Telephonic communications – Centralized switching system – Switching controlled in response to called station...
Patent
1989-05-01
1990-12-04
Dwyer, James L.
Telephonic communications
Centralized switching system
Switching controlled in response to called station...
379221, 370 56, 370 583, H04Q 1104, H04Q 3545
Patent
active
049759469
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a digital type switched telephone exchange that is designed to use a mesh type connection network to implement medium to low potential exchanges (eg. 20,000 users) or a centralized type connection network to implement high potential exchanges (eg. 100,000 users).
Modern digital switching exchanges usually include a plurality of switching modules designed to make telephone links either autonomously on their own, or alternatively through connection networks if the called party is connected to a different module than the module to which the caller is connected.
Accordingly, the cost of this type of exchange is a function of the cost of the modules and the cost of the connection network.
The cost of the modules is more or less proportional to the number of lines connected to the switched exchange while the cost of the connection network is practically independent from the number of the lines and assumes a predetermined entity, even in the presence of small capacity exchanges. Therefore, the cost of the centralized portions (connection network) constitutes the so-called starting point "base" and the cost of the exchange is not proportional to the number of lines installed in the exchange.
In order to minimize the cost per line and to allow the exchange to grow in a linear manner, a switched exchange has been developed with a mesh type connection network for keeping with the increase in the number of installed lines, (i.e. an exchange made only of connection wires and completely void of centralized organs as a consequence), which includes a voice switching section and a signalized switching section.
This type of exchange has optimum requisites as far as costs are concerned but has a saturation limit of approximately 20,000 users, that is determined from the complexity assumed by the network when the limit tends to be exceeded.
SUMMARY OF THE INVENTION
An object of the present invention is to create a switched telephone exchange which allows a mesh type network to be used in order to optimize the costs involved, as described above. At the same time, a centralized connection network is also allowed to be used, in order to convert the exchange into a high potential exchange, whenever an increase in user traffic occurs which exceeds the saturation limit.
Another object of the present invention is to provide a switched telephone exchange which includes a Plurality of modules (described in European Patent No. 73,078) designed to output/receive digital words on a voice connection network. The digital words are in a parallel form codes on H bits having I information bits, R redundancy bits and S service bits and each module includes an access unit, a concentration unit and a control circuit. The modules also include an adaptation circuit to make telephone links through a connection network of the mesh type or through a connection network of the centralized type. The centralized connection network includes a plurality of sections for switching voice signals and a distributor module for distributing signals to the modules and/or the plurality sections. A centralized connection network is conventional and centralized connection is described in the European Application No. 235,406 for example.
The adaption circuits comprise:
parallel to serial conversion means designed to receive a data stream on their input containing digital words in a parallel form coded on H bits,
which is available on the output of the concentration unit, and to convert the digital words into a plurality of data streams containing digital words in a serial form coded on I bits;
a plurality of line means designed to receive the serial data streams output by the parallel to serial conversion means or else by the connection network, on their input, after alignment operations have been carried out, and also designed to forward the serial data streams to the connection network, or to serial to parallel conversion means, after having carried out code conversion operations;
signalling processing means
REFERENCES:
patent: 4472798 (1984-09-01), Hafer
Skaperda, N. J., "Generic Digital Switching System", Internation Switching Symposium, Oct. 25-29, 1976, Session 223, pp. 1-8.
Oliver, G. P., "Architecture of System X, Part 3--Local Exchanges", Post Office Electrical Engineers Journal, vol. 73, (Apr. 1980), pp. 27-34.
IBM Technical Disclosure Bulletin, vol. 28, No. 7, Dec. 1985, "Ten-Thousand-Line Digital Central Office".
Bovo Amilcare
Canato Luigi
Dwyer James L.
Italtel Societa Italiana
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