JPH02184133A - Time division multiplex exchange - Google Patents

Abstract

PURPOSE:To accommodate many terminal equipments without increasing number of time slots in one transmission frame by allocating an idle time slot in the transmission frame to a terminal interface causing a data transmission request with an exchange section every time a data transmission request arrives from the terminal interface. CONSTITUTION:An exchange section 10 allocates an idle time slot in a transmission frame to terminal interfaces 51-5n causing a data transmission request every time the data transmission request arrives from the terminal interfaces 51-5n, the terminal interfaces 51-5n allocates a transmission data to the time slot allocated itself from the exchange section 10 and transmits the result. As a result, the time slot is allocated to the terminal interfaces 51-5n only at the data transmission. Thus, it is possible to accommodate lots of terminal equipments B1-Bn without being limited to the time slot number of one transmission frame and the extension request of the terminal equipments B1-Bn is sufficiently replied.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a time division multiplex exchange device used in a PCM multiplex transmission system that transmits audio signals and image signals by PCM multiplexing, for example. .

(Prior Art) Conventionally, the following devices are known as this type of device. FIG. 3 shows its configuration. This device includes an exchange section 1 connected to a high-speed line A, a control section 2 that controls the exchange operation of this exchange section 1, and terminal devices 81 to Bm, respectively.
are connected to terminal interfaces 31 to 3m via low-speed lines 01 to Cm, and these terminal interfaces 31
3 m and a PCM highway 4 connecting the above-mentioned exchange section 1.

Of these, the switching unit 1 connects the PCM highway 4 with each of the terminal interfaces 31 to 3 as shown in FIG.
It transmits and receives transmission frames obtained by time-division multiplexing time slots T1 to Tm corresponding to the number of m, and receives data addressed to the terminal devices 81 to Bm that arrive via high-speed line A.
Corresponding time slots T1 to T in the above transmission frame
The data is enlarged to m and sent to the terminal interfaces 31 to 3m.

On the other hand, the terminal interfaces 31 to 3m selectively take out the received data inserted in their own time slots T1 to Tm in the transmission frame and transmit the received data to the terminal devices 81 to 3m.
At the same time, the transmission data sent from the terminal devices 81 to Bm is temporarily stored and inserted into its own time slots T1 to Tm in the transmission frame.
Transmit to. However, in a system using such a switching device, it is possible to arbitrarily transmit data using PCM between each terminal device 81 to Bm and the terminal device of another station connected via the high-speed line A. Can be done.

However, such a conventional time division multiplexing device fixedly allocates time slots T1 to Tm of a transmission frame to each terminal interface 31 to 3m in advance, and transmits and receives data from each terminal device 81 to Bm to the corresponding terminal interfaces 31 to 3m. The data is transmitted by inserting it into time slots T1 to Tm. Therefore, time slots T1 to Tm
must be provided according to the number of terminal devices 81 to Bm. However, in general, the frame length of a transmission frame is fixed to a constant value, such as 125 μs in the case of voice transmission, and the time length of one time slot also depends on the switching speed of the exchange section 1, mixing, and automatic gain side g9 (
This is determined by the speed of various processes such as AGC) and is difficult to shorten. For this reason, it is difficult to significantly increase the number of time slots T1 to Tm that can be multiplexed in one transmission frame, and therefore it has not been possible to sufficiently meet requests for increasing the number of terminal devices 81 to Bm.

(Problems to be Solved by the Invention) As described above, in the conventional device, the time slots of the transmission frames transmitted between the switching section and the plurality of terminal interfaces are fixedly assigned to the terminal devices in advance. The number of installed terminal devices is determined by the number of time slots that can be multiplexed in one transmission frame, and as a result, there is a problem in that it is not possible to sufficiently meet the demand for increasing the number of terminal devices, and the present invention focuses on this point. An object of the present invention is to provide a time division multiplexing device which can accommodate a large number of terminal devices without increasing the number of time slots in one transmission frame, and can thereby sufficiently meet the demand for increasing the number of terminal devices.

[Structure of the Invention] (Means for Solving the Problems) The present invention connects an exchange unit and a plurality of terminal interfaces to which terminals are connected via low-speed lines through a data highway, and In a time-division multiplexing device that transmits a transmission frame with a fixed frame length on a data highway and inserts the transmission/reception data of each terminal interface into a time slot in the transmission frame, a data transmission request is received from the terminal interface. Each time a message arrives, the exchange section allocates an empty time slot in the transmission frame to the terminal interface that has issued the data transmission request, and each terminal interface transmits the transmission data into the time slot assigned to it by the exchange section. It is designed to be inserted and transmitted.

(Function) As a result, time slots are assigned to terminal interfaces only during data transmission, so it is possible to accommodate more terminal devices without being limited to the number of time slots in one transmission frame. Therefore, it is possible to fully meet the demand for increasing the number of terminal devices. Furthermore, in the device of the present invention, if the number of terminal devices exceeding the number of time slots enters the data transmission state all at once, some terminal devices may not be able to transmit data, but normally, the number of terminal devices exceeding the number of time slots transmit data at the same time Therefore, each terminal device can perform time-division multiplex transmission of data at any time without any practical problems.

(Embodiment) FIG. 1 shows the configuration of a time division multiplexing device in an embodiment of the present invention. In addition, in the same figure, the third
The same parts as in the figures are given the same reference numerals.

A PCM
In addition to the highway 4, a timing signal line 6 is also installed. Each of the terminal interfaces 51 to 5n includes a data transmission request sending means 5a and a data transmission means 5b as means for transmitting data with the exchange section 10. Among these, the data transmission request sending means 5a first sends a data transmission request to the exchange unit 10 via the timing signal line 6 when the terminal devices 81 to Bn are in a data transmission state. Further, the data transmission means 5b is
Transmission data sent from the terminal devices iB1 to Bn is inserted into a time slot designated by the exchange section 10, which will be described later, in response to the data transmission request, and is sent to the exchange section 10.

- The blade changing section 10 is a time slot allocation control means 1
It is equipped with 0a. This allocation control means 10a communicates with each terminal interface 51 via the timing signal line 6.
When a data transmission request arrives from ~5n, an empty time slot Ti is searched among all the time slots T1 to Tm that can be multiplexed in the transmission frame, and the specified signal of this time slot Ti is used to issue the data transmission request. This notification is sent to the terminal interfaces 51 to 5n via the timing signal line 6.

Next, the operation of the apparatus configured as above will be explained.

Suppose that several terminal devices are now in a data transmission state, and correspondingly, for example, as shown in FIG. 2(a), time slots Tl, T3 . T4. It is assumed that Tm is in use.

In this state, for example, if the terminal device Bl is now in a new data transmission state, the terminal interface 51 corresponding to this terminal device B1 sends a data transmission request to the exchange section 10 via the timing signal line 6. . Then, the exchange unit 10 selects an arbitrary time slot from among the currently vacant time slots. For example, in FIG. 2(a), the above TI, T3. T4゜T
Since time slot m is in use, for example, time slot T2 is selected from among the time slots other than these time slots. Then, the designation signal for the vacant time slot T2 is notified via the timing signal line 6 to the terminal interface 51 that issued the data transmission request. Then, the terminal interface 51 grants transmission permission to the terminal device B1 and causes the terminal device B1 to start transmitting data. As a result, from the terminal device B1 to the low-speed line C1
The transmission data sent via the transmission frame is stored once, and then read out in fixed amounts at a time, inserted into the time slot T2 assigned to itself in the transmission frame, and transmitted. The usage status of time slots in the transmission frame at this time is as shown in FIG. 2(b). Then, when the data transmission of the terminal device B1 is completed, the terminal interface 51 notifies the switching section 10 of this via the timing signal line 6, and as a result, the switching section 10 determines whether the terminal device B1 is currently using the terminal device B1. time slot T2
to open.

Thereafter, similarly, each time a terminal device on standby enters a data transmission state, a data transmission request is sent from the corresponding terminal interface to the exchange section 10, and the exchange section 1 that received this request
0, an empty time slot is selected and notified to the terminal interface 5k, and the terminal device can use this time slot to transmit data.

In this embodiment, each time the terminal devices 81 to Bn enter the data transmission state, the exchange unit 10
Since empty time slots are allocated, the limited time slots T1 to Tm can be efficiently used by a larger number of terminal devices BI to Bn. Therefore, it is possible to accommodate a large number of terminal devices 81 to Bn without increasing the multiplicity of time slots, and thereby without increasing the processing speed of switching speed, mixing, automatic gain control (AGC), etc. ,
Although the configuration is simple and inexpensive, it can sufficiently meet the demand for increasing the number of terminal devices.

It should be noted that the present invention is not limited to the above-described embodiments, and includes, for example, the configuration of the data transmission request sending means and the time slot allocation control means, the method of searching for an empty channel, the number of time slots in one transmission frame, and the installation of the terminal device. Regarding the number, etc., various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, each time a data transmission request arrives from a terminal interface, the switching unit allocates an empty time slot in the transmission frame to the terminal interface that has generated the data transmission request. Assignment, each terminal interface inserts transmission data into the time slot assigned to itself by the exchange section and transmits it, thereby accommodating a large number of terminal devices without increasing the number of time slots in one transmission frame. As a result, it is possible to provide a time division multiplexing device that can sufficiently meet requests for increasing the number of terminal devices.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a time division multiplexing device according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of how transmission frames are used by the same device, and FIG. 3 is a conventional time division multiplexing device. FIG. 4 is a block diagram showing the structure of a transmission frame used in the device. A...High speed line, 81~Bn...Terminal device, C1~
Cn...Low speed line, 10... Switching unit, 20... Control unit, 4... PCM highway, 51-5n... Terminal interface, 6... Timing signal line. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 1 Figure 3

Claims (1)

[Claims] The exchange unit and a plurality of terminal interfaces each connected to a terminal via a low-speed line are connected via a data highway, and a transmission frame having a fixed frame length is transmitted on this data highway. In a time division multiplexing device that inserts and transmits data sent and received from a terminal interface into a time slot in this transmission frame,
The switching section allocates an empty time slot in the transmission frame to the terminal interface when a data transmission request is generated from the terminal interface, and the plurality of terminal interfaces insert the transmission data into the self-assigned time slots. A time division multiplexing device characterized by transmitting data.