Power control using Steffensen iterations for CDMA systems with beamforming or multiuser detection

We present an accelerated power control algorithm applicable for CDMA based communications systems employing advanced uplink receiver techniques such as beamforming or multiuser detection. The proposed algorithm operates a fixed point power control algorithm accelerated by utilizing Aitken´s Δ₂-process (also known as Steffensen´s method) that is merged with linear MMSE filtering. The linear MMSE filter either performs beamforming or multiuser detection. The proposed algorithm shows asymptotically quadratic convergence and is benchmarked against Newton´s method. We further evaluate a lower bound on the Lipshitz constant which can be used to ensure convergence of the proposed algorithm. Numerical results are given for a fully deployed sectorized UMTS network with MMSE multiuser detection. Beside its employment within CDMA based communication systems, the proposed algorithm can also be utilized for the acceleration of computational intensive network simulations.