Communication apparatus, communication method, and computer readable medium using propagation delay for time synchronization

A communication method comprising:

• receiving, a synchronous frame describing a reference value for time synchronization with a management apparatus, which is transmitted repeatedly from the management apparatus;
• computing, each time when the synchronous frame is received, a propagation delay of the received synchronous frame;
• computing, each time when the propagation delay is computed, a propagation delay time period by adding a target value of a synchronous accuracy to the computed propagation delay;
• operating, a logical OR operation of M pieces of propagation delay time periods computed for M pieces of synchronous frames which precede a latest synchronous frame, where M is greater than or equal to 2;
• and
• deciding, based on a propagation delay of the latest synchronous frame and a logical OR operation result of the M pieces of propagation delay time periods of the M pieces of synchronous frames, whether or not to use a reference value described in the latest synchronous frame for time synchronization with the management apparatus.

A non-transitory computer readable medium storing a program to cause a computer to execute:

• a synchronous frame reception process of receiving a synchronous frame describing a reference value for time synchronization with a management apparatus, which is transmitted repeatedly from the management apparatus;
• a propagation delay computation process of computing, each time when the synchronous frame is received by the synchronous frame reception process, a propagation delay of the received synchronous frame;
• a propagation delay time period computation process of computing, each time when the propagation delay is computed by the propagation delay computation process, a propagation delay time period by adding a target value of a synchronous accuracy to the computed propagation delay;
• a logical OR operation process of operating a logical OR operation of M pieces of propagation delay time periods computed for M pieces of synchronous frames which precede a latest synchronous frame received by the synchronous frame reception process, where M is greater than or equal to 2;
• and
• a time synchronization decision process of deciding, based on a propagation delay of the latest synchronous frame and a logical OR operation result of the M pieces of propagation delay time periods of the M pieces of synchronous frames, whether or not to use a reference value described in the latest synchronous frame for time synchronization with the management apparatus.