Performance of waterfilling-based schemes for interference cancellation in 4G networks

In this work we consider the optimization of the power assigned to the user streams in a coordinated base station downlink environment with Orthogonal Frequency Division Modulation (OFDM). In this scenario the base stations perform distributed cooperative processing with a block diagonalization scheme to remove interference among users. Two schemes based on the waterfilling technique are proposed and compared to the optimal solution, which can be obtained numerically, by using convex optimization. We show that the proposed schemes achieve a performance, in terms of weighted sum rate, very close to the optimal, without the heavy computational complexity required by the numerical solution. These sum rates are compared in a simplified scenario consisting of two-user and two-cell. Other more realistic multicell scenario and some examples of achievable rates are presented too.