NZ205444A - Video switching exchange controlled over narrow-band lines - Google Patents

Abstract

1. Integrated communication system containing a narrowband communication network with narrowband switching facilities (1), a broadband switching network with broadband switching facilities (17), and digital broadband distribution switching networks with broadband distribution facilities (14), the broadband switching and distribution facilities being controlled fron the narrowband switching facilities, characterized in that in the case of a narrowband switching facility which has a digital switching network (1) and terminal modules (2, 4) connected therewith and wherein the control facilities are spatially distributed to the terminal modules (2, 4), there is provided an additional terminal module (16) which is connected to the digital switching network (1), contains the control facilities for one of the broadband switching facilities (17), and is connected via the digital switching network (1) to the narrowband communication network for the exchange of the signalling and control information necessary to handle the calls in the broadband switching network.

Description

205444 ORIGINAL Priority Date(s): 14-.

Complete Specification Filed: .. Class: ti%V!ll|Cp Publication Date: ,'rr..... P.O. Journal, No: rS5»r««S.° I —•* - 1SEPBS3 NEW ZEALAND THE PATENTS ACT, 1953 COMPLETE SPECIFICATION "INTEGRATED COMMUNICATIONS SYSTEM" WE, INTERNATIONAL STANDARD ELECTRIC CORPORATION, a Corporation of the State of Delaware, United States of America, of 320 Park Avenue, New York 22, New York, United St&tes of America3 hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement 2 0 54 4 4 The present invention relates to an integrated communication system containing a narrowband communication network, a broadband switching network, and digital broadband distribution switching networks, the broadband switching and distributing equipment being controlled from the narrowband switching equipment.

In a known integrated communication system, the broadband switching network, comprising a video switching network for video communication that is installed in a telephone central office, and the broadband distribution switching network, comprising a television-signal switching network, are controlled by the control unit of the telephone exchange. The latter must be designed for this purpose, which involves considerable expense. In addition, special signalling equipment, protocols, and procedures are necessary. For the exchange of narrowband and broadband voice-frequency and data signals, each subscriber terminal is connected to the telephone exchange and the video and television-signal switching networks by two optical fibres, one for the transmit direction and one for the receive direction, over which the different communication signals are transmitted in one direction at a time using time-division multiplexing. The high transmission capacity of optical fibres is not sufficiently utilized in that system.

An object of the present invention is to provide an 2 0544-4 integrated communication network which makes use of the existing communication infrastructure and thus reduces the cost and complexity of the broadband communication system.

Accordingly there is provided an integrated communication system of the aforementioned kind wherein the narrowband switching equipment comprises digital switching networks with spatially distributed control elements and is provided with a terminal module which contains the controllers for the broadband switching network, is connected to the narrowband digital switching network, and transfers the signalling and control information for handling the calls in the broadband switching network through the narrowband communication network.

The principal advantages of the invention are that the equipment in existing digital communication networks or in digital communication networks to be set up in the foreseeable future is also used for new broadband switching and distribution networks. No special signalling and control equipment is necessary. The communications protocols and procedures are uniform. This improves the economy of the entire telecommunications network.

An embodiment of the invention will now be explained with reference to the accompanying drawings, in which Fig. 1 shows the connection of broadband switching networks to a digital exchange in a communication system according to the invention, and 205444 Pig. 2 shows a terminal module forming part of a digital exchange and containing the controllers for a videophone switching network in an integrated communication system as shown in Pig. 1.

Connected to a narrowband switching network 1 of a modern digital exchange, e.g., a System 12 exchange, are several so-called terminal modules (see, for example, "Electrical Communi cation", Vol. 56, No. 2/3, 1981, page 135), of which a digital subscriber module 2, a common channel module 3, and a digital trunk module 4 are shown in the drawing. Each of these modules consists of a terminal 2a, 3a, 4a and a terminal control element 2b, 3b, 4b. The module 2 is connected via narrowband lines 6 to a subscriber multiplexer 7 which is connected to the subscriber facilities (not shown) by broadband subscriber lines 8. The module 3 is the common channel module for, e.g., CCITT No. 7 signalling.

Via the module 4, digital trunks 10 running to other exchange and forming speech paths are connected to the narrowband switching network. These trunks also Include the common signalling channel.

Switching control facilities 12, indicated in the drawing by a block bordered by a broken line, serve to integrate broadband services into the narrowband communication network. These are a module 13 for controlling a broadband distribution switching network 14, which module consists of a 205444 terminal 13a and a module control element 13b, and a module 16 for controlling a broadband switching network 17, which module consists of a terminal 16a and a module control element 16b. The two modules 13 and 16 may also be united into one control module.

Through the broadband distribution switching network, a few of a major number of centrally available television programs, e.g., three, are switched to the subscriber, namely those selected by the subscriber from the programs being offered. The broadband distribution switching network 14, hereinafter also referred to as "TV switching network", is connected to the module 13 by a control line 19 and to the subscriber multiplexer 7 by program distribution lines 20. The television programs are supplied to it over lines 21.

The broadband switching network 17 handles the broadband video signals necessary for video calls. It is connected to the module 16 by a control line 22, to the subscriber multiplexer 7 by broadband lines 23, and to other broadband switching networks by broadband trunks 24. In the following, it will also be referred to as the "videophone switching network".

Those parts of the integrated communication system according to the invention which are spatially assigned to the narrowband digital exchange are indicated by a bracket 26. 205444 Details of the module 16 for controlling videophone switching networks are shown in Pig. 2. Lines 28 and 28' connect the module 16 to the narrowband digital network 1, while the other modules 2, 3, 4 and 13 are connected to the switching network 1 by corresponding lines 29 to 32 (see 5 also Pig. 1).

The module 16 is duplicated for reliability; the two units are designated 16(1) and 16(11).

Each of the two modules 16(I) and 16(11) has a terminal interface 36, a terminal control unit 28, one or more control assemblies 39 and. If nec-10 essary, a remote-control assembly 40. The terminal control unit includes a microprocessor means and associated memory means (not shown) which perform Input/output functions. Each microprocessor means exchanges messages with the microprocessor means In other control elements through the terminal interface and via the narrow band digital network to perform call process-15 ing. The control assembly 39 contains three line circuit arrangements 42, 43, and 44, each of which comprises a register 46, a parallel-serial converter 47, and a line driver 48. The circuit arrangement 42 transfers the control signals of the module 16 to a videophone transit switching network 17a, which is usually of multistage design. The circuit arrangement 43 20 transfers the control signals to a videophone subscriber switching network 17b,>and the circuit arrangement 44 controls a videophone concentrator 17c. The remote-control assembly 40 contains one or more circuit arrangements 45 comprising a register 46, a parallel-serial converter 47, and a line driver 48. The latter transfers the control signals to the subscriber multiplexer 25 7. Remote control of distant broadband switching equipment by the n.z. patent oryg;s 1 CFEB 19-36 205444 assembly 40 is of importance mainly at the first configuration level of the integrated communication network.

For the implementation of broadband dialogue services, particularly the videophone service, and the distribution of television programmes in telecommunications networks, the following principles apply: Preference is given to digital signal transmission; necessity of high bit rates in the range from 3 4 to 140 mb/s (depending on the kind of A/D conversion used) as compared with other communication services; no switching of these digital signals of high bit rate through the switching networks of digital exchanges of the telephone network or of a future ISDN network; necessity of broadband switching equipment, interconnected by broadband communication systems, for videophone service; necessity of broadband distribution switching networks for TV program distribution; construction of a broadband videophone communication network completely covering a given area, and handling of telephone calls associated with the videophone service through the telephone network.

This results in the following objectives, which are attained by the communication system according to the invention in a technically and economically advantageous manner: 205444 tying the broadband communication facilities to the communication infrastructure within the framework of the entire communication network; transfer and processing of the signalling and control information for handling video calls, and - transfer and processing of the signalling and control information for selecting television programmes and, if necessary, stereo sound broadcast programmes.

For the implementation of the integrated communication system, the following features of the communication network are advantageous: digitization of the entire telephone network, both in the switching equipmetn and in the transmission equipment; - use of broadband service-integrated digital subscriber terminations, the subscriber lines preferably using optical fibres; availability of an out-of-band signalling channel, a so-called D channel, at the digital subscriber termination; signalling in the digital communication network over common signalling channels, preferably using CCITT No.7 signalling, including a "user part" for broadband services, and use of modular computer-controlled exchanges in the digital communication network which permits the addition of new functional modules performing additional tasks, as is readily possible in a System 12 exchange. 205444 Equipment for broadband services may be added to the telecommunications network: broadband switching networks for switching the video signals for videophone service; broadband transmission paths, preferably using fibre-optic cables, for interconnecting these switching networks broadband switching networks for distributing TV programs and, if necessary, stereo sound broadcast programs; broadband transmission paths, preferably using fibre-optic cables, for supplying the TV programs and, if necessary, the stereo sound broadcast programs, and - the signalling channels of the digital communication network are also used for the broadband switching services and distribution services in order to transfer control and signalling information for call setup, switching network marking, program selection, operation, maintenance, etc.: a) the signalling channel D in the local area, and b) the common signalling channels between the digital telephone exchanges.

Some of the modules of the digital exchange are also used for the broadband switching and distribution services, and other modules have to be added (see Fig. 1): use of the digital subscriber moduels 2 for subscribers with broadband services; use of the digital trunk modules 4 (narrowband with 64 54 44 kb/s in digital multiplex systems, such as DSMX2) for handling the telephone call belonging to the videophone call; use of the common channel modules 3 for the transfer of signalling and control information between the digital exchanges, and addition of modules 13 and 16 for controlling the broadband distribution networks 14 and the broadband switching networks 17, respectively, with the functions of path and direction selection, switching-network management and supervision, switching sequence control, etc.. The control fo the broadband switching and distribution networks can be implemented in one or more modules depending on system size and number of functions. For reliability, it is advantageous to duplicate the control modules.

The narrowband switching network 1 of the digital exchange is also used for the internal transfer of the signalling and control information between the modules. The integrated communication system in accordance with the invention is particularly advantageous in that it permits the equipment for handling broadband services (particularly broadband dialogues) to be inserted into the narrowband digital communication infrastructure in an appropriate manner. Since the signalling and control equipment is used for both narrowband and broadband services, an economical 205444 overall structure is obtained. The tying of the broadband switching networks 17 and the distribution switching networks 14 to the narrowband digital exchanges 1, particularly System 12 exchanges, is advantageous from an engineering point of view. It eliminates the need for separate channels, protocols, methods, and equipment for signalling and control in the broadband portion of the network. The use of the narrowband switching network for broadband communication permits a flexible assignment of the subscribers to the broadband control modules. This results in an economical implementation at different configuration levels determined by the number of subscribers and the number and kind of services used. An integrated communication system includes the narrowband telephone networks, a broadband switching network 17 for videophone service, and a broadband distribution switching network 14 for cable television service.

The narrowband switching equipment comprises digital switching networks 1 with spatially distributed controllers 2, 3, 4, etc., and a terminal module 16 which contains the control facilities for the broadband switching network 17, is connected to the narrowband digital switching network 1, and transfers the signalling and control information for handling the calls in the broadband switching network through the narrowband communication network. Advantageously, the broadband equipment is of digital design, too, and the 2054-4 signalling and control information is transferred through a network of common signalling channels.

Claims (9)

f 205444 What we claim Is:-

1. An integrated communication system containing a narrowband communication network, a broadband switching network, and digital broadband distribution switching networks, the broadband switching and distribution equipment being controlled from the narrowband switching equipment of said communication network, wherein the narrowband switching equipment comprises digital switching networks with spatially distributed control elements and is provided with a terminal module which contains the controllers for the broadband switching network, is connected to the narrowband digital switching network, and transfers the signalling and control information for handling the calls in the broadband switching network through the narrowband communication network.

2. An integrated communication system as claimed in claim 1, wherein the narrowband switching equipment is provided with a second terminal module which contains the controller for the broadband distribution equipment, is connected too the narrowband digital switching network and transfers the signalling and control information for performing switching operations in the broadband distribution equipment through the narrowband communication network .

3. An Integrated communication system as claimed in claim 1, wherein a telephone call belonging to a video call set up via broadband switching equipment is handled via the n.z. PATEiVT orvffite 1 C FEB 1986 13 L QOEfi/HJ j 205444 narrowband communication network.

4. An integrated communication system as claimed in any one of the preceding claims, wherein each subscriber line contains only one optical fibre over which the information is transmitted in both directions using wavelength-division multiplexing.

5. An integrated communication system as claimed in any one of the preceding claims, wherein the signalling and control information is transferred through a network of common signalling channels which are controlled by a third terminal module of the narrowband switching equipment.

6. An integrated communication system as claimed in any one of the preceding claims, wherein the broadband switching equipment and the broadband distribution equipment are colocated with the narrowband switching equipment.

7. An integrated communication system as claimed in any one of the preceding claims, wherein the broadband transmission paths run along the same routes as the transmission paths of the digital telephone network.

8. An integrated communication system as claimed in any one of the preceding claims, wherein the hierarchical structure of the broadband switching network is adapted to the hierarchical structure of the digital telephone network. - 14 - 205444

9. An integrated communication system substantially as herein described with reference to Figs. 1 and 2 of the accompanying drawings. INTERNATIONAL STANDARD ELECTRIC CORPORATION P.M. Conrick Authorized Agent 5/1/1223 c- k. t , - 15 -