NZ233161A

NZ233161A - Digital exchange with concentrators for digital and analog services

Info

Publication number: NZ233161A
Application number: NZ23316190A
Authority: NZ
Inventors: Jean-Baptiste Jacob
Original assignee: Alcatel Australia
Priority date: 1990-04-02
Filing date: 1990-04-02
Publication date: 1992-06-25

Description

<div class="application article clearfix" id="description"> Priority Date{s):. •. Conifj^t^ Spccific3t'K)n FU^c^- Class: (5).M..3.W.S?.. H .<?.k§3J.f.te& -^Ltbtfcatico Dale: 5..J.UH..1?.^?. <V0- Jouroat, No: \&£\ 1 TRUE COPY *eiv 2Ap*I990 '-U I NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION ATD MULTI-SERVICE DIGITAL SATELLITE CENTRE" Q f- i of the State of New South Wales, of 252-280 Botany Road, Alexandria, New South Wales, 2015, Australia, 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: 1 This invention relates to connecting analog or digital metal wire subscribers, and to connecting digital optical fibre subscribers, regardless of whether they are close to the parent centre or at a distance therefrom, and more particularly it relates to an asynchronous time-division multiservice digital satellite centre for connecting subscribers to a telecommunications network. European patent 0133703 entitled "Centre Satellite Numerique de Raccordement d'abonnes" (Digital Satellite Centre for Connecting Subscribers) describes a connection unit that may be local or remote. In addition, this "versatile" connection unit makes it possible to combine both analog and digital subscribers on concentrators connected to a digital control unit by digital multiplex lines, said concentrators being local or remote. Such connection units can be used for connecting metal wire subscribers only, ie. either analog subscribers or 144 Kbit/s digital subscribers using two 64 Kbit/s channels in circuit mode and one 16 Kbit/s channel in frame mode, known to the person skilled in the art as narrow band ISDN 2B + D lines. In addition, the multiplex lines between concentrators and the digital control unit and also between the digital connection unit and the parent centre convey all information, i.e. speech, data, and signalling, In synchronous multiplexes, eg. at 2.408 Mbit/s having 125-microsecond frames with 32 time slots each. <k,J 0 o Unfortunately, subscriber needs with new services, such as video services and data services at very high data rates, for example, can no longer be satisfied by the capacities of present subscriber lines, whereas optical fibres are capable 5 of digital data rates that may be as high as 600 Mbit/s or even more. Asynchronous time division (ATD) makes it possible to multiplex and switch all types of information (speech, images, high fidelity sound, data at any data rate, signal-1° ling, etc...) in a single form called a "cell", with cells being fixed in length, and comprising, for example, a 4-byte header portion and a 32-byte information portion. Standardisation relating to ATD is currently being performed by the CCITT. Examples of the contents of a header and de-15 scriptions of asynchronous time division can be found CCITT recommendation 1.121 at paragraphs 3.4.3, et seq, and examples of asynchronous time switching matrices can be found in:ISS 84 - Florence, 7-11 May 1984 - Session 32C, paper 2, Asynchronous Time-Division Techniques: An experimental 20 packet network integrating video-communications, by A. Thomas, J.P. Coudreuse, and M. Servel; and in ISS 1987 -Phoenix, B5 pages 567 to 372 Switching techniques for asynchronous time division multiplexing (or fast package switching) by M. Dieudonne and M. Quinquis. 25 An object of the present invention is to connect dif ferent types of subscriber such as analog and digital subscribers on metal wires asynchronous time division (ATD) 2 TP T € 4L r> z s < digital subscriber on metal wires and on optical fibres, and also synchronous sub-systems such as private exchanges (PABX) having 2 Mbit/s accesses, for example, and synchronous digital satellite centres, eg. of the type described in 5 above-mentioned European patent number 0133703. The present invention provides an asynchronous time division multi-service digital satellite centre for connecting analog and digital subscribers, the centre comprising a digital control unit and digital concentrators of at least one 10 of the following types: local, distant, and versatile distant for connecting subscribers over metal wire lines, with the control unit being connected by multiplex links to the concentrators and to a parent digital exchange, wherein the said multiplex links are asynchronous multiplex links con-15 veying cells, wherein the concentrators are multi-service concentrators delivering Information received from subscrlb-ers in the form of a cells and transmitting information to subscribers taken from the cells they receive, and wherein the digital control unit Is a multi-service control unit 20 comprising a multi-service switching network for switching the cells, and connected to the multi-service concentrators and to the parent digital exchange via said asynchronous multiplex links, and a control station connected to the multi-service switching network by controlling asynchronous 25 multiplex links conveying cells. 4 2 °7 ^ •£ J i r w i v—/ An embodiment of the present Invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows the general architecture of a multi-5 service digital satellite centre of the Invention; Figure 2 shows the general architecture of a multiservice concentrator of Figure 1, regardless of whether it is of the versatile type, or local or remote; and Figure 3 shows the general architecture of the multi-10 service control unit of Figure 1. Figure 1 shows the general architecture of a multiservice digital satellite centre CSB of the invention constituted by a multi-service control unit UCB and multi-service concentrator of at least one of the following 15 types: local for analog subscribers on metal wires, CBLA, connected to line 1; local for 2B + D digital subscribers on metal wires, CBLN, connected to lines 2; 20 local for ATD digital subscribers on metal wires, CBLNA, connected to lines 3; local for ATD digital subscribers on .optical fibres, CBLOA, connected to optical fibres 4; distant for analog subscribers on metal wires, CBEA, 25 connected to lines 5; distant for 2B + D digital subscribers on metal wires, CBEN, connected to lines 6; distant for ATD digital subscribers on metal wires, CBENA, connected to lines 7; distant for ATD digital subscribers on optical fibres, CBEOA, connected to optical fibres 8; 5 versatile local for analog, 2B + D digital, and ATD digital subscribers on metal wires, and for ATD digital subscribers on optical fibres, CBLM, connected to lines 9 and to optical fibres 10; versatile distance for analog, 2B + D digital, and ATD 10 digital subscribers on metal wires, and for ATD digital subscribers on optical fibres, CBEM, connected to lines 11 and to optical fibres 12; and synchronous-to-asynchronous and asynchronous-to-synchronous converter, 15 CAS, connected to lines 13. Each concentrator is connected to the multi-service control unit UCB by an ATD multiplex link constituted by at least two two-way multiplex lines having a data rate of 600 Mbit/s, for example, in each direction. 20 Local multi-service concentrators are situated in the same building as the multi-service control unit UCB. Distant multi-service concentrators are situated at various distances from the multi-service control UCB. The converter type concentrators may be either local or distant. Na-25 turally a multi-service digital satellite centre CSB may include all the various types of multi-service concentrator or only some of them. For local type concentrators, the multiplex lines connecting each concentrator to the multi-service control unit ^ UCB are metal wire lines when the concentrators are situated } in the immediate proximity of the said control unit, and 5 they are optical fibres when the concentrators are remote from the said control unit. For distant type concentrators, the multiplex lines connecting each concentrator to the control unit are optical fibres. Each end of each optical fibre two-way multiplex line 10 then includes two opto-electronic components, one for converting optical signals into electrical signals, and the other for converting electrical signals into optical signals. A local multi-service concentrator CBLA for analog sub-15 scribers on metal wires, connects telephone subscribers via subscriber lines 1 and it is itself connected via a multiplex link 21 to the multi-service control unit UCB. A local multi-service concentrator CBLN for 2B + D digital subscribers on metal wires is connected to 14A Kbit/s 20 lines 2, each line being two-way and being connected to a subscriber terminal installation. It is itself connected by a multiplex link 22 to the multi-service control unit UCB. A local multi-service concentrator CBLNA for ATD digital subscribers on metal wires connects multi-service sub-25 scribers on lines 3, each line being connected to a subscriber terminal installation and conveying Information cells in both directions with a line data rate of the order 7 of a few Mbit/s, eg. 2.048 Mbit/s, or else of the order of a hundred or so Kbit/s, eg. 160 Kbit/s. It is itself connected to the multi-service,control unit UCB via a multiplex link 23. A local multi-service concentrator CBLOA for subscribers on optical fibres connects multi-service subscribers on optical fibre subscriber lines 4 conveying cells of information coming from or going to a subscriber terminal installation. The line data rate of each optical fibre may be very high, taking values such as 3^ Mbit/s, 150 Mbit/s, or 600 Mbit/s. These values are given by way of non-limiting Indication. It Is itself connected to the multi-service control unit UCB via a multiplex link 24. The distant multi-service concentrators CBEA, CBEN, CBENA, and CBEOA are respectively Identical to the local multi-service local concentrators CBLA, CBLM, CBNA, and CBLOA except insofar as they are themselves located at a distance from the multi-service control unit UCB to which they are connected via respective multiplex links 25, 26, 27, and 28. A versatile local multi-service concentrator CBLM is connected to metal wire lines 9 and to optical fibres 10 for connecting analog subscribers on metal wires, 2B + D digital subscribers on metal wires, ATD digital subscribers on metal wires, and ATD subscribers on optical fibres, with the line data rates being Identical to those mentioned above for cor-responding ones of the local multi-service concentrators 8 CBLA, CBLN, CBLNA, and CBLOA. It is itself connected to the multi-service control unit UCB via a multiplex link 29. A versatile distant multi-service concentrator CBEM is identical to a versatile local multi-service concentrator CBLM except insofar as it is located at a distance from the multi-service control unit UCB to which It is connected via a multiplex link 30. A synchronous-to-asynchronous and asynchronous-to-synchronous converter CAS is connected by lines 13 to synchronous sub-systems such as private branch exchanges (PABX) and synchronous digital satellite centres, with the line data rate being 2.048 Mbit/s. It is connected to the multiservice control unit UCB via a multiplex link 31. This link is a metal wire link when the converter is in the Immediate proximity of the control unit and it Is an optical fibre link when the converter is distant therefrom. For a distant converter, the link includes opto-electronic components at each end for converting electrical signals into optical signals and vice versa. The converter itself does not form part of the invention and is of any appropriate known type. A suitable converter is described by way of example in Globecom 1985, New Orleans, pp. 791 to 794, Asynchronous Time-Division Networks: Terminal Synchronization for Video and Sound Signals, by J.Y. Cochenec, P. Adam, and T. Houdoln. The problem of synchronous-to-asynchronous and asynchronous-to-synchronous conversion constitutes the sub ject matter of paragraph 3.4.3 of above-mentioned CCITT Recommendation I 121. The multi-service control unit is connected.via an optical fibre multiplex link 32 to a multi-service telecommunications exchange. The data rate of each of the multiplex links 21 to 32 is 600 Mbit/s, for example. As mentioned above, the multiplex links 21 to 24, 29 and 31 are metal wire links or optical fibre links depending on whether the local concentrators are in the immediate proximity of the multiservice control unit, or not. The multiplex links 25 to 28, 30 and 32 are optical fibre links. Figure 2 shows the general architecture of a multiservice concentrator as shown in Figure 1, regardless of whether it is local, distant, single-purpose or versatile. A concentrator is constituted by an access unit ASC giving access to the multiplex link connecting the concentrator to the multi-service control unit, and m terminal units UT1 to UTm, each connected firstly to corresponding subscriber lines LAI to LAI, and secondly to the access unit ASC. The access unit ASC is constituted by n asynchronous interfaces IAI to IAn, where the number n of these Interfaces varies as a function of the dimensioning of the concentrator: number of subscribers, types of subscribers, traffic, etc For reasons of security and maintaining service, the number of asynchronous interfaces is not less 2 33 16 than 2. Each interface is controlled by a microprocessor raP. Each interface IA1 to IAn is constituted, for example, by a multiplexer/demultiplexer, or by a both-way asynchronous time division switching matrix. Each interface IA1 to IAn is connected to a respective both-way multiplex line LM1 to LMn, with the n multiplex lines from LM1 to LMn constituting the multiplex link connecting the concentrator to the multi-service control unit UCB. As mentioned above, this multiplex link comprises optical fibres when the concentrator is remote from the control unit, in which case each interface IA1 to IAn includes two opto-electric components (not shown) connected to respective ones of the two-way multiplex lines LM1 to LMn in order to convert optical signals Into electrical signals and electrical signals into optical signals. Each interface is also connected to each of the m terminal units UT1 to UTm. A terminal unit UT is constituted by an asynchronous time division switching matrix M having 1 inlets and n outlets, where n is less than or equal to i_, and i_ subscriber access circuits CAB each connected to a subscriber line. Each of the inlets to the matrix is connected to a subscriber access circuit CAB. The number n_ of outlets from the matrix is not less than 2, with each outlet being connected to a corresponding one of the Interfaces IA1 to IAn. The matrix M conveys calls in both directions and is controlled by a microprocessor mP. Each subscriber access cir- cult CAB is constituted by a subscriber line interface IL and by an asynchronous time division switching interface ICA. The asynchronous time division switching interface ICA 5 is connected firstly to one of the inlets to the switching matrix M, and secondly to a bus B of the microprocessor mPl for controlling and monitoring the subscriber access circuits CAB of the terminal unit. The composition of the subscriber line interface IL 10 differs depending on whether the subscriber line is a metal wire line for analog subscribers, for 2B + D or ATD digital subscribers, or an optical fibre link for an ATD subscriber. For an analog line, the subscriber line interface IL comprises, in conventional manner, an interface circuit pro-15 viding Borscht functions and an analog-to-digital and a digital-to-analog converter providing encoding, decoding, and filtering functions. For a 2B + D type 144 Kbit/s digital line, the subscriber line interface IL is either an echo cancelling cir-20 cuit such as described, for example, in Commutation et Transmission, No. 4, 1988, pp. 67 to 83, in "Equipements de Transmission RNIS a 144 Kbit/s de "Deuxieme Generation" pour reseau de distribution" ("Second Generation" 144 Kbit/s ISDN Transmission Equipments for Distribution Networks) by F. 25 Marcel, M. Wajih, and R. Cadoret, and in Revue des Telecommunications, Vol. 61, No. 1, 1987, pp. 63 to 71, in "Composants RNIS pour Lignes numeriques publiques et 12 privees" (ISDN components for public and private digital lines) by P. Van Iseghem, J.M. Danneels, M.C. Rahler, A. Kruger, and K. Szechenyl, or else a circuit transmitting in each direction alternately as described in the above-5 mentioned article in Commutations et Transmission, No. 4, 1988. For a metal wire ATD digital line whose data rate is a function of the characteristics of the line, and is about 160 Kbit/s, for example, the line interface IL is likewise 10 either an echo cancelling circuit or else an alternating direction circuit. For an ATD optical fibre line, the subscriber line interface comprises two opto-electronic components, one converting optical signals into electrical signals, and the 15 other converting electrical signals Into optical signals, together with transmit and receive amplifier circuits, and circuits for encoding and decoding signals. For a line having two optical fibres, one for each transmission direction, one of the optical fibres Is connected to the opto-20 electronic receive component and the other optical fibre is connected to the opto-electronic transmit component. When the line has only one optical fibre for both directions of transmission, then the subscriber line Interface includes an optical duplexer connected at one end to the optical fibre 25 of the line and at its other end both to the transmit and to the receiver opto-electronic components via a transmit fibre and a receive fibre, respectively. 13 Regardless of the type of subscriber line interface IL, the switching Interface ICA comprises circuits for transmlt-/""ss ting and extracting signalling cells for call processing, and for operation and maintenance purposes, these cells con-5 veying information between the microprocessor mPl controlling all of the subscriber access circuits CAB of a terminal unit UT and the multi-service control unit UCB, as well as the subscriber terminal installation on the subscribers premises. In addition, with analog subscribers or 2B + D 10 digital subscribers where information is not in the form of asynchronous time cells, the switching interface ICA also performs cellulisation and the reverse operation of decellulisation, both for signalling messages and for information (speech, images, data) on the 2B + D channels or from 15 the analog-to-digital converter of an analog subscriber line interface IL. Figure 3 shows the general architecture of a multiservice control unit UCB comprising a control station CS and a multi-service switching network RCB. 20 The control station CS is constituted by processors and peripherals therefor such as memories, ..., as required for performing functions such as call processing, operation, and maintenance of a multi-service satellite centre. In well known manner, the processors and their peripherals are pro-25 vided with sufficient redundancy to ensure that service is provided on a permanent basis with the quality required by international standards. 14 2 3 "w jS dj* 1 The central switching network RCB is constituted by two stages of asynchronous time division matrices. The matrices of the first stage have _r two-way inlets and r two-way outlets, and there are 2r of them reference Ml.l, Ml.2, ..., 5 M1.2r. The matrices of the second stage are single-sided matrices constituted by the same matrices as the first stage but folded in such a manner as to constitute matrices having 2r Inlets/outlets. There are r_ matrices in the second stage referenced M2.1 to M2.r, and each matrix is connected to the 10 2r matrices Ml.l to M1.2r of the first stage by 2r both-way multiplex links. Each matrix of the first stage and of the second stage is controlled by Its own microprocessor mP. The control station CS is connected via two multiplex links 35 and 36 to two matrices of the first stage. In Fig-15 ure 3, multiplex link 35 is connected to the matrix Ml.l and multiplex link 36 is connected to the matrix M1.2r, by way of example. Each matrix of the first stage is connected by its r_ both-way inlets to v_ multiplex lines, with the matrices of 20 the first stage being connected to both-way multiplex lines Ll.r to Ll,r, L2.1 to L2.r, ..., L2r.l to L2r.r. These both-way multiplex lines constitute the multiplex links 21 to 31 of Figure 1 connecting the multi-service control unit UCB to the various concentrator, and also the multiplex link 25 32 connecting the multi-service control unit UCB and thus the multi-service digital satellite centre CSB to a telecommunication exchange. In Figure 2 which shows the general 15 2 architecture of a concentrator, the both-way multiplex lines LM1 to LMn constitute a multiplex link connecting said concentrator to the multi-service control unit UCB shown in Figure 3. These both-way multiplex lines LM1 to LMn corre-5 spond to n both-way multiplex lines taken from the both-way multiplex lines Ll.l to Ll.r, L2.1 to L2.r, L2r.l to L2r.r, of Figure 3. As mentioned above, the both-way multiplex lines constituting the multiplex links 32 and the multiplex links 25, 10 26, 27, 28 and 30 with distant type concentrators are optical fibre links, whereas the both-way multiplex lines 21 to 24, 29 and 31 are either metal wire links or optical fibre links depending on whether the corresponding local type concentrators or converter type concentrators are in 15 the immediate proximity of multi-service control unit UCB, or not. In the switching network RCB, each of the optical fibre both-way lines is connected to a matrix of the first stage by two opto-electronic components (not shown) for converting optical signals Into electrical signals and vice 20 versa. When a both-way line is constituted by two optical fibres, one for each transmission direction, one of the fibres Is connected in the interface IA of the access unit ASC to an opto-electronic transmit component and in the switching network RCB to an opto-electronic receive compo-25 nent, while the other optical fibre is connected in the interface IA to an opto-electronic receive component and in the switching network to an opto-electronic transmit compo- 16 2 35 16 nent. For a both-way line In the multiplex link 32, one of the fibres is connected in the switching network to an optoelectronic transmit component and in the parent exchange to an opto-electronic receive component, while the other optical fibre is connected in the switching network to an opto-electronic receive component and in the parent exchange to an opto-electronic transmit component. When a both-way multiplexer line is constituted by a single optical fibre for both transmission directions, it is connected at each end to an optical duplexer which Is itself connected via one optical fibre to the opto-electronic transmit component and via another optical fibre to the opto-electronic receive component. Messages are interchanged between the control station CS and each of the microprocessors mP and mPl of the multiservice digital satellite centre, which microprocessors are used for controlling the various matrices and subscriber access circuits of the terminals used, by means of a protocol using the format of asynchronous time division cells interchanged over the multiplex lines between the subscriber access circuits CAB and the terminal unit matrices, between the terminal unit matrices and the matrices of the access unit ASC, and between the access unit matrices and the matrices of the central multi-service switching network RCB. 17 Thus, the control station CS is connected to the central switching network RCB by the two multiplex lines 35 and 36 which are connected to two different matrices of the first stage for reasons of security. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 933161 Whal we claim is:-

1. An asynchronous time division multi-scrvicc digital satellite exchange to which analog and digital subscribers arc conncctablc, Lhc exchange comprising a digital control unit and one or more digital concentrators of at least one of the following 5 types: local, distant, and versatile distant, for connccting subscribers over metal wire lines, with the control unit being conncctcd by multiplex links to the concentrators and to a parent digital exchange, wherein the said multiplex links arc asynchronous multiplex links conveying cells, the cells containing control signals or information, wherein the concentrators arc multi-scrvicc concentrators delivering information rc-10 ceivcd from subscribers in the form of cclls and transmitting information to subscribers taken from the cells they receivc, and wherein the digital control unit is a multi-service control unit comprising a multi-scrvicc switching network for switching the cclls and a control station conncctcd to the multi-scrvicc switching network, by control link in the form of asynchronous multiplex links, Lhc control links conveying 15 cells containing control signals.

2. A satellite exchange as claimed in claim 1, also including multi-service concentrators of at least one of the following Lypcs: local for metal wire connectcd asynchronous time division digital subscribers; local for optical fibre connected asynchronous time division digital subscribers; distant for metal wire connectcd 20 asynchronous time division digital subscribers; distant for optical fibre connected w' asynchronous time division digital subscribers, and versatile local for optical fibre connected and metal wire conncctcd asynchronous time division digital, synchronous digital, other digital, and analog subscribers.

3. A satellite exchange as claimed in claim 1 or claim 2, wherein a versatile dis-25 tant multi-scrvice concentrator is connectcd to asynchronous time division digital v\ 19 233161 subscribers, to other digital subscribers, and to analog subscribers over metal wires or over optical fibres.

4. A satellite exchange as claimed in any one of claims 1 to 3, wherein a multiservice concentrator comprises a plurality of terminal units and an access unit; wherein a terminal unit includes: subscriber acccss circuits each constituted by an asynchronous time division switching interface and by a line interface conncctcd to a subscriber; a switching matrix controlled by a microprocessor for the matrix and conncctcd to the asynchronous time division switching intcrfaccs; and a microprocessor connectcd to each asynchronous time division switching interface, each asynchronous time division switching intcrfacc transmitting and extracting cclls containing control signals, coming from or going to said microprocessor; and wherein the acccss unit includes asynchronous interfaces each controlled by a respective microprocessor and conncctcd firstly to the multi-service switching network via an asynchronous multiplex line and secondly to the switching matrix of the terminal unit via respective asynchronous multiplex lines.

5. A satellite exchange as claimed in any one of claims 1 to 4, also including at least one synchronous-to-asynchronous and asynchronous-lo-synchronous converter connected firstly to a synchronous multiplex link and secondly to the multi-service switching network via an asynchronous multiplex link.

6. A satellite exchange as claimcd in claim 5, wherein the multi-service switching network is constituted by a first stage of matrices and by a second stage of matrices, wherein each matrix of the first and second stages includes a controlling microprocessor, and wherein the matrices of the first stage arc connectcd to asynchronous multiplex lines in order to connect said first stage to the acccss units of the terminal units of the multi-scrvicc concentrators, to the or each converter, to the parent digital 20 * 233161 cxchangc, and to the control station which is connected to two of Lhc matrices of the first sLage by one multiplex line per matrix.

7. A satelliLe exchange as claimcd in claim 6, wherein each matrix includes a firsL pluraliLy of ports and a sccond plurality of ports, each port of Lhc firsL plurality being 5 conncctablc to each port of the sccond plurality, and wherein each of the ports of the second plurality of the first stage is connectcd to a corresponding port of the first or second pluralities of the sccond stage.

8. A satellite cxchangc, substantially as herein described with rcfcrence to Figures 1 to 3 of the accompanying drawings. JO 15 ALCATEL AUSTRALIA LIMITED P.M. Conrick Authorized Agent P5/1/1703 20 25 N.Z. PATEWT OFFICE - 7 MAV 1882 21 </div>