Kaczmarz Precoding and Detection for Massive MIMO Systems

In order to allow the operation of cheap and simple computational nodes, the reduction of the complexity related to the computation of signal processing techniques in massive multiple-input multiple-output (M-MIMO) is a desirable property to be obtained. With this in mind, several methods have been proposed to reduce the complexity of the classical combining/precoding schemes, being one of these based on the Kaczmarz algorithm (KA). Recent works demonstrated that KA-based approaches can suitably estimate the signals received and transmitted in the uplink and downlink phases; simultaneously, the procedure seemed to result in a very low computational complexity. Motivated by such context, this paper proposes a modification in the primary KA-based scheme for M-MIMO, striving to improve its rate of convergence, reducing complexity while holds the performance. Such improvement underlies the effects of pathloss and shadowing over the KA's rate of convergence, as well as in the spectral efficiency. Numerical results are given supporting that the proposed method outclasses the original proposal.