JPH09307495A - Satellite line assigning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the extension of a waiting time and to facilitate its averaging even at the time of setting a connection order without regard to a transmitting data quantity when line connection is requested from plural earth stations. SOLUTION: When line connection is requested from the plural earth stations TA to TC, a control station C compares the transmitting data quantity of the earth stations TA to TC and sets the earth station of a small transmitting quantity to be a high order to execute line assignment. In addition the control station C calculates the waiting time at the earth stations TA to TC. Thereby a total waiting time at all the earth stations TA to TC is reduced and the waiting time is averaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite line allocating method between a plurality of earth stations in satellite communication, and particularly, to transfer a large amount of data such as file transfer between computers over a satellite line over a relatively long time. The present invention relates to a satellite channel allocation method that shortens and averages waiting time during transmission.

[0002]

2. Description of the Related Art Conventionally, various techniques have been proposed for allocating satellite links between a plurality of earth stations. For example, in Japanese Unexamined Patent Publication No. 3-088434, a random access reservation composite method and a fixed allocation method are integrated, and by accommodating terminals having different data generation frequencies and generated data amounts per transmission, various services can be provided. A satellite communication system that has made it possible to provide is proposed. Also, JP-A-63
According to Japanese Patent Laid-Open No. 084211, the number of reserved slots is determined by allocating a reserved slot in the reserved area for each terminal group, providing a free area in the reserved area, and providing a table for managing the reserved area in the master station to perform line allocation processing. A line control method for reducing the number has been proposed. Further, JP-A-63-
In the 067926 publication, by allocating lines in order from the one having the same reservation slots as the number of earth stations and the data slots smaller than this, and the remaining information amount to be transmitted and the fictitious information amount caused by transmission waiting, in order. A satellite line assignment method has been proposed in which lines are fairly assigned to the earth station that originated a call regardless of the traffic volume.

Further, in Japanese Patent Laid-Open No. 61-281727, in the adaptive DAMA system, the traffic volume is predicted for the whole based on the call volume notified from each slave station, and the number of allocated lines to each slave station is calculated. An adaptive DAM that eliminates connection delays and improves line utilization efficiency by determining and specifying
Method A has been proposed. Further, JP-A-57-037
According to Japanese Patent No. 938, in a satellite communication line, an earth station having information to be sent adds a highest priority station indication to a reserved burst in which the number of reserved slots is described, and transmits the reserved burst to prevent burst collision and improve satellite utilization rate. A reservation method has been proposed to achieve this.

[0004]

Among these conventional line allocation techniques, the technique disclosed in Japanese Patent Laid-Open No. 3-088444 is a TDMA (time division multiple access) system that combines a fixed allocation system, a random access system, and a reserved allocation system. Therefore, the connection delay of the packet data waiting for the time slot allocation becomes large, and it becomes impossible to provide various services using the composite method, and the relatively long time (several minutes to several hours) There is a problem that the time slot cannot be exclusively occupied.

On the other hand, JP-A-63-084211, JP-A-63-067926 and JP-A-57-
With the technology of Japanese Patent No. 037938, it is possible to improve the utilization efficiency of the satellite line, but since the control is performed to allocate the line to each earth station regardless of the traffic volume, the transmission waiting time of each earth station There is a problem in that the average waiting time of the network and the average waiting time of the entire network cannot be shortened.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 61-281727, a prediction error occurs because the future call volume is predicted with reference to the past call volume, resulting in uncertainty of shortening the connection delay. There is a problem.

An object of the present invention is to make it possible to allocate a line to data that requires a relatively long time for transmission, while shortening and averaging the transmission waiting time of each earth station. It is to provide the satellite channel allocation method.

[0008]

According to the present invention, the same frequency band of a communication satellite is alternately used by a plurality of earth stations, and a control station allocates lines in time division based on a line connection request from each earth station. In the satellite channel allocation system for performing the above, the control station sets the channel allocation order based on the amount of data transmitted from each earth station. In this case, it is preferable that the control station preferentially allocates the earth station, which transmits a small amount of data, to a higher rank.

Further, according to the present invention, the control station sets the line allocation order based on the amount of data transmitted from each earth station and the line connection request time from each earth station. In this case, the control station calculates the waiting time of each earth station based on the line connection request time of each earth station, and gives priority to the earth station with a small amount of data to be transmitted within the predetermined waiting time, in the higher ranking. It is preferable to allocate lines to For example, the order is set for a plurality of earth stations that have made a line connection request within a predetermined time block.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 (a) is a schematic configuration diagram showing an example of a satellite communication system to which the present invention is applied. A plurality of earth stations (controlled stations) TA, TB
It shows a state in which the TC is connected to a control station S that performs line allocation via a communication satellite CS by a time division multiple access line. When it becomes necessary for each earth station TA, TB, TC to transmit data, as shown in FIG. 1 (b), a line connection request packet including transmission request time, transmission data length, transmission request station, and destination information is transmitted. Send to control station.

When the control station C receives the line connection request packet, the control station C determines the transmission order based on the information of the transmission request time and the transmission data length, and executes the line allocation. In this line allocation, as shown in the flowchart of FIG. 2, first, based on the transmission data length information, the transmission data amounts of a plurality of earth stations TA, TB, and TC that have made line connection requests are compared.
By comparing the transmission data amounts, for example, the priority of the earth station with the smaller transmission data amount is set higher than that of the earth station with the large transmission data amount. As a result, the line is allocated from the earth station, which transmits less data.

Next, the waiting time of each earth station that has made a line connection request is calculated based on the information of the transmission request time. This waiting time is calculated by calculating the waiting time of each earth station when the line allocation is executed based on the above-mentioned transmission data length so that the total waiting time is shorter and the average waiting time is shorter. Assign the line to. Further, in this case, the standard deviation of the waiting time is calculated, and the line allocation is executed so that the standard deviation becomes smaller. Moreover,
Based on the information of the transmission requesting station and the transmission destination included in the line connection request packet, the control station C allocates a line to the corresponding earth station when the transmission order is reached.

Here, for example, in FIG. 3, data A (length 3), data B (length 1), and
It is assumed that a line connection request for data C (length 4) and data D (length 2) is made at the same time. In this case, the total waiting time, the average waiting time, and the standard deviation of the waiting time are shown for all the combinations when the transmission order of the line allocation for the data A to D of each earth station is changed as described above. ing. Further, FIG. 5 is a graph showing the results of FIG. 4 with the average waiting time as the horizontal axis and the standard deviation of the waiting time as the vertical axis.

As a result, as a combination having a short average waiting time and a small waiting time standard deviation, a combination of circles indicated by arrows in the graph, that is, the transmission order number "11" and the data A to D in FIG. It is estimated that the combination transmitted in the order of "BDAC" is the most suitable of all the combinations. As you can see,
By connecting the lines in ascending order of data length, it is possible to realize a line connection with a smaller average waiting time and its standard deviation.
Actually, the control station compares the transmission data lengths of a plurality of earth stations that have requested line connection according to the procedure shown in FIG.
Based on this, the line connection request is mapped as shown in FIG. 4 and the transmission order can be determined. For example, a method in which the mapping is divided into several elements, the ranking is determined in advance and the combination of transmission orders is selected, and the like can be considered.

The control station calculates the transmission waiting time at each earth station from the transmission request time of each earth station, but since this waiting time changes from moment to moment, the transmission order based on the line allocation control is also momentary. Is changing. For this reason, if the line connection is made only by comparing the transmission data lengths, the average waiting time and the standard deviation may not always be reduced when the transmission request times are mixed. In addition, when transmission data is continuously compared with the passage of time, the line connection of the earth station with long transmission data is postponed in sequence, the waiting time is greatly increased, and the average waiting time and standard deviation are increased. It may increase. Therefore, for this purpose, for example, it is necessary to set a time block of a certain length and perform the above-mentioned comparison of the transmission data length only within this time block to establish a line connection.

[0016]

EXAMPLE As shown in FIG. 5, data having transmission data lengths of 5 (data A), 4 (data B), 3 (data C), 2 (data D), and 1 (data E), respectively. Therefore, in the case of transmitting this data by sharing one satellite line, it is assumed that the order of transmission is such that the data length is long, that is, A, B, C, D, E. When the time required for the data to wait for the transmission order is expressed by the length of the data, the respective waiting times are 0 (data A), 5 (data B), 9 (data C), 12 (data D), 14
(Data E), and the total waiting time is 4
It becomes 0, and the average waiting time becomes 8. In this example, the average waiting time is 50% of the worst value and the standard deviation of the waiting time is 65% of the worst value.

Further, as shown in FIG. 6, the case where the length of transmission data and the transmission order are irrelevant in the same combination of transmission data is shown. In this example, the data C, D, B, A, E
The respective waiting times are 0 (data C), 3 (data D), 5 (data B), 9 (data A), and 14 (data E), and the total waiting time is 31. , The average waiting time is 6.2.

On the other hand, FIG. 7 shows a case where the transmission data is transmitted in the ascending order as in the above-described embodiment. In this case, the order of data E, D, C, B, A is
The respective waiting times are 0 (data E), 1 (data D), 3 (data C), 6 (data B), 10 (data A), and the total waiting time is 20 and the average waiting time is It becomes 4.

From FIGS. 5, 6 and 7, it is clear that in such a case, the total waiting time can be minimized by arranging the transmission data in order from the shortest and transmitting the data sequentially.

In FIG. 8A, when transmission is performed in the order shown in FIG. 8, new transmission requests for data F (data length 2) and G (data length 3) are generated during transmission of data B. The case is shown. In this case, in order to minimize the total waiting time of the untransmitted data E, F, G, the data lengths of these transmitted data are compared as described above, and as shown in FIG. It is necessary to rearrange the transmission order as F, G, E. However, if this line allocation is performed in a time-continuous manner, there is a risk that long data cannot be transmitted forever.

In such a case, as shown in FIGS. 8A and 8B, the total waiting time and the average waiting time in the case of transmitting data in the order of EFG and in the case of transmitting the data in the order of FGE, respectively. As shown by the standard deviation of the waiting time, the total waiting time becomes short in the FGE order of the shortest order of the transmission data, but the standard deviation becomes large, which may cause an unfairness among the transmission data. In this case, a time block is set and data A to
By setting up to E as one time block and the data F and G as the next time block, the data E can be transmitted and its standard deviation can be reduced. Then, after the transmission of the data E, in the next time block, the line connection is executed in the same order as the above-mentioned shorter transmission data.

[0022]

As described above, according to the present invention, the control station sets the order of a plurality of earth stations for which a line connection request has been made based on the transmission data amount of each earth station, and performs the line allocation control. By setting the earth station with a particularly small amount of transmission data to the higher rank, it is possible to reduce the total waiting time for line connection in a plurality of earth stations and to average the waiting times. In addition, by setting the line allocation order according to the waiting time of each earth station, it is possible to allocate lines to earth stations with a large amount of transmission data in a certain order, and the line connection waiting time standard It is possible to prevent the deviation from unnecessarily increasing.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a satellite communication system to which the present invention is applied and a frame configuration diagram of a line connection request packet thereof.

FIG. 2 is a flowchart showing the operating principle of the present invention.

FIG. 3 is a diagram showing a relationship between a combination of line allocation and its waiting time.

FIG. 4 is a diagram showing a relationship between a waiting time and a standard deviation in the combination of FIG.

FIG. 5 is a diagram showing the relationship between line allocation and its waiting time in the first embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between line allocation and its waiting time in the second embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between line allocation and its waiting time in the third embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a combination of line assignments and its waiting time in the fourth embodiment of the present invention.

[Explanation of symbols]

 CS communication satellite C control station TA, TB, TC earth station

Claims (5)

[Claims] 1. A satellite channel allocation system in which the same frequency band of a communication satellite is alternately used by a plurality of earth stations, and a control station allocates circuits in time division based on a circuit connection request from each of the earth stations, The satellite channel allocation system, wherein the control station sets the channel allocation order based on the amount of data transmitted from each earth station. 2. The satellite channel allocation system according to claim 1, wherein the control station preferentially allocates the channel of the earth station, which transmits a small amount of data, to a higher rank. 3. A satellite channel allocation method in which the same frequency band of a communication satellite is alternately used by a plurality of earth stations, and a control station allocates circuits in time division based on a circuit connection request from each of the earth stations, The satellite channel allocation system, wherein the control station sets the channel allocation order based on the amount of data transmitted from each earth station and the time required for connection from each earth station. 4. The control station calculates the waiting time of each earth station based on the line connection request time of each earth station, and gives priority to the earth station having a small amount of data to be transmitted within a predetermined range of this waiting time. The satellite circuit allocation system according to claim 3, wherein the circuit is allocated to a higher rank. 5. The satellite channel allocation system according to claim 4, wherein the control station sets the channel allocation order for a plurality of earth stations that have requested circuit connection within a predetermined time block.