Exploiting Spatial Channel Covariance for Hybrid Precoding in Massive MIMO Systems

We propose a new hybrid precoding technique for massive multi-input multi-output (MIMO) systems using spatial channel covariance matrices in the analog precoder design. Applying a regularized zero-forcing precoder for the baseband precoding matrix, we find an unconstrained analog precoder that maxim...

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Bibliographic Details
Published inIEEE transactions on signal processing Vol. 65; no. 14; pp. 3818 - 3832
Main Authors Sungwoo Park, Jeonghun Park, Yazdan, Ali, Heath, Robert W.
Format Journal Article
LanguageEnglish
Published IEEE 15.07.2017
Subjects
antenna arrays
Baseband
cellular communication
Channel estimation
Covariance matrices
covariance matrix
Hybrid precoding
massive MIMO
MIMO
multi-user MIMO
Phase shifters
Precoding
Radio frequency
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Summary:We propose a new hybrid precoding technique for massive multi-input multi-output (MIMO) systems using spatial channel covariance matrices in the analog precoder design. Applying a regularized zero-forcing precoder for the baseband precoding matrix, we find an unconstrained analog precoder that maximizes signal-to-leakage-plus-noise ratio (SLNR) while ignoring analog phase shifter constraints. Subsequently, we develop a technique to design a constrained analog precoder that mimics the obtained unconstrained analog precoder under phase shifter constraints. The main idea is to adopt an additional baseband precoding matrix, which we call a compensation matrix. We analyze the SLNR loss due to the proposed hybrid precoding compared to fully digital precoding, and determine which factors have a significant impact on this loss. In the simulations, we show that if the channel is spatially correlated and the number of users is smaller than the number of RF chains, the SLNR loss becomes negligible compared to fully digital precoding. The main benefit of our method stems from the use of spatial channel matrices in such a way that not only is each user's desired signal considered, but also the inter-user interference is incorporated in the analog precoder design.
ISSN:1053-587X
1941-0476
DOI:10.1109/TSP.2017.2701321