission line. Estimates of the line input impedance, Zat a frequency &#x192;, and the line capacitance &#x108; are made. An estimate is then made in dependence of &#x108;, the frequency &#x192; and a value &#x393;, where &#x393; satisfies the relationship &#x393; coth (&#x393;)=Z&#xb7;j&#x3c9;&#x108;, and &#x3c9;=2&#x3c0;&#x192;. Accuracy may be improved by least squares fitting a curve to a set of intermediate values and then generating an estimate from the coefficients of the curve.

Method for transmission line analysis

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 &#x3c0;, 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 &#x3c0;.

Method and device for estimating properties of a telecommunication transmission line

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.

Method and a system for cable or subscriber loop investigation performing loop topology identification

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 &#x3b8; 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.

Method and localization unit for detecting and locating load coils in a transmission line

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.

Frequency domain echo canceller

A method is described herein that can be used to detect the presence of a load coil within a transmission line. The method can also be used to determine the number of load coil(s) present within the transmission line. In addition, the method can be used to determine the distance to the first load coil.

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Stockholm, Sweden

Antoni Fertner