A recursive, explicit and fair method to efficiently and fairly adjust TCP windows in satellite networks

Abstract

As originally specified, TCP did not perform well over satellite network systems, systems known with their rapidly time-varying network topologies. This paper addresses some vexing attributes that impair TCP performance in LEO satellite networks. The paper proposes a scheme that allows satellite systems to automatically adapt to the number of active TCP flows, the free buffer size and the bandwidth-delay product of the network. The proposed scheme controls the efficiency of the system by matching the aggregate traffic rate to the sum of the link capacity and total buffer size. This attribute helps to adjust TCP's aggressiveness and to prevent persistent queues from forming. The system min-max fairness is achieved by allocating bandwidth among individual flows in proportion with their RTTs.Simulation results elucidate that the proposed scheme substantially improves the system fairness, reduces the number of packet drops and makes better utilization of the bottleneck link. The results demonstrate also that the proposed scheme works properly in more complicated environments where connections traverse multiple bottlenecks and the available bandwidth may change over data transmission time. I. INTRODUCTIONThe need for satellite communication systems has grown rapidly during the last few years. For more than three decades, GEO satellite systems have been successful in providing some commercial services. However, requirements of lower propagation delays, in conjunction with the coverage of high latitude regions, have sparked the development of new satellite communication systems called Low Earth Orbit (LEO) satellite systems.Communication over LEO satellite networks exhibits different characteristics compared to that over the traditional satellite or wired networks. The success of LEO satellite networks in delivering high-speed access hinges on the ability of the underlying protocols to function correctly and efficiently in LEO systems. The effect of such a communication environment on the working of Transmission Control Protocol (TCP), the backbone of today's Internet protocol communication [1], underpins the research work outlined in this paper. The paper firstly addresses some vexing attributes that impair TCP performance in LEO satellite systems. It next determines the appropriate modifications to help TCP suite well in such environments.TCP usually results in drastically unfair bandwidth allocations when multiple connections share a bottleneck link. This unfairness issue appears when the number of flows

REFWA plus: enhancement of REFWA to combat link errors in LEO satellite networks

“…The figure demonsuates that for lower bit error rates, the REFWA and REFWA Plus scheme performs similarly and achieves the highest fairness (highest values of fairness index). This performance is consistent with the simulation results presented in [l] [ 2 ] . It is observed that although TCP WestwoodNR and TCP Newreno achieve relatively goad link utilization for low bit error rates (Fig.3(a)), they fail io sustain a fair service.…”

Theatre in the Sky: a ubiquitous broadband multimedia-on-demand service over a novel constellation composed of quasi-geostationary satellites

“…Use of a large number of satellites provides certainly more flexibility. It, however, leads to complex dynamic routing and mobility management issues caused by frequent handover occurrences [11,12]. Furthermore, LEO or MEO satellites can be used for only a short life span.…”