engleski

Improving TCP End to End Performance in Wireless LANs with Snoop Protocol

Many attempts have been made to improve TCP (Transmission Control Protocol) behavior in wireless environment. Networks with wireless links and mobile hosts violate many of the assumptions made by TCP, and consequence is low throughput and degraded performance. Snoop is simple protocol for improving TCP performance by modifying network-layer software only at access point without touching transport layer [1]. Only modification is taken at access point by putting something called snoop module. This paper includes a simulation-based performance analysis one of the versions of TCP protocol. The main idea is to develop our own TCP Snoop protocol and suggest some improvements for calculation of local timer at access point. For avoiding unnecessary retransmissions and for improving TCP end-to-end performance on wireless link we have introduced a simple network layer addition called Improved Snoop protocol (ISp). In our version main goal is to find best estimation of time for local timer at access point. The idea is to send locally a few probe segments in wireless channel to the wireless client. In that way we calculate round trip time on wireless channel. Our method shows good results to determine TCP local timer value of snoop module and it is used in our simulation scenario. In original Snoop protocol the timer is set to fixed value. Simulations show some improvments when the TCP-Snoop module is implemented. This mean that there are less segment losses and the system is more robust.

TCP; IP; Snoop protocol; WLAN

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