Elements of information theory
Elements of information theory
Opportunistic Multichannel Aloha for Clustered OFDM Wireless Networks
Proceedings of the Second International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks
Distributed opportunistic scheduling for ad-hoc communications: an optimal stopping approach
Proceedings of the 8th ACM international symposium on Mobile ad hoc networking and computing
IEEE Transactions on Wireless Communications
Cross-layer optimization for OFDM wireless networks-part I: theoretical framework
IEEE Transactions on Wireless Communications
Opportunistic beamforming using dumb antennas
IEEE Transactions on Information Theory
Exploiting decentralized channel state information for random access
IEEE Transactions on Information Theory
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In this letter, we present an opportunistic multi-channel CSMA protocol for OFDMA systems in frequency-selective fading channel. In order to opportunistically exploit the frequency selectivity, an OFDM-based single-channel CSMA protocol can employ water-filling power allocation as it allows a single station to utilize the whole frequency bandwidth at each time instant. In contrast, the proposed OFDMA-based multi-channel CSMA protocol achieves the multi-user diversity gain by arranging multiple stations to transmit on their favorable sub-channels simultaneously. The proposed protocol is designed as an opportunistic version of the original multi-channel CSMA protocol, which was proposed in our previous work, and adopts a channel-adaptive backoff (or transmission probability control) algorithm, enabling each station to attempt data transmission on its high-SNR sub-channel with a high probability. The opportunistic multi-channel CSMA turns out to improve the total data rate significantly over the opportunistic single-channel CSMA, and to achieve almost full multi-user diversity gain despite the distributed operation.