Data transfer method

摘要

A data transfer method having a data retransmission function, in which a sending side saves data that was sent in memory, a receiving side uses a transmission confirmation signal to request the sending side to retransmit the data when the data was not properly received, then monitors the elapsed time, and when the data is not retransmitted after the elapsed time has exceeded a set time, uses a transmission confirmation signal again to request that the data be retransmitted, and where in response to that transmission confirmation signal, the sending side retransmits the saved data to the receiving side.

主权项

1. A data transfer method of a data communication system in which a receiving side, after receiving data, sends a transmission confirmation signal to a sending side indicating whether or not the data was received properly, and the sending side makes reference to the transmission confirmation signal to identify that the receiving side did not proper receive the data and retransmits that data, the data transfer method comprising:
sending data to which a sequence number is attached from a sending side to a receiving side and saving the data in a memory of the sending side; A) in a case where the data was not received proper; sending, from the receiving side to the sending side a transmission confirmation signal which requests the sending side to retransmit the data and to which a sequence number of the data is attached; monitoring a period of time which elapses from the time when the transmission confirmation signal is sent to the sending side; when the data is not retransmitted even if the elapsed time exceeds a set time or when data which is different from the data to be retransmitted is received before the elapsed time exceeds a set time, retransmitting the transmission confirmation signal to the sending side; and retransmitting the data that is saved in the memory from the sending side to the receiving side in response to the transmission confirmation signal; and B) in a case where the data was received properly; sending, from the receiving side to the sending side a transmission confirmation signal which indicates proper reception; and deleting data having a sequence number less than (S−W) from the memory in the sending side and retaining data having a sequence number not less than (S−W) in which the maximum number of items of data that can be transmitted even when the transmission confirmation signal is not received is W, and the sequence number that is attached to the transmission confirmation signal that indicates proper reception is S.