JPS6367926A - Satellite circuit assigning system - Google Patents

Abstract

PURPOSE:To fairly assign circuits to ground stations generating calls independently of the quantity of traffic by forming reservation slots corresponding to the number of ground stations and data slots less than said number and assigning the circuits successively from a ground station having the most residual information to be transmitted and the most imagenary information generated due to transmission waiting. CONSTITUTION:In case of allowing participating ground stations to execute communication by using TDMA system, a reservation part and a data part are formed in each frame and the number of reservation slots 12-15 in the reservation part are set up equally to the number of ground stations A-D and the number of data slots 16-18 in the data part is set up to three e.g. less than said number and the data slots are assigned in accordance with the priority order of transmission allowance assigned to respective ground stations, the number of residual data to be transmitted and the number of imagenary data generated due to transmission waiting. When a ground station having the low quantity of traffic exists, the data slot can be assigned to the ground station without turning the data slots to a blank state. When the total number of data to be transmitted is less in a ground station or all data slots are assigned to other ground station, a data slot can be assigned to the ground station generating a call by using the concept of the number of imaginary data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a satellite communication system, and particularly to a multiple access system suitable for fairly allocating channels to a plurality of earth stations.

[Conventional technology]

The conventional TDMA system uses a fixed allocation method (Japanese Patent Application Laid-Open No. 16737/1983) that allocates periodic time intervals in which data can be transmitted fixedly to multiple earth stations, and a fixed allocation method that allocates periodic time intervals in advance that allow data to be transmitted in a fixed manner to multiple earth stations. Demand allocation method that allocates intervals and cancels the allocation when communication ends (Japanese Patent Laid-Open No. 1983
-31340).

The former fixed allocation method provides the highest line utilization rate when all earth stations are communicating, and has high transmission efficiency, making it ideal for communications with high traffic and a small number of users. Conversely, in the latter demand allocation method, even if there is an earth station that does not communicate, the line is used only by the earth station with which the call is occurring, increasing line usage efficiency. Therefore, it is ideal for low-traffic, multi-user communication.

In a satellite communication system, the demand allocation method is effective because multiple communication lines are likely to be used. In this method, there are reserved slots l~ for knowing whether each earth station is generating a call and data slots l~ for each earth station to transmit data. There are as many stations as there are stations.

However, among all the earth stations, if there is an earth station that wants to use the satellite line when the ground line becomes unusable due to a ground disaster, the data slot assigned to that earth station during normal communication will be wasted. Put it away. However, if you allocate data slots to the number of earth stations excluding such earth stations, if there is no empty data slot when that earth station attempts to communicate, the data slot will become empty. The disadvantage is that you have to wait until the data is sent.

(Problem to be Solved by the Invention 1) As mentioned above, the above demand allocation method does not take into consideration the case where there are earth stations that transmit data for a short period of time, and there are as many data slots as there are earth stations. If the number of data slots is less than the number of earth stations, there is a problem in that lines cannot be fairly allocated to all earth stations.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a method for fairly allocating lines to earth stations that have made calls, regardless of the amount of data traffic.

[Means for solving problems]

The above purpose is to allocate lines in descending order of the number of reserved slots equal to the number of earth stations and fewer data slots than the number of earth stations, and the amount of remaining information that must be transmitted and the number of fictitious information devices created by waiting for transmission. , If there exists an earth station where the sum of the amount of remaining information and the amount of fictitious information is equal, this can be achieved by allocating lines in order of predetermined transmission priority.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of the embodiment. 1 is a communication satellite, and there are four earth stations A, B, C, and D sharing this communication satellite. Satellite lines for each earth station A, B, C, D are 6, 7, 8
．． 9, and the frequencies of the carrier waves used are all the same. Further, a time period for transmitting a signal is allocated to each earth station so that the data transmitted from each earth station will not collide and become impossible to transmit the signal.

It is assumed that the synchronization of the signals sent by each earth station is achieved by a synchronization signal issued from a certain earth station. Here, the earth station that emits the synchronization signal is decided among the earth stations in advance, and if that station does not emit the synchronization signal, each earth station monitors the timer to see if the synchronization signal is being emitted. Then, after a certain period of time has elapsed, the next earth station will emit a synchronization signal. Here, it is assumed that earth station A emits a synchronization signal first. If earth station A determines that it is not emitting a synchronization signal, earth station B will emit a synchronization signal in the order of earth station C1 and then to the earth station if earth station B determines that it is still not emitting it. . In addition, each earth station A,
B, C, and D have their transmission priorities determined in advance.
It is assumed that earth station A originally has a high priority, followed by earth station B, earth station C9, and so on. This priority order is an order in which data can be transmitted from an earth station with a higher priority only if the conditions are the same when transmitting data.

Here, the time during which each earth station can send a signal is called a slot. As shown in FIG. 2, on the real time axis t, there is a reservation section and a data section. and,
These two reserved parts and data parts exist periodically, and the reserved part and data part are collectively referred to as a frame. The reservation section further includes reservation slots 12, 13, 14, and 15.
It is divided into Here, the number of reserved slots is the number of earth stations, and in this example, there are four reserved slots. The data section further includes data slots 1 to 16.17.
It is divided into 18 parts. The number of data slots is smaller than that of the earth station, and is three in this embodiment.

Next, a specific example will be described with reference to FIG.

First, each of the earth stations A and B at the time of the reservation section 100.

Sends the data transmission status of its own station in the reserved time slots assigned to C and D. In other words, earth station A at 105 has 6 pieces of data 109, earth station B at 106 has 3 pieces of data 110, earth station C at 107 has 4 pieces of data 111, and earth station 108 has data 112. I have two of each. It is assumed here that data is the amount of information that the earth station can send during one data slot. Each earth station transmits the number of data it currently has as information during the reservation section time. When each earth station receives this information from each earth station, each earth station arranges the earth stations in descending order of the amount of data and detects which earth station it is on. Data slots are then allocated from the earth station with the most data.

In this example, data slot 102 is assigned to earth station A at 105.
In addition, data slot 103 is assigned to 107 earth stations C, and data slot 104 is assigned to 106 earth stations B. Here, the information transmitted by each earth station at the time of the reservation unit 101 is the number of data remaining at each earth station as a result of sending data in the data portion within the same frame. In other words, earth station A has 5 pieces of data 209, and earth station B has 5 pieces of data 210.
The earth station C has three pieces of data 211, and the earth station has two pieces of data 212 and 1 degree of fictitious data 21.3. Here, fictitious data is generated at an earth station to which a data slot has not been assigned, in this case the earth station. In other words, this occurs at the earth station waiting to transmit data. Then, one fictitious number of data is generated for each earth station to which no data slot has been allocated at the time of one data slot allocation. That is, 10
The earth station No. 8 informs the reservation unit 101 that it has three pieces of data, two pieces of actual remaining data 212 and one piece of fictitious data 213 generated by waiting for transmission.

Next, each earth station that received this reservation information is shown in Figure 3 (
), it is possible to assign the earth station to the data slot 202 and the earth station C to the data slot 203, but as mentioned above, In this embodiment, earth station A has the highest transmission priority, followed by earth station B.

Since the order is from earth station C2 to earth station, data slot 203 is allocated to earth station C, and data slot 204 is allocated to earth station C.

Further, the information sent by each earth station in the reservation unit 201 sends the results when the above-mentioned steps are implemented. In other words, as shown in FIG. 3(d), earth station A has four pieces of data 309, earth station B has two pieces of data 310, and fictitious data 31 that occurred because the data slot was not allocated last time.
There is one 1, so you have a total of three pieces of data. There are two pieces of data 312 for the earth station C, and one piece of data 313 for the earth station, but the fictitious data 213 was originally generated while waiting for transmission, so if the data is sent, By eliminating one piece of fictitious data per transmission, the earth station is waiting for only one piece of data 313.

In this way, earth station A is allocated to data slot 302, earth station B is allocated to data slot 303, and earth station C is allocated to data slot 304, respectively. Next, earth station A is placed in data slot 402, and earth station A is placed in data slot 402.
03 is assigned to the earth station, and data slot 404 is assigned to the earth station B. Finally, as shown in Figure 3(f), earth station A sends two pieces of data, and earth station C sends one piece of data.
data and one fictitious data, and earth station B and earth station have no data. At this time, data slots are allocated as follows.

First, since both earth stations A and C have two pieces of data, data slot 5 is assigned to earth station A, which has a higher priority.
Assign 02. Then, data slot 503 is assigned to earth station C.

As a result, the data slots 504 become empty, so the data slots 504 are sorted again from the one with the most data.
Assign 4. In this example, earth station A is assigned.

Also, although not explained in this example, if as a result of sending all the data you have, there is fictitious data created by waiting for transmission, it means that there is no data to send. This is to prevent each earth station from transmitting information that would lead to incorrect reservations.

In this way, according to this embodiment, there is no empty data slot that existed in the prior art, and the utilization efficiency of the communication line is improved. Furthermore, it has the effect of being fairly allocated to each earth station regardless of the amount of data sent through the communication line.

〔Effect of the invention〕

According to the invention, an earth station with a low traffic volume,
Earth stations that wish to use the line during a disaster or for a short period of time use TDM.
When multiple connections are made using method A, data slots can be assigned to earth stations without leaving the data slots empty, which has the effect of improving line utilization. In addition, if an earth station that transmits a small total number of data or all data slots are assigned to other earth stations, the concept of a fictitious number of data can be used for the earth station that generated the call. Since data slots can be allocated, communication lines can be fairly allocated to each earth station.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a frame block diagram of an embodiment of the present invention, FIG. 3(a) is a frame block diagram of an embodiment of the present invention, and FIG. Figure 3 (b) shows the initial amount of data held by each earth station, Figure 3 (c)
Figure 3(d) shows data transmission twice, Figure 3(e) shows data transmission three times, and Figure 3(f) shows data transmission four times. It is a figure showing the number of data. 1...Communication satellite, 105,205,305,405°505...Earth station A, 106,206,306°40
6.506--Earth station B, 107,207°307.
407,507...Earth station C1108゜208.30
8,408,508...Earth station D, 109-112,
209~212,309,310°312~313,4
09-412,509,510...data, 213,
311, 413, 411... fictitious data.

Claims (1)

[Claims] 1. When participating earth stations communicate using the TDMA method, a time area is reserved for channel allocation and a time area is for data transmission, and the reserved area time is equal to the number of participating earth stations. In addition, the data area time is divided into fewer parts than the number of participating earth stations, and the transmission permission priority assigned to the participating earth stations in advance, the amount of remaining data that must be transmitted, and the amount of data waiting for transmission are determined. A satellite line allocation method characterized by allocating a time domain for data transmission based on the number of fictitious data generated.