EE-MAC: Energy Efficient Hybrid MAC for WSN

A novel low power medium access protocol energy efficient MAC (EE-MAC) for wireless sensor network is proposed in this paper. EE-MAC targets for improving energy efficiency, delay performance and packet delivery ratio by considering various load conditions of the network. This protocol is based on the hybrid of TDMA and FDMA approaches. The novel idea behind EE-MAC is that it uses the priority concept with hybrid MAC scheduling in order to achieve its objectives. The performance of EE-MAC is obtained through simulations for various packet sizes, traffic loads, and different scenarios which show significant improvements in packet delivery ratio, energy efficiency, and delay compared to existing protocols. 1. Introduction Wireless sensor network (WSN) is an application driven design determined by the requirements of network behaviour. Wireless sensor networks have been proposed for emergency applications, such as building fire monitoring and response. The network must be traffic and topology adaptive for this type of application. The algorithm used for communication should be delay tolerant during normal periodic monitoring and energy efficient. Conventional WSN applications like [1–3] have concentrated on inactive low-duty cycle sensing and monitoring, in-network data aggregation, and asynchronous operation designed to extend the lifetime of sensor nodes. Conversely, the applications like real-time streaming for voice and video require comparatively high bandwidth utilization, throughput, and bounded end-to-end delay of few milliseconds. Thus, the design of effective WSN medium access control (MAC) protocols has become a more challenging task and results in a very different design trade-off than other wireless networks. Existing WSN hardware devices such as MICAZ [4], Telos [5], and CMU Firefly [6] play a major role in designing WSN-MAC layer protocol. These hardware devices use CC2420 radio [7] in order to access the multiple channels. Designing MAC protocols for a given limited radio bandwidth (19.2？Kbps in MICA2 and 250？Kbps in MICAZ and Telos) and to increase the network throughput is a crucial task. Almost all of the proposed protocols for WSN MAC layer such as [8–14] use only one single physical frequency. Due to limited bandwidth of the sensor node hardware and the small MAC layer packet size, multifrequency MAC protocols of general wireless networks are not suitable for wireless sensor networks. For the operation of MAC protocol in multiple frequencies, single low-power transceiver of WSN node is not capable due its inability of simultaneous