Wireless communication system, communication apparatus, relay apparatus and wireless communication method

A communication device that is located in a communication target area and transmits an uplink signal to a relay device mountable on a moving body,

• the communication device comprising:
• a receptor configured to obtain a transmission permission signal from the relay device transmitting the transmission permission signal to the communication target area by a beam at a determined transmission level, the transmission permission signal being a signal representing transmission permission of the uplink signal;
• a transmission controller that determines an earlier transmission timing as an elevation angle of the relay device viewed from the communication device is larger on a basis of the transmission permission signal;
• and
• a transmitter that transmits the uplink signal to the relay device at the transmission timing,
• wherein
• the transmission controller derives a subtraction value, which is a variable value used for subtraction, to a larger value as a reception level of the transmission permission signal is higher, subtracts the subtraction value from a backoff counter value of zero or more derived on a basis of a predetermined upper limit value, and determines a timing at which the backoff counter value becomes zero or less as the transmission timing.

A wireless communication system comprising:

• one or more communication devices located in a communication target area;
• and a relay device mountable on a moving body, wherein
• the relay device includes:
• a timing controller that generates a transmission permission signal that is a signal representing transmission permission of an uplink signal;
• and
• a first transmitter that transmits the transmission permission signal to the communication target area by a beam, and
• the communication device includes:
• a receptor that obtains the transmission permission signal from the relay device;
• a transmission controller that determines an earlier transmission timing as an elevation angle of the relay device viewed from the communication device is larger on a basis of the transmission permission signal;
• and
• a second transmitter that transmits the uplink signal to the relay device at the transmission timing,
• wherein
• the timing controller determines a transmission level of the transmission permission signal,
• the first transmitter transmits the transmission permission signal to the communication target area by a beam at the determined transmission level, and
• the transmission controller derives a subtraction value, which is a variable value used for subtraction, to a larger value as a reception level of the transmission permission signal is higher, subtracts the subtraction value from a backoff counter value of zero or more derived on a basis of a predetermined upper limit value, and determines a timing at which the backoff counter value becomes zero or less as the transmission timing.