Skip to main content

Opportunistic Scheduling for OFDM Systems with Fairness Constraints


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.

Publisher note

To access the full article, please see PDF

Author information

Authors and Affiliations


Corresponding author

Correspondence to Zhi Zhang.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 2.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Reprints and permissions

About this article

Cite this article

Zhang, Z., He, Y. & Chong, E.K.P. Opportunistic Scheduling for OFDM Systems with Fairness Constraints. J Wireless Com Network 2008, 215939 (2007).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: