An Experimental Massive MIMO Channel Matrix Model for Hand-Held Scenarios

Abstract

A novel, experimental massive channel matrix model for indoor scenarios is proposed. In this model, the hand-held effects of smartphone users are taken into consideration, as well as the correlation and coupling at transmitters and receivers in the conventional models. Hence, the proposed model is more applicable in real environments. Measurements at 3.5 GHz are carried out in a typical indoor scenario with a massive multiple-input multiple-output (MIMO) testbed to serve as a base station and an eight-antenna handset to mimic a smartphone. Channel performance predicted by the proposed model is in good agreement with the measurement results. It is highlighted that the proposed model is more accurate than the traditional massive MIMO channel matrix models. INDEX TERMSChannel matrix model, indoor, massive MIMO, propagation. I. INTRODUCTION The Massive Multiple-Input Multiple-Output (MIMO) has established itself as a key technology for emerging wireless communication systems such as 5G [1], [2]. It can remarkably improve system performance including spectral and power efficiency [3], [4]. The performance of massive MIMO highly depends on the characteristics of the wireless channel. Hence, deep physical comprehension of the propagation mechanisms and accurate channel models for massive MIMO are becoming increasingly important [5]-[7]. In particular, channel matrix models can be employed to characterize a lot of channel performances. They are also important basis for the evolution of standardized models such as WINNER and 3GPP SCM. One of the most commonly used channel matrix models is the Kronecker model, where channel characteristics are dependent on the Kronecker product of linkend correlation matrices [8], [9]. This model has advantage in simplicity but is proved to be inaccurate as the effects between link-ends are ignored. This deficiency is solved in Weichselberger model [10], [11], where both the correlation matrices and the effects between link-ends are taken intoThe associate editor coordinating the review of this manuscript and approving it for publication was Kostas P. Peppas.

Performance comparisons of FDD MIMO and 2.6 GHz TDD massive MIMO: An experimental analysis

“…The authors in [8] investigate the potential of massive MIMO in green communications. Large number of measurement campaigns have also been held for massive MIMO [9,10,11,12,13,14,15]. The authors in [9] provide a good overview of recent 5G experimental activities in massive MIMO.…”

“…The authors in [9] provide a good overview of recent 5G experimental activities in massive MIMO. Some of the massive MIMO experimental campaigns include measurements on spectrum efficiency and capacity [10], channel to model channel matrix [11] and its characteristics [12], frequency-domain channel sounding [13], spectrum sensing in a cognitive radio-like network [14], channel hardening and user orthogonality in [15]. New trials are beginning to emerge converging 5G with massive MIMO technology.…”

An Electromagnetic Framework for the Deployment of Reconfigurable Intelligent Surfaces to Control Massive MIMO Channel Characteristics

“…Currently active research on massive MIMO technology is seeing the emergence of futuristic concepts like "extremely large aperture arrays" (ELAAs), "cell-free massive MIMO" and "large intelligent surface" (LIS), pushing the engineers to look into the spatial correlation and channel-modelling aspects from an advanced electromagnetic perspective [4]- [5]. Traditionally, researches on massive MIMO channel modelling have been either experimental/empirical [6]- [8], or based on simplified assumptions like simplified uncorrelated Rayleigh fading models or ray-tracing tracing approach. With a large number of antennas being accommodated both in the base-stations (BS) as well as user-equipments (UEs), it has become crucial for correlation analysis/channelmodelling to extract the complete electromagnetic (EM) knowledge by incorporating effects of the impinging spherical wave-fronts of near-field illumination, port-to-port mutual coupling as well as relative BS-element polarization [9].…”