JPH08172410A - Time division multiplex communication system and equipment for the system - Google Patents

Abstract

PURPOSE: To multiplex asynchronous data to DTM slots by turning prescribed unit time to one frame, timewisely dividing it to plural slots and using a specified optional slot as the one for stuff. CONSTITUTION: Input A-the input N respectively composed of clocks and data are inputted to synchronizing devices 1a, 1b,..., in. A memory 11 is provided with a capacity capable of recording more than one slot and the inputted data are written by write control by a stuff control circuit 13. Also, they are read by read control generated at the timing of multiplex clock signals received from a multiplex circuit 3 and inputted to the multiplex circuit 3. The stuff control circuit 13 counts the phase difference of the inputted clocks and multiplex clocks, sends out stuff display signals to the multiplex circuit 3 when a position difference for one slot is generated and informs that the stuffing of a TDM slot unit is to be performed. Thus, by using one slot for stuff by the communication link of 1-N in common, the TDM slot is effectively used with less hardwares.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division multiplex communication system for transmitting data encoded at a variable rate and an apparatus therefor.

[0002]

2. Description of the Related Art In recent years, with the development of digital transmission technology, for example, in the field of broadcasting, many attempts have been made to digitize an image and transmit it to each home. Further CATV
(Cable Television) has attempted to provide an interactive service called video-on-demand (hereinafter abbreviated as VOD) that enables subscribers to watch their favorite programs when they want to use that technology. There is.

On the other hand, in the field of communication such as telephones, the transmission line is replaced with an optical fiber or the like to secure a high rate transmission capacity,
Attempts have been made to transmit moving images to each home via their respective networks.

In such a situation where the boundary between the fields of broadcasting and communication is disappearing, time division multiplexing (TDM; Time) is used in order to efficiently use a large capacity transmission line.
It is conceivable to multiplex and transmit data by using a division multiplex. For example, IS
DN network (Integrated Services Di)
The time division multiplexing system used in the primary group interface of the digital network (digital network) has a transmission capacity of 64 kbps per slot and 2
It is possible to multiplex 3 (24: no D channel) B channels. By using a plurality of these slots at the same time, the maximum transmission capacity is 1.5 Mbps. On the contrary, data encoded at a speed of 64 kbps or less is multiplexed after adding surplus bits and speed-matching to 64 kbps.

That is, data of various speeds can be efficiently transmitted by using a large-capacity transmission line by time division. Further, since each terminal extracts a clock from the network and uses that clock as a reference, the demultiplexing operation is performed synchronously.

However, since the encoding of a moving image is generally performed using a clock different from the clock of the network, the data becomes asynchronous to the network. Therefore, as one of the methods for synchronizing with the slot for multiplexing data, a method of packetizing and multiplexing the data in an appropriate unit is adopted. FIG. 12 shows an example of packetizing and multiplexing the data.

Data to be transmitted in one frame time t of TDM is first added with a header indicating a data ID (order, amount of data, etc.), and surplus bits (trailer) to fill the gap of slots to be multiplexed. Is added.
The packetized data is divided into slots and multiplexed. On the receiving side, the data extracted from each slot is reconstructed based on the header information, and the original data is reproduced by removing the extra trailer.

Synchronous multiplexing can be performed by packetizing and multiplexing the data in this way, but the procedure is increased by one step to perform this processing, and there is also a problem that the device configurations on both the transmitting and receiving sides become slightly complicated. .

Further, encoding of image data includes fixed bit rate encoding for outputting at a certain constant bit rate and variable rate encoding for instantaneously varying the bit rate. In particular, the latter variable rate coding enables effective use of the transmission line due to the statistical multiplexing effect when a plurality of data of a certain level or more are multiplexed and transmitted. In general, communication by the time division multiplexing method is often used fixedly after the use slot is determined. Therefore, if the data is coded by the variable rate coding method, if a slot with a maximum instantaneous rate or more is fixedly provided, the statistical multiplexing effect cannot be obtained and conversely the transmission line is wastefully used. turn into.

FIG. 13 shows an example in which a TDM frame is encoded at a variable rate. Here, 99 slots are assigned to a certain terminal A and are displayed in time series from frame 1. The variable rate encoded data is
The generated information amount constantly fluctuates, and for example, the generated information amount increases in a scene with a lot of movement and the generated information amount decreases in a still image. In FIG. 13, the shaded area shows the actual generated data, and in a certain frame, for example, frames 1 and 4, all the allocated slots with a large amount of generated information are used, but frames 2 and 3 with a small amount of generated information are used. In such a case, many unused slots are generated in the assigned slots. Therefore, this leads to useless use of the TDM frame.

In the first place, data coded by variable rate coding produces a statistical multiplexing effect by multiplexing a plurality of data. When such data is multiplexed in a fixed slot, the effect can be obtained. There is a problem that the advantage of variable rate coding cannot be utilized.

[0012]

As described above, conventionally, a stepwise speed matching means is used when synchronously multiplexing moving image data or the like encoded with a clock different from the network clock with the network clock. The problem is that it is necessary and that the transmission line is excessively used without obtaining the statistical multiplexing effect when multiplexing the image data encoded at the variable rate. ing.

The present invention has been made in view of the above-mentioned problems, and makes it possible to multiplex asynchronous data into a TDM slot with a simple structure, and further, to vary the variable rate coding without significantly impairing the statistical multiplexing effect. An object of the present invention is to provide a time division multiplex communication system and a device therefor capable of transmitting data encoded at a rate.

[0014]

To achieve the above object, the first invention of the present application is such that a predetermined unit time is one frame,
A time division multiplex communication system in which the frame is temporally divided into a plurality of slots and information is transmitted in units of the slots, and data asynchronous with a communication path in the time division multiplex communication system is multiplexed into the slots. In doing so, the gist is to use any specified slot as a staff slot.

The second invention of the present application is that the stuffing slot according to claim 1 is below the communication link in the communication path, and a plurality of communication links are commonly used for stuffing. And

The third invention of the present application is summarized in that the frame according to claim 1 or 2 is provided with an area for indicating the presence or absence of a slot for a staff.

Desirably, (dependent claim) is good.

Further, the gist of the fourth invention of the present application is that the stuffing described in claim 1 is performed in units of frames.

The fifth aspect of the present invention is characterized in that the staff slot described in claim 2 switches the communication link used for each frame.

A sixth aspect of the present invention is characterized in that, when switching the communication links according to the fifth aspect, when a staff request is simultaneously generated in a plurality of communication links, ordering is performed in frame units.

[0021] The seventh invention of the present application is that the stuffing according to any one of claims 1 to 6 is CA.
The main point is to carry out in a downlink communication path in which a multi-point connection is made from a TV center to each terminal.

The eighth invention of the present application is a data multiplexing apparatus, wherein a predetermined unit time is set as one frame, the frame is temporally divided into a plurality of slots, and information is transmitted in units of the slots. When a data signal, a clock signal, and a multiplexed clock signal are input, multiplexing means for multiplexing data indicating the presence or absence of stuff, a storage device for temporarily storing the data signal, and a multiplexing for the clock signal Of the stuffed clock signal and the stuffing occurrence is notified to the multiplexing means when the phase difference reaches a unit slot, and the stuffing is performed in slot units by controlling reading and writing in the storage means. The point is to have and.

In the ninth invention of the present application, a predetermined unit time is defined as one frame, the frame is temporally divided into a plurality of slots, and data is transmitted in time division multiplex communication in which information is transmitted in units of the slots. A demultiplexing device for data extraction means for extracting data indicating presence / absence of stuff from slots of time-division multiplexed signals to be input, and staff for data corresponding to data indicating presence / absence of stuff extracted by the data extraction means. And a control means for controlling the extraction of the slots of the above.

It is desirable that the data demultiplexing device in time division multiplex communication in which a predetermined unit time is one frame, the frame is temporally divided into a plurality of slots, and information is transmitted in units of the slots. Stuffing of the information data is performed from the data indicating the presence / absence of stuff from the slot of the input time division multiplexed signal and the data extracting means for extracting the stuffing slot and the data indicating the presence / absence of the stuff extracted by the data extracting means. It is preferable to have a control means for performing the destuffing by controlling the data extraction circuit to enable / disable the extraction of the slot for the stuff while it is being performed.

The tenth invention of the present application is a data multiplexing apparatus which divides a predetermined unit time into one frame, divides the frame temporally into a plurality of slots, and transmits information in units of the slots. Then, the gist is to arbitrarily change the number of slots to be multiplexed in units of frames according to the information amount of the data coded by the variable rate coding.

The eleventh invention of the present application is the above-mentioned claim 1.
The gist is to collectively multiplex the information assigned to the slots described as 0 at a specific position of the frame, or to multiplex for each slot.

The twelfth invention of the present application is the above-mentioned claim 1.
The gist is that the transmission described in 0 or 11 is performed in a communication path connecting terminals by circuit switching.

A thirteenth invention of the present application is a data multiplexing apparatus, wherein a predetermined unit time is set as one frame, the frame is temporally divided into a plurality of slots, and information is transmitted in units of the slots. And multiplexing means for multiplexing data, storage means for temporarily storing input data coded at a variable rate, measuring means for measuring the information amount of data input in one frame, and this measuring Determining the number of slots allocated according to the amount of information measured by the means,
The gist of the present invention is to have control means for multiplexing data and slot allocation information by the multiplexing means in the determined slot at a specific position in one frame.

Further, in the fourteenth aspect of the present invention, a predetermined unit time is set as one frame, the frame is temporally divided into a plurality of slots, and data is transmitted in time division multiplex communication in which information is transmitted in units of the slots. A separation device,
Data extraction means for extracting allocation information and data of each slot from slots of the input time division multiplexed signal, and a slot to be extracted corresponding to the allocation information extracted by the data extraction means are determined, and the data extraction is performed. The gist is to have a control means for controlling the means.

[0030]

[Function] Stuffed pulse
By performing stuffing in units of one time-divided slot by using a multiplex technology, it is possible to synchronously multiplex asynchronous data with a communication network such as moving image data with a relatively simple configuration. Also, by varying the number of time slots to be used depending on the amount of data to be multiplexed, it is possible to expect a statistical multiplexing effect for data encoded at a variable rate.

The time division multiplex communication system of the first invention of the present application is
When data asynchronous with the communication path in the time division multiplex communication system is multiplexed into the slot, asynchronous data is synchronously multiplexed by using any specified slot as a staff slot.

In the data multiplexer of the eighth invention of the present application, when the data signal, the clock signal and the multiplexed clock signal are input by the multiplexer, the data indicating the presence or absence of the stuff is multiplexed while the data is stored in the storage device. The data signal is temporarily stored. The clock signal and the multiplexed clock signal are compared with each other, and when the phase difference reaches the unit slot, the generation of stuff is notified to the multiplexing means, and the reading and writing in the storage means are controlled to control the slot. Stuffing is performed in units, and asynchronous multiplexing of asynchronous data is performed.

The data separating apparatus of the ninth invention of the present application extracts the data indicating the presence or absence of the stuff from the slot of the time division multiplexed signal input by the data extracting means, and corresponds to the extracted data indicating the presence or absence of the stuff. Then, the extraction of the staff slot is controlled to separate the synchronously multiplexed asynchronous data.

In the time division multiplex communication system of the tenth invention of the present application, a variable rate is obtained by arbitrarily changing the number of slots to be multiplexed in units of frames according to the information amount of data coded by variable rate coding. A statistical multiplex effect is also obtained for data coded in.

The data multiplexing apparatus of the thirteenth invention of the present application is:
The allocation number of the slot is determined according to the amount of information measured by the measuring means, and the multiplexing means multiplexes the determined slot with data and slot allocation information at a specific position in one frame.

The data demultiplexing device of the fourteenth invention of the present application extracts allocation information and data of each slot from the slots of the time division multiplexed signal input by the data extraction means, and extracts corresponding to the extracted allocation information. Decide which slot to do.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a transmission side apparatus for transmitting data coded by a clock asynchronous with a communication path in a time-division time slot by a time division multiplex communication system according to the present invention. It is the block diagram which showed the structure.
The transmitting side device of the first embodiment is composed of a plurality of synchronization devices 1.
, 1n are connected to the multiplexing circuit 3 and configured. At this time, the input A including data and clock is input to the synchronization device 1a, the input B is input to the synchronization device 1b, and the input N is input to the synchronization device 1n. The synchronization device 1 also includes a memory 11 to which the data is input and a stuff control circuit 13 to which the clock is input. Further, the stuff control circuit 13 is connected to the phase comparator 15 to which the clock and the multiplex clock from the multiplex circuit 3 are input, and is connected to the phase comparator 15 to input the input clock and the multiplex clock. The counter 17 counts the phase difference and sends a stuff display signal to the multiplexing circuit 3 when the phase difference for one time slot occurs.

The memory 11 is controlled by the stuff control circuit 13, and input data is written by write control. Data is read by a read control signal generated at the timing of a clock multiplexed by the stuff control circuit 13 and input to the multiplexer 3. As shown in FIG. 2, the stuff control circuit 13 counts the phase difference between the clock input in step S11 and the multiplexed clock, and the step S13
When a phase difference of one time slot occurs, the stuff display signal is sent to the multiplexing circuit 3 in step S15 to indicate that stuffing is performed in TDM slot units.

The staff display and the stuffing operation will be described with reference to FIG. FIG. 3A is an example of a TDM frame, and in this example, it is assigned to input A from slot 1 to slot 99. And
Among them, the slot 99 is set as a stuff slot for the input A, and an area indicating the presence or absence of stuff is secured in the frame.

On the transmitting side, when the multiplexing circuit 3 receives the staff indication, the staffed information is multiplexed on the area indicating the presence or absence of the staff, and on the receiving side, how to handle the staff slot information based on this information is determined. to decide. FIG.
(B) and (c) show the case where the negative stuffing operation is performed. When the stuffing operation is not performed, the information bit is multiplexed in the slot 99, but when the stuffing occurs, the information bit is stored in the slot 99. Is not multiplexed, and the receiving side operates not to use the information in this slot. FIG.
(D) and (e) show the case where the positive stuffing operation is performed. Normally, the information is not multiplexed in the slot 99, but the operation is performed in which the information is multiplexed in the slot 99 only when the stuffing occurs.

That is, the memory 11 has a capacity capable of recording at least one slot or more, and the read control signal generated from the stuff control circuit 13 is stopped in the slot 99 when negative stuffing is performed,
Control is performed so that information is not multiplexed in the slot 99,
When positive stuffing is performed, a control signal is issued so that the information stored in the memory for one slot is multiplexed in the slot 99 by one slot more than in the normal operation.

By performing the stuffing in units of TDM slots in this way, the receiving side of this TDM frame only has to determine whether or not to extract one slot, and the asynchronous signal is multiplexed into the TDM slot. There is little increase in the amount of hardware. Further, when transmitting an image compressed by MPEG or the like, the receiving side decoding circuit has a large buffer memory at the input stage, so that the stuffing jitter is absorbed here. Therefore, the receiving side does not need any new memory or the like for absorbing the jitter.

Next, a second embodiment according to the present invention will be described by taking CATV as an example. In the case of this CATV, as shown in FIG. 4, the wiring form is such that a plurality of terminals 7a, 7b, 7c, ... Has a tree structure in which each is connected by an upstream transmission line. Here, it is assumed that image data and the like are digitally transmitted on the assumption that VOD or the like is performed on such a CATV broadcasting downlink transmission line. An example in which data is transmitted by stuffing in units of slots by the time division multiplexing method as in the first embodiment in such a communication path will be described.

In this case, since the CATV headend 5 and each of the terminals 7a, 7b, ..., 7n are multipoint connected, a plurality of communication links may be set in one TDM frame. Therefore, as shown in FIG. 5, the stuffing slot can be shared by terminals using the TDM frame. That is, since it is not necessary to allocate a staff slot to each terminal, efficient operation of time division slots becomes possible. The figure shows a state in which 99 slots are allocated to terminals 1 and 2, respectively, and used, and the final slot of one frame is set as a shared stuff slot. This slot is A
When stuffing occurs in the data multiplexing on the side, information on the A side is multiplexed, and when stuffing occurs in the data multiplexing on the B side, information on the B side is multiplexed. Which data link uses this shared staff slot is multiplexed in the staff ID area. While monitoring the ID area, the terminal side determines whether or not the data of its own link is stuffed, and controls the separation of the data from the shared slot.

FIG. 6 shows an example of the configuration of the data multiplexer of the second embodiment, which is different from the sequence control circuit 9 shown in FIG.
Has been added. Those denoted by the same reference numerals as those in FIG. 1 perform the same function, and the description thereof is omitted here. The difference from the first embodiment is that the stuff display signal from each stuff control circuit 13 is once input to the sequence control circuit 9 and then output to the multiplexing circuit 3 as a stuff request. The sequence control circuit 9 is a circuit for monitoring the collision of the stuff display signals. If a collision occurs, the stuff control circuit 13 receives a busy display signal to wait for the stuffing operation until the next frame. It is a notification. When the stuff control circuit 13 receives the busy display signal, the frame is not stuffed but is controlled to be performed in the next frame.

As described above, one T
By using the DM slot as a staff slot, one staff slot can be commonly used by each communication link in a communication path connected by multipoint connection such as CATV.
The slots can be effectively used, and additional circuits can be realized with a relatively simple structure.

T in the first and second embodiments
FIG. 7 shows a block configuration of the side that receives the DM frame. Since data modulation / demodulation, error correction, etc. are not covered here, only the case of extracting information multiplexed in the TDM frame demodulated in the baseband will be described. Referring to FIG. 7, the data extraction circuit 21 includes an extraction control circuit 23.
Are connected, the stuff information is output from the data extraction circuit 21 to the extraction control circuit 23, and the destuff control signal and the extraction control signal are output from the extraction control circuit 23 to the data extraction circuit 21.
Is output to

That is, the stuff information is first extracted from the TDM frame input to the data extraction circuit 21 and sent to the extraction control circuit 23. The extraction control circuit 23 normally indicates the TDM slot to be extracted by an extraction control signal, analyzes the received stuff information, and determines whether or not the data of its own link is stuffed. Data extraction circuit 2 with control signal
Notify 1. In the data extraction circuit 21, when the destuffing is instructed by the destuffing control signal, the stuffing slot data is extracted as information data when the positive stuffing is performed, and the data extraction of the stuffing slot is stopped in the case of the negative stuffing. Is controlled as follows. As described above, according to the present invention, the circuit configuration on the receiving side is also realized with a relatively simple configuration.

In the first and second embodiments, one frame of TDM is set for 2 ms and one slot has 128 bits. That is, the transmission capacity of one slot is 64 kbps, which is the transmission capacity capable of sending one B channel of ISDN. As for the definition of the transmission capacity of one slot, it is better to define one slot with a smaller transmission capacity for the purpose of transmitting data of multiple rates and use a plurality of slots to support large-capacity data transmission. Will be used more efficiently.

In this embodiment, one slot is set to 64 kbps, so that the slot configuration takes into consideration services from ISDN to video media services such as VOD. In other words, if 99 slots are used, a transmission capacity of about 6 Mbps can be secured. For example, MP @ ML of MPEG2 is 4
This means that it is possible to transmit image data compressed from M to about 5 Mbps with a capacity of data in consideration of an increase due to error correction or the like.

Next, a third embodiment of the present invention will be described. This embodiment converts variable rate encoded data to T
FIG. 8 shows an example of the TDM slot allocation state, which is multiplexed in the DM frame. In order to eliminate the waste of the transmission path due to the fixed allocation of slots, which has been a problem in the past, the allocated slots are made variable according to the amount of encoded data. Here again, the use of a CATV in a downlink transmission line configured by multipoint connection as shown in FIG. 4 will be described as an example. On the transmission side, the amount of data to be sent to each terminal is measured in one frame time, the number of slots to be assigned is varied according to this amount of data to multiplex the data, and the assignment information is provided in the slot assignment display area provided in the frame. To multiplex.

FIG. 8 shows an example in which the slot allocation is variable for each frame. Focusing on the terminal A allocation, FIG.
It can be seen that the slots are allocated by the amount of information as compared with. The receiving side of the multiplexed and transmitted frame determines the slot to be extracted by itself based on the information of the slot allocation indication, and extracts only the necessary slot.

As a method of displaying the slot allocation, as shown in FIG. 9, a structure may be considered in which an allocation display area is provided for each slot. With such a configuration, the slot assignment display gives each terminal number or the like as a label, and each terminal extracts a slot addressed to itself based on the label.

FIG. 10 shows a configuration example of the multiplexing circuit on the transmission side. The transmission side apparatus of this embodiment includes a plurality of synchronization devices 31.
, 31n are connected to the multiplexing circuit 33 and configured. At this time, the input A including the data and the clock is input to the synchronization device 31a, the same input B is input to the synchronization device 31b, and the same input N is input to the synchronization device 31n. The synchronization device 31 also includes a memory 311 to which the data is input and a memory control circuit 313 to which the clock is input.

The operation will be described below. First, the data encoded at the variable rate is written in the memory 311 in the information amount monitoring circuit 31a. The memory 311 has a capacity allocated by the TDM frame with respect to the input bit rate, and the memory control circuit 313 performs write control based on the input clock and read control based on the multiplexed clock and write clock. And the input data amount is calculated. Memory control circuit 31
From 3 onwards, the memory 31 is stored in one frame time of the TDM frame.
The information amount written in 1 is notified to the multiplexing circuit 33 by an information amount display signal. The multiplexing circuit 33 determines the number of slots to be used from the information amount of each signal notified by the information amount display signal, multiplexes the allocation information into the slot allocation display area of the TDM frame, and multiplexes each input signal into the determined slot. .

In the slot allocation information, when a slot is constructed as in the example of FIG. 8, information for all inputs is collectively multiplexed at the beginning of a frame, but when the slot is constructed as shown in FIG. 9, a terminal number is assigned for each slot. It is controlled to multiplex.

FIG. 11 shows an example of the structure of the receiving side demultiplexing circuit for extracting the data multiplexed in the TDM frame. Referring to FIG. 11, a slot allocation status monitoring circuit 43 is connected to the data extraction circuit 41, and the slot allocation status monitoring circuit 43 outputs slot allocation information from the data extraction circuit 41 to the slot allocation status monitoring circuit 4.
From 3, the extraction control signal is output to the data extraction circuit 41.

That is, the TDM frame is input to the data extraction circuit 41, and the slot allocation information is first extracted,
The result is sent to the slot allocation status monitoring circuit 43. In the example shown in FIG. 8, the slot allocation status monitoring circuit 43 extracts and analyzes the allocation information for its own terminal, and notifies the data extraction circuit 41 of the slot to be extracted by activating the extraction control signal. Further, in the example shown in FIG. 9, the slot allocation status monitoring circuit 43 serves as a comparator, and when the number shown in the slot allocation area matches the number of its own terminal, the data extraction circuit 41 activates the extraction control signal of the slot to be extracted. And notify you. The data extraction circuit 41 extracts the corresponding slot when the extraction control signal becomes active.

As described above, when the data coded at the variable rate is multiplexed into the TDM slot, the number of slots to be multiplexed is varied according to the amount of generated information, so that the TDM frame is effectively used.

[0060]

As described above, according to the present invention, it is possible to multiplex asynchronous data into a TDM slot with a relatively simple structure, and a variable rate code is used when transmitting data encoded at a variable rate. It is possible to transmit the statistical multiplexing effect of the coding without much loss.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a transmission-side apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure in the first embodiment shown in FIG.

FIG. 3 is a diagram showing a slot configuration in the first embodiment.

FIG. 4 is a block diagram showing a concept of a CATV wiring form.

FIG. 5 is a diagram showing a slot configuration in the second exemplary embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a data multiplexing apparatus of a second embodiment.

FIG. 7 is a block diagram showing a configuration of a main part of a receiving side apparatus corresponding to the first and second embodiments.

FIG. 8 is a diagram showing changes in slot allocation according to the third embodiment of the present invention.

FIG. 9 is a diagram showing another slot configuration example according to the third embodiment.

FIG. 10 is a block diagram showing a configuration of a main part of a transmission side apparatus of a third embodiment.

FIG. 11 is a block diagram showing a configuration of a main part of a reception side apparatus corresponding to the third example.

FIG. 12 is a diagram showing a conventional slot configuration.

FIG. 13 is a diagram showing an example of multiplexing data encoded at a conventional variable rate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Synchronizing device, 3 ... Multiplexing circuit, 5 ... CATV headend, 7 ... Terminal, 9 ... Sequence control circuit, 11 ... Memory,
13 ... Staff control circuit, 15 ... Phase comparator,
17 ... Counter, 21 ... Data extraction circuit, 23 ... Extraction control circuit, 31 ... Information amount monitoring circuit, 33 ... Multiplexing circuit, 41
... Data extraction circuit, 43 ... Slot allocation state monitoring circuit.

Claims (14)

[Claims] 1. A time division multiplex communication system in which a predetermined unit time is defined as one frame, the frame is temporally divided into a plurality of slots, and information is transmitted in units of the slots. A time division multiplex communication system characterized in that an arbitrary specified slot is used as a staff slot when data asynchronous with a communication channel in the communication system is multiplexed into the slot. 2. The time division multiplex communication system according to claim 1, wherein the slot for the staff is below the communication link in the communication path, and a plurality of communication links are commonly used for stuffing. . 3. The frame is provided with a region indicating the presence or absence of a staff slot.
Alternatively, the time division multiplex communication method described in 2. 4. The time division multiplex communication system according to claim 1, wherein the stuffing is performed in units of frames. 5. The time division multiplex communication system according to claim 2, wherein the staff slot switches a communication link to be used for each frame. 6. The time division multiplex communication system according to claim 5, wherein when the communication links are switched, when staff requests are simultaneously issued in a plurality of communication links, ordering is performed in frame units. 7. The time division multiplex communication system according to claim 1, wherein the stuffing is performed in a downlink communication path which is multi-point connected to each terminal from a CATV center. . 8. A data multiplexer that divides a frame into a plurality of slots temporally with a predetermined unit time being one frame, and transmits information in units of the slots, the data signal and the clock signal. And a multiplexing unit that multiplexes data indicating the presence or absence of stuff when a multiplexed clock signal is input, a storage device that temporarily stores the data signal, and a comparison between the clock signal and the multiplexed clock signal. When the phase difference reaches the unit slot, the stuffing is notified to the multiplexing means, and the stuffing is performed in slot units by controlling the reading and writing in the storage means. Data multiplexing device. 9. A data demultiplexing device in time division multiplex communication, wherein a predetermined unit time is defined as one frame, the frame is temporally divided into a plurality of slots, and information is transmitted in units of the slots. Data extraction means for extracting data indicating the presence or absence of stuff from the slot of the time-division multiplexed signal, and controlling the extraction of the slot for stuff corresponding to the data indicating the presence or absence of the stuff extracted by this data extraction means A data separation device comprising: a control unit. 10. A data multiplexer for dividing a frame into a plurality of slots temporally with a predetermined unit time being one frame, and transmitting information in units of the slots, which is variable rate coding. A time division multiplex communication system characterized in that the number of slots to be multiplexed is arbitrarily changed in units of frames according to the information amount of encoded data. 11. The time division multiplex communication system according to claim 10, wherein the information to be assigned to the slots is collectively multiplexed at a specific position of a frame, or multiplexed for each slot. 12. The transmission according to claim 10, wherein the transmission is performed on a communication path connecting terminals by circuit switching.
Alternatively, the time division multiplex communication system described in 11. 13. A data multiplexer that divides a frame into a plurality of slots temporally with a predetermined unit time being one frame, and transmits information in units of the slot, wherein the data is multiplexed. Conversion means, storage means for temporarily storing input data encoded at a variable rate, measuring means for measuring the information amount of data input in one frame, and information amount measured by this measuring means And a control means for deciding the number of allocated slots according to the above, and for multiplexing the decided slot with data and slot allocation information at a specific position in one frame. apparatus. 14. A data demultiplexing device in time division multiplex communication, wherein a predetermined unit time is defined as one frame, the frame is temporally divided into a plurality of slots, and information is transmitted in units of the slots. Data extracting means for extracting allocation information and data of each slot from the slot of the time division multiplexed signal, and a slot to be extracted corresponding to the allocation information extracted by the data extracting means, and the data extracting means And a control means for controlling the data separation device.