sliding window

A variable-duration window that allows a sender to transmit a specified number of data units before an acknowledgement is received or before a specified event occurs. Note: An example of a sliding window in packet transmission is one in which, after the sender fails to receive an acknowledgement for the first transmitted packet, the sender “slides” the window, i.e., resets the window, and sends a second packet. This process is repeated for the specified number of times before the sender interrupts transmission. Synonym [loosely] acknowledgement delay period.