Conference Paper

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

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... According to NR-lens, recent studies have investigated the possibility to exploit EM lens-based massive arrays operating at mm-wave as a promising solution for drastically reducing the overall system complexity [35]. In fact, by adopting a lens to collimate the beams in precise directions, it is possible to spatially discriminate signals in the analog domain [35]- [37]. Consequently, thanks to the lens, there is a unique relation between the incident and the output angles of the impinging and refracted waves, respectively. ...
... In this context, starting from our previous analysis in [37], [51], we here investigate the radio positioning capabilities of a mm-wave source by introducing a generic architecture composed of an EM processing section, that can directly operate on the wavefront curvature, and of an array architecture that collects the impinging signal, as shown in Fig. 1 The main contributions of the manuscript can be summarized as follows: ...
... Top-view of the EM processing, realized with a non-reconfigurable lens. The use of the lens allows to preserve the number of employed antennas affordable[37]. ...
Preprint
Next 5G and beyond applications have brought a tremendous interest towards array systems employing an extremely large number of antennas, so that the technology that might be in place for communication can be also exploited for positioning. In particular, in this paper we investigate the possibility to infer the position of an omnidirectional transmitter by retrieving the information from the incident spherical wavefront through its EM processing. Despite such a post-processing of the curvature wavefront has been mainly considered in the past at microwave and acoustic frequencies using extremely large antennas, it is of interest to explore the opportunities offered in the context of next 5G and beyond systems. Thus, differently from the state-of-the-art, here we first introduce a dedicated general model for different EM processing configurations, and successively we investigate the trade-off between the attainable positioning performance and the complexity offered by the different architectures, that might entail or not the use of a lens, that can be either reconfigurable or not. Indeed, we analyze also the effect of the interference, in order to evaluate the robustness of the considered system to the presence of multiple simultaneous transmitting sources. Results, obtained for different number of antennas, i.e., for different array apertures, confirm the possibility to achieve interesting positioning performance using a single antenna array with limited dimensions.
... 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. ...
... However, as we mentioned in Section III, this approach may increase both the hardware (RF chains) and the computational complexities, especially when subspace based algorithms, such as MUSIC or ESPRIT, are deployed. An approach to reduce complexity consists of the deployment of electromagnetic (EM) lens [41], [152]. ...
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