Vehicle device for a target vehicle and communication management method

1 . A vehicle device for a target vehicle equipped with a communication device using a first line and a second line with respectively different communication methods for data transmission via a wireless network, and offloads data transmission from the first line to the second line, the vehicle device comprising

at least one of (i) a circuit and (ii) a processor with a memory storing computer program code executable by the processor, the at least one of the circuit and the processor configured to cause the vehicle device to implement:

an estimation information acquirer configured to acquire estimation information that enables estimation of an offloading wait time according to an encounter probability at which the target vehicle encounters an access point of the wireless network used as the second line;

a wait time estimator configured to estimate the offloading wait time based on the estimation information acquired by the estimation information acquirer; and

an offloading determiner configured to determine whether or not offloading is performable based on the offloading wait time estimated by the wait time estimator, wherein

the estimation information acquirer acquires, as the estimation information corresponding to the encounter probability, information on the reach probability between the access points identified from hop records regarding travels of a plurality of vehicles passing through the access points,

the at least one of the circuit and the processor is further configured to cause the vehicle device to implement:

a vehicle-side selector configured to select the access point with a highest reach probability of the target vehicle based on information on the reach probability between the access points acquired by the estimation information acquirer; and

a vehicle-side reachable distance identifier configured to identify a reachable distance, which is a distance from the target vehicle, for the access point selected by the vehicle-side selector, and

the wait time estimator estimates the offloading wait time based on the reachable distance identified by the vehicle-side reachable distance identifier.

2 . The vehicle device according to claim 1 , wherein

the estimation information acquirer is configured to acquire an area-specific wait time, which is a wait time estimated to be required for using the second line, for each of divided areas respectively as a predetermined unit section, and which is determined according to the encounter probability of the target vehicle encountering the access point by using information on a distribution of access points as the estimation information according to the encounter probability, and

the wait time estimator estimates the offloading wait time based on the area-specific wait time acquired by the estimation information acquirer.

3 . The vehicle device according to claim 1 , wherein

the estimation information acquirer estimates and acquires, as the estimation information corresponding to the encounter probability, a reachable distance, which is a distance from the target vehicle to an access point that has a highest reach probability of the target vehicle, based on estimation of the reach probability performed by using the reach probability between access points identified by hop records regarding travels of a plurality of vehicles passing through the access points, and

the wait time estimator estimates the offloading wait time based on the reachable distance acquired by the estimation information acquirer.

4 . The vehicle device according to claim 1 , wherein the at least one of the circuit and the processor is further configured to cause the vehicle device to implement:

a stop time measurer configured to measure a stop time when the target vehicle stops, wherein

the wait time estimator identifies the offloading wait time by correcting the offloading wait time to be a longer time as the stop time measured by the stop time measurer increases.

5 . The vehicle device according to claim 1 , wherein the at least one of the circuit and the processor is further configured to cause the vehicle device to implement:

a communication speed identifier configured to identify a communication speed on the first line; and

a transmission determiner configured to determine whether to delay data transmission on the first line for offloading of the data transmission by using the offloading wait time estimated by the wait time estimator, wherein

the transmission determiner shortens a grace period during which data transmission on the first line is delayable, as the communication speed on the first line identified by the communication speed identifier becomes lower.

6 . A communication management method in a target vehicle and implemented by at least one processor, the target vehicle being equipped with a communication device using a first line and a second line with respectively different communication methods for data transmission via a wireless network, and offloads data transmission from the first line to the second line, the communication management method comprising:

acquiring estimation information that enables estimation of an offloading wait time according to an encounter probability at which the target vehicle encounters an access point of the wireless network used in the second line;

estimating the offloading wait time based on the acquired estimation information; and

determining whether or not offloading is performable based on the estimated offloading wait time, wherein

the acquiring of the estimation information corresponding to the encounter probability includes acquiring information on the reach probability between the access points identified from hop records regarding travels of a plurality of vehicles passing through the access points,

the communication management method further comprising:

selecting the access point with a highest reach probability of the target vehicle based on information on the reach probability between the access points acquired in the acquiring of the estimation information; and

identifying a reachable distance, which is a distance from the target vehicle, for the selected access point, and

the estimating of the offloading wait time estimates the offloading wait time based on the identified reachable distance.