JPH01270442A - Communication control system for lan - Google Patents

Abstract

PURPOSE:To use the same time slot to perform communication among three or more positions by subtracting the signal in a buffer, where the audio signal from a local node DTE is held, from a reception signal and transmitting the result to the DTE. CONSTITUTION:Nodes 2, 3 and 4 to which DTEs 5, 6 and 7 are connected and a monitor station 1 are connected by a loop transmission line 10. The monitor station 1 assigns a specific time slot Tn to communication among nodes 2, 3 and 4. When audio data from DTEs 5, 6 and 7 are denoted as A, B and C and input data to the node 2 is denoted as A+B+C, data A from the DTE 5 of one circulation before which is held in a buffer 23 is subtracted from the input signal at a terminal 21 and the input to the DTE 5 is B+C. New data A' from the DTE 5 is added at a terminal 22, and data A'+B+C is put on the time slot Tn and is transmitted.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figure 4) Means for solving the problems to be solved by the invention (Figure 1) Working examples (Figure 2) , Fig. 3) Effects of the invention [Summary] This invention relates to a communication control system in a LAN, and aims to provide a communication control system that enables simultaneous audio communication between three or more DTEs, and a monitoring station and multiple DTEs. In a LAN comprising a node and a DTE connected to the node and connected by a transmission path, the node has a buffer that holds an audio signal from the DTE connected to the node, and a buffer that holds the received signal of the node and the audio signal in the buffer. A subtraction means for subtracting the signal from the subtraction means and an addition means for adding the output of the subtraction means and the audio signal from the DTE connected to the node are provided, and simultaneous audio communication between multiple DTEs is possible using the same time slot. Configure it so that.

[Industrial application field]

The present invention is directed to a LAN (Local Area Network).
Regarding the communication control method between multiple locations in (ork),
In particular, the present invention relates to a communication control method that enables simultaneous audio communication between three or more DTEs in a LAN having a loop-shaped transmission path using transmission paths such as optical fibers. In LAN, from the viewpoint of effective use of lines, there is a strong desire to use the same line to transmit and receive not only data but also voice.

In particular, with regard to audio, there is a demand for not only one-to-one communication but also simultaneous communication connecting DTPs at multiple locations, and support for this is desired.

[Conventional technology]

As a conventional LAN system that enables communication between DTEs, for example, the LAN system shown in FIG.
There are two examples.

Figure 4 (A) shows P-P (Paint-to-Pa
int) communication. The parallel data generated at the A station is converted into serial data by the parallel-to-serial converter P/S in the node 41, and then sent to the loop 40 as n-th time slot Tn data DTn. This is received at the node 42, converted into serial data by the serial-parallel converter S/P, and transmitted to the B station. Data from station B is similarly transmitted from node 42 to node 41.

FM in the figure represents a frame header.

FIG. 4(B) shows what is called multi-drop communication. The data SD sent from station A, which is the master station, is sent to the LAN loop as data DTn in the n-th time slot. This is the received data RD for all slave stations A.
, ll-. Communication between two stations,
In order to distinguish between communication between the master station and all slave stations, for example, in communication between two stations, an address should be placed at the beginning of each time slot, and if there is no address in the time slot, should be received by all the slave stations.Also, the sending data S from slave stations B and C to the master station A
D can selectively operate the switches Ss and Sc using the signal RS, and send data to the n+1st time slot Tn+1 as data DTn+l. In this case, one time slot is allocated to each slave station. Assigned.

FIG. 4(C) is what is called a simultaneous broadcast. In this case, the master station A sends the transmission data SD to the slave stations B and C all at once, and the slave stations cannot send data.

[Problem to be solved by the invention]

In all of the above conventional technologies, the minimum necessary time width (
multiple locations (3 or more locations) using time slots)
D T P (Data Terminal Equ
ipsen t) connection could not be established.

That is, in P-P communication, only one time slot is required, but communication is performed between two DTEs, and communication between multiple locations is not possible. In addition, multi-drop communication allows communication at multiple locations, but
The problem is that each slave station requires a separate time slot for data transmission, and communication cannot be performed using the minimum number of time slots. - Communication by simultaneous broadcasting has the problem that only one-way communication is possible from the master station, and data cannot be transmitted from the slave station side.

The above points are true regardless of the type of data.

The present invention has been made in view of the above points, and in particular, it is an object of the present invention to provide a communication control method that makes use of the characteristics of voice data to enable simultaneous voice communication between a plurality of DTEs. do.

[Means to solve the problem] FIG. 1 shows a principle diagram of a communication control system according to the present invention.

In FIG. 1, IO is a loop-shaped transmission line connecting a plurality of DTEs, and an optical cable is used, for example.

1 is a monitoring station, and 2, 3, and 4 are nodes connected to the transmission path 10, respectively.

DTE5.6.7 is connected to node 2.3.4,
These transmission lines 10, monitoring station 1, nodes 2.3.4, DT
The LAN is configured by E5.6.7. Monitoring station 1
contains a time slot allocation table 8, and each node that monitors and controls the entire LAN system, such as time slot allocation, has a time slot allocation table 8, and each node has a time slot allocation table 8, which monitors and controls the entire LAN system such as time slot allocation. A buffer 23 is provided to store the transmitted data and hold it for the time necessary for the data to go around the loop, and the output of this buffer 23 is added to the input to the node 2 in the subtraction unit 21 with its sign inverted. , that is, it is subtracted. Further, the output from the node 2 is sent to the transmission path IO as a signal obtained by adding the output signal of the adder 21 to the data from the DTE 5 in the adder 22.

[Effect]

Let A be the audio data from DTE5, B be the audio data from DTE6, and C be the audio data from DTE7. Now, if the input data to node 2 is A + B + C, then terminal 2! Then, D just one round ago from buffer 23
Since data A from TE5 is subtracted, DTA5
The input to is B+C. This is a superimposition of audio data from DTE 6 and audio data from DTE 7, but due to the characteristics of the audio, the human ear can clearly distinguish audio A and audio B from each other.

Then, the new audio data A' from the DTE 5 is added to the input data B10 to the DTE 5 in the adder 22 and sent to the transmission line 10 as data A'+B+C. At the same time, audio data A' is stored in the buffer 23 in preparation for the next cycle.

Since the other nodes 3.4 have the same configuration as node 2, the DTEs 6.7 connected to each node can identify and listen to the voices from the DTEs other than their own. This means that voice communication can be performed simultaneously between multiple DTEs.

〔Example〕

In FIG. 2, which is an embodiment of the communication@control system of the present invention, node 2 is particularly shown as a representative, but other nodes 3 and 4 have similar configurations.

In the figure, the same parts 21.22.2 as the principle diagram in Figure 1.
3 is given the same number, so a detailed explanation of that part will be omitted. Reference numerals 24 and 24' denote time slot selection units, which are placed on the input side and output side of the node 2, respectively. 25.25' is a buffer, 26 is a decoder (D/A converter), and 27 is a Korg (A/A converter).
The output of the decoder 26 is sent as a received audio signal to the DTE 5, and the audio signal from the DTE 5 is converted into a digital signal by the KOG 27.

Now, it is assumed that voice communication is performed using a specific time slot Tn assigned by the monitoring station I (see Figure 1), and the voice signal A+B+C is transmitted in the form of digital data into this time slot Tn. shall be. The time slot selection unit 24 selects this time slot Tn and inputs the data A+B+C into the node 2.

This data AfB1C is passed through the buffer 23 to the terminal 21.
At this point, the audio data A from the DTE 5 of the previous round, which was held in the buffer 23, is subtracted.

Therefore, the decoder 26 receives a signal B which is a composite of the audio data B from the DTE 6 and the audio data C from the DTE 7.
Only +C is sent. Then, the decoder 26 converts it into an audio signal, which is normal analog data, and converts it into a DTE signal.
It will be sent to 5th.

Even when two people's voices are mixed, people can distinguish between the voices of each person. This can be said to be a characteristic of audio signals, and even if the signal includes audio from DTE6.7 as data B+C, when a person listens to the signal, they can be distinguished as separate audio signals.

Therefore, even if voice data generated simultaneously by DTE 6.7 is sent in the same time slot, DTE 5 can hear them separately, and the purpose of communication has been achieved.

The new audio data A' in the DTE 5 is converted into a digital signal by the KOG 27 and transmitted to the adder 22. Here, data B+C is added and transmitted to the buffer 25' as A'+B+C. The slot selection unit 24 selects a predetermined time slot Tn.
and sent out to the transmission line 10. At this time, new data A' will be stored in the buffer 23.

Note that the delay amount of the buffer 23 is the time required for the signal to go around the loop, but since this varies depending on the size of the loop, the delay amount of the SV that monitors the entire loop is
etwork 5service ProcessorS
! It is made variable according to instructions from the il@Jl monitoring device).

At the next node 3, by the same operation as node 2, DT
Only the audio signal A'+C is transmitted to E6. and,
As an output signal from the node 3, a signal A'+B'+C to which a new signal B' from the DTE 6 is added is sent to the transmission line 10.

Similarly, at the next node 4, the audio signal A'+B' is sent to DTE7.
is transmitted, and the node 4 outputs A'+B'+C' to which the new signal C' from the DTE 7 is added.

FIG. 3(A) is a diagram for explaining the outline of the operation of the entire loop constituting the LAN.
) 1, node 2.3.4, and only the transmission line IO are shown.

First, let us assume that audio signal A is output from the DTE connected to node 2. This reaches node 3 via transmission path 10, but node 3 transmits this audio signal to node 3.
to the DTH connected to. D connected to node 3
When a new audio signal B is generated from the TE, it is sent out on the transmission line 10' together with the previous signal A.

Node 4 receives the audio signal A+B and sends it to node 4.
to the DTP connected to. D connected to node 4
If no new audio signal is generated at the TP, the signal A+8 will be transmitted as is to the SVI, node 2.
When the audio signal C is generated here, the audio signal A+B+C is sent out to the transmission line 10''.

The node 2 receives the audio signal A+B+C, but since it is subtracted from the audio signal A held within the node 2, only the audio signal B+C is transmitted to the DTE side.

FIG. 3(B) shows received data and transmitted data at the node 2 of the present invention. As is clear from the comparison with the conventional example shown in FIGS. 3(B) and 3(C), in the conventional example,
In order for the signals B and C to be received by the node 2, one-to-one communication had to be performed using different time slots, but with the present invention, the signals B and C can be received at the same time.

〔Effect of the invention〕

As described above, according to the present invention, communication at three or more locations can be performed using the same time slot,
It greatly contributes to improving communication functions in LAN.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the communication control system of the present invention, FIG. 2 is a diagram showing an embodiment of the invention, FIG. 3 is a diagram explaining the operation of the invention, and FIG. 4 is a diagram showing a conventional example. l-.-Monitoring station 2.3.4-Node 5.6.7-D
T E 21 - Subtractor 22 - Adder 23 - Buffer

Claims (1)

[Claims] (1) In a LAN that includes a monitoring station, multiple nodes, and DTEs connected to the nodes, and these are connected by a transmission path, each node has a buffer ( 23), and subtraction means (21) for subtracting the received signal of the node and the signal in the buffer (23).
) and addition means (22) for adding the output of this subtraction means (21) and the audio signal from the DTE connected to the node, making it possible to perform simultaneous audio communication between multiple DTEs using the same time slot. A communication control method in a LAN characterized by the following.