4 research outputs found
3D Beamforming in Reconfigurable Intelligent Surfaces-assisted Wireless Communication Networks
Reconfigurable Intelligent Surfaces (RIS) or Intelligent Reflecting Surfaces
(IRS) are metasurfaces that can be deployed in various places in wireless
environments to make these environments controllable and reconfigurable. In
this paper, we investigate the problem of using 3D beamforming in RIS-empowered
wireless networks and propose a new scheme that provides more degrees of
freedom in designing and deploying the RIS-based networks. In the proposed
scheme, a base station (BS) equipped with a full dimensional array of antennas
optimizes its radiation pattern in the three-dimensional space to maximize the
received signal to noise ratio at a target user. We also study the effect of
angle of incidence of the received signal by the RIS on its reflecting
properties and find a relation between this angle and the BS antenna array's
tilt and elevation angles. The user receives the signal from a reflected path
from the RIS as well as from a direct path from the BS which both depend on the
BS antenna array's tilt and elevation angles. These angles and also the RIS
element's phase shifts are jointly numerically optimized. Our simulation
results show that using RIS-assisted 3D beamforming with optimized phase shifts
and radiation angles can considerably improve the performance of wireless
networks
Reconfigurable Intelligent Surfaces for Localization: Position and Orientation Error Bounds
Next-generation cellular networks will witness the creation of smart radio
environments (SREs), where walls and objects can be coated with reconfigurable
intelligent surfaces (RISs) to strengthen the communication and localization
coverage by controlling the reflected multipath. In fact, RISs have been
recently introduced not only to overcome communication blockages due to
obstacles but also for high-precision localization of mobile users in GPS
denied environments, e.g., indoors. Towards this vision, this paper presents
the localization performance limits for communication scenarios where a single
next-generation NodeB base station (gNB), equipped with multiple-antennas,
infers the position and the orientation of the user equipment(UE) in a
RIS-assisted SRE. We consider a signal model that is valid also for near-field
propagation conditions, as the usually adopted far-field assumption does not
always hold, especially for large RISs. For the considered scenario, we derive
the Cramer-Rao lower bound (CRLB) for assessing the ultimate localization and
orientation performance of synchronous and asynchronous signaling schemes. In
addition, we propose a closed-form RIS phase profile that well suits joint
communication and localization. We perform extensive numerical results to
assess the performance of our scheme for various localization scenarios and RIS
phase design. Numerical results show that the proposed scheme can achieve
remarkable performance, even in asynchronous signaling and that the proposed
phase design approaches the numerical optimal phase design that minimizes the
CRLB.Comment: 15 pages, 11 figure
3D beamforming in reconfigurable intelligent surfaces-assisted wireless communication networks
Reconfigurable Intelligent Surfaces (RIS) or Intelligent Reflecting Surfaces (IRS) are metasurfaces that can be deployed in various places in wireless environments to make these environments controllable and reconfigurable. In this paper, we investigate the problem of using 3D beamforming in RIS-empowered wireless networks and propose a new scheme that provides more degrees of freedom in designing and deploying the RIS-based networks. In the proposed scheme, a base station (BS) equipped with a full dimensional array of antennas optimizes its radiation pattern in the three dimensional space to maximize the received signal to noise ratio at a target user. We also study the effect of angle of incidence of the received signal by the RIS on its reflecting properties and find a relation between this angle and the BS antenna array\u27s tilt and elevation angles. The user receives the signal from a reflected path from the RIS as well as from a direct path from the BS which both depend on the BS antenna array\u27s tilt and elevation angles. These angles and also the RIS element\u27s phase shifts are jointly numerically optimized. Our simulation results show that using RIS-assisted 3D beamforming with optimized phase shifts and radiation angles can considerably improve the performance of wireless networks