On Determining the Sum Capacity of a Multi-Spot OFDM System

We propose an iterative method, based on the steepest descent algorithm (SDA), to evaluate the sum capacity in the uplink of a multi-spot system based on orthogonal frequency division multiplexing (OFDM) with centralized power allocation, at any given instant. Because the problem with user power constraints is non-convex, there is no guarantee that the proposed method converges to the optimal solution. However, simulation results show that its solutions by SDA outperform the distributed power control approach presented in S.T. Chung and J.M. Cioffi, (2003). Although, it can be hard to realize in a real time system, the method is an optimal tool to evaluate the maximum rate of a multi-spot system.