Efficient rate adaptation in IEEE 802.11 wireless networks

IEEE 802.11 is a predominant technology in wireless networks. Though designed to extend local area networks, it has been extended beyond its original infrastructure scope. Three medium sharing aspects must be considered to improve wireless networks throughput. These include higher data rate, power management and channel spatial reuse. -- This thesis focuses on the rate adaptation aspect of wireless networks. Though critical, IEEE 802.11 standards do not specify any rate adaptation mechanism which leaves it up to the wireless devices vendors to implement interfaces that utilize PHY multirate capability. A rate adaptation mechanism must accurately estimate the channel condition despite the presence of various dynamics caused by fading, mobility and hidden terminals, and effectively select the appropriate data rate. -- Utilizing the diverse information scope in literature, we propose hybrid rate adaptation schemes, DRA, DRALD and DRANLD, that draw channel quality information from both the sender and the receiver to effectively determine appropriate data rate. Extensive NS-2 simulations illustrate that these schemes are more adaptive to the dynamic channel conditions and their performance is better than their predecessors