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TCP in Wireless Networks: Challenges, Optimizations and Evaluations
Karlstad University, Division for Information Technology.ORCID iD: 0000-0003-0368-9221
Responsible organisation
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents research on transport layer behavior in wireless networks. As the Internet is expanding its reach to include mobile devices, it has become apparent that some of the original design assumptions for the dominant transport protocol, TCP, are approaching their limits. A key feature of TCP is the congestion control algorithm, constructed with the assumption that packet loss is normally very low, and that packet loss therefore is a sign of network congestion. This holds true for wired networks, but for mobile wireless networks non-congestion related packet loss may appear. The varying signal power inherent with mobility and handover between base-stations are two example causes of such packet loss. This thesis provides an overview of the challenges for TCP in wireless networks together with a compilation of a number of suggested TCP optimizations for these environments. A TCP modification called TCP-L is proposed. It allows an application to increase its performance, in environments where residual bit errors normally give a degraded throughput, by making a reliability tradeoff. The performance of TCP-L is experimentally evaluated with an implementation in the Linux kernel. The transport layer performance in a 4G scenario is also experimentally investigated, focusing on the impact of the link layer design and its parameterization. Further, for emulation-based protocol evaluations, controlled packet loss and bit error generation is shown to be an important aspect.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet , 2005.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2005:13
Keywords [en]
Wireless networks, TCP/IP, TCP-L, Network emulation
National Category
Computer Systems
Research subject
Computer Science
Identifiers
URN: urn:nbn:se:kau:diva-2335ISBN: 91-85335-53-3 (print)OAI: oai:DiVA.org:kau-2335DiVA, id: diva2:24680
Presentation
2005-05-18, Agardsalen, 11D 257, Karlstads universitetKarlstad, 13:15 (English)
Opponent
Supervisors
Available from: 2009-06-05 Created: 2009-04-08 Last updated: 2016-10-25Bibliographically approved
List of papers
1. TCP over Wireless Networks
Open this publication in new window or tab >>TCP over Wireless Networks
2004 (English)Report (Other academic)
Abstract [en]

This report provides an overview of common wireless network technologies used today, with emphasis on data transmission. Wireless networks are becoming increasingly used for Internet communications. As discussed in the report, the TCP protocol may experience performance degradations over wireless networks, due to non-congestion related packet loss and varying round trip times. To this end, many enhancements for TCP to the link and transport layer have been proposed. A selection of these are presented and discussed in relation to the wireless network technologies.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2004. p. 26
Series
Karlstad University Studies, ISSN 1403-8099 ; 2004:21
National Category
Computer Systems
Identifiers
urn:nbn:se:kau:diva-1556 (URN)91-85019-88-7 (ISBN)
Available from: 2008-03-26 Created: 2008-03-26 Last updated: 2018-06-04Bibliographically approved
2. Bit Error Tolerant Multimedia Transport
Open this publication in new window or tab >>Bit Error Tolerant Multimedia Transport
2004 (English)In: Perspectives on Multimedia: Communication, Media and Information Technology, Chichester: John Wiley & Sons, 2004, p. 175-191Chapter in book (Other academic)
Place, publisher, year, edition, pages
Chichester: John Wiley & Sons, 2004
Keywords
real-time transfers; bit error tolerant multimedia transport; TCP and the bit-error tolerant modification TCP-L; UDP Lite; TCP packet loss; Snoop
National Category
Computer Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-2337 (URN)10.1002/0470868651 (DOI)9780470868638 (ISBN)
Available from: 2009-06-05 Created: 2009-06-05 Last updated: 2018-06-04Bibliographically approved
3. TCP-L: Allowing Bit Errors in Wireless TCP
Open this publication in new window or tab >>TCP-L: Allowing Bit Errors in Wireless TCP
2003 (English)In: Proceedings of the 12th IST Summit on Mobile and Wireless Communications: Enabling a Pervasive Wireless World / [ed] Atílio Gameiro, Institute for Operations Research and the Management Sciences (INFORMS), 2003, p. 149-154Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a technique to improve the performance of TCP and the utilization of wireless networks.Wireless links exhibit high rates of bit errors, compared to communication over wireline or fiber. Since TCP cannotseparate packet losses due to bit errors versus congestion,all losses are treated as signs of congestion and congestionavoidance is initiated. This paper explores the possibility of accepting TCP packets with an erroneous checksum, toimprove network performance for those applications that can tolerate bit errors. Since errors may be in the TCP header aswell as the payload, the possibility of recovering the headeris discussed. An algorithm for this recovery is also presented.Experiments with an implementation have been performed,which show that large improvements in throughput can beachieved, depending on link and error characteristics.

Place, publisher, year, edition, pages
Institute for Operations Research and the Management Sciences (INFORMS), 2003
Keywords
TCP, wireless, emulation, bit error recovery, partial reliability
National Category
Computer Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-2338 (URN)972-98368-1-7 (ISBN)
Conference
IST - Mobile & Wireless Communications Summit, Aveiro
Projects
Wireless IP
Available from: 2009-06-08 Created: 2009-06-08 Last updated: 2018-06-04Bibliographically approved
4. Emulation and Validation of a 4G System Proposal
Open this publication in new window or tab >>Emulation and Validation of a 4G System Proposal
2005 (English)In: Proceedings of RadioVetenskap och Kommunikation 2005: Volume II, 2005, p. 357-362Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a wireless link and network emulator,along with experiments and validation against the "Wireless IP" 4G system proposal from Uppsala University and partners. In wireless fading downlinks (base to terminals) link-level frames are scheduled and the transmission is adapted on a fast time scale. With fast link adaptation and fast link level retransmission, the fading properties of wireless links can to a large extent be counteracted at thephysical and link layers. The emulator has been used to experimentally investigate the resulting interaction between the transport layer and the link layer. The paper gives an overview of the emulator design, and presents experimental results with three different TCP variants in combination with various link layer characteristics.

Keywords
network emulation, wireless, TCP, IP, 4G
National Category
Computer Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-2339 (URN)91-7056-122-2 (ISBN)
Conference
RVK05 RadioVetenskap och Kommunikation 2005, Linköping
Projects
Wireless IP
Available from: 2009-06-05 Created: 2009-06-05 Last updated: 2018-06-04Bibliographically approved
5. The Impact of Loss Generation on Emulation-Based Protocol Evaluation
Open this publication in new window or tab >>The Impact of Loss Generation on Emulation-Based Protocol Evaluation
2006 (English)In: PDCN'06 Proceedings of the 24th IASTED international conference on Parallel and distributed computing and networks / [ed] Fahringer, T., Anaheim, USA: ACTA Press, 2006, 1, p. 231-237Conference paper, Published paper (Refereed)
Abstract [en]

Network emulation has for a long time been an important tool for evaluating the performance of communication protocols. By emulating network characteristics, such as restricted bandwidth, delay and losses, knowledge about the behavior and performance of actual protocol implementations can be obtained. This paper focuses on the generation of losses in network emulators and shows the beneficial effects of being able to control the generation of losses in a precise way. Both the possibility to get additional knowledge about a protocol implementations behavior, as well as statistical benefits such as paired experiments are discussed. By extending the loss generation to also include bit-error generation, in addition to packet losses, a finer level of abstraction is provided. Deterministic bit-error generation allows detailed and repeatable studies of bit-error sensitive protocol behavior. TCP and a loss differentiating variant of TCP is used to illustrate the utility of improved loss generation.

Place, publisher, year, edition, pages
Anaheim, USA: ACTA Press, 2006 Edition: 1
Keywords
Networks, Network protocols, Protocol correctness
National Category
Computer Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-2340 (URN)0-88986-568-X (ISBN)
Conference
Parallel and Distributed Computing and Networks(PDCN 2006), February 14 – 16, 2006, Innsbruck, Austria
Available from: 2009-06-05 Created: 2009-06-05 Last updated: 2018-08-14Bibliographically approved

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Alfredsson, Stefan

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