Hybrid Precoding for Millimeter Wave MIMO Systems: A Matrix Factorization Approach


This paper investigates the hybrid precoding design for millimeter wave multiple-input multiple-output systems with finite-alphabet inputs. The precoding problem is a joint optimization of analog and digital precoders, and we treat it as a matrix factorization problem with power and constant modulus constraints. This paper presents three main contributions. First, we present a sufficient condition and a necessary condition for hybrid precoding schemes to realize unconstrained optimal precoders exactly when the number of data streams Ns satisfies Ns = min{rank(H), Nrf}, where H represents the channel matrix and Nrf is the number of radio frequency chains. Second, we show that the coupled power constraint in our matrix factorization problem can be removed without loss of optimality. Third, we propose a Broyden-Fletcher-Goldfarb-Shanno-based algorithm to solve our matrix factorization problem using gradient and Hessian information. Several numerical results are provided to show that our proposed algorithm outperforms existing hybrid precoding algorithms.


Electrical and Computer Engineering

Keywords and Phrases

Factorization; Millimeter waves; MIMO systems; Nonlinear programming; Optimization; Broyden-Fletcher-Goldfarb-Shanno; Constant modulus constraints; Finite-alphabet inputs; Matrix factorizations; Millimeter waves (mmwave); Nonconvex optimization; Precoding; Radio frequency chains; Matrix algebra; Hybrid precoding; Matrix factorization; Nonconvex optimization

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Article - Journal

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