TCP extensions for space communications

Abstract

The space communication environment and mobile and wireless communication environments show many similarities when observed from the perspective of a transport protocol. Both types of environments exhibit loss caused by data conuption and link outage, in addition to congestion-related loss. The constraints imposed by the two environments are also similar -power, weight, and physical volume of equipment are scarce resources. Finally, it is not uncommon for communication channel data rates to be severely limited and highly asymmetric. We are working on solutions to these types of problems for space communication environments, and we believe that these solutions may be applicable to the mobile and wireless community. As part of our work, we have defined and implemented the Space Communications Protocol StandardsTransport Protocol (SCPS-TP), a set of extensions to TCP that address the problems that we have identified. The results of our performance tests, both in the laboratory and on actual satellites, indicate that the SCPS-TP extensions yield significant improvements in throughput over unmodified TCP on errorprone links. Additionally, the SCPS modifications significantly improve performance over links with highly asymmetric data rates.

ADHOCTCP: Improving TCP Performance in Ad Hoc Networks

“…The return link is not used, in general, for data transferring. For example, in broadcast satellite networks the ratio of the bandwidth of the satellite-earth link over the bandwidth of the earth-satellite link is about 1000 [10]. On the other hand, in ad hoc networks, the degree of bandwidth asymmetry is not very high.…”

“…Our disconnection identification method is similar to TCP-ELFN [16], we use from EPLN (Explicit Packet Loss Notification) for inform sender. EPLN is based on the dynamic source routing (DSR) [10] routing protocol. To implement EPLN message, the route failure message of DSR is modified to carry a payload similar to the "host unreachable" ICMP (Internet Control Message Protocol) message.…”

A survey of TCP over ad hoc networks

“…Numerous enhancements and optimizations have been proposed over the last few years to improve TCP performance over one-hop wireless (not necessarily ad hoc) networks. These improvements include infrastructure-based WLANs [5][6][7][8], mobile cellular networking environments [9,10], and satellite networks [11,12]. Ad hoc networks inherit several features of these networks, in particular high bit error rates and path asymmetry, and add new problems caused by mobility and multi-hop communications, such as network partitions, route failures, and hidden (or exposed) terminals.…”

“…The return link is not used, in general, for data transferring. For example, in broadcast satellite networks the ratio of the bandwidth of the satellite-earth link over the bandwidth of the earth-satellite link is about 1000 [11]. On the other hand, in ad hoc networks, the degree of bandwidth asymmetry is not very high.…”

An enhanced TCP congestion avoidance scheme and its performance evaluation in high speed satellite networks

“…Satellite communication links, however, are characteristics of features like long delay and high Bit Error Rate (BER). For example, if the legacy TCP is directly used for satellite networks, the throughput that can be achieved is merely about 200 Kbps, even though the satellite link capacity reaches 1.5 Mbps with a BER at 10 -6 [2]. The reason for this disappointing result is that the congestion control mechanism in TCP invokes unnecessary rate control, leading to low bandwidth utilization.…”