TCP Context Switching Scheme to Enhance Throughput by Adapting Well to Vertical Handoff in Heterogeneous Wireless Networks

Woojin SEOK  Sang-Ha KIM  

IEICE TRANSACTIONS on Communications   Vol.E91-B   No.5   pp.1423-1435
Publication Date: 2008/05/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.5.1423
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
TCP,  congestion control,  retransmission timeout,  vertical handoff,  

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Vertical handoff is a new type of handoff that is triggered when a mobile node moves over heterogeneous wireless networks with each proving different access bandwidth, transmission latency, and coverage. A mobile node can achieve higher throughput by accessing a higher bandwidth providing wireless network. However, TCP has to experience drastic changes of the bandwidth and the latency due to the vertical handoff which must be recognized as a network congestion, and this degrades end-to-end performance. In this paper, we propose a TCP context switching scheme, named Context-Switching TCP, that maintains TCP variables separately for different types of wireless networks. Through simulations, Context-Switching TCP shows higher performance than TCP SACK for vertical handoff. Especially, it shows much higher performance gain when vertical handoff occurs frequently.