The behavior of TCP and its extensions in space

The performance of Transmission Control Protocol (TCP) in space has been examined from the observations of simulation and experimental tests for several years at National Aeronautics and Space Administration (NASA), Department of Defense (DoD) and universities. At New Mexico State University (NMSU), we have been concentrating on studying the performance of two protocol suites: the file transfer protocol (ftp) running over Transmission Control Protocol/Internet Protocol (TCP/IP) stack and the file protocol (fp) running over the Space Communications Protocol Standards (SCPS)-Transport Protocol (TP) developed under the Consultative Committee for Space Data Systems (CCSDS) standards process. SCPS-TP is considered to be TCP's extensions for space communications.; This dissertation experimentally studies the behavior of TCP and SCPS-TP by running the protocol suites over both the Space-to-Ground Link Simulator (SGLS) test-bed and realistic satellite link. The study concentrates on comparing protocol behavior by plotting the averaged file transfer times for different experimental configurations and analyzing them using Statistical Analysis System (SAS) based procedures. The effects of different link delays and various Bit-Error-Rates (BERs) on each protocol performance are also studied and linear regression models are built for experiments over SGLS test-bed to reflect the relationships between the file transfer time and various transmission conditions.; The results from the test-bed show that protocols do not show performance difference with a very small file (≤1Kbytes) for all configurations and protocols perform differently with the increase of file size, BER and link delay for both symmetric and asymmetric channel rates. Under this condition, Vegas congestion control based SCPS-TP protocol (SCPS-Vegas) performs superiorly than Van Jacobson (VJ) congestion control based TCP and SCPS-VJ protocols. We also conclude from the experiments over test-bed that the factors of file size, BER and link delay and all their interactions contribute significantly to protocol performance. The results over the satellite link show that all protocols don't have significant performance difference for 115,200 bps:115,200 bps channel rate and protocols show significant difference for all large files with higher channel rates. The experiments with error free and 120 ms delay also show that SCPS-VJ shows the highest throughput in all cases and SCPS-Vegas shows the slowest throughput. Linearly correlated file transfer time relationship between the test-bed and satellite link shows that SGLS test-bed works validly and it can be used to predict the relative performance of protocols over realistic satellite link.; Additional work with higher BERs and longer delays over satellite link needs to be done to study the effects of the BER and delay to the protocol performance over satellite when satellite link is configured properly. This might also provide us data to compare the protocol performance over test-bed and satellite link for configurations with high BERs and longer delays to verify the above results.