Time division multiplexer-demultiplexer and method of...

Multiplex communications – Pathfinding or routing – Through a circuit switch

Reexamination Certificate

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C370S535000, C370S538000

Reexamination Certificate

active

06272130

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of multiplexing and demultiplexing. More particularly, the present invention relates to time division multiplexers-demultiplexers. Specifically, a preferred embodiment of the present invention relates to a time division multiplexer-demultiplexer (mux-demux) arrangement where continuous data can be transferred together with bursty data and/or packetized data on the same tie line without disrupting the laminarity of the continuous data. The present invention thus relates to time division multiplexers-demultiplexers of the type that can be termed latency free.
2. Discussion of the Related Art
Historically, it was known in the prior art to combine multiple signals on a single tie line using time division multiplexing-demultiplexing. Prior art time division multiplexers of the type hereunder consideration, sometimes called TDMs, are well-known to those skilled in the art. A typical time division multiplexer combines (serializes) a set of parallel signals into a single bit stream while the corresponding time division demultiplexer decombines (deserializes) the single bit stream back into the set of parallel signals. For example, a conventional time division multiplexer can be provided as part of a transmitting user apparatus and combined into a communications system with a time division demultiplexer that is provided as part of a receiving user apparatus.
As is known to those skilled in the art, multiple sets of parallel signals from multiple transmitting users can be multiplexed into a single bit stream and then demultiplexed. This has utility where there are fewer tie lines (e.g., optical fibers) available than the number of transmitting users.
What is also known to those skilled in the art is that time sensitive data such as audio and video must be transmitted with laminarity in order to appear to be in real-time with full-motion and without significant jitter. Thus, a previously recognized problem has been that time sensitive data loses its laminarity when it is time division multiplexed-demultiplexed with bursty data and/or packetized data on a single tie line. What is needed therefore is a solution that permits the time division multiplexing-demultiplexing of continuous data with bursty data and/or packetized data on a single tie line without disrupting the laminarity of the continuous data.
SUMMARY AND OBJECTS OF THE INVENTION
A primary objective of the present invention is to provide a time division multiplexer and/or a time division demultiplexer which can transfer continuous data (e.g., video and audio) with bursty data (e.g., Ethernet) and/or packetized data (e.g., asynchronous transfer mode (ATM)) on a single tie line and without disrupting the laminarity of the continuous data. Another object of the invention is to combine a drop-add switch with the time division multiplexer and/or the time division demultiplexer so as to provide a networkable multiplexer and/or demultiplexer. Another object of the invention is to combine a 2:1 bypass switch with the time division multiplexer and/or the time division demultiplexer so as to provide a capability for the use of tie line redundancy and a self healing ring capability. Another object of the invention is to combine a wavelength division multiplexer with two or more of the time division multiplexers and/or the time division demultiplexers operating in parallel so as to enhance the bandwidth of a given tie line arrangement. Another object of the invention is to provide an apparatus that is cost effective. Another object of the invention is to provide an apparatus that is rugged and reliable, thereby decreasing down time and operating costs. It is yet another object of the invention to provide an apparatus that has one or more of the characteristics discussed above but which is relatively simple to manufacture and assemble using a minimum amount of equipment.
In accordance with a first aspect of the invention, these objects are achieved by providing an apparatus comprising I) a signal transmitting system for transmittal of a serialized signal including A) latency free continuous data and B) at least one member selected from the group consisting of bursty data and packetized data, said signal transmitting system including a multiplexer and a timing control block; and II) a signal receiving system for reception of said signal without disrupting the laminarity of the latency free continuous data, said signal receiving system including a demultiplexer and a computing device, such as, for example, a state machine. In one embodiment, the apparatus further comprises a drop-add switch connected to said multiplexer and/or said demultiplexer. In another embodiment, the apparatus further comprises a 2:1 bypass switch for tie line redundancy connected to said demultiplexer. In another embodiment, the apparatus further comprises a wavelength division mux/demux to increase bandwidth. Preferably, the signal transmitting system and signal receiving system operate entirely at the physical layer.
Another object of the invention is to provide a method that can be used to simultaneously transfer continuous data with packetized data and/or bursty data on the same tie line without disrupting the laminarity of the continuous data. It is another object of the invention to provide a method that is predictable and reproducible, thereby decreasing variance and operating costs. It is yet another object of the invention to provide a method that has one or more of the characteristics discussed above but which is relatively simple to set up and operate.
In accordance with a second aspect of the invention, these objects are achieved by providing a method comprising II) providing said apparatus; II) transmitting said signal on said single tie line using said signal transmitting system, wherein transmitting includes encoding a clock with said timing control block; and III) receiving said signal from said single time line using said signal receiving system, wherein receiving includes recovering said clock with said computing device. In one embodiment, the step of providing includes providing a drop-add switch for dropping and adding signals, said drop-add switch being connected to both said multiplexer and said demultiplexer and, further comprising, reconfiguring said drop-add switch using data from said signal.
These, and other, aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.


REFERENCES:
patent: 5278687 (1994-01-01), Jannson et al.
patent: 5457556 (1995-10-01), Shiragaki
patent: 5479202 (1995-12-01), Beriont
patent: 5566169 (1996-10-01), Rangan et al.
patent: 5583855 (1996-12-01), Ball
patent: 5864415 (1999-01-01), Williams et al.
IPITEK Fiber Optics, Singlemode 1310/1550nm WDM, “Wavelength Division Multiplexers”.
Hewlett Packard, “Gigabit Rate Transmit Receive Chip Set”, Technical Data, pp. 5-151, 5-152, 5-157, and 5-161.
Advanced Micro Devices, Am7968/Am7969, “TAXIchip™ Integrated Circuits”.

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