Dynamic tuning of the IEEE 802.11 protocol to achieve a theoretical throughput limit
IEEE/ACM Transactions on Networking (TON)
ISPAN '00 Proceedings of the 2000 International Symposium on Parallel Architectures, Algorithms and Networks
Proceedings of the 5th ACM international symposium on Mobile ad hoc networking and computing
Analyzing multi-channel medium access control schemes with ALOHA reservation
IEEE Transactions on Wireless Communications
Performance analysis of the IEEE 802.11 distributed coordination function
IEEE Journal on Selected Areas in Communications
Multichannel random access in OFDMA wireless networks
IEEE Journal on Selected Areas in Communications
Opportunistic multi-channel CSMA protocol for OFDMA systems
IEEE Transactions on Wireless Communications
An OFDM based MAC protocol for underwater acoustic networks
Proceedings of the Fifth ACM International Workshop on UnderWater Networks
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In this paper, we present a multi-channel carrier sense multiple access with collision avoidance (CSMA/CA) protocol for orthogonal frequency division multiple access (OFDMA) systems. The CSMA/CA system in conventional single-channel operation has the advantage of not requiring the signaling for bandwidth request and allocation over the scheduled access system but it sacrifices system efficiency significantly. We overcome the system efficiency limitation by exploiting the OFDMA system features that multiple stations can transmit simultaneously on different sub-channels, and the stations can obtain the channel information of all the sub-channels at each time instant. The OFDMA-based multi-channel CSMA/CA protocol is designed to enable the stations to contend with each other for channel access both in time and frequency domains through a two-dimensional backoff scheme. The protocol takes a generalized form of the conventional single-channel CSMA/CA protocol: It allows to segment the channel bandwidth into multiple narrow-band random access channels and adjust the transmission probability according to the multi-channel activity in a flexible manner. For throughput analysis, we devise a multi-channel p-persistent CSMA protocol that can emulate the multi-channel CSMA/CA protocol and then analyze its saturated throughput. The simulation and analysis results reveal that the proposed system performs far better than the single-channel CSMA/CA system while using the same total bandwidth and even close to the scheduled access system. Further, we examine how stringent time synchronization is required among the constituent stations in implementing of the OFDMA-based multi-channel CSMA/CA system.