TCP Performance with Vertical Handoff

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dc.contributor Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, tietojenkäsittelytieteen laitos fi
dc.contributor Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, institutionen för datavetenskap sv
dc.contributor University of Helsinki, Faculty of Science, Department of Computer Science en Daniel, Laila fi 2010-11-25T12:21:55Z 2010-11-25T12:21:55Z 2008-11-21 fi
dc.identifier.uri URN:NBN:fi-fe200909012078 fi
dc.description.abstract With the proliferation of wireless and mobile devices equipped with multiple radio interfaces to connect to the Internet, vertical handoff involving different wireless access technologies will enable users to get the best of connectivity and service quality during the lifetime of a TCP connection. A vertical handoff may introduce an abrupt, significant change in the access link characteristics and as a result the end-to-end path characteristics such as the bandwidth and the round-trip time (RTT) of a TCP connection may change considerably. TCP may take several RTTs to adapt to these changes in path characteristics and during this interval there may be packet losses and / or inefficient utilization of the available bandwidth. In this thesis we study the behaviour and performance of TCP in the presence of a vertical handoff. We identify the different handoff scenarios that adversely affect TCP performance. We propose several enhancements to the TCP sender algorithm that are specific to the different handoff scenarios to adapt TCP better to a vertical handoff. Our algorithms are conservative in nature and make use of cross-layer information obtained from the lower layers regarding the characteristics of the access links involved in a handoff. We evaluate the proposed algorithms by extensive simulation of the various handoff scenarios involving access links with a wide range of bandwidth and delay. We show that the proposed algorithms are effective in improving the TCP behaviour in various handoff scenarios and do not adversely affect the performance of TCP in the absence of cross-layer information. en
dc.language.iso en fi
dc.publisher Helsingin yliopisto fi
dc.publisher Helsingfors universitet sv
dc.publisher University of Helsinki en
dc.rights Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. fi
dc.rights This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. en
dc.rights Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. sv
dc.title TCP Performance with Vertical Handoff en
dc.type.ontasot Lisensiaatintyö fi
dc.type.ontasot Licentiate thesis en
dc.type.ontasot Licentiatsavhandling sv
dc.ths Raatikainen, Kimmo fi
dc.ths Kojo, Markku fi
dc.type.dcmitype Text fi

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