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2009 Sixth International Conference on Broadband Communications, Networks, and Systems. Broadnets 2009 (2009)
Madrid
Sept. 14, 2009 to Sept. 16, 2009
ISSN: 2150-4903
ISBN: 978-963-9799-49-3
pp: 1-6
Changmian Wang , IET Department, NTNU, Trondheim, Norway
Liuguo Yin , School of Aerospace, Tsinghua University Beijing, China
Geir E. Oien , IET Department, NTNU, Trondheim, Norway
ABSTRACT
In this work, we first study and then propose an optimal version on the medium access control mechanism known as carrier sense multiple access with collision avoidance (CSMA/CA). This protocol is adopted by many wireless communication standards, such as the IEEE 802.11 series and IEEE 802.15.4 (ZigBee). We first identify its drawbacks in a slow fading channel environment, and show that the CSMA/CA can be very energy-inefficient, especially in many wireless sensor network (WSN) applications where the traffic demand is low. In particular, we study communication over a Rayleigh fading channel, which we model by means of a time invariant Markov process. We then show that the decision regarding the optimal access time on such a channel can be formulated as an optimization problem, and that an optimal solution can be accurately derived. We also simulate a ZigBee node in a Rayleigh fading environment and the result shows that optimum channel access can save significant amount of energy compared to conventional CSMA/CA.
INDEX TERMS
carrier sense multiple access, Markov processes, optimisation, Rayleigh channels, telecommunication congestion control, telecommunication traffic, wireless sensor networks
CITATION

C. Wang, L. Yin and G. E. Oien, "Energy-efficient medium access for wireless sensor networks under slow fading conditions," 2009 Sixth International Conference on Broadband Communications, Networks, and Systems. Broadnets 2009(BROADNETS), Madrid, 2009, pp. 1-6.
doi:10.4108/ICST.BROADNETS2009.7554
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