JP3268874B2 - Data distribution system and method using communication satellite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for delivering data or information to a plurality of receiving stations in real time using a communication satellite.

[0002]

BACKGROUND ART From a technical point of view, data communication using a communication satellite is 1) one-way communication in which data flows in only one direction from a transmitting station to a receiving station, and 2) a large number of data distributed over a wide range. It has the feature that it can be transmitted (distributed) simultaneously to the receiving station.

[0003] 1) One-way communication means that when an error such as data loss occurs, a retransmission request cannot be sent from a receiving station to a transmitting station via a satellite. Therefore, if real-time retransmission is to be performed when an error occurs, it is necessary to consider using a terrestrial network (public communication line, dedicated communication line, etc.) in a complementary manner.

[0004] On the other hand, from an economical point of view, communication satellites require a high initial investment, after which only maintenance costs are required. If you have available communication satellites, their running costs will be lower. On the other hand, in data distribution using a terrestrial network, a fee is charged each time the network is used. As the number of receiving stations increases, and the farther the transmitting station and the receiving station are, the more money is charged.

The weak point of communication using a communication satellite is rain. Rainfall can disrupt communications for quite some time. Also, data transmission to only some of the receiving stations may be temporarily impossible due to local rainfall.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to retransmit lost data in real time even if an error occurs, by using a complementary terrestrial network in data distribution using a communication satellite. It is in.

It is another object of the present invention to minimize the amount charged for data retransmission using a terrestrial network.

It is still another object of the present invention to sufficiently cope with a situation where communication is interrupted for a considerably long time due to rainfall or other obstacles, thereby ensuring real-time data distribution.

A data distribution system using a communication satellite according to the present invention transmits a distribution data to a communication satellite using a protocol suitable for broadcast distribution, and receives data distributed through the communication satellite. A receiving device, capable of communicating with the receiving device via a terrestrial network and a communication satellite, storing data transmitted by the transmitting device, and transmitting data requested to be retransmitted when a retransmission request is received from the receiving device; And a retransmitting device for transmitting to the receiving device.

[0010] The transmission device includes a distribution data editing unit for performing an editing process including a process of adding a serial number incremented for each data distribution to the data to be distributed, and a distribution data edited by the distribution data editing unit. There is provided a transmitting means for transmitting data to the communication satellite.

[0011] The receiving device is a receiving means for receiving distribution data transmitted from a communication satellite. The receiving means compares the serial number added to the data received this time with the serial number of the previously received data. Check the serial number,
A first retransmission request processing means for requesting the retransmission device to perform a first retransmission through the terrestrial network when it is determined that there is a missing number; and a communication satellite from the retransmission device in response to the first retransmission request. The retransmission data to be delivered is checked, and when it is determined that there is an error in the first data retransmission, a second retransmission is requested to the retransmission device through the terrestrial network, and in response to this, the retransmission device is Second retransmission request processing means for receiving data to be retransmitted through a terrestrial network.

[0012] The retransmitting device comprises: first retransmission processing means for transmitting data requested to be retransmitted to a communication satellite when receiving a first retransmission request from the receiving device; A second step of transmitting data requested to be retransmitted when the second retransmission request is received to the receiving apparatus requested to perform the second retransmission via the ground network;
Is provided.

The transmitting device and the retransmitting device may be realized by one work station, or may be realized by separate work stations and connected by a communication line.

In a preferred embodiment of the present invention, the transmitting device and the retransmitting device are constituted by separate work stations. In this case, the transmission device and the retransmission device are communicably connected through a transmission path.

[0015] The transmitting device is means for transmitting distribution data to the retransmitting device via a transmission line, and when receiving a retransmission request from the retransmitting device, retransmits the requested data to the retransmitting device via the transmission line. Means for performing

[0016] The retransmitting device receives the distribution data transmitted through the transmission path, and compares the serial number added to the data received this time with the serial number of the previously received data. And a retransmission to the transmitting device when the serial number management processing means determines that there is a missing number between the serial number of the currently received data and the serial number of the previously received data. It has a retransmission request processing means for requesting.

The present invention also provides a receiving device effectively used in the above data distribution system.

[0018] The present invention further provides a data distribution method using a communication satellite. This method enables a transmitting station and a plurality of receiving stations to perform one-way communication via a communication satellite. It is assumed that two-way communication is connected via the.

The transmitting station distributes the distribution data to the receiving station via the communication satellite by adding a serial number which is incremented every time the data is distributed, and stores the distributed data.

When the receiving station receives the data distributed via the communication satellite, the receiving station checks the serial number of the received data. The first retransmission request is made.

When the transmitting station receives the first retransmission request, it retransmits the requested data to the receiving station via the communication satellite.

The receiving station checks the retransmitted data in response to the first retransmission request, and when it is determined that there is an error in the data retransmission, the receiving station sends the data to the transmitting station through the terrestrial network. Request for retransmission.

In response to the second retransmission request, the transmitting station retransmits the requested data via the terrestrial network to the receiving station that issued the second retransmission request.

According to the present invention, since data is distributed using a communication satellite, even if the receiving stations (receiving apparatuses) are scattered over a wide range or if a large number of receiving stations are present, the distribution is performed. No data is charged every time, and data delivery can be achieved at low cost except for initial investment.

The transmitting station (transmitting device and retransmitting device) and the receiving station (receiving device) can communicate via a terrestrial network. Therefore, even if data is lost due to rainfall or the like, the receiving station can make a retransmission request to the transmitting station through the terrestrial network.

In response to the first retransmission request, the transmitting station
Redistribute the data requested to be retransmitted through the communication satellite.
Since the data is redistributed via the communication satellite for the first retransmission request, only the use of the terrestrial network for the retransmission request from the receiving station to the transmitting station is charged. , Redelivery can also be achieved at low cost. Moreover,
Even if there is a transmission request for the same data from a plurality of receiving stations, only one re-delivery is required.

If there is still an error such as missing data as a result of redistribution in response to the first retransmission request, the receiving station makes a second retransmission request via the ground network in the same manner. . For this second retransmission request,
The transmitting station retransmits the data via the terrestrial network to the receiving station that has requested retransmission. Since communication via a terrestrial network uses a communication protocol that guarantees reliability, highly accurate data retransmission can be realized.

As described above, according to the present invention, even if an error occurs in data distribution, the corresponding data can be retransmitted and complemented in real time. In addition, since communication satellites are used as much as possible and the use of the terrestrial network to be charged is minimized, the charged amount can be kept low.

The data distribution system using a communication satellite according to the present invention is also configured to detect a failure that communication is interrupted for a predetermined time or more, and to appropriately deal with the failure to ensure real-time data. I have.

That is, the data distribution system using the communication satellite according to the present invention directs the distribution data to which the serial number is incremented for each data distribution to the communication satellite by using a protocol suitable for broadcast distribution. A transmitting device for transmitting, a receiving device for receiving data distributed through a communication satellite, and a communicable device with the receiving device via a terrestrial network and a communication satellite, storing the data transmitted by the transmitting device; And a retransmission device for transmitting data requested to be retransmitted to the receiving device when a retransmission request is received from the device.

When there is no data to be distributed even after the first fixed time has elapsed since the last data distribution, the transmitting device adds the updated serial number by incrementing the dummy data. Is provided via a communication satellite.

[0032] The receiving device may perform a dummy operation for a second fixed time equal to or longer than the first fixed time.
Failure monitoring means for checking whether or not distribution data including data has been received, and determining that a failure has occurred when distribution data including dummy data has not been received for the second predetermined time or more; A failure notification unit is provided for transmitting a failure notification including a serial number of distribution data not received due to the failure to the retransmitting device via the terrestrial network when the determination is made.

The retransmitting device has means for retransmitting requested data to the receiving device via a terrestrial network when a failure notification is received.

This distribution system also has a failure recovery function. That is, when receiving the distribution data via the communication satellite after the occurrence of the failure, the receiving device sends a restoration notification including the last serial number of the distribution data not received due to the failure to the retransmission device via the terrestrial network. The retransmission device of the retransmitting device further includes a recovery notifying unit for transmitting, and retransmits data up to the last serial number included in the recovery notification to the receiving device via the terrestrial network.

According to the data distribution method using a communication satellite according to the present invention, a transmitting station and a plurality of receiving stations are connected so as to be capable of one-way communication via a communication satellite and two-way communication via a terrestrial network. It is something to keep.

The transmitting station distributes the distribution data to the receiving station via the communication satellite by adding a serial number which is incremented each time the data is distributed, and stores the distributed data, and stores the data in the previous data distribution. Thereafter, if there is no data to be distributed even after the first fixed time has elapsed, the dummy data is distributed via the communication satellite by adding the updated serial number by being incremented.

At the receiving station, during the second fixed time period equal to or longer than the first fixed time period, the dummy dummy signal is output.
It checks whether or not distribution data including data has been received, determines that a failure has occurred when distribution data including dummy data has not been received for the second predetermined time or more, and determines that a failure has occurred. A failure notification including a serial number of distribution data not received due to the failure is transmitted to the transmitting station via the terrestrial network.

When the transmitting station receives the failure notification, it retransmits the requested data to the receiving station via the terrestrial network.

Further, when the receiving station receives the distribution data via the satellite after the occurrence of the failure, a recovery notification including the last serial number of the distribution data not received due to the failure is transmitted to the transmitting station via the terrestrial network. Send.

The transmitting station retransmits the data up to the last serial number included in the recovery notice to the receiving station via the terrestrial network.

As described above, according to the present invention, when data distribution via a communication satellite is interrupted for a predetermined time or more, data that could not be distributed due to the failure is retransmitted via a terrestrial network. Real-time property can be secured. When the fault is restored, it returns to data distribution using communication satellites again.
Only the data lost due to the failure is correctly retransmitted and complemented.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall configuration of a data distribution system using a communication satellite.

This data distribution system is roughly divided into a transmitting station, a receiving station, and a communication satellite 1 and a terrestrial network 2 serving as a medium for communication between these two stations.
It is composed of

The transmitting station transmits a radio wave carrying data to be distributed to the communication satellite 1, and transmits data from at least two work stations 13, 14, and work stations 13, 14. It includes a router 12 for distributing to the transmitter 11 or the terrestrial network 2, and a transmission line 15 for connecting the router 12 with the work stations 13, 14.

The work station 13 functions as a transmission device 30 described later, and the work station 14 functions as a retransmission device 40.
Work as The functions of the transmitting device 30 and the retransmitting device 40 may be realized by one work station. By providing the retransmission-only device 40 separately from the transmission device 30, a buffer having a large capacity for storing data to be retransmitted can be secured.

Generally, a plurality of receiving stations are provided in a distributed manner. Each receiving station includes a receiver 21 for receiving radio waves from the communication satellite 1 and demodulating data, a router 22, one or more work stations 23, and a transmission line connecting the router 22 and the work stations 23. Contains 25. Router
The reference numeral 22 sends the data received from the receiver 21 to the transmission line 25 and transmits the message from the work station 23 to the ground network 2. The work station 23 functions as a receiving device 50 described later.

Transmission lines 15 and 25 are connection type TCP /
IP (Transmission Control Protocol / Internet Pro)
tocol) and connectionless (suitable for broadcast) UDP / IP (User Datagram Protocol / Internet)
Protocol) can be used for data transmission. For example, an Ethernet LAN
(Local Area Network) or WAN (Wide Area Network)
ork) is used. Work stations 13, 14, 23
Also include computers that can use these communication protocols. The terrestrial network 2 is an existing or future laid public line or dedicated line.

FIG. 2 shows the transmitting device 30 (work station 13) and the retransmitting device 40 (work station) of the transmitting station.
14) and the functional configuration of the receiving device 50 (work station 23) of the receiving station, and the flow of data between and within them. Various "processes" or applications or I / Fs (interfaces) to be described later are realized by operations of a computer according to a processing program (process or program module).

The transmitting device 30 performs a distribution process 31,
It includes a buffer 32 and a retransmission process 33.

The retransmitting device 40 performs the receiving process 41,
Buffer 42, retransmission buffer write processing 43, retransmission request processing
44, retransmission data buffer 45, satellite retransmission buffer 46,
It includes a retransmission transmission process 47 and a retransmission response process 48.

The receiving device 50 includes a reception process 51, a reception data buffer 52, an application distribution process 53, a data reception buffer 54, an application 55, and a data acquisition I / F.
56, a retransmission request process 57 and a retransmission data buffer 58 are included.

The receiving device 50 generally includes a plurality of applications 55 (only applications of Nr. 1 are shown), and each application 55 is accompanied by a data acquisition I / F 56. The plurality of applications 55 execute different processes. For example, an application displays the distributed individual data in the form of a table on the screen of the display device, and updates the display on the display screen every time new individual data is obtained. Another application displays the distributed individual data in the form of a graph on the display screen of the display device. Still other applications indicate when a transmission error has occurred. Thus, some of the applications will be invoked by the user of the receiving device 50 (computer) and some will be launched by other processing programs of the receiving device 50. These multiple applications 55
Are assigned identification numbers Nr.1 to Nr.m.

Blocks to be described later from the transmitting station to the receiving station
From the broadcast distribution of data, that is, from the distribution processing 31 of the transmitting device 30, all the receiving devices 50 via the transmission path 15, the router 12, the transmitter 11, the communication satellite 1, the receiver 21, the router 22, and the transmission path 25 Of the block data to the receiving process 51 is performed using UDP / IP (the route is indicated by a broken line).

The same block data that has been distributed from the transmitting station to the receiving station is transmitted from the transmitting device 30 to the retransmitting device 40 in the transmitting station and stored. The transmission of block data from the transmitting device 30 to the retransmitting device 40 in the transmitting station, that is, the receiving process 41 via the transmission line 15 from the distribution process 31
The transmission of the block data to is also performed using UDP / IP (the path is shown in broken lines). The block data received by the reception processing 41 is temporarily stored in the reception data buffer 42 as described later in detail, and then stored in the satellite retransmission buffer 46 by the retransmission buffer writing processing 43.

In the transmitting station, from the transmitting device 30 to the retransmitting device
When an error occurs in the block data transmitted to 40, a retransmission request is given from retransmission request processing 44 of retransmission apparatus 40 to retransmission processing 33 of transmission apparatus 30. In response to the retransmission request, the retransmission processing 33 retransmits the block data requested to be retransmitted to the retransmission request processing 44. Such communication between the retransmission processing 33 and the retransmission request processing 44 is performed using TCP / IP through the transmission path 15 to increase reliability (the path is indicated by a solid line). The retransmitted block data passes through a retransmission data buffer 45 and is stored in a satellite retransmission buffer 46 by a retransmission buffer writing process 43.

When an error occurs in the block data broadcast from the transmitting station to the receiving station, a retransmission request is given from the receiving station to the transmitting station. This retransmission request is generated by a retransmission request process 57 of the receiving device 50, and is given to a retransmission response process 48 of the retransmitting device 40 via the transmission path 25, the router 22, the terrestrial network 2, the router 12, and the transmission path 15. The retransmission request from the receiving station to the transmitting station via the terrestrial network 2 is performed using TCP / IP that guarantees reliability (the route is indicated by a solid line).

In response to the first retransmission request, the transmitting station retransmits (re-distributes) the block data requested to be retransmitted to the receiving station via the communication satellite 1. That is, the retransmission processing 47 of the retransmission device 40 reads the corresponding block data from the satellite retransmission buffer 46, and transmits the block data to the transmission path 15, the router 12, and the transmitter.
11, via the satellite 1, the receiver 21, the router 22, and the transmission path 25, the retransmission request processing 57 of the reception device 50 is retransmitted using UDP / IP (the path is indicated by a broken line). As described above, for the first retransmission request, the block data is redistributed to all the receiving devices 50 via the communication satellite 1. Since the ground network 2 is not used, communication costs can be reduced.

For the second retransmission request for the same block data, retransmission is performed using TCP / IP via the terrestrial network 2 to ensure reliability (the route is indicated by a solid line). Shown). That is, in response to the second retransmission request, the retransmission response process 48 reads the corresponding block data from the satellite retransmission buffer 46, and transmits the transmission path 15, router 12, terrestrial network 2, router 22, transmission path 25 Is transmitted to the retransmission request processing 57 of the receiving apparatus 50 that has made the second retransmission request.

Even if no data has arrived at the receiving station for a certain period of time or longer, that is, if no communication is established, the retransmission request processing 57 and the retransmission response processing 48 are performed using TCP / IP through the terrestrial network 2. The retransmission response process 48 retransmits the missing block data to the retransmission request process 57 in response to the retransmission request.

The destinations for such broadcast distribution, retransmission request, retransmission, and the like are identified by using the addresses of the devices 30, 40, and 50 (work stations) and performing various processes 51, 5
7 and 48 are each achieved using port numbers.

As an example of real time data broadcast from the transmitting station to the receiving station, there is information that fluctuates every moment such as stock market value information, foreign exchange transaction information, and news information generated at various exchanges. . The transmission device 30 includes a plurality of information sources (for example, computers provided at various exchanges and the like).
And a public line, a dedicated line, and other appropriate media. The transmission device 30 includes an internal transmission buffer (not shown), and real time data (referred to as individual data) transmitted from these information sources is stored in the internal buffer.

FIG. 3 shows a format of block data transmitted from the transmitting device 30 to the receiving device 50 or transmitted from the transmitting device 30 to the retransmitting device 40. UDP / I
Illustration of header information according to P or TCP / IP is omitted.

A plurality of individual data obtained from each information source are distributed in blocks as described later. The message type, block and
Codes indicating the data length, status, number, crash count and serial number are added.

The message type code is real time
Data (data stored in the real data storage file of the communication device 30), dummy data (described later),
Indicates whether the data is status data.

The block data length code indicates the data length of this block.

The status code has a meaning when the message type code is status data, and indicates a state of the transmission device 30 such as whether the transmission device 30 is normal, abnormal, operating, or stopped.

The number has a meaning when the message type code is real time data, and indicates the number of individual data included in this block.

The crash count indicates the number of times the transmission device 30 has become abnormal and has been restarted.

The serial number indicates the order in which the block data is distributed, and is incremented by one each time one block data is distributed. This serial number is, as described later, the block number received by the retransmission device 40 and the reception device 50.
It is effectively used to check for missing data.

When the message type is real-time data, these codes are followed by a plurality of individual data. Each individual data has a data type (information source ID =
Information source identification code) and the code of the individual data length are attached. If all the individual data included in one block are of the same data type (obtained from the same information source), the data type code need only be assigned to one location.

FIGS. 4 and 5 show that the transmitting device 30 is a communication satellite 1
This shows the procedure of transmitting the same block data from the transmitting apparatus 30 to the retransmitting apparatus 40 when the block data is broadcasted to the receiving apparatus 50 through the retransmission apparatus 40, and the retransmitting apparatus 40 receives the same block data.

The distribution process 31 of the transmission device 30 always executes the distribution of real time data. The real time data (individual data) obtained from the information source is sequentially stored in the internal buffer of the transmitting device 30 as described above. The distribution process 31 constantly monitors the state of accumulation of the individual data in the internal buffer. Each time a fixed time T1 (for example, several hundred milliseconds) elapses after the last (previous) data distribution, it is checked whether or not there is individual data in the internal buffer. Create block data according to the format. Or
If the total data length of the individual data stored in the internal buffer exceeds a predetermined data length before the predetermined time T1 elapses after the last data distribution, the block data is similarly used using the individual data. Edit the data. It goes without saying that serial numbers are added in the editing of the block data. The serial number is counted by the serial number counter,
This serial number counter is incremented by one every time block data is delivered (including dummy data and status data delivery). The distribution processing 31 transmits the edited block data to a protocol UD suitable for broadcast distribution.
The data is transmitted to the transmission line 15 by P / IP (step 101). The block data sent to the transmission line 15 is transmitted to the router 12 and the transmitter.
The signal is transmitted to the communication satellite 1 via the transmission line 15 and is given to the reception processing 41 of the retransmission device 40 through the transmission path 15. Note that the transmission device 30 does not necessarily need to process (format conversion, etc.) the individual data obtained from the information source. Of course, some processing may be performed, but without
Is operable.

Thereafter, the distribution processing 31 stores the block data broadcasted in the retransmission data buffer 32 in preparation for a retransmission request from the retransmission device 40 (step 102).

Further, the distribution processing 31 is performed when no new individual data is stored in the internal buffer even after a lapse of a predetermined time T2 (for example, several seconds) after the last (previous) data distribution, that is, this predetermined time If no data has arrived from any information source during T2, the dummy data block is edited and broadcasted with the updated serial number (step 103). The dummy data block has no individual data in the data format shown in FIG. 3, and is obtained by editing only the codes from the message type to the serial number. This dummy data
The block is also transmitted from the transmitter 11 to the communication satellite 1 and received by the retransmission device 40 via the transmission path 15.
Is transmitted to

The receiving process 41 of the retransmitting device 40 includes the block data (real data) transmitted from the distribution process 31 via the transmission path 15.
When receiving not only time data but also dummy data blocks, the received block data is temporarily stored in the reception data buffer 42 (step 111).
), And notifies the retransmission buffer write processing 43 of the arrival of the block data (step 112).

Upon receiving this notification, the retransmission buffer write processing 43 reads the reception block data stored therein from the reception data buffer 42 and checks the serial number included in the reception block data. (Step 121).

The retransmission buffer write processing 43 stores the correct serial number of the previously received block data. If the serial number of the block data received this time is equal to the value obtained by adding 1 to the serial number of the previous received data, the serial number of the current received data is correct. If the difference between the serial number of the current received data and the serial number of the previous received data is 2 or more,
It is determined that the received data is missing for some reason.
If the current reception data is equal to the serial number of the previous reception data, the current reception data is the same as the previous reception data.

When the transmitting device 30 is down and restarted, the serial numbers are reset, so that continuity of serial numbers cannot be maintained. In this case, the retransmission buffer writing process 43 determines that the current serial number is correct. Whether or not the transmitting device 30 has been restarted is determined by the crash count code.

If it is determined by the serial number check that the current reception data is continuous with the previous reception data, the retransmission buffer writing process 43 transmits the reception data to the satellite retransmission buffer.
46, and prepares for a retransmission request from the receiving device 50 (step 122).

When the retransmission buffer writing process 43 finds a missing serial number, it requests the retransmission request process 44 to retransmit the missing block data (step 123).
).

When this retransmission request is received, retransmission request processing 44
Requests the retransmission process 33 of the transmission device 30 to retransmit the missing serial number and the data block of the serial number via the transmission path 15 by TCP / IP (step 131).

The retransmission processing 33 reads out the block data of the serial number requested to be retransmitted from the retransmission data buffer 32 and transmits the data to the retransmission request processing 44 of the retransmission device 40 through the transmission path 15 using TCP / IP. (Step 141).

Upon receiving the retransmitted data block, the retransmission request processing 44 stores it in the retransmission data buffer 45 (step 132). When a retransmission request is issued for two or more serial numbers, all data
The above process is repeated until a block is received. When all data blocks have been received, the retransmission buffer writing process 43 is notified that the retransmission process has been completed (step 133).
).

After the retransmission buffer writing process 43 issues a retransmission request, the retransmission buffer writing process 43 enters a standby state until the retransmission request process 44 notifies the end of the retransmission process. In this standby state (that is, during the retransmission process), if a data block is distributed by the transmitting device 30 through the communication satellite 1, the same data block is received by the reception process 41 through the transmission line 15. The reception process 41 stores the received data block in the reception data buffer 42 in the order of reception, and the retransmission buffer writing process 43 does not read it (step 124).

The serial number of the data block received in the standby state is larger than the serial number of the data block for which retransmission is requested. Generally, individual data is generated every moment in an information source. Therefore, the order of the serial numbers corresponds to the order of occurrence of the individual data, and the data with the smaller serial number is the data generated earlier. Storing the data in the satellite retransmission buffer 46 while keeping the time order will not cause confusion. Therefore, in order to store the data requested to be retransmitted (data generated earlier in time order) in the satellite retransmission buffer 46, the data generated later with the larger serial number is queued.

When the retransmission buffer write processing 43 receives the notification of the end of the retransmission processing, it receives the retransmitted data block from the retransmission data buffer 45, checks the serial number of the retransmitted data block, and if the result is OK. Retransmitted block data for satellite retransmission buffer
Write to 46 (step 125). Serial number check result is NG
In this case, it will return to step 123 and request retransmission again.

Thereafter, the retransmission buffer write processing 43 reads the queued data block in the reception data buffer 42 and checks the serial number (step 12).
6) If the serial number check is OK, write it into the satellite retransmission buffer (step 122), and if it is NG, issue a retransmission request (step 123).

As described above, in parallel with the delivery of the block data from the transmitting device 30 to the receiving device 50, the same data as the delivered block data is stored in the satellite retransmission buffer 46 of the retransmitting device 40. , In response to a retransmission request from the receiving device 50.

FIG. 6 mainly shows a transmitting apparatus through the communication satellite 1.
Receiving device that receives block data distributed from 30
50 shows the flow of processing in 50. The operation (steps 101 to 103) of the distribution process 31 of the transmitting device 30 is the same as that shown in FIG.

Application distribution processing 53 of receiving apparatus 50
Contains a request management table and a queue buffer.

The application 55 of the receiving device 50 notifies the type of data to be obtained to the application distribution process 53 through the data obtaining I / F 56 (step 171).
). The type of data to be acquired may be input by the user, may be determined on a program or a table, or may be one or both.

Upon receiving this notification, the application distribution process 53 proceeds to the identification number Nr.
And the requested data type are registered in the request management table (step 161).

The receiving process 51 of the receiving device 50 is performed when receiving block data (not only real-time data blocks but also dummy data blocks) distributed via the communication satellite 1. The obtained block data is stored in the reception data buffer 52 (step 151).
The application delivery process 53 is notified that the data block has arrived (step 152).

Upon receiving this notification, the application distribution process 53 reads the received data block stored therein from the received data buffer 52 and checks the serial number contained in the received data block ( Step 162).

The application distribution processing 53 is the same as the retransmission buffer writing processing 43, and
Remembers the correct serial number of the data. If the serial number of the block data received this time is equal to the value obtained by adding 1 to the serial number of the previous received data, the serial number of the current received data is correct. If the difference between the serial number of the current reception data and the serial number of the previous reception data is 2 or more, it is determined that the distribution data is missing for some reason. Also, if the current received data is equal to the serial number of the previous received data,
The received data this time is duplicated with the previous one.

When the transmitting device 30 is down and restarted, the serial numbers are reset, so that continuity of serial numbers cannot be maintained. In this case, the application distribution process 53 determines that the current serial number is correct. Whether or not the transmitting device 30 has been restarted is determined by the crash count code.

The application distribution processing 53 decomposes the data blocks that have passed the serial number check into individual data (step 163). The data type is attached to the individual data. On the other hand, the request management table stores the data type requested by the application 55 corresponding to the identification number Nr. The application delivery process 53 looks at the request management table, and among the received individual data, sends the individual data of the type requested by the application 55 to the data transfer buffer 54.
And notifies the data acquisition I / F 56 of the requesting application 55 of the arrival of data (step
163). This process is performed for all applications 55 registered in the request management table.

The data acquisition I / F 56 that has received the notification
The requested individual data is read from the data transfer buffer 54 and passed to the corresponding application 55 (step 172). The application 55 uses the individual data obtained in this way to execute a process unique to the application.

FIGS. 7 and 8 show that when the application distribution process 53 of the receiving apparatus 50 determines that there is a missing serial number in the serial number check and makes a retransmission request, the retransmitting apparatus 40 responds to the retransmission request and Receiving device for data block
50 shows the flow of the retransmission process.

If it is determined that one or a plurality of serial numbers are missing, the first retransmission request (hereinafter referred to as retransmission request 1) is transmitted from retransmission request processing 57 via terrestrial network 2 as described above. Then, it is given to the retransmission response process 48 using TCP / IP. Resend transmission processing 47 in response to this
Transmits the requested serial number data block to the retransmission request process 57 using the UDP / IP via the communication satellite 1. FIG. 7 shows the flow of the first retransmission request process.

If no data block is received after a certain period of time for retransmission request 1, or if missing data is found again in the retransmitted data, retransmission request processing 57 performs the second retransmission request process 57. A retransmission request (referred to as retransmission request 2) is transmitted to the retransmission response process 48 via the terrestrial network 2 using TCP / IP. In response to this, the retransmission response processing 48 performs TCP / IP via the terrestrial network 2.
Is used to retransmit the requested data block. This is the flow of the process shown in FIG.

First, the procedure for the first retransmission request will be described. Referring to FIG. 7, the application distribution process 53 performs a serial number check (step 162 in FIG. 6).
If a missing serial number is found, a request is made to the retransmission request process 57 to retransmit the block data of the missing serial number (step 164).

When this retransmission request is received, retransmission request processing 57
Notifies the retransmission response process 48 of the retransmission device 30 of the missing serial number and requests retransmission of the data block of that serial number (retransmission request 1) (step 171). This retransmission request message includes a code indicating that the request is retransmission request 1.

The retransmission response process 48 determines whether the received retransmission request message is retransmission request 1, and if so, transfers this retransmission request message to the retransmission process 47 (step 18).
1).

The retransmitting device 47 manages the serial number of the data block requested to be retransmitted. As described above, for the retransmission request 1, the serial number data block for which the retransmission request has been made is distributed to all the receiving devices 50 via the communication satellite 1. Therefore, it is not necessary to retransmit the data block of the same serial number many times each time there is a retransmission request from the receiving device 50. Therefore, the retransmission transmission processing 47 checks whether or not a retransmission request has already been made from another receiving device for the sequence number for which retransmission has been requested, and does not retransmit the data block for that sequence number if retransmission has already been performed (step 191). ).

For the serial number for which a retransmission request has been made for the first time,
The retransmission transmission process 47 reads the data block of the corresponding serial number from the satellite retransmission buffer 46 and distributes it to all the receiving devices 50 through the communication satellite 1 (step 192).

Upon receiving the retransmitted data block, retransmission request processing 57 of receiving apparatus 50 that has issued the retransmission request stores the retransmitted data block in retransmission data buffer 58 (step 172).
When a retransmission request is issued for two or more serial numbers, the above process is repeated until all data blocks for which retransmission has been requested have been received. When all data blocks have been received, retransmission request processing 57 proceeds to retransmission processing. The application distribution processing 53 is notified that the processing has been completed (step 173).

The application distribution process 50 enters a standby state until a retransmission request is issued from the retransmission request process 57 after the retransmission request is issued. In this standby state (that is, during the retransmission processing), the reception processing 51 may receive a data block distributed from the distribution processing 31 via the communication satellite 1. The data blocks received in such a standby state are stored in the reception data buffer 52 in the order of reception, and a queue is created. The application distribution processing 53 does not read these data blocks (step 165).

The serial number of the data block received in the standby state is higher than the serial number of the data block for which retransmission is requested. Generally, individual data is generated every moment in an information source. Therefore, the order of the serial numbers corresponds to the order of occurrence of the individual data, and the data with the smaller serial number is the data generated earlier. Passing the individual data to the application 55 in the order of time does not cause confusion. Therefore, in order to process the data requested to be retransmitted (data generated earlier in time order) and pass it to the application 55, data generated later with a higher serial number is stored in the reception data buffer 52. It is a translation.

Upon receiving the notification of the end of the retransmission processing, the application distribution processing 53 receives the retransmitted data block from the retransmission data buffer 58, and checks the serial number of the retransmitted data block. If the serial number check is OK, the received data block is decomposed into individual data, and if the individual data is registered in the request management table as in step 163, it is passed to the requesting application 55. Next, the individual data is stored in the data transfer buffer 54 and the arrival of data is notified to the data acquisition I / F 56 of the request source (step 166).

Thereafter, the application distribution processing 53
The data block stored in the reception data buffer 52 is read, a serial number is checked, and the same processing as in step 163 described above is executed.

Referring to FIG. 8, description will be made on the flow of processing relating to the second retransmission request. In this figure, steps 164, 165, 171, 172, 181, 191 and 192 are the same as those shown in FIG.

The retransmission request processing 57 sets a retransmission monitoring timer when transmitting the retransmission request 1 (step 171), and from the time when the retransmission request 1 is generated until the reception of data retransmitted in response to the request. Monitor the time. If the environment for data communication via the communication satellite 1 due to heavy rain or the like is poor, after retransmission request 1 is transmitted, retransmitted data may not be able to be received even after a certain period of time has passed (timeout detection). . The retransmission request processing 57 also checks whether or not all block data relating to the serial number for which retransmission has been requested has been received.

When a timeout is detected or missing retransmission data is detected, the retransmission request processing 57
The retransmission request 2 is notified of a serial number requesting retransmission by the message of retransmission request 2 (step 174).

The retransmission response process 48 receiving the retransmission request 2
The block data of the serial number requested to be retransmitted is read from the satellite retransmission buffer 46 and transmitted to the retransmission request processing 57 by TCP / IP via the terrestrial network 2 (step 182). This ensures that the data is retransmitted in the second retransmission.

Upon receiving the retransmitted data block, the retransmission request processing 57 stores it in the retransmission data buffer 58 (step 175), confirms that all the requested block data has been received, and notifies the end of retransmission. The application distribution process 53 is notified (step 176).

Upon receiving this notification, the application distribution processing executes the processing of steps 166 and 167 described above.

FIGS. 9 and 10 show a fault monitoring process in the receiving device 50. FIG. This is to deal with, for example, a case where a failure occurs in the communication satellite 1 and data distribution is not performed.

In FIG. 9, if no data block including dummy data is received for a predetermined time equal to or longer than the predetermined time T2 for distributing dummy data, the reception is performed. The process 51 notifies the application distribution process 53 of the fact (step 201).

Upon receiving this notification, the application distribution processing 53 creates a failure notification including a number obtained by adding 1 to the final reception serial number (the last received serial number among the continuous serial numbers without omissions), and sends it to the retransmission request processing 57. Give (step 211).

Upon receiving the failure notification, the retransmission request process 57 transmits the received failure notification to the retransmission response process 48 of the retransmission device 40 via the terrestrial network 2 using TCP / IP (step 221).

In response to this, the retransmission response processing 48 reads out the block data having the serial number (last reception serial number + 1) or later included in the failure notification from the satellite retransmission buffer 46, and transmits the block data via the terrestrial network 2. The packet is sequentially transmitted to the retransmission request process 57 using TCP / IP (step 231).

The retransmission request processing 57 stores the retransmitted data block in the retransmission data buffer 58, checks the serial number, and if the serial number check is OK, notifies the application distribution processing 53 that the data has been received ( Steps
222).

Upon receiving this notification, the application distribution process 53 decomposes the received data block into individual data and checks whether or not each individual data is registered in the request management table, as in step 166 described above. . If registered, the individual data is transferred to the requesting application 55 by the data acquisition I / F 56 via the data transfer buffer 54 (step
212).

Referring to FIG. 10, when the fault is recovered thereafter, reception processing 51 receives block data distributed via communication satellite 1. The received block data is stored in the received data buffer 52 (step 151). The receiving process 51 is an application distribution process 53
Is notified of the arrival of block data (step 152).
).

The application distribution process 52 receiving this notification performs a recovery including a number obtained by subtracting 1 from the latest serial number received via the communication satellite 1 (corresponding to the last serial number of block data lost due to a failure). A notification is created and given to the retransmission request process 57 (step 213). Retransmission request processing
57 transmits a recovery notification including the serial number to the retransmission response process 48 (step 223).

Retransmission response processing 48 receiving this restoration notification
Reads the block data up to the serial number included in the recovery notification from the satellite retransmission buffer 46 and sequentially transmits the block data to the retransmission request processing 57 via the terrestrial network 2 (step
232).

The retransmission request processing 57 converts the block data sequentially transmitted from the retransmission response processing 48 into a retransmission data buffer 58.
Stored in the application and check the serial number, application distribution processing
Notify 53. When receiving the data block having the last serial number, the retransmission request process 57 notifies the application delivery process 53 of the end of the recovery process (step 22).
Four).

The application distribution process 53 enters a standby state after receiving a recovery notification and receiving a recovery end processing notification. During this time, the block data received by the reception processing 51 is stored in the reception data buffer 52 (step 214).
).

When notified of the reception of the retransmitted data, the application distribution processing 53 decomposes the data block stored in the retransmission data buffer 58 into individual data and registers the individual data in the request management table. The individual data is stored in the data transfer buffer 54 so that the data acquisition I / F 56 of the request source can receive the individual data. This process is performed until the end of the recovery process is notified (step 215).

Thereafter, the application distribution processing 53 executes the serial number check and the disassembly into the individual data of the data block of the reception data buffer 52 in the same manner as in the above-mentioned step 167 (step 216).

Thus, even if a failure occurs somewhere in the data distribution path through the communication satellite 1, the data lost due to the failure is transmitted to the receiver 50 in real time through the terrestrial network 2. Will be.

[Brief description of the drawings]

FIG. 1 shows an overall configuration of a data distribution system using a communication satellite.

FIG. 2 is a block diagram illustrating a functional configuration of a transmission device, a retransmission device, and a reception device.

FIG. 3 shows a format of block data.

FIG. 4 is a flowchart illustrating a flow of a process of transmitting block data from a transmission device to a retransmission device.

FIG. 5 is a flowchart illustrating a flow of a process of transmitting block data from a transmission device to a retransmission device.

FIG. 6 is a flowchart illustrating a flow of a process of receiving data distributed via a communication satellite.

FIG. 7 is a flowchart showing the flow of a first retransmission process.

FIG. 8 is a flowchart showing the flow of a second retransmission process.

FIG. 9 is a flowchart showing the flow of retransmission processing when a failure occurs.

FIG. 10 is a flowchart illustrating the flow of a failure recovery process.

[Explanation of symbols]

 1 Communication satellite 2 Terrestrial network 11 Transmitter 12, 22 Router 13, 14, 23 Work station 15, 25 Transmission path 30 Transmitter 31 Distribution processing 32 Retransmission data buffer 33 Retransmission processing 40 Retransmission device 41 Reception processing 42 Reception data Buffer 43 Retransmission buffer write processing 44 Retransmission request processing 45 Retransmission data buffer 46 Satellite retransmission buffer 47 Retransmission transmission processing 48 Retransmission response processing 50 Receiver 51 Reception processing 52 Receive data buffer 53 Application distribution processing 54 Data delivery buffer 55 Application 56 Data acquisition I / F 57 Retransmission request processing 58 Retransmission data buffer

Continued on the front page (72) Inventor Hiroaki Takahashi 134 Kobecho, Hodogaya-ku, Yokohama-shi, Kanagawa Prefecture Inside the Yokohama Research Center, Nomura Research Institute (72) Inventor Hirokatsu Ogawa 1-9-1, Nihonbashi 1-chome, Chuo-ku, Tokyo No. 72, Nomura Research Institute, Inc. Inventor Michihiro Noda 134, Kobe-cho, Hodogaya-ku, Yokohama, Kanagawa Prefecture, Japan Inside Yokohama Research Center, Nomura Research Institute, Inc. (56) References JP-A-3-62630 (JP, A JP-A-3-178244 (JP, A) JP-A-58-111544 (JP, A) JP-A-1-293020 (JP, A) JP-A-5-167565 (JP, A) JP-B-46 18442 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 1/16 H04B 7/15 H04L 12/18 H04L 29/14 G06F 13/00

Claims (13)

(57) [Claims] A transmitting device for transmitting distribution data to a communication satellite using a protocol suitable for broadcast distribution; a receiving device for receiving data distributed through the communication satellite; A retransmitting device communicable via a communication satellite, storing data transmitted by the transmitting device, and transmitting data requested to be retransmitted to the receiving device when receiving a retransmission request from the receiving device. The transmission device includes a distribution data editing unit that performs an editing process including a process of adding a serial number that is incremented for each data distribution to the data to be distributed, and a distribution data edited by the distribution data editing unit. Transmitting means for transmitting the data to the communication satellite, the receiving device comprising: a receiving means for receiving distribution data transmitted from the communication satellite; The receiving means checks the serial number by comparing the serial number added to the data received this time with the serial number of the previously received data. When it is determined that there is a missing number, the first means is transmitted to the retransmitting device through the terrestrial network. First retransmission request processing means for requesting the first retransmission, and checking retransmission data distributed through the communication satellite from the retransmission device in response to the first retransmission request; A second retransmission request processing means for requesting the retransmission device to perform a second retransmission through the terrestrial network when receiving the request, and receiving data retransmitted from the retransmission device through the terrestrial network in response to the request. The retransmitting device, when receiving the first retransmission request from the receiving device, transmits the data requested to be retransmitted to the communication satellite. First retransmission processing means for transmitting the data requested to be retransmitted when the second retransmission request is received from the receiving device via the terrestrial network; A data distribution system using a communication satellite, comprising a second retransmission processing means for transmitting data to a communication satellite. 2. The transmitting device and the retransmitting device are communicably connected through a transmission path, the transmitting device transmits transmission data to the retransmitting device through the transmission path, and a retransmission request from the retransmitting device. Means for retransmitting data requested to be retransmitted to the retransmitting device via a transmission line when receiving the data, the retransmitting device comprising: reception processing means for receiving distribution data transmitted through the transmission line; A serial number management processing means for performing a serial number check by comparing the serial number added to the data received this time with the serial number of the previously received data, and the serial number management processing means receiving the serial number of the data received this time and the serial number Retransmission request processing means for requesting the transmission device to perform retransmission when it is determined that there is a missing number between the data and the serial number. Item 2. A data distribution system using the communication satellite according to Item 1. 3. The data distribution system using a communication satellite according to claim 1, wherein the transmitting device and the retransmitting device are realized by one work station. 4. The transmission apparatus according to claim 1, wherein after the previous data distribution,
When there is no data to be distributed even after the first fixed time has elapsed, a dummy data distribution process for distributing dummy data via a communication satellite by adding an updated serial number by incrementing the data. Means for checking whether or not distribution data including dummy data has been received during a second fixed time equal to or longer than the first fixed time; Failure monitoring processing means for determining that a failure has occurred when distribution data including dummy data has not been received for a second fixed time or more, and serial number of distribution data not received due to the failure when determination is made that a failure has occurred. And a failure notification means for transmitting a failure notification including the error notification to the retransmission device via the terrestrial network. And data via a terrestrial network, further comprising means for retransmitting to the receiving apparatus, the data distribution system using a communication satellite of claim 1. 5. When the receiving unit receives distribution data via a satellite after a failure occurs, the receiving device transmits a restoration notification including the last serial number of the distribution data not received due to the failure via the terrestrial network. Restoring notification means for transmitting the data to the retransmitting device, and the retransmitting device of the retransmitting device retransmits data up to the last serial number included in the recovery notification to the receiving device via a terrestrial network. 4. A data distribution system using the communication satellite according to 4. 6. A transmission device for transmitting distribution data to a communication satellite using a protocol suitable for broadcast distribution by adding a serial number incremented for each data distribution, and a data distributed through the communication satellite. A receiving device that can receive the retransmission request from the receiving device, receives the data transmitted by the transmitting device, and receives a retransmission request from the receiving device. Receiving means for receiving distribution data transmitted from a communication satellite, wherein the receiving means receives data transmitted from a communication satellite. When the serial number is checked by comparing the serial number added to the number with the serial number of the previously received data, and it is determined that there is a missing number First retransmission request processing means for requesting the retransmission device to perform a first retransmission via a terrestrial network, and checking retransmission data distributed from the retransmission device via a communication satellite in response to the first retransmission request. And performing a second retransmission request to the retransmitting device through the terrestrial network when it is determined that there is an error in the first data retransmission, and in response to the request, the data retransmitted from the retransmitting device through the terrestrial network. Receiving means for receiving a second retransmission request. 7. A transmitting station and a plurality of receiving stations are connected so that one-way communication is possible via a communication satellite and two-way communication is possible via a terrestrial network. The distribution data is distributed to the receiving station via the communication satellite by adding a serial number incremented every time, and the distributed data is stored, and the data distributed via the communication satellite is stored at the receiving station. When receiving, the serial number of the received data is checked, and when it is determined that there is a missing number, a first retransmission request is made to the communication station through the terrestrial network, and the first retransmission request is made at the transmitting station. When the request is received, the data requested to be retransmitted is retransmitted to the receiving station via the communication satellite, and the receiving station checks the retransmitted data in response to the first retransmission request. When it is determined that there is an error in the data retransmission, a second retransmission request is made to the transmitting station through the terrestrial network, and the transmitting station responds to the second retransmission request and responds to the second retransmission request. Data via the ground network
A data distribution method that uses a communication satellite to retransmit to the receiving station that issued the second retransmission request. 8. A transmitting station adds an information source identification code to each of individual data provided from a plurality of different information sources, and collects the individual data provided during the fixed time into one block at regular time intervals. Or, if the data length of the given individual data within the above-mentioned fixed time is suitable for the predetermined block length, the individual data are combined into one block, and the combined one block data is transmitted via the communication satellite via the communication satellite. The data distribution method using a communication satellite according to claim 7, wherein the data is distributed to a receiving station. 9. A receiving station registers an information source identification code of individual data to be taken in advance, decomposes received block data into individual data contained therein, and, among the decomposed individual data, 9. The data distribution method using a communication satellite according to claim 8, wherein only the information to which the registered information source identification code is added is taken. 10. A transmitting station and a receiving station, wherein the transmitting station and the receiving station can perform one-way communication via a communication satellite.
The transmitting station is connected via a terrestrial network so that bidirectional communication can be performed. The transmitting station transmits the distribution data to the communication satellite. Retransmitting means for retransmitting the received data via a communication satellite or a terrestrial network, wherein the receiving station receives the data transmitted from the communication satellite; Retransmission request means for transmitting a retransmission request to the transmitting station via the terrestrial network, wherein the retransmitting means of the transmitting station receives the first retransmission request from the receiving station and receives the first retransmission request. The first to distribute the collected data via communication satellites
And a second retransmitting means for retransmitting, via a terrestrial network, the data requested to be retransmitted to the receiving station requesting retransmission upon receiving a second retransmission request from the receiving station for the same data. A data distribution system that uses communication satellites and has retransmission means. 11. A transmitting station and a receiving station are connected so as to be capable of one-way communication via a communication satellite and two-way communication via a terrestrial network. When the first retransmission request is received from the receiving station, the data requested to be retransmitted is distributed via the communication satellite, and the same data is transmitted from the receiving station for the second retransmission. When the request is received, the data requested to be retransmitted is retransmitted to the receiving station that requested the retransmission via the terrestrial network. At the receiving station, the data transmitted from the communication satellite is received and the received data is lost. A data distribution method that uses a communication satellite to send a retransmission request to a transmitting station via a terrestrial network when there is an error. 12. A transmission device for transmitting distribution data to which a serial number incremented every time data is distributed to a communication satellite using a protocol suitable for broadcast distribution, and a data distributed through the communication satellite. A receiving device that receives the retransmission request from the receiving device, stores the data transmitted by the transmitting device, and receives a retransmission request from the receiving device. And a retransmitting device for transmitting the received data to the receiving device. The transmitting device is incremented when there is no data to be distributed even after a first fixed time has elapsed after the previous data distribution. Dummy data distribution processing means for distributing the dummy data via the communication satellite by adding the updated serial number to the received data. It is checked whether or not distribution data including dummy data has been received during a second fixed time equal to or longer than the first fixed time, and the dummy data is included for the second fixed time or more. Failure monitoring processing means for determining that a failure has occurred when distribution data has not been received, and failure determination including a serial number of distribution data not received due to the failure when the failure has been determined, via the ground network. Failure notification means for transmitting to the retransmission device, the retransmission device having retransmission means for retransmitting requested data to the reception device via a terrestrial network when receiving the failure notification; When receiving the distribution data via the communication satellite after the occurrence of the failure, the device sends a recovery notification including the last serial number of the distribution data not received due to the failure. Restoration notification means for transmitting to the retransmission device via the upper network, wherein the retransmission means of the retransmission device transmits data up to the last serial number included in the restoration notification to the reception device via the terrestrial network. A data distribution system using communication satellites to be retransmitted. 13. A transmitting station and a plurality of receiving stations are connected so as to enable one-way communication via a communication satellite and two-way communication via a terrestrial network. The distribution data is distributed to the receiving station via the communication satellite by adding a serial number incremented every time, and the distributed data is stored, and after the first data distribution, the first fixed time has elapsed. Even if there is no data to be distributed, the dummy data is distributed via the communication satellite by adding the updated serial number by being incremented, and is equal to the first fixed time at the receiving station. It is checked whether or not the distribution data including the dummy data has been received during the second predetermined time longer than the distribution data including the dummy data for the second predetermined time or more. If no fault is detected, a fault notification is sent to the transmitting station via the terrestrial network, and a fault notification including the serial number of the delivery data not received due to the fault is sent to the transmitting station. When a fault notification is received, the requested data is retransmitted to the receiving station via the terrestrial network. Further, when the receiving station receives distribution data via the satellite after the fault has occurred, it receives the data due to the fault. A restoration notice including the last serial number of the delivery data that has not been transmitted is transmitted to the transmitting station via the terrestrial network, and the transmitting station transmits the data up to the last serial number included in the restoration notice via the terrestrial network. A data distribution method using communication satellites, which is retransmitted to a satellite.