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Doctor of Philosophy
Date of Defense
Due to low cost and easy deployment, multi-hop wireless networks become a very
attractive communication paradigm. However, IEEE 802.11 medium access control
(MAC) protocol widely used in wireless LANs was not designed for multi-hop wireless
networks. Although it can support some kinds of ad hoc network architecture, it does not
function efficiently in those wireless networks with multi-hop connectivity. Therefore,
our research is focused on studying the medium access control in multi-hop wireless
networks. The objective is to design practical MAC layer protocols for supporting multihop
wireless networks. Particularly, we try to prolong the network lifetime without
degrading performances with small battery-powered devices and improve the system
throughput with poor quality channels.
In this dissertation, we design two MAC protocols. The first one is aimed at
minimizing energy-consumption without deteriorating communication activities, which
provides energy efficiency, latency guarantee, adaptability and scalability in one type of
multi-hop wireless networks (i.e. wireless sensor network). Methodologically, inspired by the phase transition phenomena in distributed networks, we define the wake-up
probability, which maintained by each node. By using this probability, we can control the
number of wireless connectivity within a local area. More specifically, we can adaptively
adjust the wake-up probability based on the local network conditions to reduce energy
consumption without increasing transmission latency. The second one is a cooperative
MAC layer protocol for multi-hop wireless networks, which leverages multi-rate
capability by cooperative transmission among multiple neighboring nodes. Moreover, for
bidirectional traffic, the network throughput can be further increased by using the
network coding technique. It is a very helpful complement for current rate-adaptive MAC
protocols under the poor channel conditions of direct link. Finally, we give an analytical
model to analyze impacts of cooperative node on the system throughput.
Wan, Zhiwen, "Cooperative and Adaptive Medium Access Control in Multi-hop Wireless Networks" (2008). FIU Electronic Theses and Dissertations. Paper 272.