Empirical Studies of Propagation Characteristics and Modeling Based on XL-MIMO Channel Measurement: From Far-Field to Near-Field

TL;DR

This paper presents comprehensive measurement and modeling of XL-MIMO channels in near-field and far-field regions, highlighting the importance of spatial non-stationarity for 6G system development.

Contribution

It provides the first large-scale indoor and outdoor XL-MIMO channel measurement campaigns with 1600 and 320 elements, respectively, and analyzes near-field to far-field transition effects.

Findings

Near-field effects significantly influence channel characteristics.

Spatial non-stationarity of angular spread is crucial for accurate modeling.

Measurement data supports improved channel models for 6G systems.

Abstract

In the sixth-generation (6G), the extremely large-scale multiple-input-multiple-output (XL-MIMO) is considered a promising enabling technology. With the further expansion of array element number and frequency bands, near-field effects will be more likely to occur in 6G communication systems. The near-field radio communications (NFRC) will become crucial in 6G communication systems. It is known that the channel research is very important for the development and performance evaluation of the communication systems. In this paper, we will systematically investigate the channel measurements and modeling for the emerging NFRC. First, the principle design of massive MIMO channel measurement platform are solved. Second, an indoor XL-MIMO channel measurement campaign with 1600 array elements is conducted, and the channel characteristics are extracted and validated in the near-field region. Then, the outdoor XL-MIMO channel measurement campaign with 320 array elements is conducted, and the channel characteristics are extracted and modeled from near-field to far-field (NF-FF) region. The spatial non-stationary characteristics of angular spread at the transmitting end are more important in modeling. We hope that this work will give some reference to the near-field and far-field research for 6G.