ER-MAC: A Hybrid MAC Protocol for Emergency Response Wireless Sensor Networks

Abstract

Abstract-This paper introduces ER-MAC, a hybrid MAC protocol for emergency response wireless sensor networks. ER-MAC is designed as a hybrid of the TDMA and CSMA approaches, giving it the flexibility to adapt to traffic and topology changes. It adopts a TDMA approach to schedule collision-free slots. Nodes wake up for their scheduled slots, but otherwise switch into power-saving sleep mode. When an emergency occurs, nodes that participate in the emergency monitoring change their MAC behaviour by allowing contention in TDMA slots to achieve high delivery ratio and low latency. ER-MAC offers a synchronised and loose slot structure to allow nodes to join or leave the network. Simulations in ns-2 show that ER-MAC outperforms Z-MAC with higher delivery ratio, lower latency, and lower energy consumption.Keywords-MAC protocol; wireless sensor networks; fire emergency. I. INTRODUCTIONWireless sensor networks (WSNs) for emergency applications such as monitoring fires in buildings must be traffic and topology adaptive. In our specified application, the communication protocol can be delay tolerant during normal monitoring and designed for energy efficiency. However, when an emergency event occurs, energy efficiency is less important than high packet delivery ratio and low latency, and the communication protocol should adapt in response.Some traffic adaptive medium access control ( In this paper, we propose ER-MAC, a hybrid MAC protocol for emergency response WSNs. While our scenario assumption is the fire monitoring in buildings, this protocol is also useful in a range of WSN emergency applications. The contributions of this paper are:

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“…The use of fixed frame in this protocol means that, it is not adaptive to the dynamics of network load traffic variations. Queue-length aware MAC (Queue-MAC) [63] is a multi-hop beacon enabled hybrid MAC protocol that addressed the issue of fixed cycle of [62]. It incorporates a dynamic duty cycled TDMA while the CSMA duty cycle remains fixed.…”

An energy efficient data aggregation based medium access control protocol using centre at nearest source approach for sensor networks in a lattice topology

“…The defect related with the crankshaft protocol is that it cannot provide good broadcast flooding delivery for sporadic traffic. ER-MAC [2] is designed for emergency purpose. During the normal monitoring the nodes make use of TDMA slot assignment.…”

“…WSNs for emergency applications such as monitoring fire must be traffic and topology adaptive [2]. For such situations there are several factors that should be satisfied by the MAC protocol.…”

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“…ER-MAC [5] is an obvious choice as this protocol was designed for emergency response applications and unlike fixed protocols, provides scalability and flexibility to the network. Since the project undertaken here is an event based application, duty cycle based and hybrid protocols could also be considered for use.…”