JPH01268332A - Data communication system - 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] [Field of Industrial Application] The present invention relates to a data communication system, and in particular, a data communication system in which a transmission frame consisting of a channel region and a packet region circulates on a loop-shaped transmission path connecting a plurality of communication stations. The present invention relates to a data communication method that allows channels to be changed without preventing real-time communication in a communication system.

[Conventional technology]

Conventionally, for example, in communication systems that transfer real-time information such as audio and image information and data information in a mixed manner,
A transmission frame is divided into a channel area and a packet area, and the ratio of these channel areas and packet areas is controlled to be changed in order to efficiently transfer the above information.

Such a technique is described, for example, in ``R.I.N.S. Basic Communication Technology'' written by Kanokogi.

[Problem to be solved by the invention]

However, according to the prior art, when changing the ratio between the channel area and the packet area on a transmission frame, communication stations using a channel adjacent to the packet area are forced to interrupt transmission, and the communication station using that channel is Since the switching to the used channel is controlled, it is not possible to change the channel without preventing real-time communication.

An object of the present invention is to provide a data communication method that allows changing communication channels without preventing real-time communication.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for communication between a plurality of communication stations connected by a loop transmission path, which consists of a packet area and a channel area circulating on the loop transmission path. In a communication system that communicates with each other via frames, when a channel located at the boundary with the packet area is in use and another channel becomes vacant, communication using the boundary channel occurs. The station is characterized in that the channel to be used is switched after notifying the destination station of an instruction to change the channel to be used to the vacant channel using the packet area.In this case, the channel to be used is changed. Instructions are 5. For example, if a group address is assigned to the plurality of destination communication stations in advance and notification is sent using a packet containing the group address, channel switching for all destination communication stations can be performed in a timely manner. .

[Effect]

According to the present invention, when a channel area becomes vacant, the ratio of the bucket 1 area to the channel area is variably controlled by switching the busy channel located at the boundary with the packet area to the empty channel. Therefore, it is possible to flexibly respond to communication requests from each communication station. Also, when allocating channels.

By assigning wide-area group addresses to multiple destination stations in advance, multiple stations can be notified of the change in channel using one packet at the same time, even when real-time information such as images is being communicated. Channel switching can be achieved without interrupting communication.

〔Example〕

FIG. 3 is a block diagram of a transmission system to which the present invention is applied.

The non-transmission system 11 includes a plurality of general communication stations 310, 320
．． 330 and the management station 302 are connected in a loop through the transmission line 301. The communication station 330 has one image information code/1 image information code/
A camera 332 is connected through a decoder (GODEC) 331, and a monitor device [312,
322 is connected, and image information can be transferred from the camera 332 to the monitor devices 312 and 322.

Note that the number of communication stations that can be connected to the transmission path 301, the types of terminals accommodated in each communication station, and the number of connections are not essential to the present invention, and only the configuration necessary for explaining the embodiment is shown. FIG. 4 is a diagram showing a transmission frame structure used in the transmission system according to the present invention.

The transmission frame 400 includes a frame header (FF) 40
1. Channel region 402. The packet region 403 consists of three types of regions, and the maximum flame in the channel region 402 is predetermined.

FIGS. 5A to 5C are diagrams for explaining changes in frame configuration due to channel change.

Figure 5 (A) shows the frames in use up to the i-th channel, and the numbers in the channels are set in advance in the daple of each communication station, with multiple communication stations as one group at the time of initial channel allocation. group address. As shown in (B) of the same figure, communication for group address 2 is completed.

When the channel is released, the packet area is expanded by changing the channel for the group address using the maximum channel number from i to 2, as shown in FIG. 1(C).

FIG. 6 is a diagram showing the packet structure on the packet area. The packet is surrounded by flags 501.

Destination address (r) A) 502, source address (SA
) 503, packet type to indicate the presence or absence of data (
)1'C)504, data (D A 'I' A )5
05 and check field (Fe2) 506. Furthermore, when performing channel setting/change, the data 505 has a configuration in which a communication channel number (CI(Nα)) 507 and a group address 508 are placed before the information field 509. Furthermore, a group address (G Ha)
508 is the individual/group aHJIJ area (I/()
) 510 and an address area (At)D) 511.

The address format is the same as the IE[:IE802 JIA standardization proposal. Furthermore, this group address (C2&)
The structure of Destination Address (DA) 508 is identical to that of Destination Address (DA) 502, except that I/G5 on Group Address (G&) 508 0 always indicates group 111 I
It is set to I.

FIG. 1 is a diagram illustrating a procedure for allocating communication channels during activation of a communication system to which the present invention is applied.

For example, when the communication station 330 in FIG. 3 receives a real-time information transmission request from a terminal, it issues an allocation request (CI<) to the management station 302.
The packet is stored in the information field C-field 509 in FIG.
Contains 0 addresses.

Upon receiving the above allocation request (Ct<), the management station allocates channel number i to one communication station (FJ station: 330) and the destination communication stations 310 and 320.
It assigns a group address K, sends a channel setting instruction packet (IC), and notifies the destination communication station 310, 320 of the channel number i and group address K. Each communication station that receives this channel setting instruction (IC)
The management station transmits a response (CA) to the management station, and receives the responses (CA) from all destination communication stations. and notifies the group address K. ↓Thus, the transmitting communication station 330
Using the second channel in 2.

Image information can be transferred. The transmission frame in this case is in the state shown in FIG. 5(A).

Note that if all channels in the transmission frame are in use, the management station 302 makes a rejection response to the channel allocation request (CR) from the transmitting station.

FIG. 2 is a diagram for explaining the procedure for changing the used channel. Now, when all the channels in the area 402 are in use and one communication station 330 is transmitting image information using the channel with the maximum number i, suppose that a part of the channel area 402, for example, the second channel, is free. Suppose. In this case, if the channel used by the first communication station 330 can be changed to the second channel,
Communication efficiency can be improved by expanding the packet area 403.

Therefore, the management station 302 monitors the channel usage status, and when an unused channel occurs, the management station 302 sends information to the communication station 330 currently using the highest numbered channel.

Issue a channel change request packet (RCR).

The RCR includes a command indicating a channel change request and the new used channel number after the change in the information field 509 of FIG.

When the communication station 330 receives the above RCR, 1 communication station 330
is sent to the destination communication stations 310 and 320 by relay communication using the group address k.

After issuing a channel setting instruction packet (RrC) and notifying that the channel to be used is to be changed to the second channel, the channel to be used is changed to the second channel.

In this case, if each destination station completes the reception channel switching operation within a predetermined time after receiving the CRC, channel switching during information transfer becomes possible with any network topology.

〔Effect of the invention〕

According to the present invention, since it is possible to change the communication channel during information transfer, the communication channel consists of real-time information and non-real-time information.
So-called mixed information can be efficiently transmitted. Therefore, it is possible to avoid temporary interruptions in information transfer due to channel changes (for example, temporary blurring of images during video conferences, etc.).

Further, after the communication channel is set, only the transmitting communication station or the management station need only store the transmitting station address and group address as a table instead of the destination communication station address, which is effective in reducing the amount of memory.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a communication channel allocation procedure in a communication system to which the present invention is applied; The figure is an overall configuration diagram showing an example of a communication system to which the present invention is applied, FIG. 4 is a configuration diagram of a transmission frame circulating on the communication system, and FIG. 5 (A)
-(C) are diagrams for explaining changes in the structure of a transmission frame due to a change in communication channel, and FIG. 6 is a diagram showing the structure of each packet in the transmission frame. 402... Maximum channel area, 4.03... Packet area, 507... Channel number area, 508...
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Claims (1)

[Claims] 1. A communication system in which a plurality of communication stations connected by a loop transmission path communicate with each other via a communication frame consisting of a packet area and a channel area circulating on the loop transmission path. , when another channel becomes vacant while the channel located at the boundary with the packet area is in use, the communication station using the boundary channel changes the channel in use to the vacant channel. A data communication system characterized in that the channel to be used is switched after notifying the destination station of the instruction using the packet area. 2. When one communication station communicates with a plurality of communication stations, a group address is assigned in advance to the plurality of destination communication stations, and an instruction to change the channel to be used is notified by a packet containing the group address. The data communication system according to claim 1, characterized in that: