FIG. 9 is a sequence diagram showing an example of a process executed by the communication system according to the second embodiment. A flow of a process of mainly releasing the connection with the access point using the vehicle M #, the access points AP2 and AP3, and the base station 10 will be mainly described below. In the example of FIG. 8, it is assumed that the vehicle M # is connected to the base station 10 and the access points AP2 and AP3.
In the example of FIG. 9, the vehicle M # transmits a request signal to the access point AP2 (step S200) and receives a response signal for the request signal (step S202). The vehicle M # transmits a request signal to the access point AP3 (step S204) and receives a response signal for the request signal (step S206). Next, the vehicle M # acquires a delay time period from the transmission of the request signal to the reception of the response signal as the communication quality with respect to each of the access points AP2 and AP3 (step S208). At the start of the process of FIG. 9, the vehicle M # and the access points AP2 and AP3 are already connected. Thus, in the processing of step S208, instead of the process using the request signal and the response signal described above, communication qualities may be acquired on the basis of data transmitted and received between the vehicle M # and the access points AP2 and AP3.
