A New Approach to Linear Estimation Problem in Multi-user Massive MIMO Systems

TL;DR

This paper introduces a novel, computationally efficient method for linear estimation in multi-user massive MIMO systems that avoids matrix inversion by incorporating channel matrix properties into a generalized dot product.

Contribution

It proposes a new approach that accounts for non-orthogonal channel columns, enabling direct computation of unknowns with reduced complexity and increased flexibility.

Findings

Achieves exact solutions with 25% less computation than QR method

Method is stable and allows computing individual unknowns

Implementation requires only twelve lines of code

Abstract

A novel approach for solving linear estimation problem in multi-user massive MIMO systems is proposed. In this approach, the difficulty of matrix inversion is attributed to the incomplete definition of the dot product. The general definition of dot product implies that the columns of channel matrix are always orthogonal whereas, in practice, they may be not. If the latter information can be incorporated into dot product, then the unknowns can be directly computed from projections without inverting the channel matrix. By doing so, the proposed method is able to achieve an exact solution with a 25% reduction in computational complexity as compared to the QR method. Proposed method is stable, offers an extra flexibility of computing any single unknown, and can be implemented in just twelve lines of code.