Analytical Throughput for the Channel MAC Paradigm
It has been shown analytically [1],[2] that significant performance improvements as compared to existing technologies (e.g., IEEE 802.11) can be achieved in random access wireless networks. In [3] we proposed a fully distributed channel access paradigm ba
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Abstract. It has been shown analytically [1],[2] that significant performance improvements as compared to existing technologies (e.g., IEEE 802.11) can be achieved in random access wireless networks. In [3] we proposed a fully distributed channel access paradigm based on the opportunistic communication principal called the Channel MAC paradigm suitable for distributed wireless networks such as ad hoc networks. In this paper, we analytically derive the throughput of the Channel MAC. It provides a throughput-limit on the channel-based MAC mechanism in shared multiple access environments without collisions or capturing effects. Both simulation and analytical results reveal possible performance improvement over existing techniques.
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Introduction
The performance of ad hoc networks with Medium Access Control (MAC) protocols such as IEEE 802.11 falls well short of what is predicted by the theoretical models [1],[2]. This is mainly due to the inability of current MAC protocols to simultaneously take into account the dynamic channel conditions, decentralised channel access and unfairness in access to the common channel [4]. The concept of opportunistic communication has been shown to increase the performances of networks with centralised control [5],[6],[7]. Recently attempts has been made to apply the concept of opportunistic communication to networks with decentralised access mechanisms such as ad hoc and sensor networks [8],[9],[10],[11]. It has to be pointed out that these proposed schemes, although exploiting diversity as a way to determine who has priority for transmission, still use a slotted access system. Hence, in the absence of a central entity which would determine who will transmit based on the “best” channel, collisions will still occur because all nodes with good channel conditions will compete for resources at the beginning of the slot [12],[8],[11]. In [3], authors proposed a new MAC paradigm, called Channel MAC, which exploits the random nature of the fading channel to determine the channel access instances in a decentralised and distributed manner. Simulation results based on a Rayleigh fading channel showed that by using the new MAC paradigm, the network can achieve significantly higher throughput for all channel conditions as H. Zhang et al. (Eds.): MSN 2007, LNCS 4864, pp. 375–386, 2007. c Springer-Verlag Berlin Heidelberg 2007
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M. Ashraf, A. Jayasuriya, and S. Perreau
compared to 802.11 MAC scheme [3]. In this paper we model the Channel MAC protocol based on two-state channel model and show that the Channel MAC protocol always outperforms 802.11 MAC protocol. The paper is structured as follows. The objectives and functionality of Channel MAC paradigm are briefly described in section II. This is followed by a description of the system model used in this study. Channel model and key definitions are illustrated here. Section IV describes the proposed analytical throughput model for the Channel MAC study. Simulation model and discussions on the results are given in the next section. Finally secti
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