An Opportunistic Scheduling Scheme with Minimum Data-Rate Guarantees for OFDMA

We tackle the problem of providing minimum data-rate guarantees for different classes-of-service in an OFDMA-based network, while obtaining a high system throughput. Our approach is based on the principles of opportunistic scheduling, leveraging multiuser and frequency diversity. By giving a higher priority for transmission to the users that have the instantaneous channel quality better than their respective average value over a time window, we add an additional degree of liberty for the packet scheduler: time diversity. Using this user-centric approach instead of a system-centric one, simulations have shown that the proposed algorithm always succeeds in fully meeting the guaranteed data- rates for all users, even under heavy loads. The size of the time window over which guarantees are provided allows for a flexible control of both the hardness of the guarantees provided and the level of the delays introduced. We present performance metrics of our low-complexity heuristic in comparison with established algorithms from the literature and provide an upper bound using a mixed-integer programming model.