Energy-Efficient Backoff Algorithms for Wireless Sensor Networks

Energy-Efficient Backoff Algorithms for Wireless Sensor Networks

S. Mehta (Inha University, Korea) and K.S. Kwak (Inha University, Korea)
DOI: 10.4018/978-1-61350-153-5.ch007
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A prime goal of wireless sensor networks (WSNs) is to minimize energy consumption than high channel efficiency and low channel access delay. Existing MAC protocols for WSNs reduce energy consumptions by introducing variation in an active/sleep mechanism, but they cannot save energy during the execution of backoff algorithm. In this chapter, we study and compare the different backoff algorithms for wireless sensor networks. We also use the concept of a geometrically increasing probability distribution for contention process. This allows us to introduce improved backoff (IB) algorithm for energy efficient MAC protocol in WSNs, where binary exponential backoff (BEB) based algorithm is widely used. With the help of numerical results we show that the IB gives edge over BEB in throughput, channel access delay, and energy efficiency under varying traffic conditions.
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Communication in wireless sensor networks is divided into several layers. Medium Access Control (MAC) is one of those layers, which enables the successful operation of the network. MAC protocol tries to avoid collisions by not allowing two interfering nodes to transmit at the same time. The main design goal of a typical MAC protocols is to provide high throughput and QoS. On the other hand, wireless sensor MAC protocol gives higher priority to minimize energy consumption than QoS requirements. Energy gets wasted in traditional MAC layer protocols due to idle listening, collision, protocol overhead, and over-hearing (I.F Akayildiz, 2002; W. Heidemann et. al., 2002). There are some MAC protocols that have been especially developed for wireless sensor networks. However, we discussed a very few MAC protocols here just to present some examples of Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) based MAC protocols for WSNs. Typical examples include S-MAC, T-MAC, and H-MAC (W. Heidemann et. al., 2002; T.V.Dam, 2003, S.Mehta,2009). In large amount of literature authors proposed new MAC protocols for WSNs but in this chapter our approach is to concentrate on backoff algorithm than a complete MAC protocol. In this chapter we introduce an energy efficient backoff algorithm, which is easy to integrate with existing energy efficient MAC protocols for WSNs.

Before going into more details about the backoff algorithms, it is useful for readers to take a glimpse at some important sensor networks MAC protocols.

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