| 摘要 |
PROBLEM TO BE SOLVED: To prevent a mobile unit from being detected as being present in a regular area, although the mobile unit is present in an irregular area, while shortening a response time.SOLUTION: An in-vehicle unit transmits a request signal from a specific transmission antenna to a regular area around a vehicle and transmits a signal for determination from another transmission antenna to an irregular area around the vehicle. A mobile unit transmits a response signal responding to the request signal to the in-vehicle unit so as to include received signal strength information representing a received signal strength of the signal for determination. In the case where it is determined based on the received signal strength information included in the response signal that the reception strength of the signal for determination is higher than a specific value, the in-vehicle unit controls an in-vehicle device by determining that the mobile unit is present in the irregular area. |
