Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1998-12-29
2001-01-23
Olms, Douglas W. (Department: 2732)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S467000
Reexamination Certificate
active
06178179
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an arrangement for allowing distribution of digital video signals, and more specifically to linking of distribution networks using different types of digital subscriber line (DSL) type signals.
BACKGROUND ART
Generally, distribution of video signals has been carried out through coaxial cable networks used to link one or more video distribution sources with a plurality of subscribers. However, due to the high cost and minimal signal quality of such coaxial cable-based distribution networks, alternative approaches have been devised for distributing video signals. For example, telephone lines have been suggested as a physical structure for supporting distribution of video signals. However, systems using the public switched telephone network (PSTN) are often bandwidth limited, providing generally only still frame or video conferencing capabilities. In addition, because telephone system carriers only typically use the PSTN for connectivity between subscribers, the PSTN does not provide any capability for dynamic routing of digitized video without the use of dedicated leased, wide bandwidth circuits. Telephone line based systems also fail to provide acceptable VCR type functional control over the distribution of video programming.
On the other hand, an enhanced public switched telephone network does provide the capability of distributing video on demand to subscribers over the PSTN. In such an arrangement, a menu of video programming information is made accessible at a subscriber's premises. A subscriber may transmit ordering information via the PSTN to available independent video information providers. Video programming can then be accessed and transmitted to the subscriber directly from a video information provider or through a central office (CO) serving the subscriber. The video information provider is typically arranged to transmit coded digital video data over wideband PSTN connected to the CO. The video data may be buffered at the central office for transmission over a plain old telephone service (POTS) line to the subscriber. Subscribers may use either a standard telephone or a dedicated control device located at a television set to order the video programming.
The central office is connected to the various subscribers for transmission of video data coded in a digital subscriber line (DSL) type format, such as very-high-data-rate digital subscriber line (VDSL) type coding, asymmetrical digital subscriber line (ADSL) coding, or rate adaptive digital subscriber line (RADSL) type coding. In such an arrangement, multiple DSL interface units are deployed to combine video information together with bidirectional signalling and POTS for transmission over an ordinary telephone wiring plant.
However, because each type of coding format has differences in advantages and disadvantages associated therewith, particularly with respect to data transfer rates and maximum permissible length of cable run, individual video distribution providers have designed independent distribution network architectures around the type of coding best suited to their respective needs. As a result, inter-system compatibility has thus far been compromised, thereby diminishing the advantages otherwise gained by using DSL signal formatting. Therefore, a need exists for a video and data signal distribution system which can operate using different types of DSL coding format.
DISCLOSURE OF INVENTION
Therefore, it is an object of the present invention to provide a system and method for distributing digitized video signals which overcomes the limitations on system compatibility found in prior arrangements.
In accordance with this and other objects, the present invention provides a method and system for distributing multiple type of digital subscriber line (xDSL) signals to end users over a telephone wiring plant, where a central office and an end user utilize different types of DSL signal format. A translator is located between the central office and the end user and includes a receiver for receiving xDSL signals transmitted on the twisted pair copper cable from either the central office or the end user, a line code translator for encoding the base data into the DSL format used by the destination device, and a line driver for transmitting the converted/encoded signal onto the twisted pair copper cable for distribution to the original destination.
In accordance with other features, the central office can transmit xDSL signals using an asynchronous transfer mode (ATM) protocol, and the translator encoder would be arranged to repackage the base data into the ATM protocol format depending on the protocol requirements of the destination terminal. In one embodiment, the xDSL format used by the central office is a very-high-data-rate digital subscriber line (VDSL) type signal format, and the DSL format used at the customer location is a rate adaptive digital subscriber line (RADSL) type signal format. In addition, buffering of the data is provided at the translator to accommodate any difference in transmission rate between the different types of DSL signal format.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
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Campbell Kurt A.
Czak John M.
Huggins Joseph P.
Kung Darwei
Phillips Bruce A.
Brooks & Kushman P.C.
Olms Douglas W.
Qwest Communications International Inc.
Sam Phirin
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