Time Scheduling, Subcarrier and Power Allocation in Multi-Service Downlink OFDMA Systems

In this paper we develop a time Scheduling, Subcarrier and Power Allocation scheme for Multi-Service Downlink OFDMA Systems. We propose a two step solution where time scheduling is separated from subcarrier and power allocation decisions. The system is modeled as a linear dynamic system with the aim of minimizing a quadratic cost function. The proposed scheduler is a Linear-Quadratic-Regulator (LQR) which achieves fairness among users by proposing an instantaneous data rate for each user in each time slot. The data rate vector proposed by the regulator is then fed as a constraint to the subcarrier and power allocation problem. This problem is formulated as a constrained convex optimization problem and we develop algorithms for subcarrier and power allocation to achieve the data rates proposed by LQR. Simulation results show good performance and better fairness among users.