JPS5875349A - Transmitting system of digital signal - Google Patents

Abstract

PURPOSE:To attain a high-speed control of connection without stopping the periodical transmission of a packet, by changing the designation of address for the packet. CONSTITUTION:In case the communication is desired with a station Z before the transmission of data is over between stations X and Y, the control information CONTn requesting the release of a call for the station X is put into a packet and transmitted in the next frame with which the transmission of data is through from the station X to the station Y. While the station Y fetches the packet and decodes the information CONTn to send the control information CONT permitting the release of the call back to the packet to be called. Thus the station X fetches this packet and transmits the packet which transferred the address information DA to the station Z in the next frame.

Description

[Detailed Description of the Invention] The invention relates to a digital signal transmission method VC that transmits data in the form of packets using a communication cable, and in particular,
The present invention relates to a digital signal transmission system that improves the conventional R'Z determination method when changing the destination of a packet.

Due to the spread of child calculations and the development of digital signal processing technology, data communication, which processes information online by combining communication systems and y''-event processing systems, is gaining popularity as an AI source.In particular, government offices, In small-scale communication systems such as in-field communication carried out within the premises of companies, etc., communication methods using communication cables such as coaxial cables are recommended due to their economical efficiency, reliability, and transmission efficiency. At the time, all the attention is on the East.

In this bucket-based communication 1G system, a communication cable for bidirectional transmission is laid on research hemlock or the like, and a large number of stations (personal stations) are connected to it. Then, each station transmits a message that is divided into data blocks of 1000 to 2 (100 pits).The message is attached with a destination, a passage, and other headers.In this communication method, the network itself The 1μJ and 4J functions are all passive transmission systems, and IJ+ILII is completely distributed to each station.Therefore, each station checks the availability of the transmission line and starts sending messages. , a collision with another bucket occurs during transmission f
In case c, both these stations stop transmitting. 1g delivery
The station that stopped the message will attempt to resend the message after a random waiting time ρ.With this type of communication system, not only users at each location can access one computer, but also users distributed in six locations. Hardware such as storage devices and liftware such as programs can be mutually used. In other words, with this communication method, devices such as high-speed or high-speed printers and Inukasho files, which were stored on a large central computer in a TSS (time sharing system), are used in a distributed manner at various locations. can do. Therefore, it can be detrimental to the consumption of resources and the efficiency of use.Furthermore, the fusion of programs and data makes it possible to develop large software systems. In addition, in such a communication method, each +ut
H'4 (Bernal Station) Ura has no priority order in terms of the use of transmission lines, and is therefore equal. Therefore, there is no master-slave hierarchy in the stations 1ij, which is often seen in the Ikenotori 1d system, and direct communication is possible between any established stations. Furthermore, since the transmission line such as the autopsy cable is completely composed of passive circuits, a highly reliable system can be easily created.

As described above, the 111 communication system has various features, but when each station starts transmitting data arbitrarily, there is a possibility that buckets will collide on the same C1 transmission path. Naturally, this collision between packets becomes more frequent as the usage efficiency of the transmission path increases as a system.

To solve these problems, a signal transmission method called Priority Ethernet or Rezapation Ethernet has been proposed.
In a system called ``hernet'', signal transmission from each station is determined in advance using a preamble within a packet. Then, when the bucket is +tq, the bucket with the higher positive value is transmitted to 'Aiko City. Reservation Ethernet (Re5ervation E)
In a system called ethernet, a station (master station) for mode specification is permanently installed, and in reservation mode, each other station (personal station)
At each time, the user is asked to check whether there is a signal that should be transmitted f and the amount of information to be transmitted. Based on this result, the +l1m number of buckets to be transmitted by each station is determined for each frame, and signals are transmitted in a time-division manner in the transmission mode.

However, according to the proposed former signal transmission method, there remains the problem of variations in transmission delay time due to evaporation and collisions between packets with the same priority.

Therefore, it is inappropriate for late-time communication, such as conversational voice communication, where the correspondence between sending and receiving in real time is visible on television. In addition, according to the latter signal transmission method, the presence of the master station causes the loss of the former JFJ...1st prize and 1st prize. In the dlJ system, if a failure occurs in the master station, data communication cannot be performed, and in this sense, the system's reliability is reduced.

As a further solution to this problem, a digital signal transmission method has been proposed that allows real-time transmission without losing the equality of each personal station. In this method, a large frame (frame) that is periodically repeated on the time axis is further divided into small frames (blocks) that are made up of 1 hour each time, and these blocks are used for each station (personal station). The aim is to provide opportunities for packet communication. This allows each station to have equality in the use of empty blocks, and also allows stations to repeat 7 frames if they occupy all of the blocks for the time required for No. 18 transmission. Since an opportunity for signal transmission is provided periodically each time a signal is received, real-time transmission is also possible.

By the way, in general, the operation of a circuit switched connection can be divided into the following three phases.

・V call setting ■: +fn it' ■The same applies to the repeat communication practice in communication systems that adopt the digital signal transmission method proposed for the open destination.The valley phase is explained below for this method. become that way.

■Call Setting Suppose that the user of a certain station or terminal device (hereinafter simply referred to as the station) wishes to communicate with another station. User v: i′,
Pick up the telephone handset and turn the dial to specify another station. The calling station puts the called station's destination number into a calling bucket of a predetermined size and sends it to an empty block on the cable. This empty block
If by chance another station specifies 7 and the bucket transmits 1t, a collision will occur between packets. In this case, both stations will temporarily stop transmitting 1, □, and randomly Set the waiting time individually,
Then, try to resend the bucket. Suppose that it is possible to send a calling packet to an empty block without causing a collision. This call is connected to the cable, 11. fc is received by all stations. Each station examines the destination information of the received packet and determines whether the destination is the local station (
This is included only in the case of Kerato. When the called station captures the packet, a calling channel is set up on the same channel as the calling station.

When the calling channel is set, the called station creates a +a call packet in which the destination information of the calling station is incorporated into a called packet of a predetermined size, and sends out a response signal. In this case as well, if two or more buckets try to occupy a vacant block on the cable at the same time, a collision between packets will occur. If a collision is detected, the operations of stopping transmission, waiting, and resending the bucket are repeated until the transmission is successful. When the called station successfully sends a called packet and the calling station captures it, a called channel is established.

(In this communication method, when a packet is sent out on the communication cable, each station receives the packet as described above. Therefore, each station uses this to check the usage status of the valley block within one frame. Therefore, refrain from using Kerato's +3 output on a program used by another station.In other words, once a two-way channel is set up using the procedure described above, Regarding these channels, no (kerato 1-j collision will occur, and digital 1-d information at a constant speed will be transmitted in real time. The calling station informs the called station of this via a packet.The called station receives this and stops transmitting the called bucket.This releases the called channel.The calling station , confirms that the transmission of the called packet has stopped.After this confirmation, the transmission of the calling bucket 1g is stopped.This also releases the calling channel and completes the series of operations for releasing the n1 call. do.

The above is the basic connection operation in this digital signal transmission system. By the way, when operating the communication system, there are cases where you wish to communicate with another station after the end of the communication with the other station, or if you make a mistake in sending the message to the correct destination immediately. There may be times when you have to call back. In this way, when the next communication is started immediately after the end of one communication, the above connection operation is repeated in the conventional method, but when the connection operation is repeated in this way, the call described in When configuring , conflicts between buckets may occur. When a collision occurs, it is expected that it will take time to set up a call, which can be a serious drawback, especially in systems that require high-speed connection operations, such as communication between computers. Furthermore, the occurrence of collisions reduces the usage efficiency of the entire system, and becomes a problem that cannot be ignored, especially when the amount of communication between each station increases.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a digital signal transmission system in which a packet that has been successfully transmitted can be used for the next communication.

In the present invention, by utilizing the fact that additional 11v information (overhead) other than transfer information is incorporated into the valley packet, a station that wishes to change the communication 11 moves is sent a packet at the end of the call. Instead of stopping the communication, the information that changes the communication partner station is incorporated into the Kerato. This information is
This is used to request the communicating party to terminate the call, and also to request the communicating station to set up a C call (using Kerat), which is currently in use. Therefore, the communication destination can be changed without interrupting communication, and the above-mentioned purpose can be achieved.

The present invention will be described in detail below with reference to Examples.

FIG. 1 shows the configuration of a communication system that employs the digital signal transmission method of this embodiment. In this system, the coaxial cable l installed as a transmission line is connected to terminators 2 and 3 for impedance mixing with a resistance value equal to the characteristic impedance. Stations X, Y, and Z are
They are connected to the coaxial cable 1 through taps (T connectors) 5X, 5Y, and 5Z, respectively. Fig. 2 shows the configuration of the transmitter and receiver for each of these stations. Packets are sent by flag F.

Destination IH report 1) A, source information SA, control information C0NT
.

It is composed of each bit of the transfer data DATA and the incorrect Shchenok code C. These are basically...
It is similar to the frame structure in High Level Data Link Control Procedure (HDLC).

Now, suppose that station X wishes to communicate with station Y.
The figure sequentially shows the signals transmitted from station X to coaxial cable 1. First, station X sets the destination information DA to the destination code of station Y in the first frame (frame number 1),
It sends out a packet whose source information SA is that of its own station X. In this packet, control information C0NTl represents a call setup request. Next frame (frame number 2) and subsequent N
When a bidirectional channel is set up with station Y, the data to be transferred is sent to station Y as transfer data DATA at that stage.

Suppose that station X desires to communicate with station Z before this data transmission is completed. In this case, in the next frame after sending data to station Y (frame number n), station 7), it decodes the control information C0NTn and returns the city control information @C0NT that approves the release of the call to the called packet. Upon receiving the called packet, station This packet includes the packet destined for station Y and the control information C0NT embedded in the 0 packet that is embedded in the same block on the frame and sent out.
l' is destination transition information including a call setup request.

All stations connected to coaxial cable 1 constantly receive all transmitted packets and capture packets with destination information DA specifying their own station. Therefore, station Z receives destination information DA that specifies its own station. 0 receives this transitioned packet and sends a called packet for response to station X. As a result, a bidirectional channel is established between station X and station Z, and the data to be transferred is sent to station 2 in 14 frames after the Z-0 bidirectional channel is established. In the next frame (frame number in+m) after data transfer is completed, -
Station X incorporates control information C0NTm' requesting call release into a packet and sends it out. When station Z responds, the call is released.

In the above connection operation, when station X changes the destination from station Y to station Z, there is a possibility that the packet first sent from station Z to station X will collide with another packet. In order to completely avoid such collisions, station X may designate to station 2 the block to which station Y sent back the control information C0NT that approves the release of the call. That is, in this communication system, a station attempting to send a new packet finds an empty block within the frame and attempts to send the packet to it. Therefore, at the stage when station Y returns the ff1) IJ control information C0NT to station It never starts sending packets to that block.

Therefore, packet collisions do not occur. Note that after station However, it may be temporarily used exclusively until it is handed over to station 2.

Of course, when station X communicates with station 2, if it is necessary to increase the number of blocks used due to an increase in transferred data, station is also possible. Also, station X is
If a block adjacent to the block it is using is free, it can be used without packet collisions to cope with an increase in transferred data. When constructing a packet by using multiple blocks consecutively, the carrier will not be disconnected between them, so this digital This is because in the signal transmission system, as long as station X increases the packet size, other stations cannot send packets to the expanded portion.

In the above explanation, we have discussed the case where station X (calling station), which takes the initiative in connecting the line, changes the called station. It is likewise possible to continue communication. In this case, at the stage when station X requests release of the call, station Y may send out a packet in which the destination code of station Z is incorporated into the destination information DA.

FIG. 4 shows the structure of a packet when information is transferred from station X to stations Y and Z in small intervals.

For example, when each station is a computer or a terminal device, such information is exchanged. In this case, station X first sends a bucket lr specifying station Y in the first frame (frame number 1) to issue a call setup request. When the call is set up, necessary transfer data DATA2 is sent to station Y in the next frame (frame number 2). Then, in the next frame (frame number 3), the destination is shifted to station Z, and a request is made to station Z to set up a call. Once the call is set up, data is transferred to station 2.

In this way, after using the idle time of communication with station Y to place a value with station Z, station Call release t-Request. When station Y responds, the call is released.

In this communication form, while changing the destination of the packet,
Information is transferred at high speed and during packet exchange. Therefore, real-time transmission is not required, but error control such as checking for code error 9 using error check code C and requesting retransmission is required.

As shown in Fig. 2, each packet includes additional information such as destination information DA and control information C0NT in its overhead portion, so in this communication form, the phases from call setup to call release are It can also be considered that this is performed independently for each packet. Furthermore, since station X requests station Y to set up a call and then requests release of the call after the nfm frame, it can be considered that one connection operation is performed as a whole, as described above.

As explained above, according to the present invention, in a multi-station communication group that transmits and receives digital information in a time-division multiplexing manner or a circuit-switched manner in a packet format using a weir cable, periodic transmission of packets is possible. Since the destination designation is changed without stopping transmission, packets do not collide with each other when setting up a call, and high-speed connection control is possible. Furthermore, information suitable for packet conversion, such as in computer communications, can be transferred efficiently by minimizing the time required for connection control.

In addition, communication ``In systems with many adversaries, by avoiding collisions,
It has the advantage of improving its usage efficiency.

[Brief explanation of drawings]

The drawings are for explaining one embodiment of the present invention.
Figure 2 is a system configuration diagram showing the outline of the communication system, Figure 2 is a configuration diagram showing the packet configuration, and Figure 3 is the transmission from the calling station when the destination is transferred from one station to another. FIG. 4 is an explanatory diagram showing the contents of a packet sent by a calling station when communication with one station is interrupted during communication with another station. 〇１・・
...Coaxial cables x, y, z...Station DA...Original sales information C0NT...Control information Applicant Fuji Xerox Co., Ltd. Representative Patent Attorney Ume Yamauchi Male! ¥-J l Figure 2 Figure-i JP73 Figure

Claims (1)

[Claims] 1.) The digital signal transmitted on the r3i communication cable is fixedly positioned within a large frame on the time axis that repeats periodically, and within this large frame on the time axis. In addition, each station is given one frame for digital signal transmission using a small frame on the divided time axis as a unit, and the multi-station system allows signals to be transmitted and received in a time-division multiplexing manner using a bucket format and in a line-switching manner. In an intercommunication group, predetermined additional information is embedded in the packet sent from the station that is trying to change the communication destination, and the pattern of the station to be communicated with can be changed without completely stopping periodic transmission of each frame of the bucket. A digital signal transmission method that has all the characteristics of changing the 2. The scope of claims characterized in that the predetermined additional information is information that informs a station with which communication is to be completed of the termination of a call, and is information that requests a new station to establish a call to establish a call. Digital 1-gigoden 14 system described in item 1.