Opportunistic multiuser scheduling algorithm for multi-carrier wireless data systems

In this paper, we propose a scheduling algorithm that reduces the feedback load and guard time requirements for adaptive modulation multi-carrier systems. Instead of fixing a probing threshold in a polling-based system, we vary the probing threshold and allow users to feed back quantized information indicating their channel’s state. The probing threshold starts with the system’s minimum threshold level and increases towards the system’s maximum depending on the number of employed modulation levels and the users’ channel state information. Numerical results show that the proposed algorithm reduces the feedback load and the guard-time requirements with a slight penalty loss in the spectral efficiency when compared to the optimal algorithm (full feedback). Furthermore, we study the effect of our algorithm on the probability of access, system throughput and scheduling delay after deriving closed-form expressions for the feedback load and the spectral efficiency.