  We optimize the throughput of a single cell multiuser orthogonal frequency
division multiplexing system with proportional data rate fairness among the
users. The concept is to support mobile users with different levels of service.
The optimization problem is a mixed integer nonlinear programming problem,
which is computationally very expensive. We propose a novel and efficient
near-optimal solution adopting a two-phase optimization approach that separates
the subcarrier and power allocation. In the first phase, we relax the strict
proportional data rate requirements and employ an iterative subcarrier
allocation approach that coarsely satisfies desired data rate proportionality
constraints. In the second phase, we reallocate the power among the users in an
iterative way to further enhance the adherence to the desired proportions by
exploiting the normalized proportionality deviation measure. The simulation
results show that the proposed solution exhibits very strong adherence to the
desired proportional data rate fairness while achieving higher system
throughput compared to the other existing solutions.
