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A study of active access-point selection algorithm for wireless mesh network under practical conditions

Chew, Chang Choon (2015) A study of active access-point selection algorithm for wireless mesh network under practical conditions. PhD thesis, Okayama University.


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As an inexpensive, scalable, and flexible Internet- access nctwork, a wireless Internet-access mesh network (WIMNET) is composed of multiple access-poants (APs) that arc connected by wireless links. WIMNET can improve the dependability to link or AP failures by allocating APs redundantly in the network field. Because the redundant APs may increase the operational cost and degrade the performance due to increasing radio interferences, only the necessary APs for communications between the hosts and the Internet gateway should be activated in conventional situations. Previously, we have proposed an actzve AP selectzon algorithm to sclect the minimum number of APs to be activated for WININET that has a single Internet gateway ('GW), such that the overall throughput is maximized, under thc assumption that every link has the same constant speed. However, our preliminary experiments for the emerging high-speed IEEE802.lln protocol that should be introduced into WIMNET found that this speed is greatly affected by the link environment such as the distance. Besides, in practical implementations of large-scale WIMNET, multiple GWs are usually necessary to increase the capacity of Internet connections, and the number of hops between a GW and a host should be limited. Furthermore, the minimum throughput should be provided to a host as QoS (Quality of Service) when it is exclusively connected with the GW. In this thesis, we first present the extension of the active AP selection algorithm to select active APs under practical conditions of link speed changes, multiple GWs, the hop count limitation, and QoS constraints. We also extend the routing algorithm used in the activc AP selection algorithm procedure and the WIMNET simulator for throughput €valuations. we verify the eEectiveness of the extended active AP selection algorithm through extensive simulations using the extended WIMNET simulator. Then, we present link speed measurement results when fiansmission Control Protocol (TCP) is adopted with IEEE 802.11ac devices from three vendors. In our measurements, we adopt different conditions for network fields such as AP locations, link distances, one or two-hop communications, wall existences, and repeater existences. Then, the experimental results show that TCP throughputs are greatly affected by vendors, communication conditions and physical conditions. In future studies, we will study the proper assignment of the minimurn link speed parameter that is critical for the active AP minimization and the overall throughput maximization, thc proper handling of dynamic traffic changes, the further algorithm extension to different hop limitations, and the systern implementation for real networks.

Item Type: Thesis (PhD)
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101-5865 Telecommunication. Telegraph.
Depositing User: En. Sharul Ahmad
Date Deposited: 12 Apr 2016 04:41
Last Modified: 12 Apr 2016 04:41
URI: http://eprints.uthm.edu.my/id/eprint/7879
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