WIRELESS COMMUNICATION SYSTEM, WIRELESS RELAY STATION MONITORING CONTROL DEVICE AND WIRELESS COMMUNICATION METHOD

1 . A wireless communication system for performing communication using a non-terrestrial network, the wireless communication system comprising:

a wireless relay station configured to stay in the air and relay wireless communication;

a ground station configured to perform transmission and reception of radio waves to and from the wireless relay station and connect the wireless communication of the non-terrestrial network to a terrestrial network; and

a wireless relay station monitoring controller configured to monitor and control the wireless relay station and the ground station via the terrestrial network, wherein

the wireless relay station monitoring controller is configured to execute:

calculating a prediction value of a rainfall attenuation amount of the radio wave at a movement candidate position in a radio relay area of the wireless relay station and a current position on the basis of weather prediction information;

predicting communication quality due to the radio wave at the movement candidate position and the current position of the wireless relay station on the basis of the prediction value;

selecting a position at which attenuation of the radio wave is predicted to be less than that in which the wireless relay station stays at a current position from among the movement candidate positions on the basis of the communication quality; and

moving the wireless relay station to the position selected by the movement position selection.

2 . The wireless communication system according to claim 1 , wherein

a movement possibility range of the wireless relay station is defined in the wireless relay area, and

the wireless relay station monitoring controller determines the movement candidate position from the movement possibility range.

3 . The wireless communication system according to claim 1 , wherein

a plurality of movement possibility positions of the wireless relay stations are determined in the wireless relay area, and

the wireless relay station monitoring controller sets the plurality of movement possibility positions as the movement candidate positions.

4 . The wireless communication system according to claim 2 , wherein

the movement possibility range of the wireless relay station is determined according to a position in the wireless relay area.

5 . The wireless communication system according to claim 1 , wherein

the weather prediction information is information of a precipitation intensity prediction value given for each area obtained by dividing the ground into a lattice shape, and

the wireless relay station monitoring controller is configured to execute, in the calculation of the prediction value of a rainfall attenuation amount:

extracting the lattice-shaped area for a propagation section of the radio wave propagating in a range from a ground surface to an upper limit of a height of the rain area;

acquiring a precipitation intensity prediction value in the extracted lattice-shaped area;

converting the acquired precipitation intensity prediction value into a rainfall attenuation coefficient;

calculating a propagation distance of the radio wave for each of the extracted lattice-shaped areas; and

calculating a prediction value of the rainfall attenuation amount of the radio wave on the basis of the rainfall attenuation coefficient and the propagation distance of the radio wave.

6 . The wireless communication system according to claim 1 , wherein

the wireless relay station monitoring controller uses a prediction value of the rainfall attenuation amount of the radio wave, a threshold of an allowable maximum attenuation amount of the radio wave, and a propagation loss at the movement candidate position with a propagation loss at the current position of the wireless relay station as a reference to predict whether or not the communication line using the radio wave will be disconnected at the current position and the movement candidate position in the prediction of communication quality,

selects a position at which line disconnection is predicted not to occur from among the movement candidate positions in the movement position selection when it is predicted that the line disconnection occurs at the current position, and

moves the wireless relay station to the position selected in the movement position selection.

7 . A wireless relay station monitoring controller for monitoring and controlling a wireless relay station staying in the air in a non-ground network, wherein the wireless relay station monitoring controller is configured to execute:

calculating a prediction value of a rainfall attenuation amount at a movement candidate position and a current position in a radio relay area of the wireless relay station on the basis of weather prediction information, for a radio wave transmitted and received between the wireless relay station and a ground station;

predicting communication quality due to the radio wave at the movement candidate position and the current position of the wireless relay station on the basis of the prediction value;

selecting a position at which attenuation of the radio wave is predicted to be less than that in which the wireless relay station stays at a current position from among the movement candidate positions on the basis of the communication quality; and

moving the wireless relay station to the position selected by the movement position selection.

8 . A wireless communication method for performing communication using a non-ground network, the wireless communication method comprising;

causing a wireless relay station staying in the air to relay wireless communication in an area,

causing a ground station configured to transmit and receive radio waves to and from the wireless relay station to connect wireless communication of the non-ground network to a ground network, and

causing a wireless relay station monitoring controller for monitoring and controlling the wireless relay station and the ground station via the ground network to execute:

calculating a prediction value of a rainfall attenuation amount of the radio wave at a movement candidate position in a radio relay area of the wireless relay station and a current position on the basis of weather prediction information;

predicting communication quality due to the radio wave at the movement candidate position and the current position of the wireless relay station on the basis of the prediction value;

selecting a position at which attenuation of the radio wave is predicted to be less than that in which the wireless relay station stays at a current position from among the movement candidate positions on the basis of the communication quality; and

moving the wireless relay station to the position selected by the movement position selection.