Abstract: The invention relates to a method and arrangement for transferring synchronizing information in a data transmission system including modem connections. The arrangement according to the invention comprises a modulator (207) that is arranged to generate an analog signal (222) modulated by synchronizing information, the frequency spectrum of said signal being located in a frequency range that falls outside the data transmission bands of the modem line connected to the network element. The arrangement includes a switching circuit (208) that is arranged to connect said analog signal to a data transmission cable (206) that forms part of said modem line connected to a network element. The arrangement includes a second switching circuit (209) that is arranged to receive said analog signal from a data transmission cable that forms part of the modem line connected to the second network element.

Abstract: The invention relates to a method for implementing adaptive Tomlinson-Harashima precoding using a digital data communications link. According to the method, the outgoing bit stream is coded into symbols, channel distortion is corrected by precoding (TML) the symbols, the precoded symbols are sent over a data communications channel (2, CHN), in which case the symbols, which have passed through the channel (2, CHN) and signal processing means for the receiver are reconstructed to form a bit stream. According to the invention, updated precoder coefficient parameter values are formed with the aid of an error variable (e), which is dependent on the symbol decisions (S?) of the receiver, the output signal of a decision-feedback equalizer, and a signal (Q) that is formed from the received signal by compensating the effect of the precoder transfer function of the received signal with an inverse precoder transfer functions.

Abstract: A method and a system for establishing a digital subscriber connection between a central site (1) and a subscriber's transmission device (5). The system comprises an optical fiber (2) between the central site and an intermediate equipment (3) on a signal path between the central site and the subscriber's transmission device, and a metallic pair cable (4) between the intermediate equipment and the subscriber's transmission device. Digital signal processing parts (12a, 12b, 14a, 14b) of a DSL-modem are distributed between the central site and the intermediate equipment. Analog signal processing parts (7) of the DSL-modem are located in the intermediate equipment. The distribution of the digital signal processing parts is selected such that the optical-fiber-carried bit rate is minimal, but on the other hand, the digital signal processing in the equipment is relatively simple.

Abstract: The invention relates to a method and system for adjusting a clock signal placed in a network element of a data network. The clock signal is adjusted on the basis of difference values formed by means of received synchronizing messages. Each difference value is a difference of a reception time value and a transmission value of a received synchronizing message. The reception time value of the synchronizing message depends on a cumulated number of periods of the clock signal at a moment of arrival of the synchronizing message, and the transmission value depends on a position of the synchronizing message in a chronological transmission order of the synchronizing messages. In the adjusting process, an adjusting effect of the difference values belonging to a lower part (304) of a margin of fluctuation (306) of the difference values is weighted more heavily than an adjusting effect of the difference values belonging to an upper part (305) of the margin of fluctuation of the difference values.

Abstract: The invention relates to a method and apparatus for improving the quality of receiver synchronization on QAM- or CAP-modulated modem connections having an adaptive linear equalizer. The invention is based on the finding that in a QAM- or CAP-modulated data transmission system where the symbol rate and the average carrier frequency are in fixed relationship with each other, the vector formed by the In-phase and the Quadrature component of the detector input signal rotates with the timing phase shift of the receiver. The quality of receiver synchronization is improved by utilizing information extracted from the vector rotation.

Abstract: Method and equipment for creating routing data in packet-switched data communications when the quality-of-service class of the data transfer packet to be routed influences the routing data. Based on protocol data, which can be, for example, an IPv4 destination address, and information of quality-of-service class, auxiliary routing data is defined, which indicates which of the routing data alternatives conforming to this protocol data corresponds to the information of quality-of-class. The routing data is created based on the interaction of the auxiliary routing data and the protocol data. The number of different combinations composed of protocol data and auxiliary routing data appearing in the practical data transfer networks is notably smaller than the number of different combinations composed of protocol data and information of quality-of-service class. This fact is utilized in the solution according to the invention for reducing the amount of required storage capacity.

Abstract: The objective of the invention is to devise a method for establishing a subscriber connection and a system applying the method. According to the method, a digital subscriber connection consisting of a composition of an optical fiber and a metallic pair cable is implemented by transporting a digital information stream in two directions over an optical fiber (2) between a central site and equipment (103) which is connected to the metallic pair cable (4) of each subscriber. According to the invention, the information streams transmitted and received over the pair cables are multiplexed onto the optical fiber by using a multiplexing method of optical signals, whereby the information streams originating from different subscribers are combined onto the fiber by means of passive optical elements and whereby the information streams transmitted from the central site are distributed to each subscriber-specific optical-to-electric conversion element (105) by means of passive optical elements.

Abstract: The invention relates to a method and system for implementing a digitally controlled sample and timing clock in a system performing analog and digital signal processing. According to the method, as the timing clock of the digital signal processing is used a clock with a controllable frequency such that said digital signal processing can have a function suited for controlling the frequency of said timing clock, and the conversion of the signal is performed in synchronism with the timing clock of the digital signal processing operation when a delta-sigma converter or a switched-capacitor filter device is employed.

Abstract: The invention relates to a method for implementing adaptive Tomlinson-Harashima precoding using a digital data communications link, According to the method, the outgoing bit stream is coded into symbols, channel distortion is corrected by precoding (TML) the symbols, the precoded symbols are sent over a data communications channel (2, CHN), in which case the symbols, which have passed through the channel (2, CHN) and signal processing means of the receiver are reconstructed to form a bit stream. According to the invention, updated precoder coefficient parameter values are formed with the aid of an error variable (e), which is dependent on the symbol decisions (S?) of the receiver, the output signal of a decision-feedback equalizer, and a signal (Q) that is formed from the received signal by compensating the effect of the precoder transfer function of the received signal with an inverse precoder transfer function.

Abstract: The invention relates to a method and system for implementing a digitally controlled sample and timing clock in a system performing analog and digital signal processing. According to the method, as the timing clock of the digital signal processing is used a clock with a controllable frequency such that said digital signal processing can have a factions suited for controlling the frequency of said timing clock, and the conversion of the signal is performed in synchronism with the timing clock of the digital signal processing operation when a delta-sigma converter or a switched-capacitor filter device is employed.

Abstract: The invention relates to a method and apparatus for improving the quality of receiver synchronization on QAM- or CAP-modulated modem connections having an adaptive linear equalizer. The invention is based on the finding that in a QAM- or CAP-modulated data transmission system where the symbol rate and the average carrier frequency are in fixed relationship with each other, the vector (I, Q) formed by the In-phase (I) and the Quadrature (Q) component of the detector input signal rotates with the timing phase shift of the receiver. The quality of receiver synchronization is improved by utilizing information extracted from the vector rotation.

Abstract: The present invention concerns a method and apparatus for implementing channel equalization on a digital communications path. According to the method, the outgoing bit stream is coded into symbols, the channel distortion is compensated for by means of symbol preceding (TML), the precoded symbols are sent over a communications channel (2, CHN), whereby means are provided for recovering symbols that have passed over the communications channel (2, CHN) and via the signal processing means of the receiver into a bit stream.