Spatial Correlations of Measured MIMO Channels with an Extremely Large Aperture Array (ELAA)

Nowadays, the demand for data traffic increases dramatically, which has posed significant challenge on the current infrastructures of cellular networks. To tackle the challenge, the massive multiple-input-multiple-output (MIMO) technology has been proposed, which can improve spectral efficiency greatly, and attract a lot of attentions in industry and academic. In spite of the great potential benefits of massive MIMO, the property of massive MIMO channel with hundreds or thousands of antennas is still an open problem. In this paper, we try to look into deeply the spatial correlation of the channels for extremely large aperture array (ELAA) with some measurements. Specifically, we analyze the correlation between two users’ channels. We also propose a novel metric to characterize the performance of multiuser MIMO (MU-MIMO), which will be used to analyze the MU-MIMO channel later. At last, we study the sinlge-user MIMO (SU-MIMO) channel in terms of the distribution of singular values and also establish the connection between the spread of singular values and UE correlation under special case.

I. Introduction

Nowadays, dramatically increasing data traffic has posed significant challenge on the current infrastructures of cellular networks. To tackle above challenges, MIMO technology has been proposed and widely adopted in LTE. In MIMO system, the spatial properties of users are exploited to serve multiple users over the same time-frequency resource, and therefore, the spectral efficiency can be improved significantly. The spatial correlation of the users’ channels determines the mutual interference and consequently system performance [1]. When the spatial correlation is high, the interference is severe and leads to performance degradation.