Multiplex communications – Channel assignment techniques – Using a separate control line or bus for access control
Reexamination Certificate
1998-03-31
2001-08-14
Nguyen, Chau (Department: 2663)
Multiplex communications
Channel assignment techniques
Using a separate control line or bus for access control
C370S907000
Reexamination Certificate
active
06275499
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to telephone networks, and more particularly to an interface between fiber optic transport media and a switching system designed for electrical signals.
BACKGROUND OF THE INVENTION
As multimedia applications increase the demand for high-bandwidth, high-bit-rate communications, fiber optics technology is rapidly advancing to supply the capacity. A family of standards for optical fiber transmissions is known as the Synchronous Optical Network (SONET) standards. SONET was born as an extension to the DS1 hierarchy, which is a hierarchy of “electrical” as opposed to “optical” signals and consists of levels of signals formed by multiplexing lower level TDM (time division multiplex) signals.
The SONET standard establishes a multiplexing format for using any number of 51.84 Mbits/s signals as building blocks. An OC-3 (Optical Carrier, Level 3) is a 155.52 Mbits/s signal (3×51.84 Mbits/s), and its electrical signal counterpart is referred to as an STS-3 signal. The STS-1 signal carries a DS3 signal or a number of DS1 or other lower level signals. A SONET STS-3 signal is created by concatenating STS-1 signals. Each SONET STS-N electrical signal has a corresponding OC-N “optical signal”. The OC-N signals are created by converting the STS-N electrical signal to an optical signal.
Although optical switching techniques have been developed, telecom companies are eager to provide as much performance as possible from their existing infrastructure. Switching systems based on the DS1 electrical signal hierarchy are in place and continue to be used for signals carrying that type of signal. Essentially these switching systems use DS0 data, which is derived from the DS1 hierarchy. For example, a DS1 signal is comprised of 24 multiplexed DS0 voice channels. Thus, there is a demand for interfaces that will permit SONET signals to be switched through switching systems designed for the DS1 hierarchy of signals.
SUMMARY OF THE INVENTION
One aspect of the invention is a controller for use in a delivery unit that interfaces telecommunications signals to a switching system. The unit controller is partitioned into a number of functional parts: a common carrier unit, a processor unit a basic interface-unit, and an expansion interface unit. The common carrier unit has a bus interface to internal buses of the delivery unit, a control data interface that formats control data transported on the delivery unit buses, a local bus for communications within the common carrier unit, and a bridge from the local bus to an expansion bus. The processor unit has a processor, associated memory, a local bus, and a bridge to the expansion bus. The processor is programmed to handle administrative and maintenance functions within the delivery unit. The basic interface unit provides an upper level manager communications link to an upper level manager unit that performs administrative and maintenance functions superior to those of the unit controller. The expansion interface unit provides a switching system communications link to the switching system. The processor unit, the common carrier unit, the basic interface unit, and the expansion interface unit are each in communication with the expansion bus.
An advantage of the invention is that it is designed to be easily adapted to different types of delivery units. It fits into a control hierarchy scheme that permits functionality specific to a particular transmission format (such as OC3) to be delegated to lower level controllers.
With appropriate programming and configuration, the unit controller will perform all the functions required for line/trunk processing for a shelf of an OC3 delivery unit.
The same unit controller can also be programmed and configured to perform the functions required for managing several shelves of a multi-shelf delivery unit.
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patent: 5784377 (1998-07-01), Baydar
patent: 5903572 (1999-05-01), Wright et al.
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patent: 6011802 (2000-01-01), Norman
patent: 6049550 (2000-04-01), Baydar et al.
Dubois Gerry R.
Wynn David W.
Alcatel USA Sourcing L.P.
Baker & Botts L.L.P.
Boakye Alexander O.
Nguyen Chau
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