JPH04132421A - Line control system - Google Patents

Abstract

PURPOSE:To prevent the reduction in the entire throughput by allowing a station to store a time of occurrence of disturbance of the sun or the like for each station in a satellite communication system and allowing the station to inform the occurrence of the disturbance of the sun to each of the other stations. CONSTITUTION:An earth station 3i(i=a-n) receives a multiple address information frame sent from a master station 2 via a satellite 1 by a transmitter- receiver 31, a communication controller 32 generates an acknowledge frame with respect to the multiple address information frame and sends it to the master station 2 by the transmitter-receiver 31. In this case, information relating to sun disturbance is stored in an earth station and the occurrence of the sun disturbance is informed to the other station based on the information by the transmitter-receiver. Then in the case of multiple address communication, a missing frame is increased due to the deterioration in the line quality of an earth station of an area and it is possible that the entire system throughput is deteriorated due to lots of retransmission requests from the stations, then the station is disconnected from a communication object of the master station before the occurrence of the retransmission request. Thus, the deterioration in the transmission efficiency is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a satellite communication system, and relates to a line control method suitable for continuing system operation in response to deterioration of line quality due to solar interference.

[Conventional technology]

Solar interference occurs every year during the spring and autumn equinoxes, earth stations, satellites,
There is an eclipse period when the sun is almost in a straight line;
During the time period when the earth station's antenna points toward the sun, the noise power in the earth station receiving system increases due to radiation noise interference from the sun. The period during which this solar interference occurs is completely predictable for each earth station, and the time period when the satellite link will be disconnected can also be predicted based on the increase in noise power due to solar interference at each earth station and the line margin. It is possible.

Japanese Patent Application No. 62-114276 proposes a method in which a threshold is set in the master station for the number of retransmission requests from slave stations when frame loss occurs, and retransmission is performed when the number of retransmission requests exceeds this value. If the number of retransmission requests does not reach the threshold, retransmission is not performed to the slave station that has requested retransmission. In this broadcast communication control method, when the solar interference described above occurs, the number of retransmission requests from slave stations in the affected area increases, and when this number reaches a threshold, the master station will be resent. If the retransmitted frame does not reach the slave station due to an increase in noise power, a response request frame is sent. If there is no response from the slave station to the response request after a certain period of time, the slave stations are separated from the control target in groups.

1:1 [In a communication system, when the solar interference described above occurs, there is no response from the receiving station to the frame transmitted by the transmitting station.

The transmitting station requests a response from the receiving station using timeout control, and disconnects the link (logical line) if there is no response.

[Problem to be solved by the invention]

As described in the section on the prior art, there is no prior art that focuses on suppressing solar interference, and the suppressing effect is not automatically exerted.

In a data communication system, generally in order to ensure the reliability of transmitted information, a receiving station returns a response to information transmitted by a transmitting station to the transmitting station. Furthermore, if information from the transmitting station is missing due to information error control, the receiving station requests the transmitting station to retransmit.

In a satellite broadcast communication system where each slave station responds individually, there are multiple receiving stations, so the operation of a slave station with degraded line quality may cause an increase in the load on the master station or interrupt the progress of the control sequence throughout the system. has a very strong influence on

The broadcast communication control method described in the prior art does not have enough time accuracy to control the line quality deterioration when the line quality deteriorates indirectly, for example, due to rain attenuation of signal power in satellite communication. By being unpredictable,
This is an effective method.

However, since the time of occurrence of solar interference is predictable,
The operation of the conventional broadcast communication system is such that when solar interference occurs, it is known in advance that the line quality of a certain slave station will deteriorate, and the slave station requests retransmission even when it is clear that it will be separated from the control target. .

Furthermore, in the disconnection control, there is a problem in that even if it is known in advance that the slave station cannot send a response back to the master station, a response request is made to the slave station.

In one-to-one satellite communication systems, the link may be disconnected even when the time for recovery from line quality deterioration due to solar interference is known in advance, and the link may be re-established after the line quality has recovered. However, there was a problem in that a series of data that had been interrupted due to solar interference had to be retransmitted from the beginning.

Therefore, an object of the present invention is to solve the above-mentioned problems in a satellite communication system by having a certain station memorize the time of occurrence of solar interference at each station, and informing each other station of the occurrence of solar interference. There is a particular thing.

[Means to solve the problem]

In a satellite communication network system composed of a plurality of earth stations, the present invention provides a first means for storing information related to solar interference in at least one earth station, and a transmitting/receiving device based on the information of the first means. a second means for notifying other stations of the occurrence of solar interference, a third means for storing the transmission order number of the next frame to be transmitted by the master station when solar interference occurs; A fourth means resumes transmission from the frame with the transmission order number that has been sent, and a fifth means suspends timeout control for the transmitted frame when solar interference occurs and operates the timeout function again when the influence of solar interference disappears. This is achieved by the sixth means of switching from the batch response method to the sequential response method when solar interference occurs.

[Effect]

Transmission of unnecessary control frames is reduced by means for storing information related to solar interference in a certain earth station and means for notifying other stations of the occurrence of solar interference based on this information via a transmitting/receiving device. Furthermore, by storing the transmission order number of the next frame to be transmitted by the master station when solar interference occurs, it is only necessary to transmit the frame after the solar interference has occurred as the retransmitted frame to the disconnected slave station. When solar interference occurs, the timeout control for the transmitted frame is temporarily stopped, and when the influence of solar interference disappears, the timeout function is activated again, thereby eliminating link disconnection due to solar interference. By switching from the batch response method to the sequential response method when solar interference occurs, it is possible to transmit as much data as possible even when line quality deteriorates without stopping data transmission in one-to-one communication.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking as an example a case where line quality deteriorates due to solar interference in a satellite broadcast communication system using satellites.

Figure 2 shows satellite 1. Each earth station 2 and 3i (i = a
" n ). Here, the earth station 2 is the master station. The master station 2 is composed of a transmitting/receiving device 21 , a line control device 229 , a communication control device 23 , and a computer 24 . The broadcast information frame transmitted from the master station 2 via the satellite 1 is transmitted via the communication control device 23 and the transmitting/receiving device 121. The communication control device 32 creates a response frame for the broadcast information frame, and transmits it to the master station 2 via the transmitting/receiving device 31.After a series of communications are completed, the computer 33 It receives and processes all received data.

The configuration of the line control device 22 is shown in FIG. The line control device 22 is connected to an interface section 50.1 which is connected to the communication control device 23 via a signal line 54. Memory 522 Time timer 5 having a table for managing solar interference occurrence status
3. And control processing bag! ! It is composed of 51 pieces. The operation of the line control device 22 will be described later.

0 Line quality deterioration control table 6 to explain the line quality deterioration management table 60 in the memory 52 using FIG.
0 is an address part 61 indicating the address of the master station 2 and each slave station 3i (i=a=n), and a line quality deterioration occurrence time part 62 indicating the time when solar interference occurs in the slave station indicated by the address part 61. , a line quality deterioration end time field 63 indicating the end time of solar interference at which the influence of solar interference ceases on the slave station indicated by the address field 61, and stores the number of cycles of the transmission sequence number and the transmission sequence number passed from the communication control device 23. The sequence number counter 64 and the transmission sequence number section 65 turn ON when solar interference starts to occur, and turn ON when the influence of solar interference disappears.
It is composed of a status flag 66 that is turned off, and an occurrence flag 67 that stores the occurrence of solar interference. In addition, the line quality deterioration management table 6o includes the master station 2 and all slave stations 3i (i=a~
The size corresponds to the number n+1 of n).

The address part 61 is a slave station 3i (i) which is a communication partner of the master station 2.
=an) or a group address in which slave stations having approximately the same solar interference occurrence time are grouped. The solar disturbance occurrence time and duration at each earth station, as well as the amount of increase in noise power, can be calculated from the geometric relationship between the sun, satellite, and earth station, and the brightness temperature of the sun. From this calculation result, the time at which the earth station becomes unable to communicate is determined as the solar interference occurrence time and the solar interference end time, and these are stored in advance in the line quality deterioration occurrence time field 629 and the line quality deterioration end time field 63.

The sequence number counter section 64 and the transmission sequence number section 65 indicate the transmission sequence number of the frame whose transmission to the slave station where the solar interference occurred was interrupted.Normally, the transmission sequence number is used cyclically. Therefore, when the sequence number counter section 64 and the transmission sequence number section 65 are viewed as a pair, they can be seen as a transmission sequence number from the beginning of a series of information. Hereinafter, this pair will be simply referred to as a sequence number and will be explained. If solar interference occurs in multiple slave stations during the transmission of a series of information, after the transmission of the series of information is completed, the broadcast information frame with the order number of the smallest value in the solar interference occurrence time field 62 is transmitted. The master station retransmits the single-line quality deterioration management table 60, which is always configured in the order of earliest solar interference occurrence time to simplify access from the control processing unit 51.

Next, the operation of the line control device 22 when solar interference occurs in the slave station 31 will be explained using FIGS. 1, 3, and 4.

In FIG. 4, in process 401, the line quality deterioration management table 60 is initialized. Next, in process 402, the time is read from the time timer 53, and in process 403, this time is compared with the line quality deterioration occurrence time field 62 in the line quality deterioration management table 60, and if the value of the time timer 53 is larger, the process is performed. In step 404, it is determined whether the status flag 66 in the line quality deterioration management table 60 is OFF, and if it is OFF, in step 405, the status flag 66 and the occurrence flag 67 are turned ON.

Then, in step 406, the address of the slave station 3i (i=a=n) at which the solar interference occurred is sent to the line controller! The communication control device 23 is notified via the interface unit 50 of 22. In response to this notification, the communication control device 23 notifies the line control device 22 of the sequence number of the next frame to be sent, and also disconnects the station at which the solar interference has occurred from the communication target.

The sequence number taken into the control processing device 51 via the interface unit 50 is set in the sequence number counter unit 64 and the transmission sequence number unit 65 in the line quality deterioration management table 60 in step 407.

If the value of the time timer 53 is smaller than the value of the line quality deterioration occurrence time field 62 in process 403, or if the status flag 66 is ON in process 404, the process advances to process 408.

Processing is performed sequentially from the beginning of the line quality deterioration management table 60,
Comparison processing 403 between the line quality deterioration occurrence time field 62 and time timer of the line quality deterioration management table 60 is performed on all slave stations 3i.
(i=a=n) is judged in process 408, and if there is a slave station that has not been executed, process 403 is executed again, and comparison processing of the line quality deterioration occurrence time part 62 for all slave stations is performed. If the process has been completed, the process moves to process 409. Processing 4
At 09, the value of the time timer 53 and line quality deterioration end time part 6
3 is compared and judged, and if the value of the 1-time timer 53 is larger, it is determined in process 410 whether the flag is ON in the status flag 66, and if it is ON, the status flag 66 is turned OFF in process 411. At the same time, the 0 communication control group notifies the communication control device 23 of the end of solar interference! 23 sends this notification to the corresponding slave station. Since the solar interference has ended, in process 412, the occurrence time and end time of the next occurrence of solar interference are recorded in the line quality deterioration occurrence time field 622 in the line quality deterioration management table 60. In step 6 processing 413, which is set in the deterioration end time section 63, it is determined whether the processing has been performed for all slave stations 3i (i=a-n), and if the processing has not been performed yet, the process returns to step 409.

When the communication has ended, it is determined in step 414 whether the communication has ended. The end of communication is notified from the communication control device 23 to the control processing device 51 via the interface section 50.
When the communication is completed, the status flag 66 is set to O in process 415.
It is determined whether it is FF, and if it is OFF, it is further determined in step 416 whether the occurrence flag is ON, and it is turned ON.
If so, the line control device 22 sends the address and sequence number stored in the line quality deterioration management table 60 to the communication control bag via the interface unit 50! Notify 23. The communication control device 23 retransmits the broadcast information frame with the order number of this notification. Next, in process 418, the counter 64. The transmission order number field 65 and occurrence flag 67 are cleared. Communication control bags other than those mentioned above [control of 23 is patent application No. 62-1]
This is similar to the control described in No. 14276.

When the line control device 22 notifies the communication control device 23 of the occurrence of solar interference, the communication control device 23 sends this notification to the solar interference generating slave station. The slave station that received the notification discards all subsequent broadcast information frames received and stores the final sequence number of the frame that was received immediately before the notification.The slave station receives a notification from the master station 2 that the solar interference has ended. If received, the subsequent data frames are received again and the value of the sequence number minus 1 of the newly received data frame is stored. At the time of retransmission from the master station 2, the missing frame is recognized based on the sequence number stored at the start of the solar interference occurrence and the sequence number stored at the end of the solar interference, and only data frames with sequence numbers between these are received.

The operation of the line control device 22 when solar interference occurs at the master station 2 is the same as when solar interference occurs at the slave station 31 described above. However, since the operation of the communication control device 23 is different, it will be explained below.

When solar interference occurs in the slave station 31 described above, the communication control device 23 controls the disconnection of the slave station 31, and then continues communication to other slave stations 31. When solar interference occurs in the master station 2, the response frame from the slave station cannot be received, and after a frame is lost in the slave station 31 for some reason, the master station 2 receives a retransmission request from the slave station 31. Unable to receive. For this reason, it is impossible to proceed with a normal transmission sequence, so when the communication control device 23 is notified of the occurrence of solar interference from the line control device 22, it stops transmitting broadcast information frames after the notification. The notification of the end of solar interference is sent from the line control device 22 by the communication control department!
! 23, transmission to the slave station 31 is started again from the broadcast information frame whose transmission was stopped. While the master station 2 stops transmitting the broadcast information frame, the slave station 31 merely waits for reception and does not require any special processing.

According to this embodiment, when solar interference occurs in a certain area, the number of dropped frames increases in slave stations in the solar interference area, and the throughput of the entire system decreases due to many retransmission requests from those slave stations. By separating the slave station from the control of the communication target of the master station in advance, a decrease in the throughput of the entire system is prevented.Furthermore, the slave station only waits for reception when notified of the occurrence of solar interference from the master station. No special control is required, and slave stations can communicate without being aware of solar interference. moreover,
The master station stores the transmission order number for each slave station or group of slave stations when solar interference occurs, so when retransmitting data to the slave station where solar interference occurs, there is no need to resend all data. By retransmitting only subsequent data, a decrease in efficiency can be prevented.

Next, as a second embodiment, a one-to-one satellite communication system using satellites will be described as an example.

FIG. 5 shows a configuration diagram of a data transfer system between computers using a one-to-one satellite communication system. Figure 5 shows satellite 50
1. Consists of earth stations 502 and 503. Here, the earth station 502 has a transmitting/receiving bag [504° line controller 229 communication controller 5o6. Consisting of a computer 507, the computer 5
The main station transmits the information frame created in step 07 via the communication control device 5o6 and the transmitting/receiving device 504.

The earth station 503 receives the information frame transmitted from the main station 502 via the satellite 501 via the transmitting/receiving device 508, creates a response frame for the information frame in the communication control device 509, and transmits the information frame to the main station via the transmitting/receiving device 508. station 50
It is a slave station that transmits to 2. After receiving the series of data, the communication control device 509 passes all the data to the computer 510.

The transmission control procedure used in many of these one-to-one communication systems is based on the HDLC procedure (JISC6363~
6365), the sender sends an information frame,
Receives a response frame from the receiving side. In this case, in anticipation of line quality deterioration, the transmitting side starts a timer when sending an information frame or a command frame to detect a line disconnection, and sends a response frame from the receiving side after a certain period of time. When reception is not possible, it is common to assume that the line is disconnected.

The line control device 22 in this embodiment has the same configuration as the line control device 22 shown in FIG. 3, and operates similarly, so a description thereof will be omitted. However, line control device 1505
A line quality deterioration management table 60 stored in the memory 52 of the
need only be for the master and slave stations. Further, in the operation of the flowchart shown in FIG. 4, processing 407 and processing 417 for exchanging counters and transmission/reception numbers are not necessary to be executed, but there is no problem even if they are executed.

Next, the operation of the communication control device 509 when a one-to-one satellite communication system is used will be explained using FIG.

In process 600, notification of the occurrence of solar interference is sent to the line control device 22.
kara uke takes. Based on this notification, the communication control device 509 stops the above-described timeout control for line disconnection monitoring in process 601, and notifies the other station of the occurrence of solar interference in process 602. And 4 of the next transmitted frame! Preparation is performed in process 603. After transmitting the frame in process 604, process 60
The communication control device 22 is in a waiting state for the delay time preset in step 5. In post-processing 606, it is determined whether a response frame has been received, and if it has not yet been received, the process returns to process 604 and the frame for which no response has been received is transmitted.

If the response frame can be received in process 606, it is determined in process 606 whether there is a solar interference termination notification from the line control device 22, and if there is no solar interference termination notification, process 6
Returning to step 03, the next frame to be transmitted is prepared. If the solar interference ends in process 607, process 608
restarts timeout control for line disconnection monitoring and returns to normal operation.

According to this embodiment, noise increases due to solar interference.

The decrease characteristic is gradual over time, and there is a possibility that transmit frames and response frames can be transmitted and received at the rise and fall of these frames. In some cases, transmission can be performed regardless of the situation, and the decrease in transmission efficiency can be kept to a minimum.

〔Effect of the invention〕

In a satellite communication system where deterioration in line quality can be predicted, in the case of broadcast communication, the number of dropped frames increases due to deterioration of the line quality of earth stations in a certain area, and the throughput of the entire system is reduced due to many retransmission requests from these stations. When lowering the throughput, it is possible to prevent the overall throughput from decreasing by separating the master station from the communication target before a retransmission request occurs.

In addition, the slave station only enters a reception waiting state upon notification of line quality deterioration from the master station, and does not require any special control, and can be controlled only by the master station's management. It is possible to communicate without being aware of the time when deterioration occurs. Furthermore, by storing the transmission order number when line quality deteriorates.

When retransmitting data to a slave station where line quality deterioration has occurred, the utilization efficiency of one line can be ensured by retransmitting only the data after the occurrence of line quality deterioration without retransmitting all data.

In one-to-one satellite communication systems, by stopping timeout control for line disconnection monitoring when line quality deterioration occurs, link disconnection during data transmission is prevented, unnecessary response requests to slave stations due to timeouts are eliminated, and line quality is improved. After recovery from deterioration, communication can be resumed without resetting the link, thereby preventing a drop in transmission efficiency.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a line control device according to an embodiment of the present invention, and FIG.
The figure is a configuration diagram of a data broadcast communication system using a satellite according to an embodiment of the present invention, FIG. 3 is a diagram showing a line quality deterioration management table for managing the state of line quality deterioration, and FIG. 4 is a diagram of a line control device. FIG. 5 is a block diagram of a one-to-one satellite communication system, and FIG. 6 is a processing flow diagram of a communication control device. 1...Satellite, 2...Master station, 3...Slave station, 4...
transmission path. 21.31... Transmitting/receiving device, 22... Line control device,
23.32... Communication control device, 24.33... Computer, 50... Interface unit, 51... Control processing device, 52... Memory, 53... Timer, 60... Line quality deterioration management table , 6 address part, 62... line quality deterioration occurrence time part, 63... line quality deterioration end time part,
64... Sequence number counter, 65... Transmission sequence number section, 66... Status flag, 67... Occurrence flag, 501
=-Satellite, 502,503...Earth station, 504°50
8... Transmitting/receiving device, 506, 509 river communication control L
−− 柘J ” − ” Light Ward (Rigano 柨子 1 Nod – 2 Whisper Picture (b) ■−1111

Claims (1)

[Scope of Claims] 1. In a satellite communication network system consisting of a plurality of earth stations, a first means for storing solar interference occurrence time and end time information for each earth station in a certain earth station;
A line control system characterized by providing a second means for notifying other stations of the occurrence of solar interference based on information from the first means. 2. In the line control system according to claim 1, a third means for storing the transmission order number of the next frame to be transmitted at the transmitting station when solar interference occurs; and after the solar interference has ended, the third means A line control system characterized in that a fourth means is provided for restarting transmission from a frame having a transmission order number stored by. 3. In the line control method described in claim 1, in a one-to-one satellite communication network system, timeout control for line disconnection monitoring is temporarily stopped when solar interference occurs, and when the influence of solar interference has disappeared. A line control system characterized in that a fifth means for operating again is provided. 4. In the line control method described in claim 3, in a system having means for continuously transmitting information frames to obtain a collective response, a sixth means for confirming a response for each information frame may be provided. , a line control method characterized in that the means for obtaining a collective response is switched to the sixth means while timeout control for line disconnection monitoring is stopped;