JPH0365060B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention provides a method for controlling multiple access (Demand Assigned Multiple Access≡
DAMA) method.

In recent years, the construction of telephone networks using satellites has become popular, but most of them use the pre-assignment method, in which lines are fixedly assigned, or the International Telecommunications Satellite Organization (Intelsat) uses multiple connections between 50 to 60 stations. Spade System (Single Channel)
por Carrier PCM Multiple Access Demand
Assignment Equipment) is common. In the future, as satellites become more powerful, plans for telephone networks in depopulated areas in which many small ground stations will be interconnected via the same satellite are likely to be realized. In this situation, several hundred
It is necessary to efficiently process calls from several thousand small traffic stations using an economical system. That is, there is an urgent need for a multiple access system based on inexpensive equipment that can be accommodated in each small ground station.

In order to meet such demands, an object of the present invention is to provide a multiple access system in which multiple access functions are distributed to each ground station using inexpensive equipment, centered on a central station equipped with a simple circuit monitoring function. It is in.

This invention sends a vacant line signal to a downlink available for communication, indicating to the desired station the line on which a call signal for requesting a call should be issued, and indicating the line on which all slave stations waiting for reception should receive the signal. In a multiple connection system with a central station, all stations desiring a call send call signals to the corresponding uplink lines; upon receiving the call signal, the central station immediately stops transmitting the above-mentioned aerial line signals; The present invention provides a multiple connection system characterized in that the call signal group received instead of a signal is sent as is through a downlink; all call requesting stations and all reception standby stations receive the call signal group. be.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows the frequency arrangement of a transponder for a telephone line using a satellite. In a wireless telephone line, two channels (upper and lower) form a pair to form a telephone line. In the diagram, 1000, 1000´, 1001 and
1001', 1002 and 1002', and 1003 and 1003' are each paired to form four telephone lines. For convenience, the former of each pair is defined as a downlink, and the latter is defined as an uplink. Conventionally, in order to perform connection processing for each line, a control line is provided in addition to these call lines, and each ground station performs connection control via the control line. In this case, all stations must be equipped with transmitters and receivers dedicated to the control line, and the processing capabilities of the central station that mediates control signals also become considerably large.

The invention therefore proposes multiple access without any such dedicated control rounds. Figures 2 to 5 below
The scheme of the invention is illustrated in the figure.

First, the central station monitors only the line usage status in the satellite's transponder, and if an empty line exists, it sends an empty line signal to the downlink. Second
100 shows the central station, 101 shows the call requesting station, and 1010 shows the idle line signal. Next, as shown in FIG. 3, the station desiring to make a call receives the idle line signal 1010, learns of the existence of an available idle line, and sends a call signal 1011 to the central station through the corresponding upstream line.

Next, as shown in Figure 4, the central station sends the requesting station
Upon receiving the call signal from 101, the station learns that this idle line will be used for telephone calls, and stops the idle line signal in order to prevent other stations from transmitting call signals.

Next, as shown in FIG. 5, the central office transmits the received call signal as is instead of the idle line signal. Since the station to receive the information is intercepting the same idle line, it will respond only if this line connection information is addressed to its own station.

Let us now consider a case where the station desiring to talk issues a call signal to multiple stations at the same time. Figure 6 shows this situation. In this case, the two ground stations 101 and 102 send call signals.
If 1011 and 1012 are sent at the same time, the central station will send them back as they are, so each station will
It can be seen that two waves 1011' and 1012' were received at the same time, resulting in double capture.

As described above, by sending the call signal received by the central station back to all stations as is, each station wishing to make a call can independently confirm that the call signal it has sent is suffering from double capture.

As described above, according to the present invention, by simply installing a central station that has a simple function of detecting idle lines, all other connection control is performed by each slave station, without using complicated control procedures. It is possible to reduce the cost of the entire system, and also to increase the reliability of the system through distributed control.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a transponder frequency arrangement for a satellite telephone line. 2 to 5 are diagrams for explaining the continuous procedure of the blank line signal sending type of the present invention. FIG. 6 is a diagram for explaining double capture of an empty line.

Claims (1)

[Claims] 1 Send an empty line signal to the downlink air line where you can talk,
In a multiple access system that has a central station that indicates to a station desiring a call the line on which it should issue a call signal for a call request, and also indicates the line on which all slave stations waiting to receive calls should send a call signal, all stations desiring a call must issue a call signal. Sends the signal to the corresponding upstream line; upon receiving the call signal, the central station immediately stops transmitting the idle line signal; instead of the idle line signal, the received call signal group is sent as is through the downstream line. A multiple access system characterized in that all call requesting stations and all reception standby stations receive the call signal group.