JPS60206342A - Data transmission system - Google Patents

Abstract

PURPOSE:To make the multiple use of a network possible without requiring a carrier detecting circuit by transmitting a packet of a base band to retrieve usable channels. CONSTITUTION:At a transmission time, a control part 20 of a transmitting station selects a used channel (n) (CHn) and transmits it as a packet to a network 10 through a base band transmitting part 21. After transmission, only when a transmission inhibiting packet or a negative acknowledge (NAK) from another transmitting station is not received within a prescribed time by a base band receiving part 22, a modulating and transmitting part 23 is set to the CHn by a channel select line 24, and data is transmitted through the modulating and transmitting part 23. If another transmitting station uses the CHn when said transmission request is performed, this transmitting station transmits the inhibiting packet or the NAK preferentially to the other packets to assert his use right of the CHn. The packet having the constitution shown in the figure is used for this channel retrieval, and addresses of all other transmitting stations are put in the field of a destination address 31, and a desired channel is put in the field of data 35.

Description

[Detailed Description of the Invention] Technical Field With the recent development of local networks, various types of information have come to be sent and received between arbitrary terminals via a single bus. Installation locations are limited to offices and are now being introduced into some homes as small area networks. In the latter case, television common listening lines are seen as a promising transmission line, and analog/digital signals are sent and received by frequency division.

The present invention relates to a system for transmitting data (signals) using a plurality of frequency channels provided on such a transmission path.

<Prior Art> When transmitting data (signals) using any channel among a plurality of frequency channels, it does not necessarily matter which channel each terminal uses arbitrarily. In other words, it is necessary to claim and secure the right to use the channel in some way.

As one method, for example, the same applicant's March 2, 1980
As in the patent application dated January 1, ``Data Transmission System,'' each transmitting station searches for an empty channel by carrier detection, and thereafter uses that channel to send data (signals) to the other station. There is a method of securing a channel by transmitting a packet using the baseband and then transmitting a carrier to that channel at a predetermined timing after receiving an acknowledgment response (ACK).

In this method, since each transmitting station has means for searching for empty channels, channels to be used can be determined at the individual station level, and the time required for searching is short and efficient. Also, the channel to be used always depends on the current channel usage status)
Since v is determined, erroneous recognition does not accumulate and the reliability is high compared to the method of searching for empty channels while memorizing the history. However, this method has drawbacks such as the need for a carrier detection circuit for each channel on the transmitting station side, and the fact that channels are secured by the continuation of carriers, so data transmission is often performed with carriers being interrupted midway. There is also.

<Object of the Invention> The present invention eliminates the need for a carrier detection circuit and eliminates the need for a carrier detection circuit by searching for an available channel using baseband packet transmission.
It describes a method that can also handle data (signals), and provides a data transmission system that can easily transmit data (signals) by using multiple networks.

<Example> Hereinafter, the present invention will be described in detail according to the embodiments shown in the drawings.

FIG. 1 is a diagram showing an example of a system configuration to which this method is applied. In the figure, 10 is a network, 11-
13 is a transmitting station, and 14 and 15 are receiving stations. Data (signals) are transmitted from the transmitting stations 11 to 3 to the receiving stations 14 to 5 via the network 10.

FIG. 2 is a block diagram showing a detailed example of the transmitting station shown in FIG. At the time of transmission, the control unit 20 first selects the channel (Vn) to be used by an appropriate method, packetizes it, and
It is sent to the above-mentioned network 10 via the baseband transmission line 21' and the baseband transmission section 21. At the time of packet transmission, it is assumed that a suitable concave line competition such as C3MA/CD is performed. After that, the channel/L'n is secured only if no transmission prohibition packet or non-permission response (NAK) from another transmitting station is received via the baseband receiver 22 and line 22' within a predetermined time. The modulation transmission section 23 is set to channel Vn by the channel select line 24, and the data (signal) is sent out via the data (signal) line 23' and the modulation transmission section 23.

On the other hand, if a transmitting station sends a packet that wishes to use this channel while another station is using channel lVn, the transmitting station currently using channel n will be prohibited in priority over other packets. By sending a packet or NAK, the right to use channel /I/n is asserted. The transmitting station denied the use of channel /L'n performs the same operation for other channels lVm, for example, and searches for empty channels.

FIG. 3 shows an example of a packet used for such a channel search. The packet includes a destination address 31, a self address 32, a control word 33, and a bite count 3.
4. Data 35 and frame check code 36. In this case, the destination address 31 is addressed to all other transmitting stations, and the desired channel is included in the data 35 and transmitted.

After acquiring a channel, in most cases it is necessary to notify the other receiving station that data will be transmitted using the acquired channel and to check whether data can be received. If there is a packet reception function, it is very difficult to perform this linking work using bucket 1-, and if the receiving station is configured to always pay attention to the above-mentioned channel, it is possible to perform this linking work directly using that channel. good. In any case, the acquired channel is on the verge of being no longer needed by the transmitting station and can be used continuously regardless of the presence or absence of carriers. Once the transmission is finished, the transmitting station will no longer send prohibited packets or NAKs for that channel.
stop the return function.

By the way, one way to select a channel to use is to register in memory the channel to be used each time you receive a broadcast packet for channel usage consultation, and when you want to use the channel, select it from memory. It is efficient to select an empty channel in advance and then secure the right to use the channel in the same manner as described above. In this case, when transmission ends, it is necessary to take appropriate actions such as broadcasting a packet for relinquishing the right to use the channel to all other transmitting stations and canceling the registrations in use.

FIG. 4 is a flowchart on the transmitting station side explaining the above operation, and FIG. 5 is a timing chart showing an example of data transmission. At point A on the timing chart, the transmitting station that has issued the transmission request selects a check IL/n randomly or based on past history, etc. (step S1), and uses packet 40 to check the use of vH. A consultation is conducted (step S2).

At this time, the transmitting station that happens to be using CHACK/l'n by signal 43 prohibits the use of that channel by transmitting NAK40' (steps S and o of other transmitting stations). When NAK'e is received (step 53), packet 41 is sent in the same way regarding the chat/I'm.
Step S1, S2) to send a NAK, confirm that the NAK has not been received, and acquire the right to use Chat/I'm in step S3. S4), and sends out data (signal) 44 (step S7). If you get the channel/I/m,
If another transmitting station asks for the right to use channel m by means of packet 42 (step s8. s!+), it transmits NAK 42' (step S+o) and prohibits this.

The dotted line in Fig. 4 shows the case where the link is established by basepan packet transmission after channel acquisition (not shown in the timing chart). As a notification, step S5) waits for ACK from the other station (step Sa) and establishes the link.

<Effects> As described above, according to this method, when transmitting and receiving data (signals) via some of multiple frequency channels, the transmitting station uses Broadcast all channels at once, and ban packets or NA within a specified time.
Only when K is not received, it is determined that the channel has been acquired, and from then on, data (signals) are transmitted using that channel. If it is pointed out, the channel can be used independently and continuously by returning a prohibited packet or NAK.
For example, it becomes possible to transmit high-speed data, data in various formats, or continuous signal transmission, and provides a useful data transmission system that effectively multiplexes buses.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a system configuration to which the method of the present invention is applied, FIG. 2 is a block diagram showing a detailed configuration example of a transmitting station, FIG. 3 is a diagram showing an example of a packet format, and FIG. The figure is a flow chart explaining the operation of the transmitting station, and FIG. 5 is a timing chart showing an example of data transmission. 10... Network, 11, 12, 13, transmitting station, 14, 15, receiving station, 20...
...-control section, 21 ...... baseband transmission section,
22... ...Baseband receiving section, 23.
...Modulation transmission section, 24 ...- ...Channel selection line, 21' ... -Baseband transmission line, 227 - ...Base Band reception line, 23'... Data (signal) line, 40, 41, 42, - Broadcast packet, 40'.
42'...NAK. 43・44...Signal (data). Agent Patent Attorney Aihiko Fukushi (and 2 others) 01) 3rd/)

Claims (1)

[Claims] l. Means for transmitting and receiving packets using baseband, or means for transmitting packets and transmitting and receiving ACK/NAK, which is connected to a network that transmits and receives signals through multiple channels including baseband through frequency multiplexing;
a plurality of transmitting stations each having at least means for transmitting a signal to each of some or all of the channels other than the baseband; and a plurality of transmitting stations connected to the network and receiving signals from each of some or all of the channels other than the baseband. In the system, the transmitting station selects a channel to be used at random or by a predetermined method, and sends packets containing the channel to all transmitting stations at once. 11 packets or non-permission response (NAK)
) is not received within a predetermined time, the user acquires the right to use the channel and sends/receives data or signals with the desired receiving station, while broadcasting the channel currently being used. A data transmission system characterized in that, after receiving the packet, a transmitting station that has been approached for the right to use the packet transmits a prohibition packet or a NAK, giving priority to other packets.