Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system ishaving strong resemblance to terrestrial GSM (Global System for Mobilecommunications) at the upper protocol layers and TCP (Transmission ControlProtocol) is one of them. This space segment technology as well as terrestrialtechnology, is characterized by periodic variations in communication propertiesand coverage causing the termination of ongoing call as connections of MobileNodes (MN) alter stochastically. Although provisions are made to provideefficient communication infrastructure this hybrid space and terrestrialnetworks must ensure the end-to-end network performance so that MN can moveseamlessly among these networks. However from connectivity point of viewcurrent TCP performance has not been engineered for mobility events inmulti-radio MN. Traditionally, TCP has applied a set of congestion controlalgorithms (slow-start, congestion avoidance, fast retransmit, fast recovery)to probe the currently available bandwidth on the connection path. Thesealgorithms need several round-trip times to find the correct transmission rate(i.e. congestion window), and adapt to sudden changes connectivity due tohandover. While there are protocols to maintain the connection continuity onmobility events, such as Mobile IP (MIP) and Host Identity Protocol (HIP), TCPperformance engineering has had less attention. TCP is implemented as aseparate component in an operating system, and is therefore often unaware ofthe mobility events or the nature of multi-radios' communication. This paperaims to improve TCP communication performance in Mobile satellite andterrestrial networks.
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