JPH0690195A - Satellite communication system - Google Patents

Abstract

PURPOSE:To prevent the communication fault of an in-band channel from occurring due to disturbance such as rainfall in a star-type satellite communication network by forming the star-type satellite communication network with a master station and plural slave stations, providing a transmission channel for notification to slave station resistant to the distrubance in the master station, and providing a small transmitter which can vary a transmission level in the slave station. CONSTITUTION:The master station 1 is equipped with a reception level measuring instrument 5 which monitors the reception level of the in-band channel from each slave station 3, and each slave station is equipped with a transmission level adjuster 10 which can freely adjust a transmission level. The master station monitors the reception level of the in-band channel from each slave station, and when the decrement(increment) of the reception level is recognized, the information of such decrement(increment) is notified to a corresponding slave station by using an out band, and the slave station corrects the transmission level based on the information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication system, and particularly, in a satellite communication line of a star network, satellite communication capable of preventing communication failure due to data collision from a plurality of slave stations to a master station. Regarding the scheme.

[0002]

2. Description of the Related Art Conventionally, in a star type network in which a master station and a plurality of slave stations communicate with each other, in a satellite communication system in which a slave station randomly accesses an in-band channel allocated to secure a communication path, Since the transmission data from the station may collide on the satellite link, if the slave station detects that the communication from the slave station did not reach the master station, the slave station is determined by a statistical random number. It takes a method to try again after waiting for time. Here, the transmission level of each slave station was always fixed.

[0003]

The above-mentioned conventional satellite communication system is a very effective workaround against the communication failure caused by the collision between the slave stations, but the transmission / reception level is lowered due to rainfall or the like. In the case of a communication failure due to, the transmission level is fixed, so there is a drawback that there is no effect.

[0004]

The satellite communication system of the present invention has a broadcasting outbound channel capable of communicating from a master station to a plurality of slave stations, and a multiplex communication capable of communicating from the slave station to the master station. In a star-type satellite communication system with an access inbound channel, the master station measures the level of the in-band channel of each branch, and when the level of the received in-band channel changes, the outbound is used to reach the corresponding branch. Means for notifying the level information, and the corresponding branch office has means for correcting the transmission level of the in-band channel by receiving the level information.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a master station waiting for a broadcasting channel capable of communicating with a group of slave stations, 2 is a satellite, and 3 is a slave station capable of randomly accessing a communication channel to the master station. The master station 1 is equipped with a data receiver 4 and a data transmitter 7, and the slave station 3 is equipped with a data receiver 8 and a data transmitter 11.
Or it is equipped.

Next, the operation of this embodiment will be described. The out-band from the master station 1 to the slave station 3 uses a broadcasting channel, and the communication from the slave station 3 to the master station 1 is performed by each slave station randomly accessing the inban channel. It has been realized. Although not shown in FIG. 1 as one slave station, in reality, in a star satellite communication network, it is assumed that a plurality of slave stations exist for one master station. The in-band channel from the slave station to the master station is packet communication in slot units, but since it is a random access method, there is a possibility of collision between transmission data of the slave station data. As a countermeasure, when the disappearance of data is detected by the communication protocol, each slave station has a function of retransmitting the data after a lapse of time determined by a statistical random number, as described in the conventional example.

The signal format of FIG. 2 is a data format of an out-band channel for broadcasting from the master station 1 to the slave station 3. This signal format is packet header 2
0, packet data 21 and packet header 20
An address 23 of an arbitrary slave station is written in. Each slave station takes in only the data addressed to itself by this address and discards the data addressed to other stations. In the packet data 21, pure data from the external ground type or the reception level information of the slave station 3 received by the master station 1 is put. Further, the packet header 20 includes a slave station address 23 and a data identification flag 22. By this value, the packet data 21 following the packet data 21
Identifies whether it is pure data or reception level information. As shown in FIG. 1, the reception level measuring device 5 of the master station monitors the reception level of the in-band channel from each slave station.
It is possible to measure each slot which is an access unit. When the reception level measuring instrument 5 shows a decrease (or an increase) in the reception level for the received data from any slave station, it is assumed that the characteristics of the communication path have changed due to the disturbance of weather conditions such as rainfall, and the level data is created. The device 6 creates outband data with the reception level as packet data and transmits it to the corresponding slave station. The corresponding slave station determines whether the outband data received by the data receiver 8 is addressed to itself by the data discriminator 9 and, at the same time, uses the identification flag 22 to discriminate whether the received data is pure data or level information. If the packet data is pure data, it is transferred to an external device on the ground system. When the packet data is level information, the transmission level adjuster 10 is notified, the transmission level is increased (or decreased) based on the level information, and the communication failure is prevented.

[0010]

As described above, according to the present invention, the master station has a transmission channel for broadcasting which is resistant to disturbances such as rainfall, and the reception level measuring device for monitoring the reception of the in-band channel from each slave station. Since each slave station has a transmission level adjuster that can freely adjust the transmission level, the master station measures the reception level from each slave station, notifies the slave station of the information, and the slave station By correcting the transmission level based on the information, it is possible to prevent the communication failure of the in-band channel due to the disturbance such as rainfall.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a format of Outvan data according to the present embodiment.

[Explanation of symbols]

 1 master station 2 satellites 3 slave stations 4, 8 data receiver 5 reception level measuring device 6 level data generator 7, 11 data transmitter 9 data discriminator 10 transmission level adjuster

Claims (1)

[Claims] 1. A star-type satellite communication system having a broadcast outbound channel capable of communicating from a master station to a plurality of slave stations and having a multiple access inbound channel capable of communicating from the slave station to the master station. , The master station has means for measuring the level of the inbound channel of each slave station, and means for notifying the corresponding slave station of the level information using the outbound when the level of the received inbound channel changes, A satellite communication system, wherein the slave station has means for correcting the transmission level of the inbound channel by receiving the level information.