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 formultiuserOFDM 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.
Highlights
Emerging broadband wireless networks which support highspeed packet data with a different quality of service (QoS) demand more flexible and efficient use of the scarce spectral resource
Liu et al described a framework for opportunistic scheduling to exploit the multiuser diversity while at the same time satisfying three long-term QoS/fairness constraints [10,11,12]
We propose an opportunistic scheduling framework for multiuser orthogonal frequency-division multiplexing (OFDM) systems
Summary
Emerging broadband wireless networks which support highspeed packet data with a different quality of service (QoS) demand more flexible and efficient use of the scarce spectral resource. Good scheduling schemes in wireless networks should opportunistically seek to exploit the time-varying channel conditions to improve spectrum efficiency, thereby achieving multiuser diversity gain. Allowing only users close to the base station to transmit at high transmission rate may result in very high throughput, but may sacrifice the transmission of other users Such a scheme cannot satisfy the increasing demand for QoS provisioning in broadband wireless networks. To solve this problem, Liu et al described a framework for opportunistic scheduling to exploit the multiuser diversity while at the same time satisfying three long-term QoS/fairness constraints [10,11,12].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
