SE439566B - SET TO ASTADKOMMA DISTRIBUTED CONTROL OF A DIGITAL WIRELESS MULTIPLE SUBSCRIPTION SYSTEM AND MULTIPLE SUBSCRIPTION SYSTEM TO CARRY OUT THE SET - Google Patents

Description

7802272-0 2 to the group switch via the same paths that connect the speech signals, thereby eliminating awkward and expensive individual control paths.

In accordance with another aspect of the invention, subscriber calls are divided into initiation and end call halves under subscriber control and separated by the group switch, thereby avoiding undesirable interactions between them so as to obtain simplified software requirements.

In modern telephone switching systems, it is currently required that large amounts of data indicating the condition of the lines and connecting lines served by such a switching system must be able to be stored, which also applies to necessary measures to be taken by the switch in response to different line and connecting line conditions. Examples of data used are the subscriber's service class, the call's connection line class, subscriber restrictions, translations from telephone directory number to equipment number, translations from equipment number to telephone directory number, and translation of number code to switching system, ie. translations of area code and telephone exchange code with alternative paths, etc. In a previously known system with centralized control, the data in question is stored in a common memory which is doubled for reliability and which is accessible by computers for common: control, whereby these computers can perform serial operations on the basis of sampled data.

In these prior art systems with shared load or shared control of many operations, more than one processor must be able to access a common memory to obtain data simultaneously.

Different problems arise in such a system in that the processors interfere with each other, whereby the result is that the connections in practice have increased losses, and these losses increase as the number of computers increases.

Decentralized control systems, in which distributed control functions are included, have become known in the past. A prior art switching system, in which stored program controllers are distributed in the system, is described in U.S. Pat. No. 5,974,343.

Another prior art switching system is described in U.S. Patent No. 5,860,761, in which a successively controlled switching system utilizing register control switches a complete call at a time instead of the initiation and end call halves as described in accordance with the present invention. .

Prior art systems have concentrated on obtaining ff "ß .m1 ä» f »11: -. ... vi, 1 Poos onani-vf, 802272_o - .. ii 3 f ~ -_f. ~ - ~ - en high efficiency of the processing function- Multi-processing was introduced to achieve better processing capability but still with the aim of not providing a greater capacity than required.This contributed to undesirable interactions between software packages, where modification or addition of a feature could interfere with the current operation nos other features in a way that was 1 largely unpredictable.This in turn led to a detailed examination of software packages whenever a feature or a traffic-sensitive quantity was changed (which is sometimes referred to as regression testing). The larger the software packages became, the more research needed to be carried out, constantly re-examining old characteristics to ensure that they could still be used.

A main reason for this previously existing problem lies in the constructions used so far in systems with common control, where a processing function for controlling a stored program is used jointly in time for a variety of tasks that must be performed at the request of the randomly initiated and terminated traffic. . These constructions also make it possible for errors in the software resp. temporary hardware failures to cause the computer program to "jump" to unwanted and unpredictable memory modes, thereby canceling the proper operation of the entire software package.

In accordance with the present invention, this regression testing process is eliminated by designing the system in such a way that a processing function can be assigned to each call during the entire duration of the call in question.

In accordance with the present invention, each ongoing call has its own assigned computer system including a microprocessor that handles the call independently of the other calls being processed simultaneously. A system design is thus achieved, where an assigned processor is present for each call. This idea of having an assigned processor per call allows software packages to be designed in such a way that they do not need to be disturbed to handle another call. The present invention extends beyond assigning a processor function per ongoing active call, namely in that the principle is extended to include the provision of a processing function assigned to each termination (line or connection line) at the telephone exchange. The treatment function can be located at a distance from the telephone exchange at a remote concentration point or even in the telephone. In addition, there is a central communication switching path, not only for the speech signals but also for the total traffic, which path has been created by the need of the individual processing functions to occasionally communicate with each other and with certain centralized functions, such as centrally stored data. maintenance modules, human-machine boundary equipment, etc.

When an excess of processing functions is performed independently but in interaction with each other and largely asynchronously in relation to each other, this represents a distribution of the control function from a central location to each individual line and / or connection line termination. The communication via the treatment functions takes place via a hardware border equipment. Each processing function refers only to the characteristics of the specific line / connection line that it is assigned to serve. Thus, it can be examined or tested once in detail, after which it will continue to work with functions that have been tested in a similar way via the common border equipment. The addition of a new feature, ie. a new facility, to a processing function assigned to a particular line may not work properly (before a detailed examination has been performed) with respect to another existing line that does not have the new feature, but it can not prevent two such existing lines from interacting with each other, since it has nothing to do with the connection of a call between two existing lines. Sufficient controls with regard to the hardware are present in the communication limit equipment so that incorrect transmissions between treatment packages can be detected and can be noticed by maintenance personnel. It may also be impossible for a treatment function to change the work instructions for any other treatment function. According to the present invention, all that a processing function can do is to obtain data via a hardware equipment, whereby the remote processing function can choose to work with respect to the data in question in accordance with its own set of stored instructions. As an example of such hardware communication equipment, mention may be made of the continuously expandable switching network described in U.S. Pat. No. 4,173,713.

By using a processor for each termination, functions which have previously required hardware logic circuits and electromechanical means as well as tone frequency means can be performed when program- F "l: we,.», .F ïï = ._ "__ z 'w 1.1: - -. ' in 7802272-'0 5 item control of the processor. According to the present invention, these functions are performed on the basis of one line per connection line, and they include but are not limited to transmitting ring signal on the line, tone detection and tone stringing, testing or listening on the line, analog-to-digital conversion, etc. to enable transmission and switching information in time division multiplex (Empty).

As is generally known, current time division multiplex transmissions transmit analog amplitude information such as digital values, for example by delta modulation or by pulse code modulation (PCM modulation), amplitude information being sampled at periodically consecutive times and represented by binary words. These binary words are transmitted as data bytes in periodically consecutive time slots, which, if assigned to a communication link, form a time channel. Switching of time slots between channels by means of time switches which utilize slot changes is generally known and is described, for example, in U.S. Pat. No. 3,770,895.

Analog-to-digital conversion logic, either in a line circuit boundary equipment of the type described in U.S. Pat. No. 4,161,633 or in a digital telephone set, is controlled by microprocessor logic, whereby the same microprocessor logic can also be adapted to control telephone exchange switching to telephone exchange databases. Each such device or group of devices is controlled by an assigned microprocessor which includes a programmable memory with a memory updating capability through its digital channel to the telephone exchange. Although a single microprocessor could be assigned to serve each subscriber device, a group of subscribers can be served by each microprocessor using local distribution multiplexers that utilize multiprocessor logic so that a common program memory can serve and be accessed by, for example, between 30 and 60 subscribers. .

In accordance with the present invention, the above-mentioned control functions are distributed between the individual lines and the connecting lines to the extent that can be determined by the time and space switching function elements in the telephone exchange, regardless of whether the programmed line and switching control functions are local, located at the telephone exchange further down the line.

The method of distributed control according to the invention can most advantageously be used in conjunction with a substantially non-blocking switching network which switches not only voice and data traffic (revenue traffic) but also switches "overhead" traffic. , accessing the various databases such as inputs to translation devices, human-machine boundary equipment data, billing and traffic collection means, etc. Although a number of digital electronic switching systems may be used in connection with the present invention, a particularly suitable switching system is mw with another aspect of the invention, switching control instructions are connected to the digital switches via the same paths that connect the speech signals to the switches, since the speech path is the only available path via which a remote subscriber apparatus can transmit such control data. Consequently, digitized speech signals and digital control signals are transmitted via multiplex on a common correlation path through the group circuitry to both establish and maintain and terminate communication between calling and called subscribers.

In accordance with a further aspect of the present invention, a half-call method will be described, according to which e.g. one line may be a two-wire coin line while another line may be a business line of a PABX. Each processing function associated with each such line is programmed in such a way that it knows its own service class and its line signaling border equipment and also knows the common central border equipment and knows how to establish communication via the group switch to another half-call machine. A connection is thus made between the two lines without the need to know the complex conditions when it comes to handling all possible combinations of calls. In some cases you have to perform a connection or send signals in the forward direction resp. backwards.

These signals must be connected to the standard limit equipment in such a way that they are understandable to the other half-call units.

The present invention relates to a system and a method for by means of a subscriber controlled distributed microprocessor control of the individual subscriber lines and connecting lines which are served by a telephone exchange or local station in such a way that the voice channels are used for transmission of control data. There is a standard hardware switching equipment for a digital switching matrix for the distributed subscriber control, and it also works in such a way that f '“" * \,, -, _ Q; = Ä' \, -. / »Ï ~» ~ = 1 .-, l _ _ '* »PIA-e ska, so H fa so ~» "_-. lä _ -e / - j _: 'z' f e max, _. rr- vsozzvz-o 7 it separates initialization and end call halves to prevent interactions between them. A plurality of subscriber lines corresponding to the security block level use a common memory together, and they are connected via terminal multiplex lines to the switching matrix for bidirectional transmission of data therebetween, while via the same terminal multiplexer a bidirectional transmission takes place between individual subscriber line control microprocessors. of data from the memories for the Digital Switching Matrix also receives, switches and transmits initiation and end call halves, using simplified software, between the subscribers which are connected by means of the described network.

The present invention thus has for its main object to provide a switching system with distributed control for an expandable local station or telephone exchange, wherein subscriber lines and connecting lines communicate via a standardized hardware boundary equipment through a group switch. Another object of the invention is to provide uniformly manufacturable distributed control circuits for each subscriber line or group of subscriber lines, each distributed control providing control for a number of subscriber lines which is less than the safety block level. A further object of the invention is to provide a digital switching system and a control for this system without duplication of switching and control circuits in the previously known systems with common control, while at the same time monitoring lines other than lines where an error may occur. . A further object of the invention is to provide a distributed device with a built-in module, built up in modules, stable, with solid state components or LSI components and intended for a switching system with many subscribers without the limitations regarding the connection that exist in systems with joint management and stored programs. The invention also intends to provide control by means of one microprocessor per call in a system with many subscribers. Another object of the invention is to provide a distributed control in a system for many subscribers, where one can easily add additional subscriber lines or facilities to the system without this having any adverse effect on the existing system, and the software is distributed only for the service class per line, thereby obtaining both simplified maokinware and simplified software. Another object of the invention is to provide a distributed control of the initiation and, '! §El%?'? 3 "0. _ 8 endpoint halves under subscriber control and separated by switching Hg ië æieeeäfjvar thereby thereby undesirable interaction between these halves is further eliminated: An object of the invention is to provide distributed control for a system with many subscribers, which system allows errors, whereby all communications between subscriber & control circuits and system data databases take place via a common group switch and there is no difference in the group switch between a call from fi line to line and a call to a translator, Earigengm precious, multi-threaded guide assembly leader is eliminated.

The invention is described in detail in the following with reference to the accompanying drawings, in which Fig. 1 shows a simplified block diagram of a switching system with distributed control in accordance with the present invention, Fig. 2 shows a curve which illustrates the economic conditions of the present invention in comparison with prior art systems, Fig. 5 shows the relationship between the commonly used memory according to the present invention and other system elements, Fig. 4 shows a commonly used memory in accordance with the invention, Fig. 5 shows a call control unit and a line termination unit in accordance with the invention, and Fig. 6 shows a translator subsystem used in accordance with the invention.

Fig. 1 shows at 100 the construction of the switching system with distributed control. A group switch matrix 102 of the type described in more detail in the above-mentioned Swedish patent application serves as the center for all system switching. Such a switch is usually substantially non-blocking. The group switching matrix 102, which may alternatively be designed as a concentrator or decondentrator or as some other type of pulse code modulation switch, provides room switching and time slot exchange for interconnecting any time slot on any incoming multiplex line to any other time slot. another outgoing multiplex line. The switch 102 includes a control device for selecting an internal path for controlling traffic, in such a way that blocking does not substantially occur, via the speech path to enable the distributed control on the subscriber lines.

Diagnostic programs that can locate errors down to the level corresponding to an exchange record, ie. a printed circuit board or a module, are decentralized and included in the microprocessor control for the subscriber lines, whereby there is one microprocessor per security block, which security block e.g. can include from 1 to 60 lines. This decentralized diagnostic programming prevents the interaction between a fault mode on one line and traffic on other lines. Since this method of switching diagnoses from a central control device to a single microprocessor does not need to maximize the throughput of the processor, the distributed software can be designed in such a way that an arbitrary level of maintenance and test ability or examination ability is obtained. The multi-stage group switch 102 is illustrated in a simplified manner and shows a first step comprising subgroups 1, 2, 3 ........ N at 104, 106, 108 resp. 110. The above control for selecting an internal path for each of the above switches in the first stage subgroup is illustrated at 112, 114, 116 and 112, respectively. 118. At the 102 Mzte stage of the matrix, switching subgroups 1-N are illustrated at 120 and 122, with their respective path selection guides located at 124 and 126.

The switching matrix 102 forms boundary equipment at a common hardware boundary equipment formed by a multiplex group 148 of the subscriber line circuits 128, to which the individual subscriber lines are connected and switched at the telephone exchange or the local station. To each multiplex subgroup 148, the traffic from individual subscriber lines after analog-to-digital conversion is connected by means of the microprocessor-controlled line circuit 128, and the line circuits 128 provide digital-to-analog conversion for the return traffic back to the two-wire analog lines and connecting lines 152 and 13 of the same. Line circuit 128 includes a microprocessor, for example of the type Intel 8080 or of some other suitable type, said microprocessors serving the subscriber line. The elements of the subscriber line circuit 125 are described in more detail in the above-mentioned Swedish patent application. Individual digital subscriber lines 150, subscriber carrier system lines 136 and digital connection line groups 138 are connected to the telephone exchange's digital terminator 140 which enables buffer processing and call control and which is switched directly as required by the group switch 102. Required databases and translators as debited at 142 information memory 142, and the operating circuits 146 are connected to the group switch. The translators at 42 interpret numbers dialed by subscribers on a finger pad or keypad, said interpretation taking place in the usual way as with conventional translators, but in the present case the translators are also used to help achieve the distributed control function by they operate with the only data communication path formed by the speech paths between the line circuits 128 and the group switch 102, one of these speech paths being illustrated at 204. The construction of the said translators will be described in more detail with reference to Fig. 6. the same switching network provides both a data communication line and a voice path between the subscriber lines. Since the individual line circuits 128 control the connection of paths to the switching network, the previously required central processor functions will be effectively eliminated.

In Fig. 2, the curves (a) - (dj) show the cost per subscriber line achieved by means of the present system in comparison with the case of previously known systems. The present system can be expanded into modules to serve a growing number of subscriber lines, for example from 1000 lines to 100 000 lines, with significant savings compared to previously known systems, the reason for this being the savings that can be achieved by means of manufacturing methods with large volume for the production of a variety of microprocessor controlled line circuits with distributed control instead of large and expensive wiring. or program multiple central line controllers working with program logic as well as the necessary »doubling that has occurred in the past as a safeguard against catastrophic failure.

The number (a) represents one of the generally known electro-mechanical step-by-step switches or selectors which enables direct control by each subscriber over the voice path by means of a line search arrangement which is controlled directly by the subscriber's finger disk. This system can expand with the growth of the telephone exchange within a large range and with a slowly increasing cost per line as a result of the system becoming more inefficient and less flexible as it grows. Kbrvan (b) represents register / translator control for step-by-step switching of a previously known type, in which case a register transmitter and a translator are used to add flexibility in the numbering plan and in facilities. Duplication of the common parts of the register transmitters and the translator function is required, which means that the cost ratio per line becomes high at its lower end.

The knob (c) illustrates previously known control systems with common logic and wiring, such as the coordinate selector of type no. 5. These systems not only have the inconvenience of equipment doubling, as mentioned above, but they can also only output fi. 7 ”wï, 4 ', * \ _, ___ f: I I f'.

FÜIm llriitzerfln at ”.å r Q ti iii,. 'zsozzvz-o: i 11: expands within a comparatively small interval, e.g. 8: 1, which is to be compared with 100: 1 or more according to the present invention.

Furthermore, the system with common control and wiring logic does not enable direct subscriber control regarding the switching in the voice path.

The curve (s) also illustrates the relationship between cost per line and the number of lines in electronic switching systems which are previously known and which are designed with control by means of stored programs. it is thus seen that at a certain maximum number of lines a sharp interruption occurs, since the expansion of the system is limited by the interconnection capacity of the processors.

Curve (d) shows the ratio of the cost per line to the number of lines according to the present system. Because one controls an element, such as a microprocessor, per line or group of lines and because, as will be described below, the present system utilizes a standardized hardware boundary equipment which is built in modules and which is uniformly manufacturable as a group switch instead of communication via software channels as previously done, the present system can be easily expanded at almost constant cost from, for example, 1000 subscribers to 100,000 subscribers. As the switching system expands, throughput will be automatically added. This ratio plus the expansion of the array of group matrices with similar modules removes the upper limit of expansion normally found in the case of telecommunications exchanges with common control and with a common stored program, which in the case of the invention takes place without any loss of flexibility for features. The expansion in modules also makes it possible to add new facilities and services to a module or to modules without extensive re-testing of the existing facilities in the way that now constitutes a limitation in control systems with a jointly stored program.

Referring to Figs. 5, 4 and 5, the call control, the shared memory, and the distributed control will now be described. Call control is performed on the basis that a call end circuit 128 contains a call control unit 502 per end and involves processing at different times for controlling both the initiation and end halves of a call. The call control unit (CCU) comprises a microprocessor H02 with a private memory 516, a boundary equipment 512 for a commonly used program memory, a boundary equipment 518 for an energy supply unit, and a pair of boundary equipment ports 212, 214 for the switching network. 102 used in common with QI i. 'Zeozàvz-o pig' ._ - _ ...-. | other microprocessors and having an address capability of about 256 k-bytes and a digital filtering capability. In general, the call control unit (CCU) 502, which will be described with reference to Fig. 5, provides direct current and low frequency control up to 300 Hz to provide battery supply and ring signal current functions, speech rate processing at 500-5800 Hz and call processing. The speech frequency processing is performed in the speech frequency processor 500 under the control of the microprocessor 102. Each two-wire subscriber line 152 is connected to a high voltage limit equipment and analog-to-digital converter 502, respectively. digital-to-analog converter 504.

The digital output signal from the analog-to-digital converter 502 is digitally filtered by the processor 500 and converted into a bit stream, such as a serialized, 14-bit linear pulse code modulation code supplemented with additional bits for controlling the group switch 102 and for enabling communication. between different call controllers and translators. The digital filtering enables conversion_ from two-wire operation to four-wire operation and compensates for the loss characteristics of the current subscriber line or connection line 152. The microprocessor 402 is programmable, thereby enabling equalization and loss and gain control which is equivalent to dimming. Furthermore, the outputs of the analog-to-digital-lf converter 502 are filtered for frequencies between 500 and 5800 Hz digitally to provide tone detection. The processor 500 also generates digital signals and connects them to the digita1 analog converter 504 for generating tone frequency signals in the range 500-5800 Hz for signaling in the form of busy tones, ring tones, etc. on the subscriber's return line 152.

Fingerboard pulses and equivalent tone signals are received and processed by the microprocessor 402 so that it can be determined when access to common databases and translators is required to obtain additional data. A set of instructions relating to the individual line operation capabilities of the line / connection line is accessed from the shared memory 200 via the memory port 512 and the data / address bus 506.

This access is limited to a single safety block or a bus conductor and thus does not use the switching matrix 102 to obtain the data in question. Thus, a distribution of software control instructions to the individual lines resp. the connection lines so that the different line and connection line blocks can freely contain different combinations of software vseavvz-o 15 instructions, which represent different lines / connection line service classes and bits corresponding to different features or facilities. Thus, it is not necessary to store all software instructions on a distributed basis, which means a saving from a storage point of view. Different combinations of software instruction interactions with each other via standard boundary equipment lines 212 and 21% are also prevented by the group switch 102. Jetta enables facility modification, addition, deletion. Furthermore, only a certain microprocessor can reach the initialization or end half of the software, which is determined by the direction of the connected call.

The channel clock line 506, the data and address conductor 506 and the request / grant lines 308 are connected to the memory port 512 together with a main clock signal on the line 5110 and give rise to the communication between modules described above. The limit equipment ports to the switching network 102 comprise the output switches 520 and 522 and the input switches 524 and 526.

This distributed control, by which call control processing is distributed so that each call can utilize an individual microprocessor for the duration of each call, eliminates the prior requirements of complicated, commonly used algorithms for a single processor. can be used jointly for several calls. Distributed control can be performed by means of a microprocessor per charge, per termination or per safety block.

In accordance with the present invention, one microprocessor is provided per termination, i.e. per line / connection line, which means e.g. one microprocessor per subscriber line. In any case, a microprocessor is assigned to a line for at least the time that a call is being made via that line.

Fig. 3 shows a program arrangement which is used in common for 60 terminations, wherein said arrangement can be regarded as a security block. Each termination circuit 128 which forms boundary equipment for the subscriber lines to the group switch provides, as described above, conversion from two-wire operation to four-wire operation, digitizes incoming analog signals, and performs digital filtering and other digital tone frequency processing and call control.

The assigned microprocessor, which includes a private memory and which performs call control, translation, generation of control signals for route selection, and various diagnostic functions, is connected to a commonly used memory 200 via a memory port in the circuit I28. In Fig. 3, 60 termination circuits 128 use the memory 200 in common. Each line, such as POÛR GUÅLITY ._ ... M ff- 7802272-0 14 line 212, from the termination circuit 128 is multiplexed to a 32-channel-6 group 204, i.e. a common communication path, for transmitting read-bit linear pulse code modulation in series with the sampling rate 8 kHz, two of the mentioned channels being assigned for communication with other system modules in accordance with timing signals from the commonly used memory 200 and the system clock or system clock. the pacemaker.

Each termination processor typically includes 4 k bytes of private memory and has access to the shared memory utilized by a plurality of microprocessors, said shared memory typically having the address capability of 256 k bytes.

Both program memories and memories with fixed data are used in common. However, the personal data memory, which also provides "boot belt type" start-up instructions for each microprocessor, is not used in common to reduce the interaction between microprocessors. In any system with shared memories, there are potential problems due to processor disputes. with respect to memories, access time required to reach certain segments of the shared memory, and complications in hardware and software to overcome the above.

The shared memory 200 may comprise a multiport memory, as shown in Fig. 4, each microprocessor 402 in the call controller 302 being able to access the memory via its own memory port, for example the port 516, with access via the data / address collection conductor 306, which is multiplied to other memory ports at the multiple point 513, and the request / grant line 308, which is individual to the memory port 516. Only 60 lines or less disputes the shared memory, as shown. An arbitration circuit E16 means that only a single microprocessor at a time can reach the commonly used memory 200, thereby eliminating processor dispute problems. A shared memory controller 312 controls the addressing of the shared memory 200 and the transmission of data from this memory to the memory port 304 via the data / address bus 506, which is bidirectional. Parity is generated and checked for both data and addresses at the memory port 512 and by the controller 312. The commonly used memory 200 may comprise RAM semiconductor chips, which are organized into 52-bit words to provide the above-mentioned 250 k-bit grouping capability. A master clock or master clock transmitter in the clock signal distribution circuit 511 generates the different synchronous timing signals required by the arbitration circuit as soon as the memory ports, such as the port 512, the controller 312 and the common memory 202, are commonly used. the termination control means 128 (60 as an example in Fig. 3), and the commonly used memory 200 forms boundary equipment to the group switch via lines 204, 206, 208 and 210.

In a typical switch y, the outlet x forms boundary equipment towards line 2'4 and the outlet x + 1 forms boundary equipment towards line 208. Another typical switch Y + 1 has an outlet X which forms boundary equipment towards line 206 and an outlet x + 1 which forms boundary equipment towards line 210.

As mentioned above, 32 time slots are applied to each of the lines 204-210 by multiplexing. It is seen that each speech termination circuit 128 is connected to two termination multiplex circuits which contain the 30 channels and which have synchronized timing, so that the outputs of the termination circuits and the inputs of the group switch 102 are synchronized to obtain the required parallel to serial conversion and vice versa. to the parallel conversion between the same. The private memory 516 of the microprocessor 402 may be a dewormed, programmed ROM or PROM. The private memory also includes a rewrite memory capability of the order of 4 k-bytes-8 k-byte for remaining software and variable data that may include service class data.

The translator 202 shown in Fig. 6 will now be described. The translator 202 can be advantageously used in a distributed control device, and it operates with the only data communication path between the security block modules and other switching subsystems provided by the voice switch 102. The disadvantages of prior art translators in switching systems with centralized stored programs and meet telephone station requirements and customer data modifications are overcome by means of the present system. The translator 202 includes a memory 550, a control processor 552 which includes a microprocessor 554 with associated program memory 556, and translator access ports to the group switch 102, three of eight of these aco ports being shown at 558, 560 and 562. The translator may is duplicated as needed with regard to increased telephone exchange traffic, reliability and service life. The translator receives service class information of different types, billing data, statistical information, etc., at the same time as it performs the normal translation function, ie. translation of telephone directory number into equipment number (DN / EN) by feeding a table in memory 550, translation of equipment number into m eUALQy, in »X» than, '1802272-0 16 telephone directory number (EN / DN), translation of area code or telephone station code to connection line path, and translation of connection line path to equipment number.

Each speech termination circuit 128 is connected to two termination multiplex lines, as described with reference to Fig. 3, each termination multiplex line comprising 52 channels, and each termination multiplex line being connected to a terminal switch output, which in turn is connected to the inputs of the group switch 126. As an example, 960 termination circuits, identical to circuit 128, are connected to the group switch in a typical telephone station configuration. The 30 terminating circuits connected to a terminating multiplex each have their second interface connected to a second terminating multiplex, so the car terminating multiplexers which jointly use the 30 terminating circuits are connected to the outlet with the same number in two consecutive switches in step 1. The 60 termination circuits that jointly use a program memory are converted into four termination multiplexes, so four groups of four termination multiplexes will be connected to each pair of switches in step 1. Each speech termination circuit 128 therefore includes two equipment numbers, and the DN / EU translator function continuously monitors the condition, ie. the busy / idle state of each initiation call half ooh end call half in the speech end circuit. The Genevaret on request for DN translation contains the equipment number for a free termination and an indication of whether the alternative equipment number is busy, free or booked. If both terminals are busy, the information in question is returned to the microprocessor 552, the microprocessor controlling an initiation call half selecting a network path to the termination equipment number and signaling the required call connection information. The microprocessor that controls the end of the call sends a confirmation signal to the DN / EN translator, or to another translator function, to confirm that the end is now busy and to identify the equipment that initiates the call. The translator memory 550 may comprise a CCD memory or a magnetic bubble memory or other solid state memory which may contain at least 90 k memory words, of which 80 k words are allocated to the translator memory and 10 k words are allocated to the translator memory memory, the word lengths being for example 16,24 or vsozzvz-o 17 52 bits, depending on the data structure. The access ports 558-562 are electrically identical to speech termination circuits of the switching matrix and are identifiable and selectable by means of equipment numbers in a manner similar to the termination circuits. The distribution of the above-mentioned access ports is such that a fault in a switch module does not render more than one port unusable, and a fault in any switch in step 1 does not render more than half of the ports unusable. The equipment numbers assigned to the access ports are selected so that an algorithm in the program memory 556 can derive any other equipment number from any given equipment number. Functionally, each access port includes means for selecting from the pulse code modulated multiple line the contents of the channel defined by the corresponding equipment number, means for identifying control messages between microprocessor and microprocessor in the channel, a buffer register containing one or more such messages, an output buffer, means for inputting such messages in the correct channel in the output termination multiplexes 564, 566 and 568, and means for outputting messages to keep the transmission path free while the translator's microprocessor 554 is generating output data.

Access ports 558, 560 and 562 also include input lines, as indicated. Data is extracted from the translator memory 550 in response to messages received at the inlet ports, and re-entry and modification of data in the memory 550 in the microprocessor is controlled according to the programming in the program memory 556. The processor 554 may be the same microprocessor used in the termination circuits 128, and it is also illustrated at 402 as part of the call controller 502. The translator memory 550 includes the required translation tables. Typically, translation access exceeding four milliseconds has a probability of less than 100: 100, and the average time to complete translation access is usually less than 2 milliseconds. Customer data modification and telephone station data modification are performed by reprogramming the memory 556, whereby one can add customer facilities or increase the number of lines or connecting lines served by a station.

The invention is not limited to the embodiment described above and shown in the drawings, but this is only an example of the invention and its application.

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Claims (18)

A method of achieving distributed control of a digitally switched multiple subscriber system, characterized in that digitized speech signals form boundary signals from at least one subscriber line to a common communication path together with at least digital control signals for each path selection therefor. the subscriber line coupled call, that said subscriber lines are interconnected by a digital switching matrix via the common communication path in response to said path selection control signals, and that said digitized speech signals are multiplexed at each boundary equipment with said digital path selection signal paths so that the common and multiplexing the communication path. 2. A method according to claim 1, characterized in that each call includes an initiation call half and an end call half and that the boundary signaling step includes coupling the initiation call halves to the common communication path and receiving the end call halves from the common communication call path and each termination call path. are controlled individually by the switching matrix. 3. A method according to claim 2, characterized in that the digital control signals for path selection are arranged on the basis of each individual line. Ä. 4. A method according to claim 2, characterized in that said digital control signals for path selection are arranged on the basis of each individual call. Digitally switched multiple subscriber system (100) with distributed control for carrying out the method according to any one of claims 1-4, characterized in that it comprises a plurality of boundary equipment means, each of which forms a boundary equipment for at least one subscriber line to a common multiplex communication path and includes means for generating at least digital control selection path paths for each associated call, further a switching matrix (102) coupled to said common communication path for interconnecting the subscriber lines in response to said path selection control signals, and means at each boundary equipment means for deriving digitized speech signals, said speech signals and the digital control signals for path selection being multiplexed on the common communication path. _ vsezzvz-o 19 System according to claim 5, characterized in that said switching matrix (102) comprises a multi-stage group switch (1-M). 7. A system according to claim 5, characterized in that said boundary equipment means includes a first memory means assigned to a first group of subscriber lines and a second memory means assigned to a second group of subscriber lines. 8. A system according to claim 7, characterized in that said first memory means is assigned to a subscriber line and said second memory means is assigned to a security block of said subscriber lines. A system according to claim 8, characterized in that each boundary equipment means comprises microprocessor means (402) forming the first memory means and said path selection control means as well as means for providing access to said second memory means and said second memory means being a multi-port means. memory with bidirectional access to a number of microprocessor means corresponding to the number of subscriber lines in said security block. 10. A system according to claim 5, characterized in that said means for generating control signals for path selection includes a microprocessor and an associated memory as well as means for providing access to the microprocessor for each individual call. 11. ll. A system according to claim 5, characterized in that said means for generating said control signals for path selection includes a microprocessor and an associated memory for providing said control on the basis of each individual line. 12. A system according to claim 5, characterized in that said digitized speech signals are pulse code modulation coded. 13. A system according to claim 5, characterized in that said digitized speech signals are delta modulation coded. leeward. 14. A system according to claim 5, characterized in that said digitized speech signals are differential delta modulation coded. 15. l5. System according to claim 5, characterized in that said digitized speech signals are connected in series to said common communication path. 7802272-0 20 16. A system according to claim 9, characterized in that it comprises translator means connected to the common communication path for effecting translation between said plurality of boundary equipment means connected thereto and said switching matrix. 17. A system according to claim 10, characterized in that said boundary equipment means includes digital filtering means for generating said digitized speech signals. 18. A system according to claim 6, characterized in that each call includes an initiation call half and an end call half and said boundary equipment means includes means for coupling the initiation call halves to the common communication path and for receiving end call calls from said common callers. independently switches said initiation and end call halves.