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Opportunistic Scheduling for OFDM Systems with Fairness Constraints
EURASIP Journal on Wireless Communications and Networking volume 2008, Article number: 215939 (2007)
Abstract
We consider the problem of downlink scheduling for multiuser orthogonal frequency-division multiplexing (OFDM) systems. Opportunistic scheduling exploits the time-varying, location-dependent channel conditions to achieve multiuser diversity. Previous work in this area has focused on single-channel systems. Multiuser OFDM allows multiple users to transmit simultaneously over multiple channels. In this paper, we develop a rigorous framework to study opportunistic scheduling in multiuser OFDM systems. We derive optimal opportunistic scheduling policies under three QoS/fairness constraints for multiuser OFDM systems—temporal fairness, utilitarian fairness, and minimum-performance guarantees. Our scheduler decides not only which time slot, but also which subcarrier to allocate to each user. Implementing these optimal policies involves solving a maximal bipartite matching problem at each scheduling time. To solve this problem efficiently, we apply a modified Hungarian algorithm and a simple suboptimal algorithm. Numerical results demonstrate that our schemes achieve significant improvement in system performance compared with nonopportunistic schemes.
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Zhang, Z., He, Y. & Chong, E.K.P. Opportunistic Scheduling for OFDM Systems with Fairness Constraints. J Wireless Com Network 2008, 215939 (2007). https://doi.org/10.1155/2008/215939
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DOI: https://doi.org/10.1155/2008/215939