Communication device, non-transitory computer-readable medium storing a communication program

In a transmitter (2001), when generating a transmission frame having no limitation to a window size, a batch-transmission-end flag generating circuit (2004) and a sequence number generating circuit (2005) respectively adds a batch-transmission-end flag and a sequence number to the transmission frame. In a receiver, if an omission of a sequence number is detected as a result of analyzing sequence numbers of frames having received from the transmitter (2001), retransmission request is made when receiving a frame whose batch-transmission-end flag indicates the end. In this way, retransmission is possible in data transmission using UI frames, and the communication efficiency can be improved.