JP2609417B2 - Satellite broadcast method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite broadcast communication between a broadcast master station and a broadcast slave station. Satellite broadcast communication in which broadcast data relating to a data reception error is immediately transmitted to the broadcast slave station as a retransmission frame from the broadcast master station.
It is about the method .

[0002]

2. Description of the Related Art Hitherto, as a method of setting a bidirectional type broadcast communication line, a broadcast master station (hereinafter simply referred to as a master station) has been changed to a broadcast slave station (hereinafter simply referred to as a slave station). Line is TDM
A (Time Division Multiple Access) method for allocating the number of time slots according to the data rate, or the SCPC method (F for allocating one carrier to one channel)
A method of allocating a dedicated channel by a DMA method is known. Also, as a method of setting a response line from each slave station to the master station, a method of appropriately assigning a broadcast slave station to each time slot in a TDMA frame by the TDMA method is used. The response data from each of the slave stations has been transparently returned to the master station by a TDMA frame. Incidentally, as a method of assigning a slave station to each time slot in a TDMA frame, there are a pre-assignment TDMA scheme in which a slave station is fixedly assigned to each time slot and a random access TDMA scheme in which a slave station is randomly assigned to each time slot. Although any known TDMA system is known, in each of the satellite broadcasting systems, any TDMA system is fixedly adopted.

[0003]

By the way, in the conventional satellite broadcast communication, the response data from each of the slave stations to the master station is often based on a pre-assigned TDMA system. This is because, when it is necessary for the master station to collect responses from all slave stations with respect to line setting, delivery confirmation, line release, and the like, the master station can reliably collect responses from all slave stations. On the other hand, in the case of the pre-assigned TDMA method, when a retransmission request is returned as a response from the slave station, a problem that a retransmission frame cannot be immediately transmitted from the master station to the slave station occurs. It is. More specifically, after the line is set, broadcast data (frame format) sequentially transmitted from the master station is received by each of the slave stations, and the presence or absence of a data reception error is detected in frame units. If a data reception error is detected in any of the slave stations, a retransmission request for broadcast data relating to the data reception error is returned from the slave station to the master station as a response. However, the response is made only after the appearance of the time slot fixedly assigned to the own station, and therefore, the return of the response to the master station is delayed as the time slot is located later. Due to the tendency, the master station cannot quickly perform the retransmission process for the response.

On the other hand, the response data is random access TD
When returned to the master station by the MA system, collision of response data cannot be avoided. When a retransmission request is made from a slave station based on a data reception error,
When responses to a delivery confirmation request or the like from the master station are made from all slave stations, contention in use for the same time slot is likely to occur, and therefore, response data from two or more slave stations is time-dependent. There is a high possibility that the master station will receive a duplicated state, and collision of response data cannot be avoided. In particular, when a response needs to be sent back to the master station from all the slave stations, the probability of the response data colliding is high, and it takes a long time for the master station to collect the response from all the slave stations. Therefore, it is undeniable that the transmission efficiency of the broadcast data is greatly reduced. Incidentally, here, a problem in a case where response data from two or more slave stations are received by the master station as a time-duplicated state (a collision state of response data) will be specifically described with reference to FIG. Shows a problem when the retransmission request from the slave station to the master station is returned by the random access TDMA method. As shown in the figure, in this example, five slave stations a to e as slave stations, and a three-frame time as a propagation delay time between the master station and the slave station (this propagation delay is caused by the intervention of a communication satellite or the like). It is assumed that a delay exists. As can be seen from the figure, the broadcast data is transmitted according to broadcast data transmission timings T1 to T13.
While transmitted sequentially from the master station in the order of frame numbers, the slave station a
In each of ~ e, the broadcast data from the master station is sequentially received as being delayed by three frames in accordance with the reception timings T4 ~ T13 ~. Here, for example, assuming that a data reception error with respect to the broadcast data of frame number 2 is detected at the reception timing T5 in the slave stations a and b, the slave stations a and b simultaneously request retransmission at the time. The master station returns the retransmission request to the reception timing T
8 at the same time. However, the master station detects the level of the received signal,
It is known that the data is abnormal and a retransmission request collision has occurred, but since the identification of the slave station and the broadcast data frame number relating to the data reception error is not allowed, the frame retransmission processing cannot be performed. Has become. The fact that this retransmission request collision is also known to the slave stations a and b based on the fact that the retransmission frame is not received even after waiting for a certain time from the point of transmission of the retransmission request is different from the slave stations a and b. At the timing, a retransmission request having the same content is returned to the master station again. At the master station, since these retransmission requests can be normally received at different timings, it is assumed that the broadcast data frame number relating to the data reception error is 2, and the broadcast data of frame number 2 is retransmitted to the slave station. Is what it is.

[0005] A first object of the present invention is that a retransmission request based on a data reception error is promptly returned to a master station in a state where a slave station and a broadcast data frame number relating to the data reception error can be identified. In addition, the present invention provides a satellite broadcasting method in which a retransmission frame can be transmitted from a master station to a slave station immediately. A second object of the present invention is to make it possible for the master station to confirm the data reception state of all slave stations during the transmission of broadcast data,
In addition, in a state where the slave station and the broadcast data frame number relating to the data reception error are identifiable, a retransmission request based on the data reception error is promptly returned to the master station, and the master station immediately transmits a retransmission frame. It is intended to provide a satellite broadcasting method which can be transmitted to a slave station. A third object of the present invention is to provide a method in which two or more retransmission requests based on a data reception error are returned to a master station in a state in which the slave station and the broadcast data frame number relating to the data reception error cannot be identified. Another object of the present invention is to provide a satellite broadcasting method in which a retransmission frame can be promptly transmitted from a master station to a slave station. A fourth object of the present invention is to make it possible for the master station to confirm the data reception status of all the slave stations during the transmission of broadcast data, and to request two or more retransmission requests based on the data reception error to be associated with the data reception error. In the case where the station and the broadcast data frame number are returned to the master station in a state where they cannot be identified, the master station provides a satellite broadcast communication method in which a retransmission frame can be transmitted to the slave station immediately.

[0006]

A first object of the present invention is that a response to a master station is made by a pre-assigned TDMA system for a line setting availability response, a delivery confirmation response, and a line release acknowledgment from each of the slave stations. When a data reception error is detected at the slave station, the reception response is a retransmission request,
This is achieved by making a response to the master station using the random access TDMA system.

A second object of the present invention is to provide a pre-assigned TDMA system for a response to the master station with respect to a line setting availability response, a delivery confirmation response, and a line release acknowledgment from each of the child stations, while transmitting broadcast data during transmission. Is it the broadcast parent station of
From the acknowledgment response to these acknowledgment requests , the data reception status of each broadcast slave station can be confirmed at any time by the broadcast master station, and if a data reception error is detected by the slave station, the reception response is a retransmission request. This is achieved by making a response to the master station using a random access TDMA method.

A third object of the present invention is that a response to the master station is made by a pre-assigned TDMA system with respect to a line setting availability response, a delivery confirmation response, and a line release acknowledgment from each of the slave stations, while a data reception error occurs. When a response to the master station is received by the random access TDMA method, a retransmission request from each of two or more broadcast stations is overlapped in time. If it is detected as
Waiting for the end of the transmission of the broadcast data that is currently in the transmission state, the transmitted broadcast data transmitted before the time corresponding to the propagation delay between the master station and the slave station from the time of the detection is used as a retransmission frame as a child frame. This is achieved by being transmitted to each station.

A fourth object of the present invention is to provide a pre-assigned TDMA system for a response to the master station with respect to a line setting availability response, a delivery confirmation response, and a line release acknowledgment from each of the slave stations, while the broadcast data is being transmitted. Is it the broadcast parent station of
From the acknowledgment response to these acknowledgment requests , the data reception status of each broadcast slave station can be confirmed at any time by the broadcast master station, and if a data reception error is detected by the slave station, the reception response is a retransmission request. If a retransmission request from each of two or more broadcast stations is detected as a time-duplicated state at the master station when a response is made to the master station using the random access TDMA scheme, Waiting for the end of transmission of the broadcast data in the transmission state, the transmitted broadcast data transmitted before the time corresponding to the propagation delay between the master station and the slave station from the time of the detection is converted to the slave station as a retransmission frame. This is achieved by being transmitted to each.

[0010]

Among the various responses from each of the slave stations, the line setting availability response, the delivery confirmation response, and the line release acknowledgment are transmitted to the master station by the pre-assign TDMA method.
The retransmission request during broadcast data transmission is random access TD.
A response to the master station is made by the MA system. Even if the broadcast data is being transmitted, if necessary, the delivery confirmation
Depending on the acknowledgment , the data reception state of each slave station can be checked at any time by the master station. When a retransmission request is returned to the master station by the random access TDMA method, the retransmission request is returned to the master station via the time slot at the forefront of the time slots in the TDMA frame. After that, the retransmission frame can be immediately transmitted to the slave station. Further, when retransmission requests from two or more slave stations are simultaneously returned to the master station via the same time slot, the slave station and broadcast data relating to the data reception error cannot be identified by the master station. At this time, if the propagation delay time between the master station and the slave station is known in advance, the broadcast data relating to the data reception error can be easily specified as a frame number, and therefore, the broadcast data of that frame number is retransmitted. What is necessary is just to transmit to a child station as a frame.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. First, the pre-assign / random access TDMA frame on the response line (inbound line) according to the present invention will be described. FIG. 2 shows an example of the frame format. As shown in the figure, a reference station synchronization burst R as a time reference transmitted from the reference station, a plurality of data bursts D ₁ , D ₂ ,..., D _{n -1} , D _n and a guard time (protection time) GT. It has become. Now, in the case of a pre-assigned TDMA frame, data bursts D ₁ , D ₂ ,..., D _n−1 , D _n
Each of the slave stations is fixedly assigned one-to-one. For example, the slave station a can return a response from its own station only via the data burst D _1.
The slave station b can return a response from its own station to the master station via only the number ₂ . On the other hand, random access TDMA
In the case of a frame, data bursts D ₁ , D ₂ ,...
... D _n-1, D _n each has to have been a well usable from any slave station.

FIG. 3 also shows data bursts D ₁ , D ₂ ,.
..., D _n-1 and D _n are shown as an example. As shown in the figure, a preamble (including a demodulation symbol, a unique word (burst synchronization code) UW, etc.) PA, a station identification number (a number assigned in advance to a slave station (receiving station)) SID, and a flag (in the HDLC frame) F, frame check sequence (data error detection code) FCS, and response data (transmission area for various response data such as retransmission request) DAT
A.

Here, the satellite broadcast system according to the present invention will be described. FIG. 4 shows an outline of the whole system. As shown in the figure, a broadcast transmitting apparatus 31 and a master station 32 are arranged on the broadcast data transmitting side, while a plurality of slave stations 34, 35 and slave stations 34,
Broadcast receiving devices 36 and 37 corresponding to 35 are arranged. In this case, the slave station 34 and the broadcast receiver 3
6 and the slave station 35 and the broadcast receiving device 37 have a function of transmitting response data to the master station 32, respectively.
35 is provided with a function of receiving and processing response data from each of them. Prior to performing the satellite broadcasting, the master station 32 and the slave station 34 are arbitrarily specified in a state where the slave station designated as the receiving station is arbitrarily designated by the master station 32 or the group address. , 35 can perform satellite broadcasting by a satellite line using a communication satellite 33. At this time, transmission of broadcast data from the master station 32 to the slave stations 34 and 35 is performed by the SC.
Performed by outbound lines 32a, 34a, 35a set as PC lines or TDMA lines,
Broadcast data conforming to the DLC frame is sequentially transmitted, but in a state where the broadcast data is sequentially transmitted, the slave station 3
If there is a retransmission request from any of the slave stations 4 and 35, the broadcast data related to the data reception error is retransmitted as a retransmission frame while the sequential transmission of the broadcast data is temporarily interrupted.
4, 35. In addition, child station 3
The transmission of various response data from 4, 35 to the master station 32 is based on T
An inbound line 34b set as a DMA line,
35b and 32b, the response data is transmitted to the master station 32 by a pre-assignment TDMA method or a random access TDMA method according to the type. That is, when each of the slave stations 34 and 35 transmits the line setting availability response, the delivery confirmation response, and the line release acknowledgment, the pre-assigned TDMA system is used.
When a data reception error is detected in the slave station, a reception response is a response to the master station 32 as a retransmission request, which is made using the random access TDMA method.

Here, the operation of the slave stations 34 and 35 in a state where the broadcast data is sequentially transmitted from the master station 32 will be described in detail. , 35 are sequentially received, and whether or not a data reception error exists in each broadcast data is checked by the frame check sequence FCS included therein, but the broadcast data is normally transmitted. When received, no response is transmitted to the master station 32. However, when it is determined that there is a data reception error in the broadcast data, a retransmission request for the broadcast data has been transmitted to the master station 32 as a response by the random access TDMA method. At this time, the retransmission request includes data bursts D ₁ , D ₂ ,.
from among the _n-1, D _n, but any one is transmitted in a state of being occupied optionally, usually one that is transmitted most foremost position of the time slot, i.e., the data bursts D _1. In addition, even if the broadcast data is sequentially transmitted, a delivery confirmation request is sent from the master station 32 to the slave stations 34 and 35 as necessary, in order to check the reception state at each of the slave stations 34 and 35. When transmitted, each of the slave stations 34 and 35 needs to transmit the reception status up to that point to the master station 32 as a delivery acknowledgment by the pre-assignment TDMA method. In the parent station 32, the child stations 34, 3
The reason for this is that it is necessary to know the reception status of each of the devices 5 reliably and promptly.

As described above, the slave stations 34 and 35 send the master station 3
The transmission of various response data to the base station 2 is performed by a TDMA line, but FIG.
Whether the TDMA line is used as a pre-assign,
It indicates whether it is used as random access. As can be seen, the line setting availability response at the time of the line setting request, the delivery acknowledgment at the time of the delivery confirmation request, and the line release acknowledgment at the time of the line release request are used as pre-assignments. , That is, the retransmission request at the time of transmitting the broadcast data is used as a random access.

FIG. 5 shows the operation according to the present invention when the retransmission request from the broadcast slave station to the broadcast master station is transmitted by the random access TDMA system in comparison with FIG. 8 described above. It is a thing. As in the case of FIG. 8, it is assumed that a data reception error for the broadcast data of frame number 2 is detected at the reception timing T5 in the slave stations a and b. The retransmission requests are returned from the slave stations a and b to the master station at the same time at the same time. On the other hand, the master station receives the retransmission requests at the reception timing T8 at the reception timing T8 with a delay of three frames. ing. Up to now, the frame retransmission process has been performed without any processing on the assumption that the reception state is a collision of a retransmission request. However, in the case of the present invention, the master station is transmitted at the transmission timing T9. The broadcast data of frame number 2 can be transmitted immediately. This is because, when the propagation delay time between the master station and the slave station is known in advance, it is easy for the master station to determine which of the already transmitted broadcast data has a data reception error. Can be specified. However, the retransmission request does not always collide. In this case, since the slave station and the broadcast data frame number related to the data reception error can be identified by the master station, the broadcast data frame number It is only necessary that the broadcast data of frame number 2 be transmitted promptly.

Finally, the configurations and operations of the master station and slave stations according to the present invention will be described below with reference to FIGS. That is, as shown in FIG. 6, when a (broadcast) line setting request is sent from the above-mentioned broadcast transmitting apparatus (31) to the master station, the request is sent to the line connection control unit 73 via the terminal interface unit 70. And the line is established under the initiative of the line connection control unit 73. The line setting request from the line connection control unit 73 is the one that is framed by the data frame creation unit 71b in the transmission unit 71 and then transmitted from the transmission modulation unit 72 to the slave station via the transmission buffer 71c. . On the other hand, in the slave station, the line setting request via the communication satellite is demodulated by the reception demodulation unit 80 and then processed by the reception frame processing unit 81 to identify the request as a line setting request. It has become. If it is determined that the request is a line setting request, the terminal interface unit 82 connected to the broadcast receiving device (36, 37) is activated, while the response frame creating unit 87 creates a response frame. In addition, it is transmitted from the burst modulation section 86 to the master station as a line setting availability response. At the time of transmitting the line setting permission / inhibition response, the burst modulating unit 86 pre-assigns a pre-assigned TDM signal based on an instruction from the allocation method control unit 84.
Since the system is set to the A system, the line setting availability response is transmitted by the pre-assign TDMA system. In the master station, the line setting availability response from the slave station is demodulated by the burst demodulation unit 76 and then processed by the reception frame processing unit 75b in the reception unit 75, and only the information part (response data) in the frame is extracted. After that, it is transferred to the line connection control unit 73. If the line connection control unit 73 confirms that all the line setting availability responses from the previously addressed slave stations are line setting acknowledgments, the line with each of the slave stations is established. For the first time, the mode has been shifted to the broadcast data transmission mode.

In the broadcast data transmission mode, the transmission data from the broadcast transmission device (31) is sequentially framed as broadcast data by the data frame creation section 71b via the terminal interface section 70 and the data buffer 71a. Above, the data is transmitted from the transmission modulation section 72 to the slave station via the transmission buffer 71c. On the other hand, in the slave station, the broadcast data transmitted via the communication satellite is received by the reception demodulation unit 8.
After being sequentially demodulated at 0, the received data is processed by the reception frame processing unit 81, whereby the broadcast data is identified, and the presence or absence of a data reception error is detected in broadcast data units. I have. At this time, the burst modulation unit 86 is set to the random access TDMA system via the allocation system control unit 84. As described above, the reception frame processing unit 81 detects the presence or absence of a data reception error in broadcast data units, but if no data reception error is detected, the broadcast data is broadcast via the terminal interface unit 82. If a data reception error is detected from certain broadcast data while being transmitted to the receiving devices (36, 37), a retransmission request frame is created by the response frame creation unit 87, and then a random number is sent from the burst modulation unit 86. This is transmitted as a retransmission request to the master station by the access method. The retransmission request from the slave station is demodulated by the burst demodulation unit 76, and the received frame processing unit 75b in the reception unit 75
The frame retransmission process is performed by transferring the data to the retransmission control unit 71d after the processing, and the collision detection unit 74 detects the presence or absence of collision of a separate retransmission request at this time. It has become something. When a collision of the retransmission request is detected, the broadcast data specified from the propagation delay time between the parent station and the child station is immediately retransmitted as a retransmission frame, but if the retransmission request does not collide, Is
Based on the broadcast data frame number extracted from the retransmission request, the broadcast data of that frame number may be transmitted promptly.

In FIG. 6, the transmission confirmation section 75a transmits the transmission confirmation request from the slave station as a response to a transmission confirmation request that is made as needed during the transmission of the broadcast data or a response to the delivery confirmation request that is made after the transmission of the broadcast data. After confirming the delivery confirmation response, the delivery confirmation response is transferred to the terminal interface unit 70. In FIG. 7, a unique word is detected by the unique word detection unit 83, and the synchronization control unit 85 performs synchronization control to synchronize with the synchronization burst of the master station based on the detection timing. I have.

[0020]

As described above, according to the first aspect, in the state where the slave station and the broadcast data frame number relating to the data reception error are identifiable, the retransmission request based on the data reception error is promptly made. A satellite broadcast communication method that allows a retransmission frame to be immediately transmitted from the master station to the slave station after being returned to the master station. When the data reception status of the station is confirmed by the master station, and the slave station and the broadcast data frame number relating to the data reception error are identified, the retransmission request based on the data reception error is promptly sent to the master station. 4. A satellite broadcasting method in which a retransmission frame can be immediately transmitted from a master station to a slave station after being returned.
According to the above, when two or more retransmission requests based on a data reception error are returned to the master station in a state where the slave station and the broadcast data frame number related to the data reception error cannot be identified, the master station sends In the satellite broadcast communication method in which the retransmission frame can be transmitted to the slave station promptly, according to the fourth aspect, the data reception status of all the slave stations during the broadcast data transmission can be confirmed by the master station. In addition, when two or more retransmission requests based on a data reception error are returned to the master station with the slave station and the broadcast data frame number related to the data reception error being unidentifiable, the master station promptly sends the request. A satellite broadcasting method in which a retransmission frame can be transmitted to a slave station is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining whether a TDMA line is set to pre-assignment or random access in each of slave stations according to a communication mode in a master station.

FIG. 2 is a diagram showing a frame format of an example of a pre-assign / random access TDMA frame according to the present invention.

FIG. 3 is a diagram illustrating a format of an example of a data burst in a TDMA frame;

FIG. 4 is a diagram showing an outline of an entire system of a satellite broadcast communication system according to the present invention;

FIG. 5 is a diagram for explaining an operation according to the present invention when a retransmission request from a broadcast slave station to a broadcast master station is transmitted by a random access TDMA scheme;

FIG. 6 is a diagram showing a configuration of an example of a master station according to the present invention;

FIG. 7 is a diagram showing a configuration of an example of a slave station according to the present invention;

FIG. 8 is a diagram for explaining a problem when a retransmission request from a broadcast slave station to a broadcast master station is transmitted by a random access TDMA scheme;

[Explanation of symbols]

31: broadcast transmission device, 32: master station, 33: communication satellite, 3
4, 35: slave station, 36, 37: broadcast receiver

Claims (4)

(57) [Claims] Broadcast data from a broadcast master station is sequentially transmitted as a data frame conforming to an HDLC frame on an outbound line to a plurality of broadcast slave stations simultaneously via a communication satellite. Each of the slave stations transmits a reception result for each piece of broadcast data sequentially received in frame units to a broadcast master station via a communication satellite as a reception response by a TDMA frame on an inbound line. A broadcast communication method , which is performed prior to a satellite broadcast, in response to a line setting request from a broadcast master station, a response to the line setting availability from each of the broadcast slave stations, and during broadcast data transmission or broadcast. A delivery acknowledgment response from each broadcast station in response to a delivery confirmation request from the broadcast master station, and a line release from each broadcast station in response to a line release request from the broadcast master station, performed after the data transmission is completed. Regarding the release acknowledgment, a response to the broadcast master station is made by a pre-assigned TDMA system in which a broadcast slave station is fixedly assigned to each time slot. When a data reception error is detected in a broadcast station for each broadcast data to be received, a reception response from the broadcast station can be used as a retransmission request, and each time slot can be used by any broadcast station. A satellite broadcast communication method in which a response to a broadcast master station is made using the random access TDMA system described above . 2. Broadcast data from a broadcast master station is sequentially transmitted as a data frame conforming to an HDLC frame on an outbound line to each of a plurality of broadcast slave stations via a communication satellite at the same time. Each of the slave stations transmits a reception result for each piece of broadcast data sequentially received in frame units to a broadcast master station via a communication satellite as a reception response by a TDMA frame on an inbound line. A broadcast communication method , which is performed prior to a satellite broadcast, in response to a line setting request from a broadcast master station, a response to the line setting availability from each of the broadcast slave stations, and during broadcast data transmission or broadcast. A delivery acknowledgment response from each broadcast station in response to a delivery confirmation request from the broadcast master station, and a line release from each broadcast station in response to a line release request from the broadcast master station, performed after the data transmission is completed. For the release acknowledgment, while the response to the broadcast master station with a pre-assignment TDMA scheme Dohoko station in the time slots each being fixedly assignment is made, the broadcast master station in the middle of the broadcast transmission data Delivery of
From the delivery acknowledgment against the confirmation request, as needed check accepted by the data reception state is broadcast master station for each Dohoko station,
During broadcast data transmission, when a data reception error is detected by the broadcast station for each broadcast data sequentially received in frame units, the reception response is a retransmission request, and each time slot has any broadcast data. A satellite broadcast communication method in which a response to a broadcast master station is made by using a random access TDMA system which is also made usable by a station. 3. Broadcast data from a broadcast master station is sequentially transmitted as a data frame conforming to an HDLC frame on an outbound line to each of a plurality of broadcast slave stations via a communication satellite at the same time. Each of the slave stations transmits a reception result for each piece of broadcast data sequentially received in frame units to a broadcast master station via a communication satellite as a reception response by a TDMA frame on an inbound line. A broadcast communication method , which is performed prior to a satellite broadcast, in response to a line setting request from a broadcast master station, a response to the line setting availability from each of the broadcast slave stations, and during broadcast data transmission or broadcast. A delivery acknowledgment response from each broadcast station in response to a delivery confirmation request from the broadcast master station, and a line release from each broadcast station in response to a line release request from the broadcast master station, performed after the data transmission is completed. Regarding the release acknowledgment, a response to the broadcast master station is made by a pre-assigned TDMA system in which a broadcast slave station is fixedly assigned to each time slot, and the broadcast acknowledgment is sequentially received in frame units during broadcast data transmission. When a data reception error is detected at the broadcast slave station for each broadcast data to be transmitted, the reception response is a retransmission request,
When a response to the broadcast master station is made using the random access TDMA scheme in which each time slot is made available to any broadcast slave station, the broadcast master station:
If a retransmission request from any two or more broadcast stations is detected as a time-duplicated state, the system waits for the end of transmission of broadcast data that is currently in a transmission state. , Satellite broadcast communication in which transmitted broadcast data transmitted before a time corresponding to a propagation delay between a broadcast master station and a broadcast slave station is transmitted to each broadcast slave station as a retransmission frame.
How . 4. Broadcast data from a broadcast master station is sequentially transmitted as a data frame conforming to an HDLC frame on an outbound line to each of a plurality of broadcast slave stations via a communication satellite at the same time. Each of the slave stations transmits a reception result for each piece of broadcast data sequentially received in frame units to a broadcast master station via a communication satellite as a reception response by a TDMA frame on an inbound line. A broadcast communication method , which is performed prior to a satellite broadcast, in response to a line setting request from a broadcast master station, a response to the line setting availability from each of the broadcast slave stations, and during broadcast data transmission or broadcast. A delivery acknowledgment response from each broadcast station in response to a delivery confirmation request from the broadcast master station, and a line release from each broadcast station in response to a line release request from the broadcast master station, performed after the data transmission is completed. For the release acknowledgment, while the response to the broadcast master station with a pre-assignment TDMA scheme Dohoko station in the time slots each being fixedly assignment is made, the broadcast master station in the middle of the broadcast transmission data Delivery of
From the delivery acknowledgment response to the confirmation request , the data reception status of each broadcast station can be confirmed at any time by the broadcast master station,
During broadcast data transmission, when a data reception error is detected by the broadcast station for each broadcast data sequentially received in frame units, the reception response is a retransmission request, and each time slot has any broadcast data. When a response to the broadcast master station is made using the random access TDMA scheme that has been made available by the station, retransmission requests from any two or more broadcast slave stations are overlapped in time at the broadcast master station. If it is detected as a broadcast state, it waits for the end of the transmission of the broadcast data that is currently in the transmission state, and transmits it before the time corresponding to the propagation delay between the broadcast master station and the broadcast slave station from the point of detection. A satellite broadcast communication method in which the transmitted broadcast data transmitted is transmitted to each broadcast station as a retransmission frame.