Performance Evaluation of CCSDS File Delivery Protocol (CFDP) in Deferred NAK mode over Geostationary Earth Orbit (GEO)-Satellite Links

The Consultative Committee For Space Data Systems (CCSDS) file delivery protocol (CFDP) offers selectable quality of service, according to mission requirements and transmission capability, ranging from an unacknowledged option to a fully acknowledged option providing error recovery through retransmission. The performance of CFDP in the deferred NAK mode has been evaluated in a theoretical manner. In this paper, we present an experimental performance evaluation of CFDP in the deferred NAK mode over the direct, point-to-point geostationary earth orbit (GEO)-satellite links simulated using a test-bed. We compare CFDP running over TCP with the CCSDS space communication protocol standards (SCPS) protocol stack to see which one is more effective over a GEO-satellite link. The experimental results show that CFDP does not have performance advantage over other protocols over a less lossy channel with a BER less than or equal to 10^-6. However, along with the increase of BER, CFDP shows significant performance advantage. Quantitatively, for a symmetric channel with BER=10^-5, CFDP-TCP protocol has the highest throughput which is 2000 bytes/sec higher than SCPS-VJ and almost 3500 bytes/sec higher than SCPS-Vegas. The throughput advantage of CFDP with BER=10^-5 is 1500 bytes/sec over SCPS-VJ and 2800 bytes/sec over SCPS- Vegas, over asymmetric channel with BER=10^-5.