Telephonic communications – Telephone line or system combined with diverse electrical... – Having transmission of a digital message signal over a...
Utility Patent
1998-10-30
2001-01-02
Woo, Stella (Department: 2643)
Telephonic communications
Telephone line or system combined with diverse electrical...
Having transmission of a digital message signal over a...
C379S093280
Utility Patent
active
06169788
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to data communication, and more particularly to a communication server apparatus having distributed switching and method.
BACKGROUND OF THE INVENTION
A communication server provides access to communication facilities. For example, a communication server having a bank of modems may provide subscriber access to the modems for data communication. A communication server may be associated with its own dedicated communication network, or with an existing communication network, such as the public switched telephone network (PSTN).
As communication networks provide greater connectivity and access to information, there is an increasing demand for data communication at higher rates. One solution to provide increased data rates replaces existing twisted pair wiring with high bandwidth media, such as coaxial cables or fiber optic links. Other solutions adopt improved communication techniques using the existing hardware infrastructure. For example, digital subscriber line (XDSL) technology provides higher bandwidth data service over existing twisted pair wiring.
To deliver data service to the subscriber, a communication server may provide a dedicated or permanent connection to its communication facilities. For example, an existing communication server at a central office provides enough communication facilities to simultaneously service all PSTN subscribers. However, all telephone subscribers may not desire data service. Furthermore, the subscribers that desire data service may not simultaneously access the communication server.
SUMMARY OF THE INVENTION
In accordance with the present invention, the disadvantages and problems associated with communication servers have been substantially reduced or eliminated. In particular, a communication server apparatus having distributed switching and method are disclosed that provide data service to a number of subscribers using a reduced number of XDSL communication facilities.
According to one aspect of the present invention, a communication server includes a modem pool that comprises a plurality of XDSL modems. The communication server also includes a plurality of line interface modules. Each line interface module has a plurality of inputs each coupled to a twisted pair data line and has a plurality of outputs each coupled to one of the XDSL modems. Each line interface module operates to detect a need for data service on a requesting twisted pair data line and to couple the requesting twisted pair data line to an output associated with a selected XDSL modem. A controller is coupled to the XDSL modems and to the plurality of line interface modules. The controller operates to select one of the XDSL modems in response to a detected need for data service. The controller further operates to direct the line interface module to which a requesting twisted pair data line is coupled to couple the requesting twisted pair data line to the output associated with the selected XDSL modem.
Important technical advantages of the present invention include a communication server that provides data service to a number of subscribers using a reduced number of XDSL communication facilities. Over-subscription of data service is accomplished by selectively coupling a number of twisted pair data lines to a reduced number of XDSL modems. A controller polls the data lines in succession to determine which subscribers of the communication system need data service. Upon detecting a need for data service on a selected data line, the controller directs a switch to couple the selected data line to an available modem. The communication server may then provide data service suitable for high bandwidth applications, such as video-on-demand, multimedia, or Internet access.
Another important technical advantage of the present invention includes a communication server that provides over-subscribed XDSL data service using the existing infrastructure of the public switched telephone network (PSTN). Asymmetric digital subscriber line (ADSL), symmetric digital subscriber line (SDSL), high-speed digital subscriber line (HDSL), very high-speed digital subscriber line (VDSL), or other suitable XDSL technology can provide higher bandwidth data service over existing twisted pair wiring. These technologies may support data service simultaneously with traditional telephone service using a separation technique, such as frequency division multiplexing. In one embodiment, a splitter divides each incoming twisted pair subscriber line into a twisted pair phone line and a twisted pair data line. The phone line is coupled to a telephone switch to provide telephone service and the data line is coupled to the communication server to provide over-subscribed XDSL data service. The communication server and splitter may be located at a central office of the PSTN.
Another important technical advantage of the present invention includes the management and monitoring of XDSL data service provided to subscribers. To accomplish this, the communication server maintains an activity table to determine status information on twisted pair data lines and XDSL modems. In addition, the communication server can track subscriber usage, monitor subscriber information and generate billing and demographic information. In a particular embodiment, an activity detector disconnects a subscriber after a predetermined period of inactivity to release a modem for use by another subscriber.
An important technical advantage of the present invention is the distribution of the switching function to allow scalability of the number of supported data lines and over-subscription of XDSL modems.
A further important technical advantage of the present invention includes isolating the switch from the data lines and subscriber lines. The switch can thereby operate without constraints imposed by technical requirements for interaction with the data lines and subscriber lines. For example, isolation of the switching matrix allows CMOS switches to be used rather than more expensive solid state relays or mechanical relays.
Yet another important technical advantage of the present invention includes the ability to provide a two-wire isolated interface that can use a single switch to couple a data line to a specific modem. The present invention thus allows one switch per modem per data line configuration. The isolation system of the present invention can transform the data line impedance to an intermediate impedance in order to increase system performance. Other important technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.
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Hall Clifford L.
Ham Ronald E.
Locklear, Jr. Robert H.
McCullough Jason
McHale John F.
Baker & Botts L.L.P.
Cisco Technology Inc.
Woo Stella
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