Time measurement apparatus, computer-readable recording medium storing time measurement program, and time measurement system

1 . A time measurement apparatus comprising:

a memory and

a processor coupled to the memory and configured to:

select, from among a plurality of anchors for each of which an own installation position is registered, a predetermined anchor for which an installation position that geographically corresponds to a declaration position declared by a terminal is registered; and

specify, as round-trip communication delay time between the terminal and the predetermined anchor, time measured based on a reception time point of a first packet received by the predetermined anchor from the terminal and a reception time point of a second packet based on a response packet that responds to the first packet and is received by the predetermined anchor from the terminal.

2 . The time measurement apparatus according to claim 1 , wherein

the processor specifies, as the round-trip communication delay time, difference time measured based on the reception time point of the first packet and the reception time point of the second packet.

3 . The time measurement apparatus according to claim 1 , wherein

that the processor verifies appropriateness of the declaration position based on a collation result of password information attached to the response packet and password information attached to the second packet and the round-trip communication delay time.

4 . The time measurement apparatus according to claim 3 , wherein

the processor determines that the declaration position is appropriate when the collation result indicates an agreement of password information attached to the response packet and password information attached to the second packet.

5 . The time measurement apparatus according to claim 3 , wherein

the processor determines that the declaration position is fraudulent when the collation result indicates a disagreement of password information attached to the response packet and password information attached to the second packet.

6 . The time measurement apparatus according to claim 3 , wherein

the processor selects, from among a plurality of probes for each of which an own installation position is registered, a predetermined probe for which an installation position that geographically corresponds to the declaration position is registered,

specifies first difference time of the reception time point of the first packet received by the predetermined anchor from the terminal and the reception time point of the second packet based on the response packet that responds to the first packet and is received by the predetermined anchor from the terminal, and second difference time of a reception time point of a third packet received by the predetermined anchor from the predetermined probe and a reception time point of a fourth packet based on a response packet that responds to the third packet and is received by the predetermined anchor from the predetermined probe, and

verifies the appropriateness of the declaration position based on the first difference time and the second difference time.

7 . The time measurement apparatus according to claim 3 , wherein

the processor selects, from among a plurality of probes for each of which an own installation position is registered, a predetermined probe for which an installation position that geographically corresponds to the declaration position is registered, and selects another anchor that is installed at a position of different direction from the predetermined anchor and of a longer distance than a distance between the predetermined anchor and the terminal,

specifies third difference time of a reception time point of a fifth packet received by the another anchor from the terminal and a reception time point of a sixth packet based on a response packet that responds to the fifth packet and is received by the another anchor from the terminal, and fourth difference time of a reception time point of a seventh packet received by the another anchor from the predetermined probe and a reception time point of an eighth packet based on a response packet that responds to the seventh packet and is received by the another anchor from the predetermined probe, and

verifies the appropriateness of the declaration position based on the third difference time and the fourth difference time.

8 . A non-transitory computer-readable recording medium storing a time measurement program causing a computer to execute a process of comprising:

selecting, from among a plurality of anchors for each of which an own installation position is registered, a predetermined anchor for which an installation position that geographically corresponds to a declaration position declared by a terminal is registered; and

specifying, as round-trip communication delay time between the terminal and the predetermined anchor, time measured based on a reception time point of a first packet received by the predetermined anchor from the terminal and a reception time point of a second packet based on a response packet that responds to the first packet and is received by the predetermined anchor from the terminal.

9 . A time measurement system comprising:

a terminal;

a plurality of anchors for each of which an own installation position is registered; and

a processor configured to:

select, from among the plurality of anchors, a predetermined anchor for which an installation position that geographically corresponds to a declaration position declared by the terminal is registered; and

specify, as round-trip communication delay time between the terminal and the predetermined anchor, time measured based on a reception time point of a first packet received by the predetermined anchor from the terminal and a reception time point of a second packet based on a response packet that responds to the first packet and is received by the predetermined anchor from the terminal.