JPS6170838A - time division multiplexer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a time division multiplexing device for data transmission.

For economical use of transmission paths, a well-known method is to configure transmission data from a plurality of terminal devices into one multiplexed frame using a time division multiplexing method, and to transmit the data through one relatively high-speed transmission path.

One such multiplexing method is so-called statistical time division, which improves the effective transmission capacity by constructing a multiplexed frame with only valid data, rather than assigning fixed time positions within a frame to multiple terminal devices. There is a multiplexing method.

In statistical time division multiplexing equipment, transmission error control is applied independently to multiplexed frames, and by retransmitting frames in which a transmission error has occurred, the transmission error in that section does not affect the terminal equipment. is often done.

Such a function is generally an appropriate service for terminal devices that use a relatively simple transmission control method, but for other terminal devices, the transmission delay effectively added by retransmission may become a problem. .

[Conventional technology]

FIG. 2 is a diagram showing an example of the configuration of a statistical time division multiplexing communication system.

Data transmitted from the terminal devices 1-1 and L2 to 1-n is time-division multiplexed by a statistical time-division multiplexing device (hereinafter referred to as a multiplexing device) 2, and the configured multiplexed frame is transmitted over the transmission path. 3, the signal is transmitted to the opposing multiplexing device 4.

The multiplexing device 4 distributes the data of the received multiplexed frame to each of the terminal devices 1-1.1-2 to l-n, and transmits the data to the terminal devices 5-1.5-2 to 5-n, respectively.

FIG. 3 is a block diagram showing the detailed configuration of the multiplexers 2 and 4.

The terminal devices 1-1.1-2 to 1-n are connected to receiving circuits 1O-1 to 10-n of the multiplexer 2, respectively.

The multiplexing control unit 11 scans the receiving circuit 1O-1=lO-n, extracts valid data, and configures the data portion of the multiplexed frame.

The multiplexed frame has, for example, the configuration shown in FIG.
-n valid data and the data length indication hide are concatenated in the order of terminal device number, and only a data length indication byte indicating data length 0 is placed at a time position corresponding to a terminal device without valid data.

The transmission control unit 12 adds a header 31 for transmission control before the data portion 30, adds a check bit string 33 after it, and sends it to the transmission path 3 via the common control unit 13. The value of the next frame number 16 in the storage section 14 is set in a part of the frame number section of the header 31, and the next frame number 16 is incremented by one.

Further, the transmission control unit 12 stores the data portion 30 in the storage unit 14.
is stored in the area 17 along with the frame number set above, and is stored until a response confirming receipt of the frame is received.

In the multiplexer 4, the common control section 20 receives the multiplexed frame and passes it to the reception control section 21.

The reception control unit 21 checks the received frame for transmission errors, etc. using a known method, and if the multiplexed frame is received normally, the header 31 and check bit string 33 are removed and the frame is passed to the distribution control unit 22. If a transmission error is detected,
Erase received frames.

The distribution control unit 22 connects the data of the data portion 30 of the received frame to the respective terminal devices 5-1, 5-2 to 5-n according to the data length display byte corresponding to each terminal device. ~23-n buffers.

Each transmitting circuit 23-1 to 23-n transmits the data in the buffer,
It is sent to the terminal devices 5-1, 5-2 to 5-n at appropriate timing.

The reception control unit 21 notifies the transmission control unit 24 of the result of inspecting the received frame. If received normally, the transmission control unit 24 returns a notification of the last received frame number to the transmitting multiplexer 2 using a known method.

If there is an abnormality in the received frame, the transmission control unit 24
sends back to the multiplexer 2 a retransmission request specifying the frame number to be received.

When the reception control section 15 of the multiplexing device 2 receives the received information and detects the above response from the multiplexing device 4, it notifies the transmission control section 12 of the response.

When the transmission control unit 12 is notified of the frame number of normal reception, the transmission control unit 12 transmits the data portion 30 of the transmission information held in the storage unit 14.
Among them, those up to the notified frame number are deleted.

When the frame number of the retransmission request is received, the next frame number 16 is set as the frame number of the request, and among the data held in the area 17, data corresponding to the next frame number 16 is retransmitted.

If another transmission error occurs in the retransmitted frame, retransmission is repeated in the same manner as described above.

[Problem that the invention seeks to solve]

If correct data is received through the retransmission process as described above, the terminal devices 5-1, 5-2 to 5-n can avoid receiving data that has encountered a transmission error, and in this sense, the transmission quality can be improved. Can be done.

However, terminal equipment generally has some kind of transmission error control function of its own, and as a function for this purpose, it uses a method of monitoring communication interruption time and detecting interruptions longer than a predetermined time as transmission abnormalities. There is something.

In a terminal device that uses such a method, there is a possibility that a communication interruption caused by detecting a transmission error between multiplexers 2 and 4 and discarding a received frame as described above will be detected as an abnormality. , the terminal device that is determined to be abnormal in this way will transmit and receive control information between the opposing terminal devices, regardless of the transmission error control of the multiplexer 2.4.
Perform error recovery procedures such as data retransmission.

As a result, data due to retransmission between multiplexers 2 and 4,
There is a problem in that the retransmission data based on the control between the terminal devices is transmitted redundantly, and the receiving terminal device again becomes in a state where it is judged as a transmission error.

[Means for solving problems]

The problem described above is that the transmission data of multiple terminal devices is configured into a multiplexed frame by the transmitting side time division multiplexing device and transmitted through one transmission path, and the receiving side time division multiplexing device at the other end of the transmission path configures the transmission data into multiplexed frames. , the multiplexed frame is distributed and transmitted to different lines of the multiple terminal devices, and if a transmission error occurs in the multiplexed frame, the receiving side time division multiplexer discards the multiplexed frame, and the transmitting side In a communication system that retransmits the multiplexed frame, the time division multiplexer provides a retransmission indication for the multiplexed frame, and the transmitting side time division multiplexer specifies the retransmission indication of the multiplexed frame to be retransmitted. If the retransmission indication of the received multiplexed frame is a predetermined value, the receiving side time division multiplexer
This problem is solved by the time division multiplexing device of the present invention, which discards the transmission data of a specific terminal device among the plurality of terminal devices among the data of the multiplexed frame.

[Effect]

That is, a retransmission frame is marked with an indication that it is a retransmission, and the multiplexing device on the receiving side can identify the terminal device that performs the above-described time monitoring as a specific terminal device.

In this way, when the multiplexing device on the receiving side detects that the received frame is a retransmission, it discards the data of the specific terminal device.

Therefore, regarding the above-mentioned specific terminal device, retransmission is substantially only based on control between the terminal devices, and data duplication does not occur.

Note that, as is clear from the previous explanation, if the delay time until receiving the retransmitted data is shorter than the determination time of the terminal device's communication interruption monitoring, it is better to pass the retransmitted data to the terminal device ( However, even in that case, if retransmission is repeated several times and the delay time increases, it is necessary to discard the data in the same way as above.

If there is such a time relationship, the number of retransmissions will be indicated on the display of the retransmission frame, and if retransmissions exceed a certain number of times, the data of the specific terminal device will be discarded, but if the number of retransmissions is less than that, the number of retransmissions will be discarded. The data that can be received by retransmission is also passed to the specific terminal device.

〔Example〕

FIG. 1 (al is a diagram showing the configuration of an embodiment of the present invention.

3, and the same parts as in FIG. 3 are designated by the same reference numerals.

Normal transmission and reception are performed in the same manner as in the conventional example. However, the multiplexed frame has header 3 as shown in Figure 1(b).
After 1, there is a retransmission indicator 32, and in frames that are not retransmitted, the retransmission indicator 32 is always 0.

When the multiplexer 2 on the transmitting side receives a retransmission request as in the past, the transmission control unit 12 sets the frame number of the request in the next frame number 16 and starts retransmission as in the past; The previous value of frame number 16 is stored in new frame number 18, and the retransmission flag 19 is set to 1.

In the transmission multiplex frame configuration process, the transmission control unit 12 determines that if the retransmission flag 19 is not O, the new frame number 1 is
It is checked whether 8 and the next frame number 16 match, and if they do not match, data having a frame number matching the next frame number 16 is read from the area 17, and a frame is constructed using this data.

At this time, set l in the frame retransmission display section 32,
Indicates that this is a retransmitted frame.

When the new frame number 18 and the next frame number 16 match, retransmission has finished, so set the retransmission flag to O.
Start normal sending processing.

Even when a retransmission request for a retransmission frame is further received in a state where retransmission has been started as described above, retransmission is performed from the requested frame number using the same control as above. however,
In this case, if the retransmission flag 19 is checked and it is detected that it is not already O, the process of moving the previous value of the next frame number 16 to the new frame number 18 is not performed, and the new frame number 18
holds the value set when the first retransmission request was received.

The distribution control unit 22 of the multiplexing device 4 on the receiving side holds a specification table 25 for specific terminal devices. For example, the specification table 25 is 1 each
The bits are made to correspond to terminal devices, and "l" indicates a specific terminal device.

In the data distribution process of the received frame, the distribution control unit 22 refers to the specification table 25 for each data distribution to each terminal device, and if the specification is 1, if the retransmission display unit 32 of the received frame is 1, then , discard the data of the terminal device. Furthermore, the data in the buffers of the corresponding transmitting circuits 23-1 to 23-n are also erased.

As a second embodiment, the transmission control unit 12 sets the retransmission flag 1
If a retransmission request is received while 9 is not O, the value of the retransmission flag 19 is incremented by 1. In addition, the value of the retransmission flag 19 is set in the retransmission display section 32 of the transmission frame, and the frame is transmitted.

In the same distribution process as described above, the distribution control unit 22 of the multiplexer 4 determines whether the value in the retransmission indicator 32 of the received frame is smaller than a certain value (for example, 2) even if the bit in the specification table 25 is 1. In this case, the received data is transmitted to the corresponding terminal device, and the received data is discarded in the same manner as described above only when the value exceeds a certain value.

With this method, even if a specific terminal device is able to receive correct data in one retransmission, error control will not be activated in the terminal device.

However, if the communication interruption monitoring time of the terminal device is 0, at least 1
This method can be applied only when the retransmission time is sufficiently longer than the previous retransmission time.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, transmission errors and control are improved in a communication system in which a terminal device that monitors communication interruption time is connected to a statistical time division multiplexing device. It has a significant industrial effect of improving transmission efficiency.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the configuration of an embodiment of the present invention, Figure 2 is a configuration diagram of a communication system, Figure 3 is a configuration diagram of a conventional multiplexing device, and Figure 4 is a diagram of a conventional multiplexing device. FIG. 3 is a configuration diagram of a frame. In the figure, 1-1 to 1-n, 5-1 to 5-n are terminal devices, 2.4
is a multiplexing device, 10-1 to 10-n are receiving circuits, 11
12.24 is a multiplexing control unit; 12.24 is a transmission control unit; 13.
20 is a common control unit, 14 is a storage unit, 15.21 is a reception control unit, 16 is a next frame number, 17 is an area,
18 is the new frame number, 19 is the retransmission flag
22 is a distribution control section, 23-1 to 23-0 are transmitting circuits, 30 is a data section, 31 is a header, and 32 is a retransmission display section. Figure 1 (f2) 5-n Figure j (b) Figure 4

Claims (3)

[Claims] (1) Transmission data from multiple terminal devices is configured into a multiplexed frame by a transmitting side time division multiplexer and transmitted through one transmission path, and the receiving side time division multiplexer at the other end of the transmission path multiplexes the data. If a transmission error occurs in the multiplexed frame when the multiplexed frame is distributed and transmitted to different lines of the multiple terminal devices, the receiving side time division multiplexer discards the multiplexed frame, and the transmitting side time division multiplexer discards the multiplexed frame. In a communication system that retransmits the multiplexed frame, the transmission side time division multiplexer sets the retransmission indication of the multiplexed frame to a specific value. When the retransmission indication of the received multiplexed frame is a predetermined value, the receiving side time division multiplexing device transmits the data to a specific terminal device among the plurality of terminal devices among the data of the multiplexed frame. A time division multiplexing device configured to discard transmitted data. (2) The specific value set in the retransmission indication of the multiplexed frame to be retransmitted is a value indicating that the frame is a retransmission frame, and the predetermined value of the retransmission indication of the received multiplexed frame is the value set in the retransmission indication of the multiplexed frame to be retransmitted. The time division multiplexing device according to claim 1, wherein the time division multiplexing device is a value. (3) The specific value set in the retransmission indication of the multiplexed frame to be retransmitted is a value indicating the number of retransmissions of the frame,
The time division multiplexing apparatus according to claim 1, wherein the predetermined value of the retransmission indication of the received multiplexed frame is all values larger than a certain set value.