Space communications urgently need an effective transmission control mechanism. This paper presents an experimental, comparative analysis of window-based transmission control, rate-based transmission control, and a hybrid of the two over error-prone, congestion-free, high-latency, point-to-point space communication links simulated using the space-to-ground link simulation (SGLS) test-bed. The results revealed that the traffic shaping mechanism of rate-based transmission protocol is more effective than the bursting flow of window-based protocol over simulated space communication links with a high error rate and a long link delay. The window-based transmission mechanisms show performance degradation due to traffic bursts and frequent packet retransmissions caused by their acknowledgment (ACK)-clocked transmission control algorithms. Pure rate-control is always preferable to other mechanisms in the simulated congestion-free, error-prone, point-to-point, geostationary-Earth orbit (GEO)-space communication channels, and its advantages become more pronounced when the channel rates are asymmetric. The performance differences come from their different behavior in controlling data transmission.of window-based and rate-based mechanisms over direct, point-to-point satellite links. In a general point-to-point satellite network, the only hop in the network is over the satellite channel with a guaranteed bandwidth capacity provided, and it only exhibits the problems associated with the satellite channels without the network congestion imposed as in the shared network [18]. Furthermore, we have been studying the performance of the mentioned transmission mechanisms over the dedicated, congestion-free, point-to-point communication links, especially in an environment with a high BER and high latency involved. A typical scenario of point-to-point space communication considers the satellite to be another node on the Internet. In this scenario, the ground-based satellite controller can transfer data files between the satellite and the ground control center just as if transferring files across the Internet. This will allow Earth-science and space-science instrument designers to organize data in normal file mode formats for instrument and housekeeping data and takes advantages of networking protocols to manage the data transfers [19]. As an example of application scenarios, satellites at the low Earth orbit (LEO) and geostationary-Earth orbit (GEO) may communicate with a ground station via a direct radio link in the point-to-point topology as shown in Fig. 1. As another application example, the direct, point-to-point link functions as the interplanetary communication backbone link between the outer-space planets and the Earth, as well as the Earth-based infrastructure elements such as a ground station for the deep space network. Please see [10] for a detailed discussion on this application.A space network protocol suite, Space Communication Protocol Standards (SCPS) [20], was developed under the Consultative Committee for Space Data Sy...

No abstract

No abstract

Channel error rate LabVIEW host computer LabView ratechange computer LabView ratechange computer R1 -forward link R2 -return link R2 R2 R2 R1 R1There is an urgent need to find the best congestion-control mechanism for space Internet. This article presents an experimental study of rate-based congestion control, window-based congestion control, and a hybrid of the two in a simulated small-satellite environment. ABSTRACTThere is an urgent need to find the best congestion-control mechanism for space Internet. This article presents an experimental study of rate-based congestion control, window-based congestion control, and a hybrid of the two in a simulated small-satellite environment using the space-to-ground link simulation (SGLS) testbed. The study is done by examining the throughput performance and transmission behavior of pure rate-control and a variant of each of the window-based Transmission Control Protocol (TCP) selective acknowledgment (TCP-SACK) and TCP-Vegas congestion-control mechanisms, with and without the channel-rate control being hybridized. The study reveals that the trafficshaping mechanism of a rate-based transmission mechanism is more effective than the bursty flow of window-based mechanisms in error-prone space environments with a long link delay. Pure rate-control is preferable to other mechanisms in space in which channel resource reservation is available. The performance differences arise from their different behaviors in controlling data transmission.