JPS585557B2 - Subscriber line switched communication path system - Google Patents

Description

[Detailed description of the invention] The present invention relates to a subscriber line switched communication path system.

In recent years, there has been a trend toward the realization of communication networks that target so-called multi-traffic such as various data services and image services in addition to telephone services.

Even now, simple data services using so-called touch-tone telephones or data services within the voice band via acoustic couplers are being put into practical use, and new services other than telephone calls will continue to increase in the future, and the degree of telephone use will continue to increase. It is fully expected that the subscriber call volume will increase from the current level.

Therefore, future communication network traffic is expected to have characteristics such as an increase in subscriber call rates, longer connection hold times, and an increase in local intra-area calls, and will require lower block rates and A communication network with high reliability and high serviceability is required.

In view of the above circumstances, an object of the present invention is to divide the incoming call volume into steady call volume and fluctuating call volume, and to provide a common relay transmission line and a common relay transmission line corresponding to each. An object of the present invention is to provide a subscriber line switching communication path system in a subscriber line switching system with a low block rate and high reliability, which can save a large amount of traffic, can flexibly deal with overtraffic, and has a low block rate.

A feature of the present invention for achieving the above object is that, in a subscriber line switched communication path system that exchanges and connects telephone signals and/or various data signals, a plurality of line concentrators installed in each predetermined area and a main exchange An individual relay transmission line is arranged between each concentrator and the main exchange, and a common relay transmission line is arranged between the plurality of line concentrators and the main exchange, and the line concentrator transmits the transmitted signal. A first memory that temporarily stores the transmitted signal and sends it to the individual relay transmission path, a second memory that temporarily stores the transmitted signal and sends it to the common relay transmission path, and a third memory that receives and temporarily stores the received signal from the individual relay transmission path. , a fourth memory for receiving and temporarily storing received signals from the common relay transmission path, and a slave exchange control device for controlling operations of the first memory, the second memory, the third memory, and the fourth memory. If the call volume in each of the line concentrators exceeds the transmission capacity of the individual relay transmission path, the call connection in each of the line concentrators is performed using the second memory and the fourth memory to connect the fluctuating call volume. Hereinafter, the method of the present invention, which consists in connecting to the master exchange and processing via a common relay transmission path, will be explained in detail with reference to the drawings.

FIG. 1 shows an example of the configuration of a subscriber line switching system according to the method of the present invention. 3d.

The slave exchanges 3a to 3d are assigned to one unit for each divided area formed by appropriately dividing the area covered by the master exchange 2, and the slave exchanges thus assigned serve as terminals of subscribers within the assigned area. (for example, a telephone).

In the illustrated embodiment, the area covered by the master exchange 2 is divided into four, and each slave exchange 3a to 3d is assigned to a terminal device 4a, . . . , 4ny5a, .
, 6at..., 6n, and 7a,..., 7n.

Between the slave exchanges 3a to 3d and the master exchange 2, there are individual relay transmission lines 8 to 11 that individually connect each slave exchange and the master exchange, and at least two slave exchanges and the master exchange that connect each other. Common relay transmission lines 12 to 14 are provided to enable connection.

Each slave exchange receives a connected call from a subscriber within its own area, and if the called party is a subscriber within the slave exchange's own area, the call connection is returned within the slave exchange. If the called party is a subscriber outside the slave exchange's own area, it has a line concentration function that outputs the line from each output 15 to 18 of the slave exchange. There is.

The concentration ratio of these slave exchanges is selected to be, for example, about 100:24, and therefore, in this case, if 25 or more call connections are requested to one slave exchange, call loss will occur.

In order to prevent this, for the steady traffic volume (24 in the current example), which is the average traffic volume given as a standard in conventional switchboard design, individual relay transmission lines are installed corresponding to each slave switch. The variable call volume is the overload that exceeds the steady call volume, the unbalanced load between each node, or the equivalent overload due to hardware failure. are connected to the parent exchange via a common relay transmission path.

A switching operation for sending call connections corresponding to a steady call volume to an individual relay transmission path and sending call connections corresponding to a fluctuating call volume to a common relay transmission path in one slave switch is provided for each slave switch. This can be realized by switching the switches 24 to 35 provided at the outputs 15 to 18 of the respective slave exchanges using the slave exchange controllers (SC) 19 to 22.

Therefore, according to such a configuration, for example, the slave exchange 3a
When a connection call occurs from a subscriber terminal within the assigned area of , if the called station is within the local area of slave exchange 3a,
Due to the switching function of the slave exchange 3a, the calling station and the called station in this case are connected within their own area only via the slave exchange 3a.

When the called station is outside the local area, this connection call is preferentially connected to the individual relay transmission line 8, and when the call volume increases and exceeds the steady traffic volume, the transmission line 8 is loaded to its full capacity. The variable traffic volume is connected to the common relay transmission line 12 or 14.

Therefore, even if the call rate of the subscribers in the slave exchange 3a increases for some reason, call losses are less likely to occur.

Since this increase in call rate is thought to occur randomly between each assigned area, looking at the subscriber line switching system 1 as a whole, it is possible to achieve an extremely low block rate compared to the conventional system, and to improve reliability. is significantly improved.

In the figure, reference numeral 23 indicates a master exchange control device (MC) for receiving or transmitting dial information, hook information, etc. between the subscriber side and the master exchange side, and controlling the master exchange 2. ).

In the configuration described above, call connections can only be made within the local area without using the parent exchange, but between subscribers belonging to two different slave exchanges that can be connected via the common relay transmission path 12 and 13. Connections (intra-group connections) and connections between subscribers accommodated in different common relay transmission paths (inter-group connections) are configured so that they can be performed by slave exchanges without going through the master exchange 2, and connections between subscribers accommodated in different common relay transmission paths are performed by slave exchanges without going through the master exchange 2. It may be configured such that only incoming connections and outgoing connections (outgoing connections) with subscribers in the area are performed via the main exchange 2.

Figures 2 and 3 show exchange functions that allow connection within the local area,
A more concrete example of a slave exchange equipped with a function of sending call connections for a steady call volume to a separate relay transmission path and sending call connections for a fluctuating call volume to a common relay transmission path regarding connections with people will be shown in more detail. has been done.

FIG. 2 shows a circuit on the transmitting side of the slave exchange 3a.

This slave exchange 3a is configured as a digital exchange, and transmission signals from subscriber terminals 4a and 4b are transmitted through transformers 36 and 37, respectively, to an analog digital converter (hereinafter abbreviated as A/D converter) 38. , 39, is converted into a digital signal, and is applied to one input of an AND circuit 40, 41.

The outputs of address decoders (ADD DEC) 42 and 43 are connected to the other inputs of the AND circuits 40 and 41, and these address decoders are connected to the slave exchange control device 1.
The address signal S1 from 9 is decoded, and only when the address code given in advance to these address decoders matches the contents of the sent address signal S1,
The respective gates are opened and the digital signal from any one A/D converter is sent to the bus line 44.

That is, the signals from the terminals 4a and 4b are time-division multiplexed and sent to the bus line 44.

Among the signals sent to the bus line 44, signals in which the called party is a subscriber within the slave exchange 3a are returned on the bus line 44, as will be explained in detail later with reference to FIG. connection is established within the local area.

Regarding a call connection that requires a connection other than a connection within its own area, the called party is identified by the slave exchange control device 19, and then written in the first memory 45.
The contents of 5 are read at a predetermined timing by a first read address controller (RAC) 46, outputted to the individual relay transmission line 8 in the form of a time division multiplexed signal, and inputted to the main exchange 2 (see FIG. 1). will be processed.

If the traffic volume of a call connection for which connection other than local connection is requested exceeds the transmission capacity (steady traffic volume) of the individual relay transmission line 8, the second memory 41 and the second read address controller (RAC) 48, the variable call volume is sent to the parent exchange via the common relay transmission line 12 using the same time division multiplexing method.

In this case, other slave exchanges are connected to the common relay transmission path 12, and call connection signals corresponding to the fluctuating call volume in the other slave exchanges are being transmitted, so the second read address controller 48 is idle. 2nd memory 4 to the time slot
7 is controlled by the slave exchange control device 19 and the master exchange control device 23.

Although one slave exchange has been described above, other slave exchanges are also configured to perform similar operations.

FIG. 3 shows a circuit on the receiving side of the slave exchange 3a, in which signals from the individual relay transmission line 8 and the common relay transmission line 12 are sent to a first write address controller (WAC) 49, respectively.
, a third memory 50, and a second write address controller (WA
C) 51 and the fourth memory 52.

The time-division multiplexed signal input via the individual relay transmission line 8 is first sequentially written to a predetermined address in the third memory 50 by the first write address controller 49, and the contents in the third memory 50 are A read signal S2 from the slave exchange control device 19 is sent to the bus line 44 common to the transmitting side.

The bus line 44 has an AND circuit 53 which is a gate circuit.
, a digital-to-analog converter (hereinafter abbreviated as a D/A converter) 54, and a transformer 55 to the terminal device 4a.

The other terminal device 4b is similarly connected to the bus line 44 via an AND circuit 56, a D/A converter 57, and a transformer 58.

In order to input the signal sent to the bus line 44 to a predetermined terminal device, an address decoder is connected from the slave exchange control device 19 to the other input of the AND circuits 53 and 56 in synchronization with the read signal S2. 59 and 60, an address signal S3 having address contents corresponding to this predetermined terminal device is sent, the AND circuit corresponding to this predetermined terminal device is opened, and the signal sent to the bus line 44 is changed to the desired state. It is configured to be input to a terminal device.

In the same manner, necessary signals can be input only to desired terminals for time division multiplexed signals input via the common relay transmission line 12.

Furthermore, regarding the signal sent to the bus line 44 to be connected within its own area, the slave exchange control device 19 similarly causes an AND circuit corresponding to the terminal on the called side to connect the signal to the bus line 44. The address signal S3 is opened in synchronization with the sending of the address signal S3 and is sent out so that it is input only to the required terminal device.

As can be seen from the above explanation, the bus line 44 contains a mixture of signals looped back within the slave exchanger 3a, signals from the common relay transmission line 8, and signals from the common relay transmission line 12. Appropriate control links are established for the child exchange phase controller 19 and the parent exchange controller 23 so that these signals do not exist on the bus line 44 at the same time.

In the above embodiment, an example is shown in which two subscribers are connected to the slave exchange 3a, but the number of subscribers is not limited to two, and it is possible to connect as many subscribers as necessary. Of course.

Further, other slave exchanges can also have a similar configuration.

According to such a configuration, in each slave exchange, call connections for a steady traffic volume are sent to the master exchange via an individual relay transmission path, and call connections for a variable traffic volume are sent to the master exchange through a common relay transmission path common to several slave exchanges. Since the call volume is sent to the master exchange via Averaging can be achieved, and since the fluctuating traffic volume is transmitted through the common relay transmission path, the common relay transmission path can be kept to the minimum necessary.
It is possible to construct an economical communication path that can suppress an increase in equipment cost compared to an increase in the capacity of the subscriber line switched communication path as a whole.

Furthermore, even if a failure occurs in any of the relay transmission lines, it is possible to avoid an immediate disconnection, making it possible to construct an extremely reliable line as a public circuit.

According to the present invention, as described above, the common relay transmission path can be significantly saved compared to the conventional method, and a communication network with a low block rate, high reliability, and high serviceability can be created without a large increase in equipment costs. It can produce remarkable effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of a communication path according to the present invention, and FIG. FIG. 3 is a circuit diagram showing details of the slave switch in FIG. 1. 1... Subscriber line exchange system, 2... Parent exchange A3a to 3d... Child exchange, 4a to 4n.
, 5a to 5n, 6a to 6n, 7a to In...
・Terminal device, 8 to 11 ・・Individual relay transmission line,
12 to 14... Common relay transmission line, 19 to 2
2... Control device for child exchange, 23...
Control device for main exchange.

Claims (1)

[Scope of Claims] 1. In a subscriber line switched communication line system that exchanges and connects telephone signals and/or various data signals, etc., it consists of a plurality of line concentrators installed in each predetermined area and a master exchange, and each line concentrator An individual relay transmission line is arranged between the equipment and the main exchange, and a common relay transmission line is arranged between the plurality of line concentrators and the main exchange, and the line concentrator temporarily accumulates the transmitted signal and transmits the signal to the individual relay. A first memory that sends out to the transmission path, a second memory that temporarily stores the transmitted signal and sends it out to the common relay transmission path, a third memory that receives and temporarily stores the received signal from the individual relay transmission path, and the common relay transmission path. a fourth memory for receiving and temporarily storing received signals from the first memory, the second memory,
A control device for a slave switch that controls the operation of the third memory and the fourth memory is provided, and the control device controls the call connection in each of the concentrators so that the call volume in each concentrator exceeds the transmission capacity of the individual relay transmission path. If the second memory and the fourth memory are used, the variable call volume is connected to the main exchange via the common relay transmission path and processed. . 2. The subscriber line switching channel system according to claim 1, wherein at least one of the line concentrators has a switching function for call connections between subscribers within its own area.