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Energy Efficiency of MAC Protocols in Wireless Sensor Networks

Wireless sensor networks (WSNs) have appealed to researchers due to their wide range of application areas such as target detection and tracking, environment monitoring, and tactical systems. For WSNs, various medium access control (MAC) protocols with different objectives have been proposed. Designing energy-efficient MAC protocols has a significant influence on the network lifetime in WSNs. However, short sensing ranges result in dense networks and thus it becomes necessary to achieve an efficient MAC protocol subject to energy constraints. In this paper, we study the energy efficiency of typical MAC protocols in WSNs systematically. The MAC protocols are categorized into contention-based, TDMA-based, hybrid, and cross layer MAC protocols according to channel access policy, and their pros and cons are qualitatively compared. Then, the typical MAC protocols are evaluated in terms of energy efficiency using the ns-2 network simulator and compared to each other quantitatively.