JPH04266236A - Communication system - Google Patents

Abstract

PURPOSE:To send information with a short allowable transmission time even when the information is an isochronous signal being information, such as voice signals and dynamic images, occurring continuously at a prescribed interval. CONSTITUTION:A reserved slot is used for communication for a voice signal and a moving picture being continuous information. In this case, a station 1a managing the communication using the reserved slot 8 is provided among stations provided to transmission lines 4, 5, and the management station 1a allocates the information to the reserved slot 8 continuously at each prescribed interval when the voice signal and the moving picture are sent. Thus, the presence of transmission information is sequentially inquired from the management station 1a to other general stations 1b-1f by using a non-reservation slot 9 to ensure the reserved slot 8 at each prescribed interval to the general station having the transmission information.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a local area network in which communication traffic is transmitted in fixed-length transmission units called slots, in which communication traffic consists of discretely generated non-isochronous signals such as data, voice and images, etc. The present invention relates to a communication system that efficiently transmits a mixture of isochronous signals that are continuously generated at regular intervals.

0002

2. Description of the Related Art FIG. 3 shows the configuration of a conventional bus-type local area network in which transmission paths are provided in opposite directions. In the figure, 1 such as 1a and 1b are communicating stations; 2b etc. 2 is a slot generator, and between these stations and the slot generator, the signal transmission direction A,
Transmission lines 4a, 4b, etc. 4 and transmission lines 5a, 5b with B opposite to each other
etc. 5.

FIG. 4 shows an example of the format of a transmission frame transmitted on the transmission path 4 and the transmission path 5, where 6 indicates a frame that is repeated every 125 μs, and this frame 6 is given for controlling the frame. frame header 7 and
Reserved slots 8a, 8b, etc. 8, non-reserved slots 9a,
The reserved slot 8 is a slot whose use is determined in advance by a station, and the non-reserved slot 9 is a slot that is shared by stations 1 on the transmission path without limiting the station to use it. In this way, usage rights are obtained through competitive control.

FIG. 5 shows the slot formats of the reserved slot 8 and non-reserved slot 9. 10 indicates a reserved/non-reserved slot identification bit, and a value of 1 indicates a non-reserved slot; If so, indicate the reserved slot. 35
is a slot usage status bit indicating whether or not the slot is in use; 11 is an access control area (6 bits) used to control transmission on the bus of reserved slot 8; 12
is a reserved area, and 13 is a VCI (
14 indicates HEC (header error correction), and 15 indicates an information section (48 octets).

Furthermore, FIG. 6 shows the protocol configuration and information flow at station 1 on the transmission path, and the same configuration is used for transmission path 4 and transmission path 5, respectively. , only those for the transmission line 4 are shown. Note that the broken lines in the figure represent the paths through which information flows within the station.

FIG. 7 is a diagram showing a method of dividing information to be transmitted into slots, where 30 represents information to be transmitted, 31 such as 31a, 31b, etc. represent information on slots into which the divided information is inserted, 32, such as 32a and 32b, indicate the entire divided slots.

Furthermore, FIG. 8 shows the state of the slots transmitted from a certain station on the transmission path.
33 such as 33b indicates slots transmitted by other stations to the transmission path. Also, here, the actual transmission time is the time from transmitting the slot corresponding to the beginning of the information to the end of transmitting the slot corresponding to the end, and the actual allowable transmission time is the allowable transmission time for transmitting this information. each represents.

Next, the operation will be explained. As shown in FIG. 3, the transmission path is double-configured, and the transmission directions A and B are opposite to each other. Slot generation and termination devices 2 located at both ends of such a bus generate and terminate fixed-length slots, which are units of transmission flowing on a transmission path.

As shown in FIG. 4, the format on the transmission path 4 and the transmission path 5 has a frame 6 of 125 μs, and a frame header 7 in the frame contains information indicating the start of the frame and information on the transmission path. Abnormal information etc. are shown. Further, the reserved slots 8 and the non-reserved slots 9 are arranged consecutively, for example, as shown in FIG. 4. Further, the format of each slot is as shown in FIG.

The operation of the station is based on the Institute of Electrical and Electronics Engineers (I)
IEEE) Local Area Network Standards Organization Working Group 802.6 Publication Document (IEEE 80
2.6 Proposed Standard DQD
B MAN D12:1990.2), when communicating using non-reserved slots, all stations on the transmission path that have signals to transmit compete to use the slots.

When every slot is received, it is converted from a serial bit stream to a parallel byte stream at the physical layer, and the reserved/unreserved slot demultiplexing layer separates the reserved slots from the non-reserved slots, as shown in FIG. After that, processing is performed for each slot. On the other hand, when transmitting, the data is multiplexed in the reserved/non-reserved slot multiplexing layer, converted into a serial bit stream in the physical layer, and sent out to the transmission path.

The processing of non-reserved slots after they are separated into reserved slots and non-reserved slots is as follows. When information to be transmitted occurs, as shown in Figure 6,
The non-reserved slot exchange control layer divides the information into slots as shown in FIG. 7, and the reserved/non-reserved slot access control layer divides the information into slots for the number of slots required for transmission. A transmission request is written in the slot header of the slot flowing through the transmission path 5. By inspecting the slot header of the slot flowing through the transmission path,
The number of slot transmission requests at the upstream station with respect to the transmission path 5 is recognized.

Further, the reserved/non-reserved slot recognition bit 10 and the slot usage status bit 3 of the slot header shown in FIG.
5 to recognize the number of unreserved and empty slots. If the number and the number of transmission requests become the same, it is determined that the transmission slot has been allocated to the own station, and
Next, when a non-reserved slot and an empty slot is detected for the transmission path 4, information is written in the information section 15 of the slot shown in FIG. 5, and the slot usage status bit 35 is sent out as being in use.

On the other hand, when receiving a slot, the VCI 13 of the slot header flowing through the transmission path shown in FIG. 5 is checked, and if it is addressed to the local station, the information transmitted by that slot is copied into the station. If it is not addressed to the local station, it will not be copied internally.

[0015]

[Problem to be Solved by the Invention] When slot transmission is performed through the above operation, information is transmitted in units of slots, so if multiple stations on the transmission path start transmitting at the same time, one station may A slot transmitted by another station may interrupt the slot sent by another station. In other words, as shown in FIG. 8, if slots 32a, 32b, 32c, and 32d are transmitted from a certain station in the order, slots 33b, 33c, 33d, and 33e transmitted from other stations during that time are
, 33f.

As a result, as shown in FIG. 8, it becomes impossible to capture and transmit the transmission slot 32 within the expected time. For this purpose, among the information 30 shown in FIG.
There is a possibility that the actual transmission time required from transmitting the slot 32a corresponding to the first part to transmitting the slot 32d corresponding to the last part may increase. In this case, when the information to be transmitted is continuous information at regular intervals, such as audio and moving images, the permissible transmission time is generally narrow. That is, since one transmission path is shared, information may arrive late due to the slot 33 transmitted by another station, and there is a problem in that continuous information may not be transmitted.

The present invention was made to solve this problem, and even for isochronous signals such as audio and moving images, which are information that occurs continuously at regular intervals, the permissible transmission time is limited. The present invention provides a communication method using reserved slots that enables the transmission of short information.

[0018]

[Means for Solving the Problems] In the communication system according to the present invention, one management station and a plurality of general stations are connected by a shared transmission path, and information that continuously occurs at regular intervals and irregularly occurs in the general stations. In a communication system that mixes and transmits information that occurs discretely at intervals into slots, a frame for transmitting information consists of a frame header, a slot area that carries information that occurs continuously, and information that occurs discretely. , the slot area consists of a reserved slot area and a non-reserved slot area, each slot in the slot area consists of a slot header and an information section, and the slot header indicates whether the slot is a reserved slot or a non-reserved slot. It consists of a reservation type bit that identifies the slot, a usage status bit that indicates whether the slot contains information and is in use, and a connection identifier that identifies the communication partner. The management station assigns a connection identifier, distinguishes between reserved slots and non-reserved slots using the above reservation type bit, generates a slot, sends it to the transmission path, and sends it to the transmission channel. If information that occurs periodically is transmitted using the non-reserved slots, information that occurs continuously is transmitted using the reserved slots, and information that occurs discretely is transmitted, the usage status bit is empty. When a certain non-reserved slot is received, the information is divided and placed in the slot, and the usage status bit in the slot header of the non-reserved slot is set as being used, and the slot is sent to the transmission path.
In the case of information transmission that occurs continuously, the management station inquires of each general station whether there is a transmission request or not using the non-reserved slots mentioned above, and each general station responds to the inquiry by inquiring whether there is any transmission request or not. If there is a transmission request in response, the management station adds a connection identifier to the reserved slot for the information transmission of the general station making the transmission request, checks the position of the reserved slot in the frame, and performs the transmission. The general station that has the information is notified of the position in the frame of the reserved slot secured using the non-reserved slot, and from then on, the general station transmits the above transmission information using the reserved slot allocated by the management station. is transmitted to the management station, and the management station transmits the information received through the reserved slot to the destination station using a reserved slot to which a connection identifier from the management station to the general station is attached. .

[0019]

[Operation] In the present invention, since the permissible transmission time is long for data signals which are non-continuous information, the conventional slot transmission method is used. Concerning audio and moving images, which are continuous information, communication is performed using reserved slots. At this time, among the stations provided on the transmission path, a station is provided that manages communication using reserved slots. Then, when transmitting audio and moving images, the management station continuously allocates information to reserved slots at regular intervals. To this end, the management station uses non-reserved slots to sequentially inquire of other general stations about the presence or absence of transmission information, and reserves reserved slots at regular intervals for general stations that have transmission information.

[0020]

[Examples] Examples of the present invention will be described below. FIG. 1 shows an example of communication between five general stations and one management station. Numbers 1 such as 1a and 1b represent stations, among which 1a represents a management station, and 1b, 1c, 1d, 1e, and 1f represent general stations. Reference numerals 2 such as 2a and 2b indicate slot generating and terminating devices. 4a, 4b, etc. 4 and 5a, 5b, etc. 5 are transmission paths in which the directions of transmission are opposite to each other, 21a, 21b, etc. 2
1 represents a communication path for communicating between stations. The formats of frames and slots flowing on the transmission path are the same as in the conventional example, and are in accordance with FIGS. 4 and 5. Furthermore, the method of dividing information into slots is the same as in the conventional example, and follows FIG. 7.

FIG. 2 shows a communication sequence for allocating reserved slots between the management station and general station shown in FIG. 25, such as 25a and 25b, indicates a communication sequence between the management station and the general station. Identification of communication paths will be explained below using FIG. 1. Communication between the management station 1a and the general stations 1b to 1f is via VCI allocated as shown in Figure 1.
distinguished by the value of For example, since VCI=1 is assigned to communication from the general station 1b to the management station 1a, the VCI 13 shown in FIG. 5 in the slot transmitted from the general station 1b to the management station 1a is 1. written. Similarly, from the general station 1c to the management station 1a, VCI=
2 is VCI=8 from the general station 1d to the management station 1a.
VCI is allocated, and for communication from the management station 1a to the general station, VCI is allocated from the management station 1a to the general station 1f.
= 5 etc. Therefore, in reserved slot communication, VCI1 of the slot on the transmission path shown in FIG.
3, the communication path 21 shown in FIG. 1 can be identified.

In the case of transmission of non-isochronous signals such as data,
Transmission is performed using a method similar to that shown in the conventional example using non-reserved slots. At that time, each slot header is reserved/
Set the non-reserved slot identification bit to 1.

[0023] In the case of transmitting isochronous signals such as audio and moving images, the transmission is performed using the method described below. Communication between the reserved slot management station and the general station will be explained using FIGS. 2 and 4. The transmission format when transmitting reserved slots is the same as that shown in FIG. 4, which is a conventional explanatory diagram. In communication between the management station and the general station, first, the management station 1a sends an unreserved slot to the general station 1b using the transmission path 5 with the slot usage status bit 35 set to 1 as shown in FIG. 9, the presence or absence of transmission information is inquired as in the communication sequence 25a. In this case, since the communication is from the management station 1a to the general station 1b, VCI=6 is used. On the other hand, in the general station 1b, the presence or absence of transmission information and, if there is transmission information, the occurrence interval of the information are determined by the communication route with VCI=1, in the same manner as in the case of the above inquiry.
The notification is made using communication sequence 25b.

If the notification of the communication sequence 25b indicates that there is transmission information, the management station 1a determines the position of the reserved slot 8 to be used in the frame 6 according to the interval of occurrence of the transmission information, in the same way as the transmission information inquiry. to VCI=6
The notification is made using the communication sequence 25c using the non-reserved slot 8 of . The management station 1a reserves a reserved slot 8 for transmitting information from the management station to the next destination station. That is, if the general station 1b is transmitting to the general station 1e, a reserved slot 8 for transferring information from the management station 1a to the general station 1e is secured in the frame 6 on the transmission path 4.

[0025] Furthermore, if the transmission is to the general station 1c,
Similar reserved slots 8 are reserved for frames on the transmission path 5. If the above reservation slot 8 corresponds to the occurrence interval,
If it cannot be secured, the general station 1b is notified that transmission is impossible. If there is transmission information, the general station 1b divides the information into slots as shown in FIG.
The data is continuously transmitted to the management station 1a using reserved slot 8 where 5 is 0. In this case, from general station 1b to management station 1
Since the communication is for a, VCI=1 is used for all slots. Also, at this time, the usage status bit 35 of the slot is changed to 1.

When the management station receives the slot, it transmits it to the next destination station. In this case, the destination station is general station 1.
e, reserved slot 8 of transmission path 4 with VCI=4
If the destination station is general station 1c, VCI=
7 and transmits using the transmission path 5. In this case, as in the case of transmission from the general station 1b to the management station 1a,
All slots forming the transmitted information are transmitted consecutively.

When the above operations are completed, the next general station 1c
The transmission path 4 is used to inquire about the presence or absence of transmission information using the non-reserved slot 9 with VCI=7. Then, the same operation as for the general station 1b is performed. Additionally, there is also a transmission path for transmitting a non-reserved slot 9 to inquire about the presence or absence of information to the general stations 1d to 1f and to notify the use position of the reserved slot 8 in the frame 6, and a transmission path from the general stations 1d to 1f. It is assumed that the same operation is performed except that the transmission path for transmitting the non-reserved slot 9 that returns a response to the management station 1a regarding the presence or absence of information and the reserved slot 8 for transmitting information are switched.

The above operations are repeated in sequence, and when the operation for the general station 1f is completed, the same operation is performed again for the general station 1b. When the transmission of information is completed, the management station 1a is notified of the completion of the transmission using the non-reserved slot 9. This allows the management station to release the reserved slot in frame 6 that was used for transmitting the information and use it for communication with other stations.

Although the embodiments of the present invention have been described with respect to a network in which the transmission path is configured in the form of a bus, the present invention can be similarly applied to a network in which the transmission path is configured in the form of a ring.

[0030]

As described above, according to the present invention, when transmitting audio and images, it is possible to transmit using the reserved slots allocated by the management station, so that transmission from other stations between slots on the transmission path is possible. It is possible to prevent interruptions in the slots that have been created. Therefore, audio and image transmission can be performed with less fluctuation time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating an example of communication between a general station and a management station.

FIG. 2 is a diagram showing the passage of time and a communication sequence between a management station and a general station.

FIG. 3 is a configuration diagram of a network.

FIG. 4 is a frame format diagram on a transmission path.

FIG. 5 is a format diagram of each slot within a frame.

FIG. 6 is a diagram showing a protocol configuration at a station on a transmission path.

FIG. 7 is an explanatory diagram showing a method for dividing information into slots.

FIG. 8 is an explanatory diagram showing a method when a certain station divides a frame into transmission slots.

[Explanation of symbols]

1 Station 2 Slot generation and termination device 4 Transmission line 5 Transmission line 6 Frame 7 Frame header 8 Reserved slot 9 Non-reserved slot 10 Reserved/non-reserved slot identification bit 11 Access control area 12 Reserve area 13 VCI 14 HEC 15 Information section 20 Internal station Communication path 21 Communication path 25 between management station and general station Sequence 30 between management station and general station Transmission information 31 Slot information part 32 Entire slot 33 Slot 35 transmitted by other station Slot usage status bit

Claims (1)

[Claims] Claim 1: One management station and a plurality of general stations are connected by a shared transmission line, and information that occurs continuously at regular intervals and information that occurs discretely at irregular intervals at the general stations are slotted. In communication methods that transmit mixed signals,
A frame for transmitting information consists of a frame header and a slot area in which continuously occurring information and discretely occurring information are carried, and the slot area consists of a reserved slot area and a non-reserved slot area. Each slot consists of a slot header and an information section, and the slot header includes a reservation type bit that identifies whether the slot is a reserved slot or a non-reserved slot, and a reservation type bit that identifies whether the slot contains information and is in use. The connection identifier in the reserved slot is used to distinguish the virtual communication path between the management station and the general station.
The management station allocates a connection identifier, differentiates between reserved slots and non-reserved slots using the reservation type bit, generates slots, sends them to the transmission path, and transmits discretely occurring information using the non-reserved slots. , when information that occurs continuously is transmitted using the reserved slots, and when information that occurs discretely is transmitted, when the non-reserved slot whose usage status bit is empty is received, the information is divided and transferred to the slot. In the case of information transmission that occurs continuously, the slot is sent to the transmission path with the usage status bit in the slot header of the non-reserved slot set as being in use.
The management station inquires of each general station about the presence or absence of a transmission request using the non-reserved slots mentioned above, and each general station responds to the inquiry with the presence or absence of transmission information, and if there is a transmission request, the management station The station adds a connection identifier to the reserved slot for information transmission by the general station that has the transmission request, checks the position of the reserved slot in the frame, and sends the above information to the general station that has the transmission information. The general station notifies the position in the frame of the reserved slot secured using the non-reserved slot, and thereafter causes the general station to transmit the above transmission information to the management station using the reserved slot allocated by the management station. At the station,
A communication system characterized in that the information received through the reserved slot is transmitted to the destination station using a reserved slot to which a connection identifier from the management station to the general station is attached.