An experimental investigation of cross‐layer optimal packet size in space Internet

Abstract

AbstractStudies of optimal packet size determination in space communication can be found in the literature. However, they are done in an analytical manner. In this paper, we present an experimental study of the cross‐layer optimal packet size for a Transmission Control Protocol (TCP) Internet Protocol (IP) enhancement, Space Communication Protocol Standards (SCPS), using a personal computer (PC)‐based testbed. We study the optimal packet size at the medium access control (MAC) layer considering the cross‐layer interactions at the physical layer. We investigate how the cross‐layer MAC packet size needs to be adjusted for optimal throughput performance based on the feedback of the bit‐error rate (BER), space‐link delay and symmetric/asymmetric channel‐rate configurations at the physical channel, and find the cross‐layer optimal packet size for the maximum throughput over the space‐Internet channels. We find that the default TCP/IP packet size of 1500 bytes for the terrestrial Internet should be chosen as the cross‐layer MAC packet size for optimal throughput performance over space channels with round‐trip time (RTT) around 250 ms and BER⩽10−6. As the channel BER at the physical layer increases, the optimal MAC packet size should be reduced to around 1000 bytes. We also find that it is more significant to have an optimal packet size for asymmetric channel than symmetric channel but the optimal packet size remains the same at a given BER for both channel ratios in our experiment. To our knowledge, this is the first paper to investigate the cross‐layer optimal MAC packet size over space‐Internet channel in the proposed approach. Copyright © 2006 John Wiley & Sons, Ltd.