Showing papers on "High-bit-rate digital subscriber line published in 2000"

Wide area communication networking

Abstract: A wide area communications network (500) includes a first digital subscriber line (502). A first network interface device (504) connects to the digital subscriber line (502). The first network interface device (504) separates an ISDN channel (508) from a digital subscriber channel (510). An ISDN telephone (508) is connected to the network interface device (504). A protocol translator (512) is connected to the network interface device (504) by the digital subscriber channel (510). A hub (514) is connected to the protocol translator (512). A plurality of devices (516, 518) is connected to the hub (514). A digital subscriber line access multiplexer (506) is connected to the first digital subscriber line (502). The digital subscriber line access multiplexer (506) separates the digital subscriber channel from the ISDN channel (522). A public switched telephone network (523) is connected to the ISDN channel (522). An asynchronous transfer mode network (526) is connected to the DSLAM (506) by a first virtual circuit (524) of the digital subscriber channel. An ISP (528) is connected to the DSLAM (506) by a second virtual circuit (530) of the digital subscriber channel. A LAN (532) is connected to the ATM network (526) by the first virtual circuit (524).

Method and apparatus for the generation of analog telephone signals in digital subscriber line access systems

Abstract: A method and apparatus for providing analog telephony services over a digital subscriber loop access system is presented including Asymmetric Digital Subscriber Loop (ADSL) utilizing spectrum above the POTs band for data services. An ATM (110) cell is utilized on an ADSL linecard (160). Echo cancellation is used to enhance the voice quality in compressed voice signals. The ATM cells can be transmitted to a subscriber residence (190) or a business and one to four additional analog telephone lines allowing first telephone line to be operated as an analog connection over the twisted wire pair (180).

Method and system for providing facsimile service over a digital subscriber line

Abstract: A system (500) that provides facsimile service over a digital subscriber line (502) has a facsimile machine (504) coupled to an ATM switch (506). The ATM switch (506) is coupled to the digital subscriber line (502), wherein the digital subscriber line (502) includes a first virtual circuit and a second virtual circuit. An interworking unit (508) is coupled to the second virtual circuit. The second virtual circuit is connected to the facsimile machine (512). A public switched telephone network (510) is connected to the interworking unit (508). A facsimile machine (512) is connected to the public switched telephone network (510).

Method for converting an existing subscriber to a wireless communications system

Abstract: A subscriber conversion system determines at least one code for an existing subscriber of a first wireless communications system to be converted to a second wireless communications system. When the existing subscriber obtains a wireless unit to be used in the second wireless communications system, the conversion system uses the at least one code provided to the existing subscriber to link existing subscriber information from the first wireless communications system to information associated with wireless unit for the second communications system, thereby improving the efficiency of the conversion process. For example, if a service provider wishes to convert from GSM to CDMA, the service provider can provide a secret code and an identification number, such as a directory number (DN), as the codes to the existing GSM subscriber. The subscriber obtains a CDMA wireless unit and commences an activation process to activate the CDMA wireless unit. As part of the activation process, the subscriber provides the secret code and the identification number to the conversion system. The conversion system determines if the secret code and the identification number correspond to the secret code and identification number provided to an existing GSM subscriber. If so, information which is characteristic of the CDMA wireless unit, such as the ESN, DN and/or IMSI, is associated with at least a portion of existing GSM subscriber information, such as billing information and/or features or services. As such, the conversion system uses existing subscriber information to reduce the time required to convert the existing subscriber to the wireless communications system based on the second radio standard.

Configurable scalable communications equipment protection method system

Abstract: A method and system for configurable and scalable line interface card protection or redundance useful for a range of low speed digital to high speed digital and optical signal types such as STS-1, STS-3, VT1.5, DS-1/T1, DS-3/T3, ATM, ADSL, HDSL, OC-1, OC-3, OC-12, OC-48, OC-192, OC-768, STM-1, STM-4, STM-16, STM-64, E1, E3, J1, J2, and EtherNet and Token Ring LAN signals. A daisy-chain alternate signal path, signal selectors, and alternate front panel entry points are provided to a front-access telecommunications shelf system. Signal interface cards can be designated as primary cards to handle traffic under normal conditions, or as protection cards, without hardware constrained or slot-specific card requirements. Variations of 1:N protection, and multiple groups of 1:N configurations and partitions can be defined without changes to cabling or backplane design variations through setting of relays and signal selectors on each card. As such, any signal present on a cable connected to a primary card may be re-routed to any card designated as a protection card, by first routing the signal through a protection relay on the failed card to a cable to a neighboring card, through a data selector on the neighboring card onto the backplane, and to a selected protection card.

Method of allocating access rights to a telecommunications channel to subscriber stations of a telecommunications network and subscriber station

Abstract: Method and subscriber station for allocating access rights to a telecommunications channel of a telecommunications network to at least one subscriber station (5, 10, 15, 20) of said telecommunications network. According to the method information signals are transmitted to the at least one subscriber station (5, 10, 15, 20) and access authorization data (45, 50, 55) is transmitted to the at least one subscriber station (5, 10, 15, 20) via said information signals. An evaluation unit (60) of the at least one subscriber station (5, 10, 15, 20) receives the access authorization data (45, 50, 55) and verifies whether said access authorization data (45, 50, 55) contains an access threshold value (S). This access threshold value (S) is compared with a random number or pseudo-random number (R) and the access right to a telecommunications channel allocated to the at least one subscriber station (5, 10, 15, 20) in accordance with the comparison result.

Digitally-tunable echo-cancelling analog front end for wireline communications devices

Abstract: The present invention, generally speaking, provides a digitally-tunable, echo-cancelling analog front end (AFE) for wireline digital communications. The analog front end is especially useful in a High-bit-rate Digital Subscriber Line (HDSL) or HDSL2 environment. An analog echo simulation path is provided capable of simulating echo from a wide variety of echo paths. Digitally controlled attenuators are provided in the transmission path and in the analog echo simulation path. Also provided is a digital-tunable equalizer stage. The equalizer stage is tuned to match the characteristics of the receive path. The same arrangement may be adapted for various DSL technologies, i.e., xDSL. There results an analog front end that is well-adapted to high-speed wireline communications.

System and method of providing a bi-directional DSL connection

Abstract: A system for providing a bi-directional digital subscriber line connection to a network includes a digital subscriber line access multiplexer with a pool of digital subscriber line modems, and switching logic connecting customer premises to the modem pool. The switching logic has more inputs than outputs, and is configured to share access to the modem pool among the inputs on a per-session basis. A session has a dedicated modem connection to the network to provide a limited number of simultaneous dedicated digital subscriber line bi-directional connections to the network.

Fiber-optic subscriber transmission system

Abstract: A fiber-optic subscriber transmission system is provided for accommodating a plurality of digital subscriber line signals and telephone signals. A plurality of subscribers is connected through telephone lines with remote nodes, which are connected with a terminal office through optical fibers. Remote nodes convert the signals sent by subscribers through telephone lines into digital signals. Then, the remote nodes convert the digital signals to light signals by time-division multiplexing and send them to the terminal office through optical fiber cables. The terminal office receives the light signals and extracts the original subscriber signals by demultiplexing and D/A conversion of the received light signals. Telephone signals and xDSL (x digital subscriber line) signals, which are multiplexed in the subscriber signals, are separated by a splitter and terminated by a telephone switch and an xDSL access multiplexer, respectively.

System to pre-qualify copper subscriber loops for high bandwidth access service using subscriber or network generated tones

Abstract: The system to pre-qualify copper subscriber loops for high bandwidth access service determines electrical characteristics of a subscriber line served by a central office switch from a location remote from said subscriber line absent a direct metallic connection exclusively to said subscriber line. This is accomplished where the subscriber line has subscriber equipment connected thereto at an end distant from said central office switch by establishing a communication connection through the central office switch between the service provider and the subscriber equipment connected to said subscriber line. In response to the establishment of this communication connection, electrical signals, comprising subscriber or network generated tone signals, are applied to the subscriber line to enable the service provider to determine the electrical characteristics of the subscriber line by analyzing the received tone signals.

Method and system for qualifying subscriber loops for xDSL service

Abstract: A method and system for single-ended qualification of subscriber loops for xDSL services is disclosed. Subscriber loop database record are screened for disqualifying devices or services on the loop. If none are found, a set of predetermined electrical characteristics of the subscriber loop are derived from information in the database, or measured using test equipment at a central office end of the subscriber loop. The electrical Characteristics are used to assess the noise margin for the loop. If the assessed noise margin suggests that the loop does not qualify, the loop is modeled to assess if it will qualify in the presence of repeaters. The method and system are particularly well suited for qualifying a loop for HDSL or HDSL2 service.

A CMOS HDSL2 analog front-end

Abstract: HDSL2 is the second generation of High-bit-rate Digital Subscriber Line service. ANSI HDSL2 standard requires full duplex transmission with a symmetric payload of 1.544 Mb/s over the full Carrier Serving Area (9 kft, with noise) on a single twisted pair, i.e., same level of service and performance that the traditional HDSL provides over two twisted pairs. There is also tremendous interest in the industry to provide variable rate service over longer cable lengths. HDSL2 transmission spectrums provide robust performance in a mixed crosstalk environment and are spectrally compatible with other services like ADSL, HDSL, T1, etc. The Upstream (US) and Downstream (DS) spectrums overlap and deliver over 16.5 dBm transmit power to the line. This requires the HDSL2 Analog Front-End (AFE) to process a large echo signal along with a weak receive signal.

Copper based interface system and regulated power source

Abstract: Method and apparatus for providing a regulated and current limited power source to support bidirectional telephone delivery circuitry and methods for a multiplicity of telephone subscriber lines to a downstream distribution terminal using only two preexisting transmission lines for carrying the regulated and current limited power along with a multiplicity of HDSL TDM communication channels.

Method and system for verifying spectral compatibility of digital subscriber line connections

Abstract: A system for verifying spectral compatibility of a communication system that utilizes at least one digital subscriber line protocol includes a plurality of digital subscriber line access multiplexers and a communications channel coupling the plurality of digital subscriber line access multiplexers. Each digital subscriber line access multiplexer is operable to transmit and receive at least one message over the communications channel. The message comprises information related to a training of a digital subscriber line modem by a carrier.

System to pre-qualify copper subscriber loops for high bandwidth access service using subscriber voice signals

Abstract: The system to pre-qualify copper subscriber loops for high bandwidth access service determines electrical characteristics of a subscriber line served by a central office switch from a location remote from said subscriber line absent a direct metallic connection exclusively to said subscriber line. This is accomplished where the subscriber line has subscriber equipment connected thereto at an end distant from said central office switch by establishing a communication connection through the central office switch between the service provider and the subscriber equipment connected to said subscriber line. In response to the establishment of this communication connection, electrical signals, comprising voice signals, are applied to the subscriber line to enable the service provider to determine the electrical characteristics of the subscriber line by analyzing the received electrical signals.

Long reach SDSL system spectrally compatible with ADSL systems

Abstract: A method and apparatus for achieving longer data transmission distances in Symmetrical Digital Subscriber Lines (SDSL) systems, while providing spectral compatibility with Asymmetrical Digital Subscriber Lines (ADSL) systems is disclosed. The method and apparatus enables deployment of SDSL and ADSL in any mix in a binder group of twisted pair copper wires without sacrificing performance of either system. The apparatus transmits signals from opposite ends of the twisted pair subscriber loop using first and second discrete frequency bands. The advantages include longer service reach and deployment without regard to ADSL/SDSL services mix in a binder group.

VDSL, from concept to chips

Abstract: Over the previous decades, successive DSL technologies have increased the transmission speeds over the telephone access network from 33.6 Kbit/s for analog modems to about 8 Mbit/s with ADSL. VDSL, or Very high-speed Digital Subscriber Line, puts the copper loop in an even higher gear. VDSL can transport data at tens of Megabits-per-second (Mbit/s) over conventional copper twisted pairs that have been used for more than a century - till the emergence of HDSL and ADSL - to carry only voice calls or low-speed data. Whereas ADSL (Asymmetric DSL) brings you Internet downloads at high speeds and good quality video, VDSL can deliver several films simultaneously. To enable such super-fast traffic, the frequency band over which the system operates has to be increased, from about 1 MHz for ADSL to over 10 MHz for VDSL. This requires faster digital signal processing and analog (integrated) components with higher bandwidths. In addition the system has to withstand loop impairments that were inexistent or less stringent for other DSL variants. Once again (as for ADSL) Discrete MultiTone (DMT) transmission turns out to deliver the required performance. If carefully implemented, DMT can be combined with frequency division duplexing (FDD) without requiring filters for up- and downstream frequency band separation, resulting in extreme flexibility for spectral shaping and band allocation, while simplifying the design. This paper takes you in a couple of pages from the concepts up to the implementation of a system on chip. It shows how a very performant and flexible FDD-DMT system can be integrated while meeting the requirements on power and size.

Theoretical and practical limits of next-generation high-speed digital subscriber loops

Abstract: For the single-pair HDSL (HDSL2), the concept of having different upstream and downstream power spectral densities is highlighted. The signal-to-noise ratio (SNR) at the input of the central office HDSL terminal unit (HTU-C) can be enhanced by boosting the power output of the remote user HDSL terminal unit (HTU-R). Further improvement in performance can be achieved by reducing the HTU-C NEXT interference. Two techniques are proposed to reach this goal. The first approach is to reduce the HTU-C transmitter power in the downstream direction for shorter reach cables. The second approach is borrowed from the analog frequency-modulation preemphasis/deemphasis frequency tilting in the upstream direction. Combining the three techniques leads to at least 6-dB SNR margin improvement for the full reach carrier serving area loops.

Copper based interface system and data frame format

Abstract: A Bidirectional telephone communication system for supporting a multiplicity of subscriber lines at a downstream distribution terminal using only two of a multiplicity of pre-existing transmission line pairs connected between an upstream distribution terminal and the downstream distribution terminal. Standard PCM data packets are mapped into and disguised as standard European HDSL formatted data.

A network pedestal unit in a telecommunications network

Abstract: A telecommunications network (10) includes a network pedestal unit (20) that receives and sends telephony information from and to a digital loop carrier (16). The digital loop carrier (16) provides and receives telephony information to and from a switching element (12). The network pedestal unit (20) includes a high speed digital subscriber line interface (30), a processing unit (32), and a subscriber interface (34). In the downstream direction, the high speed digital subscriber line interface (30) receives telephony information over a twisted pair link (22) operable to carry the telephony information at an increased bandwidth rate. The high speed digital subscriber line interface (30) decodes the telephony information from the twisted pair link (22) for transfer to the processing unit (32). The multiplexing unit (32) extracts particular telephony information according to its intended destination. The subscriber interface (34) receives extracted telephony information from the processing unit (32) for transfer to a particular subscriber coupled thereto.

Serialized HDSL multiplexer - demultiplexer protocol

Abstract: A high bit rate digital subscriber line (HDSL) communications scheme employs a serialized multiplexer—demultiplexer protocol, that enables both HDSL channels to be successfully transmitted over an asynchronous, serialized communication link. A service channel supplies control information used by a far end device to extract each HDSL channel from the serialized bit stream. A data channel interface circuit combines a pair of data channel segments of two 784 kbps HDSL channels into a standard 1.544 Mbps T1 serial data stream. The data channel interface circuit contains a register bank which stores embedded operations channel (EOC) information extracted from the two HDSL channels. Auxiliary HDSL signaling information stored in the data channel interface circuit is controllably accessed by a communications control processor for application to an output multiplexer. A framer unit supervises the operation of output multiplexer controllably and injects auxiliary (framing and time alignment) service channel signals to the output multiplexer. The framing structure of the serialized HDSL protocol provides a contiguous sequence of framing bits, HDSL asynchronous channel bits, bit-stuffing majority bits, a stuffing bit, a signaling bit, and 1.544 Mbps T1 payload bits.

Telecommunication system with allocation of access rights for a telecommunications channel to subscriber stations of a telecommunications network

Abstract: The channel access allocation method uses information signals transmitted to a telecommunications network subscriber station (5,10,15,20) for transfer of channel access authorization data, evaluated by an evaluation unit within the subscriber station, by comparing an access threshold value with a pseudo-random number (R), for allocation of the channel access rights An independent claim for a subscriber station with access to a telecommuications channel is also included

Method and apparatus for high speed data transmission over a four-wire subscriber line

Abstract: Disclosed is an architecture and method for high speed transmission over a four-wire subscriber line. Each modem in the present invention includes a V.90 transmit section and a V.90 receive section. The V.90 transmit section is dedicated to transmitting data over one pair of a four-wire subscriber line, while the V.90 receive section is dedicated to receiving data over the other pair of the four-wire subscriber line. The present invention permits full-duplex transmission at 56 Kbps over a four-wire subscriber line.

Using asymmetric digital subscriber line (ADSL) for fast Internet and multimedia services

Abstract: In this paper the design of an experimental ADSL network and the applications used are presented. Digital subscriber line (DSL) technologies enable the use of twisted pair copper telephone lines, that reach practically every home and business (public switched telephone network) with very large bandwidth, typically from 1.5-6 Mbps downstream and 640 kbps upstream, by placing a pair of modems at the user (home) and at the C.O. (PTT Central Office) side. After a small introduction on broadband access networks the design of an experimental ADSL network is presented. Furthermore, the design of high bandwidth, rich in content applications taking advantage of the high speed ADSL network is given.

Digital subscriber line multiplexer

Abstract: A system and method for increasing the number of lines receivable by a subscriber of digital telecommunication services when the pre-existing interior lines of the subscriber's premises is less than the number of digital lines to be received is provided. A master multiplexor is located at the subscriber's side of a network interface connector and is connected to a slave demultiplexor located within the subscriber's premises via an interior, pre-existing twisted-pair line. In a first embodiment, two or more digital lines extend from the central office of the service provider to the subscriber's premises terminating at the network interface connection. Digital data received from the digital lines is multiplexed by the master multiplexor across the interior, pre-existing twisted pair line to the slave demultiplexor. The slave demultiplexor demultiplexes the digital data and provides it to two or more digital lines located within the subscriber's premises to which digital data receiving devices are connected. In a second embodiment, one or more digital lines and one or more analog lines from the central office are multiplexed by the master multiplexor to the slave demultiplexor which provides the demultiplexed digital data to digital lines and analog data to analog lines, both of which, located within the subscriber's premises. In a third embodiment, broadband services for multiple tenants comprising multiple protocols are provided over one or more lines from the CO to a NIC at a multi-tenant dwelling. The requirements for each subscriber in a multi-tenant dwelling are then subdivided by a master multiplexor, and multiplexed, if required, over one or more single interior twisted-pair to a slave demultiplexor at the respective tenants premises.

Path replacement during the conversion of a three-party telecommunications connection into a two-party telecommunications connection

Abstract: After the telecommunications switching center (VST B), via which a three-party telecommunications connection is held between two subscriber lines and an additional subscriber line or between two subscriber lines and a switching position, has received a request from the additional subscriber line or from the switching position, a new direct telecommunications connection is established between the two aforementioned subscriber lines. In addition, the existing partial connections of the three-party telecommunications connection between these two subscriber lines and the additional subscriber line or the switching position are terminated.

An improved channel model for ADSL and VDSL systems

Abstract: This paper examines existing channel models used with xDSL systems and identifies a key shortcoming - namely, the implicit assumption that all impulse noise originates at the transmitter. Based on extensive data collected from the local loop, a new model is proposed which addresses this problem by combining a digital filter model of the transmission line with a distributed noise source. This better reflects the nature of a real telephone line, and thus provides a more solid basis for simulation and optimisation of xDSL systems.

The Alcatel experience of DSL deployment

Abstract: Incumbent telcos desire to make the optimum use of their existing copper pair networks in order to deliver the new services required by their customers. This enables the incumbent telcos to compete with new operators who use alternative technologies, without incurring the very high costs of building new infrastructure. The technologies used by the new operators include cable TV systems, which can be extended to offer not only broadcast TV, but also telephony, fast Internet access and other data services, as well as video on demand. Other competing technologies are satellite, which can be combined with a telephony back channel to provide a limited interactive service, radio microwave distribution, and all fibre systems. However, the price performance combination of the DSL technologies is so attractive that even new operators are increasingly making use of them. There is now a range of different DSL technologies available for high speed transmission over copper, which are appropriate to the requirements of different customers. These include HDSL and SDSL for symmetric services mainly to business customers, ADSL for asymmetric services to residential and SOHO customers, and VDSL for very high-rate symmetric or asymmetric services to business or residential customers. VDSL has a relatively short range, and is thus often operated from street cabinets, although operation from exchange buildings is sometimes done. HDSL, SDSL, and ADSL can be operated from exchange buildings or street cabinets as appropriate. This paper outlines the range of Alcatel DSL products, and the experience of their deployment.

Method for prequalification of subscriber lines for high speed data services

Abstract: A method and system for determining the high speed data service capability of a subscriber line includes sending an embedded test signal to a subscriber line. A reflected signal received in response to the test signal is analyzed for determining transmission characteristics of the subscriber line. Based on the reflected signal, a determination about the high speed data service capabilities of the subscriber line is made and stored for future reference.

Radio interface unit in fiber loop carrier-curb system

Abstract: PURPOSE: A radio interface unit in the FLC-C(Fiber Loop Carrier-Curb) system, as installed in the ONU(Optical Network Unit) of the FLC-C system, is provided to carry out an ATM(Asynchronous Transfer Mode) cell type interface between the ATM cell bus and the subscriber line CONSTITUTION: A radio interface unit is comprised of an SRAM part(210), an ATM cell bus connection part(220), an ATM cell processing part(230), a line connection part(240) and a HDSL(High bit rate Digital Subscriber Line) connection part(250) The SRAM part(210) is a memory storing routing information for ATM cells The ATM cell bus connection part(220) is interfaced with an ATM cell bus(125) to input and output the data of the ATM cell unit The ATM cell processing part(230) interfaced with the ATM cell bus connection part(220) performs the function of assembling and disassembling in an ATM adaptive layer The line connection part(240) and the HDSL connection part(250) are interfaced with a subscriber line(123)