Expected file delivery time of prompt NAK mode in CCSDS file delivery protocol

To support the file transferring in deep space communication environment, the Consultative Committee for Space Data Systems (CCSDS) File Delivery Protocol (CFDP) was developed. The prompt negative acknowledgment (NAK) mode was analyzed, and a deferred-prompt trigger method and automatic repeat-request (ARQ) timer setting rule for the single-hop point-to-point file transfer operation was proposed, which minimized the expected time taken to transfer a file under the constraint of the maximized throughput. Performance measures was mainly concerned for the expected file delivery time and compared with the other NAK modes, the simulation results show that deferred-prompt NAK mode has a better performance in conditions.