Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2000-06-23
2004-03-02
Sam, Phirin (Department: 2661)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S404000, C370S420000, C370S452000
Reexamination Certificate
active
06700892
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention relates in general to communication systems. More particularly, the invention relates to a system for distributing to a plurality of users information coming from E
1
or T
1
links.
BACKGROUND OF THE INVENTION
The E
1
and T
1
multiplexing systems are widely used in the field of communication for transmitting data in a digital form from one location to another. In many cases, the digital data that is transferred over the El or T
1
carrier represents the human voice, such as a telephone call, or a general analogue signal, that is transformed, e.g., by Pulse Code Modulation (PCM) into digital form. In other cases of growing frequency in recent years, the E
1
and T
1
links are used for transferring digital data between computer systems or computer users in remote locations.
The E
1
multiplexing system that is mostly used in Europe comprises Time Divisional Multiplexing of up to 31 individual channels of data (hereinafter also referred to as “time slots” or “slots”), while the T
1
multiplexing system that is mostly used in the USA comprises Time Divisional Multiplexing of up to 24 individual channels of data. The Time Divisional Multiplexed data in the E
1
or T
1
carriers is generally data that is sampled from a plurality of individual sources, then serially grouped into frames, wherein each data slot in a frame relates to a different channel and generally includes data from a different source.
In a typical digital access network, a local exchange (LE) is connected to an Access System, which in turn comprises a plurality of Access Devices. The communication between the LE and the Access System is based on E
1
/T
1
links, which serve as the media for transmitting/receiving the users' voice/data and signaling information. The modern Access Devices that use CCS (Common Channel Signaling) protocols such as V.5.2 or GR303 enable connections between a large number of users to the LE by assigning one or more time slots in each frame for signaling information and supporting the allocation of the rest of the users' data to the E
1
s data slots on a per call basis, allowing the connection of a large number of users to the LE by E
1
bundle.
The Access Devices of the prior art use “classical” point-to-point connection of their E
1
links to the LE, wherein each E
1
transceiver of any Access Device is connected to a corresponding E
1
transceiver of the LE. Since each Access Device is able to support a finite number of users, the full utilization of the Local Exchange capabilities to support a few thousands of users requires additional links between LE and new Access Devices, and additional connections between Access Devices, which leads to an increase of the cost, installation and management difficulties and data delays.
It is therefore an object of the invention to provide an E
1
or T
1
system that is relatively simple, even when the number of users and/or the number of E
1
/T
1
links is high.
It is another object of the invention to provide an E
1
/T
1
system that is integral, i.e., a system that can be easily expanded to serve more users and/or E
1
/T
1
links, without adding to its complexity.
It is still another object of the invention to reduce the number of transceivers in the system, while increasing the usage of each existing transceiver.
It is still another object of the invention to decrease the total data transfer delay in the system, by reducing the data delays due to the need to transfer specific data blocks between different Access Devices.
It is still another object of the invention to reduce the number of connections in the system and the switching complexity.
Other objects and advantages of the invention will become apparent as the description proceeds.
SUMMARY OF THE INVENTION
The invention relates to a method of exchanging data streams between a local exchange and a number of access devices for serving a plurality of destination users, the method comprising steps of: (a) providing a local exchange capable of generating at least one output data stream and of receiving at least one corresponding input data stream for carrying data blocks respectively relevant to one or more of the access devices; (b) providing two or more said access devices, each permitting passage there-through of at least one data stream carrying data blocks, being capable of extracting from said at least one data stream data blocks relevant to this particular device, and of introducing there-into data blocks to be transmitted from this particular device to the local exchange; (c) arranging one or more close loop data streams, each being intended for serving said two or more access devices using one of said output data streams and the corresponding input data stream of the local exchange, by causing the output data stream leaving the local exchange to pass through said two or more access devices in a chain-like manner and return to the local exchange as the input data stream.
Preferably, each of said data streams is a stream comprising data frames carrying the data blocks arranged in time slots. A pair of said input stream and said corresponding output stream of the local exchange forms one E
1
link. Alternatively, a pair of said input stream and corresponding to it said output stream forms one T
1
link.
According to the most preferred version of the method, the step of arranging one or more close loop data streams is performed by chain-like interconnecting the access devices situated in different access systems.
As will be further explained in detail, the access device is preferably a user interface card, and the access system is an access shelf adapted to contain a number of the user interface cards.
Preferably, the method of the invention further comprises a step of forwarding the extracted data blocks from each said access device to the respective destination users, and a step of receiving, at each said access device, data blocks to be transmitted from the respective destination users to the local exchange.
Preferably, the said step of forwarding the extracted data blocks to destination users comprises a sub-step of passing thereof from at least one of said access devices named a master device via a slave access device to the destination users associated therewith, as well as a sub-step of receiving data blocks intended for transmission from the destination users associated with the slave device, thereby increasing the number of the destination users served by the master device.
The invention further relates to a system for exchanging data streams between a local exchange and a number of access devices for serving a plurality of destination users, the system comprising: (a) a local exchange having at least one transceiver capable of generating one output data stream and of receiving a corresponding input data stream for carrying data blocks respectively relevant to one or more of the access devices; (b) two or more of said access devices, wherein each particular device has at least one transceiver permitting passage through the device of a data stream carrying data blocks, the device being capable of extracting from the stream data blocks relevant to the particular device, and of introducing into the stream data blocks to be transmitted from the particular access device to the local exchange; said two or more access devices being arranged in at least one chain, each of the chains to be served in a close loop by at least one of said transceivers of the local exchange, said close loop being formed by connecting the output of the transceiver of the local exchange to the input of the transceiver of a first device in the chain, the output of the transceiver of a last device in the chain is connected to the input of the transceiver in the local exchange, wherein the output of the first device in the chain being connected to the input of the transceiver of a last device in the chain either directly or in a chain-like manner via intermediate access devices if present in the chain.
According to the most preferred embodiment of the s
ECI Telecom Ltd.
Nath & Associates PLLC
Novick Harold L.
Richmond Derek
Sam Phirin
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