JPH11205315A - Multiple-address communication method using satellite channel and multiple-address communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the communication system where a reception station can surely recognize as to what files are sent by multiple-address communication and a satellite channel is effectively utilized. SOLUTION: A Web server 21 of a transmission station 20 sends a file list denoting files which are to be sent by multiple-address communication to a reception state via a general public telephone network 60 (or satellite channel) before a file is sent to a plurality of reception stations 31, 32,..., 3n by multiple- address communication via a satellite 10. The transmission station 20 confirms that the corresponding reception state receives the file list, and then it sends the file by multiple-address communication via a satellite channel. Each of the reception stations 31, 32,..., 3n compares the received file with the file list to surely recognize whether or not the reception of the file is finished. When the reception is not finished, each reception station makes a request to the transmission state 20 for re-transmission of the file via the general public telephone network 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transmitting station and a plurality of receiving stations connected to each other via a satellite line and a general public telephone network, and the transmitting station is connected to the plurality of receiving stations via a satellite line. The present invention relates to a broadcast communication method and a broadcast communication system for performing a broadcast communication of a file via a PC.

[0002]

2. Description of the Related Art In a conventional intranet service or Internet service, a general client and a Web server are connected via a general public network to provide a file transmission service. However, in the intranet service and the Internet service, in recent years, not only small-capacity text but also large-capacity files such as still images and moving images have been increasing as files to be transmitted. In the case of transmission of such a large-capacity file, file transmission takes a great amount of time in a service via the general public network because the transmission speed of the general public network is low. In order to reduce the file transmission time, systems using satellite communication instead of the general public network have been introduced.

[0003] In such a satellite intranet service or satellite Internet service, a client sends a Web request.
Since the file request signal to the server b has a small capacity, it is transmitted through a general public telephone network, and a file corresponding to the file request signal often has a large capacity, so a satellite line is often used. For example, when constructing a satellite intranet service system with one transmitting station and a plurality of receiving stations,
A plurality of receiving stations receive the same radio frequency carrier transmitted from the transmitting station, and the receiving stations receive necessary files. When a file request signal is output from the receiving station, the file is transmitted from the Web server of the transmitting station to the transmitting server, and then transmitted to the client via a satellite line.

[0004]

As described above, in the conventional communication service system, when the client issues a file request signal, the line condition of the satellite line is poor due to bad weather, and the requested file cannot be received or the receiving station cannot receive the file. Even if the requested file cannot be received due to the failure of the satellite receiving device, it is possible to recognize that the file has not been received, so that it is possible to take measures such as issuing a file retransmission request. However, in the case of a file that is distributed without the client issuing a file request signal, such as a file broadcasting service, the file cannot be received due to the line status of the satellite line or the failure of the satellite receiver at the receiving station. Even if there is no file, there is a problem that it is not known that the file has been sent. In such a case, it is difficult for the transmitting station to confirm whether all of the plurality of receiving stations have been able to reliably receive, so the same file is transmitted a plurality of times to increase the probability of receiving a file at the receiving station. It also prevents files from being missed at stations. However, sending the same file to the client a plurality of times via the satellite line is not efficient from the viewpoint of effective use of the satellite line.

The present invention has been made in view of the above problems, and when a file is broadcast, the receiving station can reliably recognize what file is sent by the broadcast, An object of the present invention is to provide a communication method and a communication system that do not need to send a file a plurality of times.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a communication system in which a transmitting station and each of a plurality of receiving stations are connected via a satellite line and a general public telephone network. In a communication method in which a transmitting station broadcasts a file to a plurality of receiving stations via a satellite line, the transmitting station may receive the broadcast before transmitting the file by broadcasting. A station and a file identifier are stored as a file list, and the file list is transmitted to a corresponding receiving station.When the receiving station receives the file list, the receiving station stores the file list and stores the file list. Transmitting to the transmitting station that the list has been received, the transmitting station confirming that all the corresponding receiving stations have received the file list, Is that performing the broadcast communication of the file.

According to such a configuration, before a file is sent from the transmitting station by broadcast, the receiving station obtains a file list indicating what file is sent by broadcast. be able to. On the other hand, the transmitting station can recognize whether or not all the corresponding receiving stations have received the file list from the response from the receiving station. The receiving station can then determine whether or not all the files have been received by comparing the file sent by broadcast with the file list. Thus, if the reception is not completed, the transmitting station can be requested to resend.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of a communication system using a satellite line and a general public telephone network according to the present invention, FIG. 2 is a block diagram showing an internal configuration of a Web server and a transmission server in FIG. 1, and FIG. FIG. 3 is a block diagram showing an internal configuration of a receiving station. As is apparent from FIG. 1, a communication system according to an embodiment of the present invention includes a satellite 10 for forming a satellite link and a satellite 1.
0, a transmitting station 20 using a satellite link between
A plurality of receiving stations 31, 32,
, 3n, and one end of each of the receiving stations 31, 32,.
n, lines L31, L32,..., L3n connected to each other, a general public telephone network 60 to which the other ends of the lines L31, L32,. L56, a router 50 connected to the other end of the line L56, a line L25 connecting the router 50 and the LAN L1, and a Web server (web server) arranged for exchanging data with the outside of the transmitting station 20 And a LANL2 to which the transmitting station 20 and the Web server 40 are connected.

The transmitting station 20 has LANL1 and LANL2
, A transmission server 22 connected to the LANL 1, and a satellite communication device 23 for transmitting a file transmitted from the transmission server 22 to the satellite 10. The satellite communication device 23 is connected to the transmission server 2
Modulator (MO) that modulates the file etc. sent from
D) 231, a transmission frequency converter (UP CONV) 232 for converting the transmission frequency of the output of the modulator 231, and a high power amplifier (HPA) 233 for amplifying the converted output.
And an antenna 234 for transmitting the output of the high power amplifier 233 to the satellite 10.

The Web server 21 of the transmitting station 20
As shown in FIG. 2, a LAN for interfacing with the transmission server 22 via the LAN when transmitting a file or the like.
An interface function unit 214, a storage unit 215 for storing information such as a broadcast service file, a LAN interface function unit 221 for taking an interface at the time of file transmission with the external Web server 40, and a router 50 of LANL1. It comprises an interface function unit 211 that takes an interface, a CPU 212 that controls and manages the entire Web server 21, and a distribution file list recording function unit 213 that stores a list of files to be distributed.

[0011] The transmission server 22 is connected to the Web via the LAN.
A LAN interface function unit 221 for interfacing with the server 21 and a satellite communication device interface function unit 224 for interfacing with the satellite communication device 23
And a storage unit 22 for storing information such as files to be distributed.
3 and a CPU 22 that controls and manages the entire transmission server 22
And 2.

The CPU 212 of the Web server 21 controls the following units based on a request received from the router 50 via the interface function unit 211. The distribution file list recording function unit 213 stores a list of files distributed by the Web server 21 via the transmission server 22 and the satellite communication device 23. The storage unit 215 stores a given file. The LAN interface function unit 216 accesses the Web server 40 and receives a necessary file when instructed by the CPU 212 (for example, when a necessary file does not exist in the storage unit 215). The LAN interface function unit 214
The file specified by the PU 212 is read out from the storage unit 215, and transferred to the LAN interface function unit 221 of the transmission server 22 so as to be transmitted to the specified destination.

In the transmission server 22, the CPU 2
22 stores the file received via the LAN interface function unit 221 in the storage unit 223,
It instructs the satellite communication device interface function unit 224 to transmit the file to the received destination. The satellite communication device interface function unit 224 reads the designated file from the storage unit 223, instructs the read file to be transmitted to the designated destination, and instructs the modulator 231 (FIG. 1) of the satellite communication device 23. hand over. The modulator 231 modulates the file sent from the transmission server 22, the transmission frequency converter 232 converts the frequency of the output, and the high power amplifier 233 amplifies the converted output.
The signal is transmitted from the antenna 234 to the satellite 10.

As shown in FIG. 1, each of the receiving stations 31, 3
Reference numerals 2, 3 and 3n denote antennas 311 and 111, respectively, for receiving signals transmitted from the satellite 10 via a satellite line.
312 to 31n and a tuner (LNB) 321,
322,..., 32n, and a satellite receiving terminal (computer) 331, which receives a signal addressed to the own station from signals from them.
332,..., 33n, and the satellite receiving terminals 331, 332,
Modems 341, 342, which connect .about.33n to the general public telephone network 60 via lines L31, L32,.
, 34n. As described above, each of the satellite receiving terminals 331, 332,..., 33n is constructed from substantially the same components, but this is for ease of explanation and is not limited to this. .

[0015] Satellite receiving terminals 331, 332, ..., 33n
Is configured as shown in FIG. 3, and software generally used on the Internet or an intranet is installed, and operates as a client in this system. Satellite receiving terminals 331, 332, ..., 33
n, the CPU 376 communicates via the local bus 374 or the bridge 375 and the PCI bus 373.
Each part is controlled via. The satellite reception card 371 receives data including file information and the like from the tuner 302 attached to the antenna 301.

The received data is stored in a memory 379 or a SCSI (Scuzzy; Small Computer System).
m Interface) 378 to the hard disk 380. The stored data that needs to be displayed is displayed on the display device 38 via the image processing card 372.
1 is displayed. A transmission / reception signal between the two via the general public telephone network 60 such as a request from the CPU 376 to the transmission station 20 is transmitted to the local bus 374, the interface 377, the modems 341, 342, to 34n, the lines L31, L32, ~, L3n, general public telephone network 60,
The communication is also performed via the line L56, the router 50, and the line L25.

Next, the operation of the above communication system will be described. A receiving station, for example, receiving station 31 is transmitting station 2
It is assumed that a file request signal has been issued to the device 0 via the line L31. The transmitting server 21 of the transmitting station 20 includes a general public telephone network 60, a line L56, a router 50, and a line L.
The interface function unit 211 receives a file request signal input via the interface 25. The CPU 212 searches the storage unit 215 based on the file request signal received by the interface function unit 211, and if there is a corresponding file, reads out the corresponding file from the storage unit 215 and sends it to the designated destination as necessary. It is delivered to the transmission server 22 for transmission via the satellite 10. The file transferred to the transmission server 22 is transmitted from the satellite communication device 23 via the satellite 10, and the receiving station 31 receives the file. If the requested file cannot be received due to bad weather or a malfunction of the satellite receiver, etc., the receiving station can recognize that the file cannot be received normally, so respond by requesting the file transmission again. it can.

A file based on the file request signal from the above-mentioned receiving station 31 (even when it is not based on the file request signal) may need to be broadcasted to other receiving stations 32-3n. In this case, a file list including a transmission destination and a file identifier indicating a file to be transmitted is recorded in the distribution file list recording function unit 213,
Before transmitting the file, the receiving station 3
1 to 3n. At this time, together with the transmission of the file list, a response to the reception of the file list is requested. If there is a file list reception response from all the corresponding receiving stations, the transmitting station 20 can confirm that all the corresponding receiving stations hold the file list.

On the other hand, if the receiving station that has received the file list cannot normally receive the file indicated by the file identifier in the file list, it determines that some abnormality has occurred. Along with this, it is possible to request that the corresponding file be transmitted again, and the broadcast transmission can be completely executed. In addition to requesting a reply so that all the receiving stations receive the file list, the file list of the broadcast may be transmitted periodically at a predetermined time. In this case, if the receiving station does not receive the file list at a predetermined time, it can determine that some abnormality has occurred and request the transmission of the file list again.

That is, in this communication system, the Web server 21 of the transmitting station 20 transmits a file to a plurality of receiving stations 31, 32,.
Before transmitting to the public telephone network 3n, a file list indicating what files are to be transmitted by broadcast is sent to the public telephone network 60.
(Or via satellite 10) to the receiving station. The transmitting station 10 confirms that the corresponding receiving station has received the file list, and transmits the file by broadcasting using a satellite line. The receiving station can reliably recognize whether or not the reception of the file has been completed by comparing the received file with the file list. If the reception has not been completed, for example, a request may be made to the transmitting station via the general public telephone network to transmit again.

[0021]

As described in detail above, in the communication method and communication system according to the present invention, the transmitting station and each of the plurality of receiving stations are connected via a satellite line and a general public telephone network. When the transmitting station broadcasts a file to the plurality of receiving stations via a satellite line, the transmitting station transmits the file by broadcasting.
The receiving station to receive the broadcast and the file identifier are stored as a file list, and the file list is transmitted to a corresponding receiving station.When the corresponding receiving station receives the file list, A list is stored, and the fact that the file list has been received is transmitted to the transmitting station.After confirming that all the corresponding receiving stations have received the file list, the transmitting station confirms that the file list has been received. Broadcast communication.

Thus, before a file is transmitted from the transmitting station by broadcasting, the receiving station can obtain a file list indicating what file is transmitted by broadcasting. On the other hand, the transmitting station can recognize that all the receiving stations have received the file list by responding to the reception of the file list from all the receiving stations. The receiving station then compares the file sent by broadcast with the file list,
It is possible to determine whether all the files have been received, and therefore, if the reception is not completed, it is possible to request the transmitting station to resend the data, and if the satellite communication function is impaired due to weather, etc., There is an effect that the receiving station can prevent the file from being missed even if the broadcast is not performed a plurality of times.

Further, if the above-mentioned broadcast communication is performed at a predetermined time, there is no retransmission request even if there is no response that the file list has been received from the receiving station. Can be automatically recognized. Except for transmission of large-capacity files, the satellite line can be used more effectively by using a general public telephone network.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a communication system using a satellite line and a general public telephone network according to the present invention.

FIG. 2 is a block diagram showing a Web server and a transmission server in FIG. 1 in detail.

FIG. 3 is a block diagram showing a receiving station of FIG. 1 in detail.

[Explanation of symbols]

1 ... communication system, 10 ... satellite, 20 ... transmission station,
21, 40 Web server, 22 transmission server, 2
3 ... satellite communication device, 31, 32, ..., 3n ... receiving station, 50 ... router, 60 ... general public telephone network, 231
… Modulator (MOD), 232… Transmission frequency converter (UP CONV), 233… High power amplifier (HP)
A), 234, 311, 312, ..., 31n ... antenna, 321, 322, ..., 32n ... tuner (LN
B), 331, 332,..., 33n...
341, 342, ..., 34n Modem, L31, L3
2, ~, L56 ... line.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04L 12/58 H04L 11/20 101B // H04N 7/173

Claims (7)

[Claims] 1. A transmitting station and each of a plurality of receiving stations are connected via a satellite line and a general public telephone network, and the transmitting station transmits the file to the plurality of receiving stations via a satellite line. In the broadcast method for performing broadcast, the transmitting station stores a receiving station to receive the broadcast and a file identifier as a file list before transmitting the file by broadcast, and the file Transmitting the list to a corresponding receiving station, the corresponding receiving station, when receiving the file list, stores the file list and transmits to the transmitting station that the file list has been received; The station performs the broadcast of the file after confirming that all the corresponding receiving stations have received the file list. Communication method. 2. A transmitting station and each of a plurality of receiving stations are connected via a satellite line and a general public telephone network, and the transmitting station transmits the file to the plurality of receiving stations via a satellite line. In the broadcast communication method of performing the broadcast communication, the transmitting station stores a receiving station to receive the broadcast communication and a file identifier as a file list before performing the broadcast communication, and Transmitting the file list at a predetermined time to the receiving station, and when the corresponding receiving station can receive the file list at the time, stores it, and only when the file list cannot be received, The transmitting station requests retransmission of the file list, and when the transmitting station is not requested to retransmit the file list within a predetermined time after the time, the transmitting station receives the file list. A broadcasting method comprising the step of performing broadcasting of the file after confirming that the file has been taken. 3. The broadcast method according to claim 1, wherein the transmission of the file list from the transmitting station and the transmission of a response or request from the receiving station are performed via the general public telephone network. 4. A transmitting station and each of a plurality of receiving stations are connected via a satellite line and a general public telephone network, and the transmitting station transmits the file to the plurality of receiving stations via a satellite line. In a broadcast communication system that performs broadcast communication, the transmitting station stores the receiving station to receive the broadcast and a file identifier as a file list before transmitting the file by broadcast, and It has a file list transmitting means for transmitting a list to a corresponding receiving station, and the corresponding receiving station, when receiving the file list addressed to itself, stores the file list and receives the file list. Further comprising a file list receiving means for transmitting a message to the transmitting station, wherein the transmitting station receives the file list from all of the receiving stations. A broadcast communication system comprising a file broadcast communication means for performing broadcast of the file after confirming that the file has been taken. 5. A transmitting station and each of a plurality of receiving stations are connected via a satellite line and a general public telephone network, and the transmitting station transmits a file to the plurality of receiving stations via a satellite line. In a broadcast communication system that performs broadcast communication, the transmitting station stores a receiving station to receive the broadcast communication and a file identifier as a file list before performing the broadcast communication, and File list transmitting means for transmitting at a predetermined time to the receiving station to perform, the corresponding receiving station, when it can receive the file list at the time, stores and receives it Means for requesting retransmission of the file list only when the transmission has failed, and the transmitting station transmits the file list within a predetermined time after the time. A broadcast communication system, comprising: a file broadcasting means for performing a broadcast of the file when the receiving station confirms that the file list has been received, when not requested. 6. The broadcast communication system according to claim 4, wherein the transmission of the file list from the transmitting station and the transmission of a response or a request from the receiving station are performed via the general public telephone network. 7. The transmitting station comprises: a satellite communication device for transmitting and receiving communication with the satellite; and a web server having one end connected to the satellite communication device and the other end connected to the general public telephone network via a router. And a transmission server, wherein each of the plurality of receiving stations is connected to the transmitting and receiving device for transmitting and receiving communication with the satellite, and is connected to the transmitting and receiving device.
A satellite receiving terminal that operates as a W client; and a modem that connects the satellite receiving terminal to the general public telephone network via a line. The file list transmitting unit transmits the file list to the web server. Storing the file indicated in the file list for the transmission server, and transmitting the file list stored by the web server via the general public telephone network or a satellite communication device, The file list receiving means drives a satellite receiving terminal to store the file list in the satellite receiving terminal, and the file broadcast communication means causes the web server to receive the file list by the satellite receiving terminal. Confirm, when there is confirmation of reception, instruct the web server, the file list Are files and the transmission server has, broadcast system according to claim 4 or 5, wherein the satellite communication device is adapted to broadcast via satellite.