AOA Estimation with EM Lens-Embedded Massive Arrays - Invited Paper

Abstract

Recently, EM lens-embedded massive array antennas have been proposed for next 5G mobile wireless communications, as the adoption of a lens allows to discriminate the AOA of signals in the analog domain, with the possibility to preserve the processing complexity lower with respect to traditional massive arrays. In fact, in such a way, complex ADC chains can be avoided and the number of required antennas can be decreased. By exploiting these advantages, in this paper we study the possibility to use a single EM lens massive array at mm-wave for the AOA estimation of the received signal. In this perspective, ML estimator and practical approaches, tailored for the considered scenario, are derived. Results, obtained for different number of antennas, confirm the possibility to achieve interesting AOA estimation performance with an extremely compact architecture.

Radio Positioning With EM Processing of the Spherical Wavefront

“…Top-view of the EM processing, realized with a NR-lens. The use of the lens allows to preserve the number of employed antennas affordable [49].…”

“…NR-lens can be implemented with different techniques, either including dieletric materials with ad-hoc designed surfaces (e.g., convex lenses), or antenna arrays or sub-wavelength spatial phase shifters [46], [47]. By adopting a lens to collimate the beams in precise directions, it is possible to spatially discriminate signals in the analog domain [46], [48], [49]. Consequently, thanks to the lens, there is a unique relation between the incident and the output angles of the impinging and refracted waves, respectively.…”

“…This operation allows reducing the number of antennas with respect to traditional massive arrays, and to move from discrete beamforming architectures towards continuous-aperture phased arrays. Indeed, the use of such lenses has already been investigated only in far-field [46], [48], [49], and their performance has not yet been characterized in the Fresnel region. In addition, while NR-lenses are passive and thus not reconfigurable, R-lens based solutions are programmable in real-time.…”

“…Other interesting opportunities account for the execution of mathematical operations with layers of metamaterials [63], the realization of electronically reconfigurable transmitarray [64], or reconfigurable reflectarray technology [65]. In this context, starting from our analysis in [49], [66], [67], here we investigate the radio positioning capabilities of a mm-wave source by introducing a generic architecture composed of an EM processing section, which can directly operate on the spherical wavefront, and of an array architecture that collects the impinging signal, as shown in Fig. 1.…”

Direct position estimation from wavefront curvature with single antenna array

“…Recently, it has also been studied the possibility to exploit electromagnetic (EM) lens-based massive arrays operating at mm-wave as a promising solution for drastically reducing the overall system complexity [7]. In fact, by adopting a lens to collimate the beams in precise directions, it is possible to spatially discriminate signals in the analog domain [7]- [9]. Consequently, thanks to the lens, there is a unique relation between the incident and the output angles of the impinging and refracted waves, respectively.…”