Optimal Resource Allocation for MIMO OFDM-CDM Systems under Power, QoS and Fairness Constraints

In this paper we consider resource allocation for throughput maximization and QoS/fairness support in the downlink of a multiuser multi-antennas OFDM-CDM systems with transmit zero-forcing beamforming. The impact of the relaxation of the QoS/fairness constraints on the system throughput is analyzed. The resource allocation problem, with relaxable constraints, formulated as a nonlinear nonconvex optimization problem is efficiently and globally solved through geometric programming in his convex form. Simulation results are provided for different values of the relaxation parameters and illustrate the achievable trade-off between system throughput and QoS/fairness requirements