Abstract: Method and apparatus for modeling a network are described in which a 1 port measurement is made on the network by inputting an excitation signal at one port of the network and recording the results reflected back to the port. A 1 port parametric model of the network is generated whereby as much information about the topology of the network is included in calculating initial values of the parameters. Then the values of the parameters of the 1 port parametric model are optimized by reducing the difference between the results of the measurement step and results calculated using the 1-port parametric model and the excitation signal.

Abstract: A device and method for exchanging data frames are disclosed. In one aspect, the device exchanges data between a WAN and one or more LAN segments in an optimized way leading to a better quality of experience for the user. The device comprises an interface exchanging data frames over an access network, at least a first and second subnet interface exchanging data frames and arranged for being coupled to a network, a memory storing classification rules, a classification agent extracting information from an incoming data frame and applying the rules to the extracted information to determine the interface via which the incoming data frame is to be forwarded, and a Quality of Service monitoring agent for retrieving Quality of Service information from the subnet interfaces and dynamically updating the classification rules according to the QoS information.

Abstract: A method and apparatus for modeling a network comprising a plurality of transmission lines is described, the method and system being adapted to measure loop parameters of first transmission line to provide measured loop parameters, determine a topology of the first transmission line by analyzing the measured loop parameters with reference to at least a one model of a plurality of models for transmission lines of different topologies, select a further model for estimating crosstalk related parameters based on the determined topology, and estimate at least one crosstalk related parameter based on the determined topolgy and the selected further model.

Abstract: A device and method for exchanging data frames are disclosed. In one aspect, the device exchanges data between a WAN and one or more LAN segments in an optimized way leading to a better quality of experience for the user. The device comprises an interface exchanging data frames over an access network, at least a first and second subnet interface exchanging data frames and arranged for being coupled to a network, a memory storing classification rules, a classification agent extracting information from an incoming data frame and applying the rules to the extracted information to determine the interface via which the incoming data frame is to be forwarded, and a Quality of Service monitoring agent for retrieving Quality of Service information from the subnet interfaces and dynamically updating the classification rules according to the QoS information.

Abstract: Methods for matching adaptive hybrids (15) to lines (16) for making reflectograms of the lines (16) measure (1) input impedances (Zmeas) of the lines (16), model (2) characteristic impedances of the lines (16) via physical models (Zphymod), estimate (3) parameters of the physical models (Zphymod) via cost functions which depend on the measured input impedances (Zmeas), convert (30) the modelled characteristic impedances into impedance values (13), and set (31) the adaptive hybrids (15) with the impedance values (13). Unwanted near-end reflections are minimised and wanted reflections can be measured. The physical models depend on frequencies s, Bessel functions Ji and parameters ai related to geometrical dimensions A, D and L and material constants ?, ? and ? of the lines (16).

Abstract: In the course of a reflectometry-based qualification procedure of a local loop, which connects customer premises to a central office of a telecommunication network, and in the event of being unable to identify the loop termination associated with the customer premises, a second reflectometry measurement of the local loop is carried out with a different impedance load at the customer premises. Next, the two reflectograms are compared with each other in the time domain in order to delineate among all the reflections those at the customer premises and to determine therefrom the position of the customer premises in the local loop.

Abstract: Modems (1) for coupling network-units (40) to devices (50) and comprising receivers (21) for receiving first data from the network-units (40) and transmitters (22) for transmitting second data to the network-units (40), which first data is destined for the devices (50) and which second data originates from the devices (50), are provided with detectors (31) for detecting parameters (p1) of the first data and adjustors (32) for, in response to detection results, adjusting parameters (p2) of the second data, to reduce the chance on network congestion networks (4). Calculators (33) calculate the parameters (p2) of the second data as a function of the parameter (p1) of the first data. The parameter (p2) of the second data is made substantially equal to the parameter (p1) of the first data between a minimum value (bmin) and a maximum value (bmax). The parameters (p1,p2) comprise a bitrate. The network-unit (40) forms part of an access network (4) and the device (50) forms part of a subscriber network (5).

Abstract: A multi-carrier receiver selects antennas (A31, A32), i.e. carriers whereto a small amount of power and data is allocated, for estimation of characteristics of a narrowband disturber (RFI-Signal-3) in the Radio Frequency Interference band (RFI-Band), a predetermined band for e.g. radio amateur transmission. These antennas (A31, A32) can be selected amongst all carriers located inside the Radio Frequency Interference band (RFI-Band) and at least two carriers (C1, C2) located outside the Radio Frequency Interference band (RFI-Band).

Abstract: In the process of estimating attributes of a transmission line from reflectometry measurements, small yet important reflections may be drowned in the immediate reflected signal owing to the mismatch between the reference impedance with respect to which the 1-port scattering parameter of the line has been determined and the characteristic impedance of the line. The major part of the near-end reflections are eliminated by estimating the characteristic impedance of the line, and by converting the 1-port scattering parameter of the line from the reference impedance base to the estimated characteristic impedance base. However, there is still a residual influence of the near-end reflections. It is then highly necessary to determine a time zone wherein the residual near-end reflections are enclosed so as their contribution is further neutralized in the process of estimating attributes of the transmission line.

Abstract: Methods for matching adaptive hybrids (15) to lines (16) for making reflectograms of the lines (16) measure (1) input impedances (Zmeas) of the lines (16), model (2) characteristic impedances of the lines (16) via physical models (Zphymod), estimate (3) parameters of the physical models (Zphymod) via cost functions which depend on the measured input impedances (Zmeas), convert (30) the modelled characteristic impedances into impedance values (13), and set (31) the adaptive hybrids (15) with the impedance values (13). Unwanted near-end reflections are minimised and wanted reflections can be measured. The physical models depend on frequencies s, Bessel functions Ji and parameters ai related to geometrical dimensions A, D and L and material constants ?, ? and ? of the lines (16).

Abstract: The invention relates to a modem and a method for providing bit loading computation in a multi-carrier communication system, using a plurality of simultaneous different carriers or tones by measuring the signal to noise ratios (SNRs) for carriers and by determining in dependence of the SNR a related number of bits to be allocated to the respective carrier. The method comprises the steps of providing a sliding window having a frequency width able to contain a predetermined number of the carriers, moving the sliding window over the frequency spectrum of the carriers through a plurality of positions of the window with respect to the carrier frequencies, and when the window contains the predetermined number of the carriers and there is at least one further carrier to be positioned in the window as a new carrier for bit allocation, the window is moved such that on entering a new carrier into the window at one of its borders, a carrier already in the window at the other frequency border leaves the window.

Abstract: In a multi-carrier transmission system, a clock timing error (&tgr;e) is calculated at the receiver's side and used for synchronisation between a transmitting modem and a receiving modem (RX1). The clock timing error (&tgr;e) is calculated from phase errors (&phgr;0, &phgr;1, . . . , &phgr;i, . . . , &phgr;N-1) detected for a plurality of pilot carriers during a tracking mode in such a way that the share (Ai) of a phase error (&phgr;i) detected for a particular pilot carrier in the clock timing error (&tgr;e) depends on the transmission quality (SNRi) of that pilot carrier over the transmission medium in between the two modems. In this way, the robustness of the synchronisation for norrowband noise near a pilot carrier is improved significantly.

Abstract: A multicarrier receiver (RX′) comprises the cascade connection of a sliding Fourier transformer (SLIDING FFT) which subsequently Fourier transforms parts of an incoming cyclically extended multicarrier symbol (MS), and a per-carrier frequency domain equaliser (PC-FEQ) including for each carrier a tapped delay line (TD1, TD2, . . . , TDN/2) for equalising the Fourier transformed parts of the incoming multicarrier symbol (MS). The per-carrier frequency domain equaliser (PC-FEQ) allows to optimise the system capacity individually per carrier, and in a preferred embodiment of the invention includes tapped delay lines (TD1, TD2, . . . , TDN/2) with adaptive complex taps, with an adaptive length and with an individual delay that may differ for different carriers.

Abstract: In the process of estimating attributes of a transmission line from reflectometry measurements, small yet important reflections may be drowned in the immediate reflected signal owing to the mismatch between the reference impedance with respect to which the 1-port scattering parameter of the line has been determined and the characteristic impedance of the line.

Abstract: A circuit for an apparatus is an active circuit that synthesizes self-induction. The active circuit comprises only one operational amplifier. With the use of tunable capacitors, the inductor synthesized by the active circuit becomes a tunable inductor.

Abstract: In the course of a reflectometry-based qualification procedure of a local loop, which connects customer premises to a central office of a telecommunication network, and in the event of being unable to identify the loop termination associated with the customer premises, a second reflectometry measurement of the local loop is carried out with a different impedance load at the customer premises. Next, the two reflectograms are compared with each other in the time domain in order to delineate among all the reflections those at the customer premises and to determine therefrom the position of the customer premises in the local loop.

Abstract: In a multi-carrier transmission system, a clock timing error (&tgr;e) is calculated at the receiver's side and used for synchronization between a transmitting modem and a receiving modem (RX1). The clock timing error (&tgr;e) is calculated from phase errors (&phgr;0, &phgr;1, . . . , &phgr;i, . . . , &phgr;N-1) detected for a plurality of pilot carriers during a tracking mode in such a way that the share (Ai) of a phase error (&phgr;i) detected for a particular pilot carrier in the clock timing error (&tgr;e) depends on the transmission quality (SNRi) of that pilot carrier over the transmission medium in between the two modems. In this way, the robustness of the synchronization for narrowband noise near a pilot carrier is improved significantly.

Abstract: The invention relates to a modem and a method for providing bit loading computation in a multi-carrier communication system, using a plurality of simultaneous different carriers or tones by measuring the signal to noise ratios (SNRs) for carriers and by determining in dependence of the SNR a related number of bits to be allocated to the respective carrier. The method comprises the steps of providing a sliding window having a frequency width able to contain a predetermined number of the carriers, moving the sliding window over the frequency spectrum of the carriers through a plurality of positions of the window with respect to the carrier frequencies, and when the window contains the predetermined number of the carriers and there is at least one further carrier to be positioned in the window as a new carrier for bit allocation, the window is moved such that on entering a new carrier into the window at one of its borders, a carrier already in the window at the other frequency border leaves the window.

Abstract: A method and apparatus for modeling a network comprising a plurality of transmission lines is described, the method and system being adapted to measure loop parameters of first transmission line to provide measured loop parameters, determine a topology of the first transmission line by analyzing the measured loop parameters with reference to at least a one model of a plurality of models for transmission lines of different topologies, select a further model for estimating crosstalk related parameters based on the determined topology, and estimate at least one crosstalk related parameter based on the determined topolgy and the selected further model.

Abstract: A time error compensation arrangement (TCOMP) that compensates for a time error (&egr;, &Dgr;k) between a transmitter sample clock in a multi-carrier transmitter and a receiver sample clock (CLK) in a multi-carrier receiver (RX1, RX2) includes a digital time correction filter (FILTER, FILTER′), operative in time domain, to compensate for a linearly increasing contribution (&Dgr;k) in the time error (&egr;, &Dgr;k) and rotation means (ROTOR), operative in frequency domain, to compensate for a second, remaining contribution (&egr;) in said time error (&egr;, &Dgr;k).