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A Modified AODV with Ack-Path Traffic Rerouting for TCP Performance Improvement in Ad Hoc Wireless Networks

In this thesis, a modified routing protocol, MAODV (Modified Ad Hoc On-Demand Distance Vector), is proposed for wireless Ad Hoc networks. MAODV uses ACK paths for rerouting data traffic whenever there is a route failure. We create new flags in the routing information of AODV to timely notify TCP layer the network status. After a route failure, the source node monitors ACK packets from the destination node. Every ACK packet when it is received from the destination node, its carried information is used to update the routing tables. Thus, without any interruption, TCP can take the reverse route of the ACK forwarding paths to continue to transmit the rest of data packets. In our proposed scheme, without decreasing the size of TCP congestion window (CWND), a lost packet can be immediately retransmitted as soon as the first duplicate ACK is received. We use NS-2 to simulate the proposed MAODV. From our simulation results, we have shown that when the position of route failures is near the source node, it may take more time to find new data paths. Hence, MAODV has the advantages by taking the reverse ACK paths to transmit data packets before new routing paths are found. Finally, we have demonstrated that MAODV performs better than TCP-BuS (BUffering capability and Sequence information) and the original TCP, when there are many hops between the source node and the destination node. On the other hand, when the position of route failures is near the destination node, the advantages of MAODV become not so significant because there exists some local repair mechanisms to be applied.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0827104-203122
Date27 August 2004
CreatorsLin, Chun-Hsien
ContributorsChun-Hung Richard Lin, Tsang-Ling Sheu, Sheau-Ru Tong, Rung-Hung Gau
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0827104-203122
Rightsunrestricted, Copyright information available at source archive

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