Communication device, method for communication device, and program product for communication device

A computer program product for a communication device to correct a delay time, the communication device including a first clock and being configured to communicate with an outside communication device to transmit and receive packets through a communication network, the outside communication device including a second clock, the computer program product stored on a non-transitory computer readable medium and comprising instruction configured to, when executed by at least one processor, cause the at least one processor to:

• receive first packets transmitted from the outside communication device;
• transmit second packets to the outside communication device;
• acquire
• a first delay time that is a time length from a second device transmission time when the first packet is transmitted from the outside communication device to a first device reception time when the communication unit receives the first packet, the second device transmission time being a time indicated by the second clock, the first device reception time being a time indicated by the first clock, and
• a second delay time that is a time length from a first device transmission time when the communication unit transmits the second packet to a second device reception time when the outside communication device receives the second packet, the first device transmission time being a time indicated by the first clock, the second device reception time being a time indicated by the second clock;
• select one of the first packet and the second packet as a target packet;
• calculate a correction value as a time difference of the first clock and the second clock based on a first minimum delay time that is a minimum value among the first delay times acquired in a predetermined period or a second minimum delay time that is a minimum value among the second delay times acquired in the predetermined period, and
• correct the delay time of the target packet using the correction value.

A method of correcting a delay time for a communication device including a first clock and configured to communicate with an outside communication device to transmit and receive packets through a communication network, the outside communication device including a second clock, the method comprising:

• receive first packets transmitted from the outside communication device;
• transmit second packets to the outside communication device;
• acquire
• a first delay time that is a time length from a second device transmission time when the first packet is transmitted from the outside communication device to a first device reception time when the communication unit receives the first packet, the second device transmission time being a time indicated by the second clock, the first device reception time being a time indicated by the first clock, and
• a second delay time that is a time length from a first device transmission time when the communication unit transmits the second packet to a second device reception time when the outside communication device receives the second packet, the first device transmission time being a time indicated by the first clock, the second device reception time being a time indicated by the second clock;
• select one of the first packet and the second packet as a target packet;
• calculate a correction value as a time difference of the first clock and the second clock based on a first minimum delay time that is a minimum value among the first delay times acquired in a predetermined period or a second minimum delay time that is a minimum value among the second delay times acquired in the predetermined period, and
• correct the delay time of the target packet using the correction value.