| 摘要 |
PROBLEM TO BE SOLVED: To realize efficient data transmission in response to a time when a terminal station exists in the communication area of a base station for wireless communication between the base station and the terminal station. SOLUTION: A bit stream of original information to be sent is divided into wireless frames in advance, and a packet length is changed depending on how many frames are included in response to a vehicle speed of a vehicle with the terminal station mounted thereon in each communication area. The vehicle speed can be detected based on e.g. a difference (Doppler shift amount) between a frequency of a wireless signal sent from the base station and a frequency of a wireless signal received by the terminal station and the terminal station informs the base station about the vehicle speed. The area resident time for data transmission is calculated on the basis of the vehicle speed and the length of the packet able to be sent is calculated depending on the resident time, and a packet is formed by number of frames with the packet length and transmitted.
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