Adaptive Beamforming for Antenna Arrays in Cellular Systems Based on a Duality Between Uplink and Downlink Channels

This paper presents a beamforming algorithm for antenna arrays attending to both power and signal-tointerference-plus-noise (SNIR) ratio constraints. The proposed adaptive approach makes use of the least-mean-square (LMS) algorithm as well as exploits the duality idea between uplink and downlink channels. Since a reference signal is used, the proposed approach does not require any direction-of-arrival (DoA) algorithms for estimating the angle-of-arrival (AoA) of the signals. The proposed algorithm exhibits both low computational complexity and very good stability conditions. Through numerical simulations the performance of the proposed algorithm is verified.