Transcript TCP Over Wireless BY

Ankur Vyavaharkar
Gagandeep Gill
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TCP overview
TCP fundamentals
Wireless Network
Simulation using Opnet
Mobility and TCP
Improvements
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Connection oriented end-to-end data transfer protocol.
 reliable end-to end transmission of data achieved by
error and retransmission.
 Congestion control over the internet.
Much better suited for wired networks than wireless
networks.
End-to-end semantics
 Acknowledgements sent to TCP sender confirm
delivery of data received by TCP receiver
 Ack for data sent only after data has reached
receiver
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Efficient use of higher bandwidth networks.
Avoiding Dead Lock situation.
Transmits certain segments with sequence
numbers.
Effective flow control
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Communication over wireless links is often
characterized by sporadic high bit-error rates, and
intermittent connectivity due to handoffs.
When packets are lost in networks for reasons other
than congestion, these measures result in an
unnecessary reduction in end –to-end throughput and
sub- Optimal performance.
TCP performance in wireless networks suffers from
significant throughput degradation and very high
interactive delays.
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Low quality wireless links
Mobility
High probability of transmission errors
Low data rates
Long delays
Lower bandwidth
Handovers
SCENARIOS
Mobility and TCP
Link Layer protocols
 Indirect-TCP protocol
 The snoop Protocol
 Selective Acknowledgments
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Window limitation.
Selective acknowledgement (SACK).
TCP byte counting.
Split connection.
Last hop solutions.
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A comparison of different TCP flavors are
made.
Reno performs well when congestion is less (
i.e. one drop)
It can be seen from the graph that Modified
TCP Tahoe perform best in a wireless scenario
when congestion is more.
Slow Start and congestion avoidance is very
important algorithm for improvement in TCP
performance.
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Some mechanisms to improve TCP/IP
performance over Wireless and mobile computing
environment , Wen- Tsuen Chen; Jyh-Shin Lee;
Parallel and Distributed Systems 2000 proceedings
Seventh International Conference 4-7 July 2000
pp . 437-444.
Performance enhancement techniques for TCP
over wireless links Yanmaz, E.; Wei, S.-C.; Tonguz,
O.K.;
Vehicular Technology Conference, 2005. VTC 2005Spring. 2005 IEEE 61st Volume 4, 30 May-1 June
2005 Page(s):2245 – 2249.
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A reconfigurable protocol setting to improve TCP over
wireless Chiasserini, C.-F.; Meo, M.;
Vehicular Technology, IEEE Transactions on
Volume 51, Issue 6, Nov. 2002 Page(s):1608 – 1620.
The effect of reordering and dropping packets on TCP
over a slow wireless link , Nehme, A.; Phillips, W.;
Robertson, W.; Electrical and Computer Engineering,
2003. IEEE CCECE 2003. Canadian Conference on
Volume 3, 4-7 May 2003 Page(s):1555 - 1558 vol.3
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M. Meyer, J. Sachs, Performance Evaluation of a TCP
Proxy in Wireless Networks, IEEE Wireless
Communications, October 2003, pp. 70-79.
Xylomenos, G.; Polyzos, G.C.; Mahonen, P.; Saaranen,
M.; Communications Magazine, IEEE Volume
39, Issue 4, April 2001 Page(s):52 - 58 .
S. Floyd, “A report on recent developments in TCP
congestion control,” IEEE Communications Magazine,
vol. 39, no. 4, pp. 84–90, April 2001.
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JTCP: jitter-based TCP for heterogeneous
wireless networks
Wu, E.H.-K.; Mei-Zhen Chen;
Selected Areas in Communications, IEEE
Journal on
Volume 22, Issue 4, May 2004 Page(s):757 766