الفهرس 
Chapter 1:IntroductionOnly 14 pages are availabe for public view
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Abstract
In recent years, Wireless Sensor Networks (WSNs) have found advanced applications in modern society. The WSNs suffer from limited energy resources. Therefore, managing the energy constraints and exploring new ways to minimize the energy consumption during the operation of the nodes are critical issues. This problem is mainly due to the nature of such networks being energy self-dependent, typically on a battery. The energy limitations in WSNs has incited wide research addressing the development of various techniques to deal with. One of these techniques is the development of Medium Access Control (MAC) protocols, especially engineered to cater to sensor network energy requirements. In this regard, the researchers have developed and introduced various MAC protocols. However, almost all of these protocols can be fitted in one of three main classes; contention-based, schedule-based protocols and hybrid protocols. This thesis introduces two efficient energy consumption MAC protocols for WSNs. The two proposed MAC protocols can be considered as a modification of the Multi-Layer MAC protocol to achieve energy efficiency which is the main design factor in WSNs. The proposed MAC protocols aim to save energy by using periodic wake up and sleep modes. Sensor nodes are allocated into different unequal duration layers so that the listen periods of the different layers are non-overlapping. Distributing the nodes among the layers depends on the node energy, and this distribution allows all nodes, which have small amounts of energy to sleep longer than nodes, which have great amounts of energy. Therefore, this distribution increases the fairness between the nodes in energy consumption. The results of the numerical simulations show that the two proposed MAC protocols outperform other MAC protocols in terms of energy efficiency.