الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The wireless LAN standards IEEE 802.11 (a/b/g) provides multi-rates capabilities, therefore, networkdevices adapt their transmission rate dynamically under varying conditions to achieve high network performance. Rate adaption is a critical component of network performance. High mobility environment and large transmission distance are challenging problems. These problems cause dramatically degradation in wireless network performance. In this thesis we present a solution to overcome these problems based on robust rate adaption algorithm. There are two main contributions of the thesis:(i) we introduced and updated performance evaluation study conducted in IEEE 802.11 networks for most existing open loop and closed loop rate adaptation algorithms; the simulation results showed that the Robust Rate Adaptation Algorithm (RRAA) has the best performance except for long transmission distance and mixed mobility channel condition, and (ii) we proposed a modified RRAA algorithm to address the weakness of the RRAA algorithm. Modified RRAA uses hybrid technique between fixed and adaptive rates. Moreover, it uses adaptive packet size during transmission to achieve maximum throughput of channel. Thesis extensive experiments showed that, Modified RRAA outperforms pure RRAA solutions; with throughput improvement up to 63.27% in scenarios contains mixed mobility node state at long transmission distance between nodes.