COMMUNICATION APPARATUS ACTIVATION METHOD, WIRELESS COMMUNICATION SYSTEM AND WIRELESS COMMUNICATION APPARATUS
A communication device activation method performed by a wireless communication system including one or more communication devices installed on a ground and a wireless communication device that moves includes an activation signal generation step of generating an activation signal for activating the one or more communication devices, a frequency variation application step of applying, to the activation signal generated by the activation signal generation step, a frequency variation that compensates for a Doppler variation indicating a time variation in a Doppler shift that occurs in the activation signal, and a transmission step of transmitting the activation signal to which the frequency variation is applied by the frequency variation application step from the wireless communication device to the one or more communication devices.
1 . A communication device activation method performed by a wireless communication system including one or more communication devices installed on a ground and a wireless communication device that moves, the communication device activation method comprising:
generating an activation signal for activating the one or more communication devices;
applying, to the activation signal generated, a frequency variation that compensates for a Doppler variation indicating a time variation in a Doppler shift that occurs in the activation signal; and
transmitting the activation signal to which the frequency variation is applied from the wireless communication device to the one or more communication devices.
2 . The communication device activation method according to claim 1 , wherein
at least one of variation amounts of the frequency variation to be applied to the activation signal is calculated by subtracting Doppler tolerance indicating a variation range of the variation amount that is allowable for the communication device to demodulate and decode the activation signal from a maximum value of a variation amount of the Doppler variation.
3 . The communication device activation method according to claim 2 , further comprising:
changing the variation amount of the frequency variation to be applied to the activation signal at a predetermined interval.
4 . The communication device activation method according to claim 3 , wherein
the variation amount of the frequency variation changed at the predetermined interval is calculated by subtracting an odd multiple of the Doppler tolerance from the maximum value of the variation amount of the Doppler variation.
5 . The communication device activation method according to claim 3 , wherein,
the variation amount of the frequency variation is changed such that an area on the ground where activation of the communication device is possible by the activation signal immediately before the variation amount of the frequency variation to be applied is changed and an area on the ground where activation of the communication device is possible by the activation signal immediately after the variation amount of the frequency variation to be applied is changed are not adjacent to each other.
6 . The communication device activation method according to claim 1 , further comprising:
applying a frequency shift for compensating for a Doppler shift generated in the activation signal to the activation signal generated.
7 . A wireless communication system including one or more communication devices installed on a ground and a wireless communication device that moves,
the wireless communication device comprising:
an activation signal generator configured to generate an activation signal for activating the one or more communication devices;
a frequency variation applicator configured to apply, to the activation signal generated by the activation signal generator, a frequency variation that compensates for a time variation in a Doppler shift that occurs in the activation signal; and
a transmitter configured to transmit the activation signal to which the frequency variation is applied by the frequency variation applicator, and
the communication device comprising:
a receptor configured to receive the activation signal transmitted from the wireless communication device; and
an activation controller configured to cause an own device to be in an activated state according to the activation signal received by the receptor.
8 . A wireless communication device in a wireless communication system including one or more communication devices installed on a ground and the wireless communication device that moves, the wireless communication device comprising:
an activation signal generator configured to generate an activation signal for activating the one or more communication devices;
a frequency variation applicator configured to apply, to the activation signal generated by the activation signal generator, a frequency variation that compensates for a time variation in a Doppler shift that occurs in the activation signal; and
a transmitter configured to transmit the activation signal to which the frequency variation is applied by the frequency variation applicator.