Wireless lans with smart antennas /
Ulukan, Erdem (2005) Wireless lans with smart antennas /. [Thesis]
Smart antenna systems not only enable users to have high quality links but also increase network throughput by allowing spatial reuse of wireless channels by the use of directional transmission. However performance of smart antenna systems is limited because of the increased hidden terminal problem and deafness of nodes. In this work, we have proposed the Angular MAC (ANMAC) protocol that avoids both problems through medium access tables in the nodes that keep track of the locations of the destination nodes as well as all communicating neighbors. We present detailed performance analysis of ANMAC considering different topologies and traffic scenarios, and we show that SDMA cannot be fully exploited without a smart scheduler. We have also proposed ANMAC with Location based Scheduling (ANMAC-LS) and compared its performance with other smart antenna approaches and omni 802.11 MAC. We prove the efficacy of location based scheduling in wireless networks with smart antennas, and we also show the effects of antenna orientation on throughput, using realistic antenna patterns and the ANMAC protocol. We have also analyzed the effect of contention window size on the performance of the network. By adjusting the contention window according to channel conditions, we can always get the maximum network throughput. We propose an updating algorithm for contention window, and we have analyzed the results both analytically and through simulations.
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