Clustered Double-Scattering Channel Modeling for XL-MIMO With Uniform Arrays

Abstract

Extra-large multiple-input multiple-output (XL-MIMO) systems reveal themselves as a potential candidate for the sixth generation (6G) of wireless communication systems due to their features. As XL-MIMO has a large antenna array, and, typically, the urban environment is plenty of obstacles and reflectors, the spatial non-stationarities are introduced in the signal received at the base station (BS), which means that only a portion of the antenna array is visible to users; hence, accurately modeling XL-MIMO channels is paramount. Previous works on XL-MIMO channel modeling have adopted the non-stationarities only in a spatial sense, do not considering spatial-time evolution scenarios. Moreover, simplified models with only one set of clusters between the BS and the mobile user (UE) are usually adopted; hence, there is a lack of understanding regarding such channels modeling in the literature. This work proposes and extensively analyzes a double-scattering XL-MIMO channel model, by admitting two types of scattering clusters, one placed at the BS side, and another one located near the UEs. In addition, two distinct antenna array configurations are included in the analysis, the uniform linear and planar arrays (ULA and UPA). We propose a new double-scattering channel model under UPA arrangements, suitable for modeling spatial non-stationarities scenarios in XL-MIMO dynamic environment subject to BS-cluster and UE-cluster correlation, and birth-death channel clusters and scatterers. Numerical results for signal-to-interference-plus-noise ratio (SINR), condition number (CN), and spectral efficiency (SE) performance metrics considering different XL-MIMO channels and system configurations are analyzed via Monte-Carlo simulations, under linear combiners MRC, ZF, and MMSE. Also, we characterize the impact of the number of visible clusters per user, the birth-death rate growth effect on the channel clusters and scatterers, and the favorable propagation effect according to the size of visibility region (VR) overlap. It can be observed that the birth and death processes has a significant impact on the system performance. Under the proposed clustered double-scattering channel modelling, the analyzed XL-MIMO linear receivers presented an SINR degradation when the number of UEs increase substantially around 3 to 4 dB for the MMSE, while the ZF and MRC receivers present a decrease of 1 to 2 dB, approximately, in SINR for the considered dynamic configuration compared with static scenarios. INDEX TERMS uniform linear array (ULA), uniform planar array (UPA), extra large MIMO (XL-MIMO), channel modeling, spatial non-stationary; visibility region, birth and death Poisson process (BDPP). I. INTRODUCTION E XTRA-LARGE multiple-input multiple-output (XL-MIMO) is a promising research direction of multiantenna technology for the sixth-generation (6G) of wireless communication networks [1]-[3]. The main idea of XL-MIMO is to employ a significant number of antennas (10 3 or more) at the base station (BS), which can be widely spread, e.g., on the ...

Retracted: Non‐stationary 3‐D GBSM channel model for V2V communications

“…In addition, the work published in ref. [41] is insufficient since it ignores the spherical assumptions or nonstationary effect on channel statistics. In ref.…”

Very large scale integration architectures of discrete transforms for digital signal processing applications

“…- [53], [61], [63], [66], [68]- [89] [43], [46], [49], [53], [62], [90]- [97] [49], [60], [65], [87], [98]- [116] [44], [45], [47], [50], [52], [53], [86], [117]- [129] In this setting, the antenna spacing can be smaller than the conventional half-wavelength.…”

“…It is worth noting that the above works focused on only one XL-MIMO design. However, to promote the practical implementation of these schemes, it is also necessary to consider multiple XL-MIMO designs and compare their performances in a unified manner [49], [53], [86], [87], [123], [127]. The considered XL-MIMO designs and characteristics for these works are summarized in Table VII.…”

“…Besides, the antenna spacing for the ULA scheme was half-wavelength. In [87], the authors considered the UPA-based XL-MIMO with point antennas and the ULA-based XL-MIMO. The number of antennas and the antenna spacing were 256 and half-wavelength, respectively.…”

“…• Spatial Non-Stationary Property: In conventional mMIMO, the channel is spatially stationary due to the moderate array dimension. However, in XL-MIMO, the extremely large array aperture would result in the spatial non-wide sense stationary properties [54], [60], [61], [63], [72], [73], [87]. When the array aperture is extremely large, different regions of the array would observe the propagation environment in different views, which means that the regions can observe the signal transmitted from a certain propagation path but with different powers or the signal transmitted from different propagation paths.…”