JPS61139132A - Control system for time division multiplexer - Google Patents

Abstract

PURPOSE:To restrict influences of the error of one frame between statistical multiplexers (STDM) within one data link related to it to prevent influences of this error upon all data terminal equipments (DTE) by dividing DTEs to plural groups and providing plural logical data links on a line between STDMs in accordance with each group. CONSTITUTION:Data of DTEs belonging to a group A are transferred with a data link (a), and those of DTEs belonging to a group B are transferred with a data link (b), and those of DTEs belonging to a group C are transferred with a data link (c). Since data links (a), (b), and (c) are controlled independently of one another, the control of the other data links is not affected when the retransmission control between STDMs is performed because of the error of one frame on one data link. That is, the error of one frame between STDMs has influences upon only DTEs belonging to the group related to the data link but has not influences upon DTEs belonging to the other groups.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to a time division multiplexer, particularly a so-called statistical multiplexer (STDM).
This invention relates to a control method for a sfon multiplexer.

[Prior art] In STDM, one transmission path is connected to multiple data terminal devices (
DTE), the data from each DTE is divided into short blocks and the blocks are collected into one
It is sent to the other party's STDM through the main transmission path. On the receiving side STDM, the short block is re-edited for each destination DTE and sent to each DTE.

FIG. 4 shows an example of an STDM connection form.

The operation will be briefly explained with reference to FIG.

Data sent from DTEl to DTE1', from DTE2 to DTE2', and from DTEn to DTEn' is first sent to S
Enter T D M (1). STDM (11 is each DT
The data received from E is collected as one frame and transmitted to STDM (21. In that case, DTEl, DTE
2. If you send all continuous data from DTEn after sending it, the delay due to passing through STDM (1) will become large, so every time one to several bytes are received from each DTE, data from all DTEs should be sent together. S T D M (
2) Send to. STDM in Figure 5 (11 and S T D
On the line connecting M (21), frames containing data from each DTE are flowing.

One frame contains data from multiple DTEs, and when received by S TDM f21,
The data is ordered so that it can be seen from which DTE the data was sent. STDM (2) separates the data of each DTE from the received frame and sends it to the corresponding DTE. In this case, if all continuous data addressed to each DTE is accumulated in S TDM (21) until it is received, S
Since the delay caused by passing through the TDM (21) becomes large, the data received from the STDM (11) is sent to the DTE as soon as a certain amount of data is accumulated.

Frames flowing between STDM (1) and STDM (2) are transmitted using a transmission control procedure with an error control function, for example 1 (DLC (High-1 level Data
Link Control Procedures
) forwarded by If the receiving STDM detects an error in the data in the frame, the corresponding frame is retransmitted from the transmitting STDM. As a result, S
Data transmission between TDMs can be error-free from the DTE's perspective.

By performing the above-described control, more data can be transmitted between STDMs than in simple TDM. That is, when a certain DTE is not transmitting data, by transferring data from another DTE, the total line speed between the DTE and the STDM can be made larger than the line speed between the STDM.

[Problem that Qming attempts to solve] When a transmission error occurs between STDMs and retransmission processing is performed between STDMs using the transmission control procedure, the resulting delay causes the receiving STDM side to The arrival of the subsequent part of the data may be delayed and there may be no data to send to the DTE. Since the data that should normally be sent continuously to the I)TE stops midway, the data becomes an error. In order to prevent this error from occurring, a method has been considered in which pad characters are sent to the receiving DTE until subsequent data arrives. However, in transmission control procedures where pad characters are not defined (e.g. HDLC
) is used as a DTE procedure, the data being sent will be in error in the above situation. Since frames between STDMs include data from multiple DTEs, a delay due to retransmission of one frame between STDMs causes data errors for multiple DTEs on the receiving side. If one frame between STDMs contains data addressed to all DTEs, there is a possibility that the data for all DTEs on the receiving side will be stopped midway, resulting in an error. When data addressed to a DTE becomes error, the data is retransmitted through subsequent error control between the DTEs.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a communication system in which a plurality of data terminal devices share a transmission path and perform data transmission, in which each data terminal device and the transmission path are connected to each other. When transmitting data by connecting a time division multiplexer that performs statistical time division multiplexing control between the data terminals, the data terminal equipment is divided into multiple groups, and the communication between the time division multiplexers is controlled according to each group. It is characterized by providing logical data links on the line.

[Function] According to the present invention, the DTE is divided into a plurality of groups, and a plurality of logical data links are provided on the line between the STDMs in correspondence with each group.
1 where a frame data error is related to the frame
It remains within the data link and no longer affects all DTEs.

(Example〕 FIG. 1 shows a system configuration diagram of an embodiment of the present invention.

In FIG. 1, 1 and 2 are time division multiplexers (STDM) that perform statistical time division multiplexing control, 3 is a data terminal equipment (DTE> group) on one side, and 4 is a data terminal equipment (DTE> group) on the other side. DTE) group, 5 to 7 are logical data links a
”-c.

FIG. 1 shows an example of dividing the DTE into three groups.

Group 4Al from DTEl to l! +1 to m is group B'', and m''1 to n is group C. Corresponding DTEI' to n' are similarly divided into groups A,', group B', and group C'. Data transfer between group A and group A' is STDM
Use data link a between. Data transfer between group B and group B' uses data link b.

Data transfer between group C and group C' uses data link C.

Data links a, b, c are realized by HDLC,
The value of the address part in the HDLC frame format is the value for each data link a, b, cg,
For example, 1. 2. 3, they can coexist on the same physical line.

FIG. 2 shows an example of the frame format of each data link. In FIG. 2, F is a flag, A is an address, C is a control, and Fe2 is a frame check sequence. In the illustrated example, data link a is at address
"01", data link b uses address X'02', data link C-ta uses data link a, data of group B DTE uses data link b, data of group C DTE uses data Transferred using link C. Data links a, b, and c are controlled independently, so even if one frame on one data link becomes an error and retransmission control is performed between STDMs, control of other data links will not be affected. . In other words, a single frame error between STDMs only affects the DTEs of the group related to that data link, and only affects the DTEs of other groups.
Does not affect TE.

FIG. 3 is a block diagram of an STDM according to an embodiment of the present invention, in which 10 is a DTE compatible transmission/reception control section, 11 is a data editing division control section, 12 is a data link control section, 1
3 is a trunk line control unit, and 14 is a trunk line.

The DTE-compatible transmission/reception control unit 10 performs transmission/reception control for each DTE. For transmission data, the data editing division control unit 11 collects and edits several bytes of data for each DTE and creates data to be sent to the trunk line, and for reception data, it collects and edits several bytes of data for each DTE and creates data to be sent to the trunk line. Control is performed to divide data into data for each DTE. The data link control unit 12
Controls data transmission and reception between STDMs based on DLC. The trunk line control unit 13 performs control to sequentially arrange the transmission and reception frames of each data tank control unit 12 and send them to the trunk line 14, and control to distribute frames received from the trunk line 14 to each data link control unit 12 by address.

[Effects of the Invention] As described above, according to the present invention, an error in one frame of data between STDMs does not affect all DTEs, and only the DTEs in the group related to the data link where the error occurred This makes it possible to limit the impact to As a result, error retransmission processing due to transmission control procedures between DTEs can be reduced, and an efficient multiplexing system can be achieved.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of one embodiment of the present invention, FIG. 2 is a diagram showing an example of a data link frame format, and FIG. 3 is a diagram showing an example of a data link frame format.
FIG. 4 is a block diagram of an STDM according to an embodiment of the present invention, FIG. 4 is a diagram showing an example of the connection form of the STDM, and FIG. 5 is a diagram illustrating the operation of a conventional example. In Figure 3, 10 is D
TE compatible transmission/reception control unit; 11 is a data editing division control unit;
12 is a data link control unit, 13 is a trunk line control unit, 14
is a relay line. (Te"Cree-7(L) (Te"-7S>7C)

Claims (1)

[Claims] In a communication system in which multiple data terminal devices share a transmission path for data transmission, a time division multiplexing device that performs statistical time division multiplexing control is connected between each data terminal device and the transmission path to perform data transmission. A control method for a time division multiplexer, characterized in that data terminal equipment is divided into a plurality of groups, and a logical data link is provided on a line between the time division multiplexers corresponding to each group. .