Communication system, communication device, method, and recording medium of program

A communication device comprising

• a retransmission controller configured to, when receiving a retransmission request (RACK) packet prompting transmission of a next data packet that is repeatedly transmitted by a reception side at an unarrival determination time interval for determining that a next data packet does not arrive on and after reception of an acknowledgement (ACK) packet returned by the reception side for a transmitted data packet, specify a data packet that has not reached the reception side, by use of time difference information based on time information of the most recently received ACK packet or the most recently received RACK packet and time information of the currently received RACK packet, and then retransmit the specified data packet, wherein
• the time information is a time stamp added by the reception side to each of the ACK packet and the RACK packet when transmitted, or a time stamp added by the retransmission controller to each of the ACK packet and the RACK packet when received.

(canceled)

A tangible and non-transitory recording medium of a retransmission control program causing a computer to function as

• a retransmission controller configured to, when receiving a retransmission request (RACK) packet prompting transmission of a next data packet that is repeatedly transmitted by a reception side at an unarrival determination time interval for determining that a next data packet does not arrive on and after reception of an acknowledgement (ACK) packet returned by the reception side for a transmitted data packet, specify a data packet that has not reached the reception side, by use of time difference information based on time information of the most recently received ACK packet or the most recently received RACK packet and time information of the currently received RACK packet, and then retransmit the specified data packet, wherein
• the time information is a time stamp added by the reception side to each of the ACK packet and the RACK packet when transmitted, or a time stamp added by the retransmission controller to each of the ACK packet and the RACK packet when received.