Abstract
Abstract of the PRIN2022 INdoor Smart Illuminator for Device Energization and NEXt-generation communicaTions (“INSIDE-NEXT”) (Prot. 2022WHJNE5; CUP J53D23000900006) The INSIDE-NEXT Project aims to realize an advanced Wireless System for the indoor distribution of signals with both communication and energization purposes, through the exploitation of microwave and millimeter-wave (mmWave) mobile signals of the 5th generation and beyond (B5G). In the INSIDE-NEXT consortium’s opinion, the main bottleneck in future scenarios, where a widespread use of a huge number of devices with reduced cost per information transfer (the so called “smart dust”) also needing for energy-autonomy, thus letting the paradigms of Internet of Things (IoT) and Industrial IoT feasible in practice, is represented by the availability of smart and real-time reconfigurable transmitting structures able to dynamically decide in which direction the signal must be sent. At base-station level, solutions in this perspective are already theoretically envisaged and some realizations have started appearing, but the possibility to create a simpler and cheaper intelligent node even inside the buildings is still an open issue. The INSIDE-NEXT project aims at bridging this gap through the proposal and realization of a smart indoor illuminator based on the joint TMA-FDA technique and supported by real-time channel estimation and an intelligent beamforming decision strategy. The innovative idea is twofold: it consists of the usage of modern radiating strategies relying on both the capillary and simultaneous distribution of information signal and power, and the support of Ray Tracing (RT) propagation models for the design and deployment of the radiating system in a real environment affected by multipath propagation, as well as for the choice of the optimum beamforming technique. Based on geometric optics (GO) and its extensions like the Uniform Geometrical Theory of Diffraction (UTD), RT models represent an effective tool for determining coverage in complex scenarios, because they are intrinsically suited to consider the effects of the interaction between the signals emitted by the transmitter and any obstacles and objects that populate the propagation environment. With the assistance of RT prediction, the system will allow to illuminate multiple devices and optimize the overall energy efficiency. In particular, especially when power signals are involved, radiating strategies able to focus the energy on precise spots of the indoor scenarios will be adopted. From the beamforming architecture -or “radio-frequency (RF) shower”- point of view, they will be realized by adopting and combining two strategies: the Time Modulated Array (TMA) technique, in which the simultaneous availability of multiple radiation/reception directive patterns, reconfigurable in real-time, will be allowed, thus letting the showers to reach/be-reached-by users present in any location inside the building. Moreover, when power signals for the energization of randomly placed devices/sensors will be needed, the technique of Frequency Diverse Arrays (FDAs) could also play a strategic role, because the different frequency signals sent by the radiating elements of the array can constructively recombine in a defined region of the space, and this region can be dynamically selected through a real-time time-control of the multi-tone excitations, thus optimizing the RF power distribution. FDAs are a promising solution to control the beam steering, at a lower cost with respect to traditional phased arrays. However, their performance is intrinsically affected by the fact that the position of the focusing spot rapidly changes with time, and the focusing capability is also affected by multipath propagation which introduces fading dips in the received power. Such effected can be mitigated by evaluating the field propagation in the selected environment with the aid of RT, and optimizing the feeding signal of the FDA through the use of a time-controlled (time-gating) techniques, that keeps more stable the focusing spot around the desired position. More in general, the advanced capabilities of the smart showers to capillary send the signal in the desired regions will be achieved with the aid of a RT-assisted beamforming technique, capable of choosing the best power allocation in real-time, and exploiting fruitful reflections to avoid obstacles and to reach non-line-of-sight (NLOS) targets. A proper design of realistic showers also needs advanced optimization techniques able to simultaneously take into account the complex dynamics of the radiating architectures and the high number of degrees of freedom. In this way, thanks to the exploitation of AI-based strategies, a real-time reconfiguration will be possible. The main expected results of the project will be: 1. Design and prototyping of TMA and FDA antenna solutions 2. Optimization of the TMA radiating systems configuration using AI-based techniques to best exploit the available degrees of freedom 3. Optimization of the FDA radiating systems configuration using ray tracing techniques and time-controlled driving techniques to account for the multipath effect and time-varying behavior 4. Use of ray tracing for optimal deployment of the illuminators in typical indoor propagation environments, as well as for real-time beamforming assistance. A complete Demonstrator of the System in the microwave range will constitute the final outcome of the INSIDE-NEXT Project: the realization is highly expected because of the research units theoretical/practical expertise. From this point of view, original radiator layouts will be developed and realized, mainly exploiting circular symmetry: in this way, the same optimized control sequence could be exploited for the energization of energy-hungry devices placed in different planes, by simply rotating the order of the sequences applied at the array excitation ports. Main outcomes of the project: - Design and realization of a microwave illuminator operating at 2.45 GHz: the chosen architecture relies on the time-modulation technique of the excitation of the array elements. This advanced technique allows a simple and fast reconfiguration of the radiating capability of the array by simply pilot microwave switches at the antennas port. Moreover, an original array layout exploiting circular symmetry has been realized: it consists of eight elements arranged in a spoke-like configuration. Each spoke is made of three radiating patch antennas connected in a series-fed topology. The originality of the solution relies not only on the circular layout (that allows the reuse of the same time-modulated driving sequences to illuminate different φ-planes by simply exchanging the role of the excitation ports), but mostly on the presence of only 8 control ports, despite the high-number of radiating elements (therefore, highly directive architecture). - The simplicity of the feeding strategy has allowed the realization of an home-made switch control-board: it makes use of 8 switches ADG901 and one microcontroller STM32. A deep investigation on the modulation frequency- and power-handling capabilities of the board has been carried out, thus also bridging a gap of the existing literature. - Development of a customized System-by-Design (SbD) optimization tool: the approach combines evolutionary optimization algorithms and advanced sampling strategies, enabling an efficient exploration of the design space (i.e., the degrees of freedom of the optimization process, consisting of the shape of the on-off waveforms at the array ports) while significantly reducing the computational cost associated with full-wave or circuital simulations. This tool is able to synthesize, almost in real time, the needed control sequences for a specific beamforming activity. - Definition of the RT-assisted beamforming algorithm: the aforementioned optimization tool integrates Ray-Tracing information (therefore, a detailed electromagnetic description of the propagation environment) into the beamforming optimization process to account for multipath propagation and its impact on the array performance. This integration provides a consistent framework for the evaluation and design of beamforming strategies under realistic propagation conditions. - A wide measurement campaign in a realistic scenario has been carried out at the end of the project to evaluate the system’s performance under various conditions (i.e., synthesis of several simultaneous beams pointing in different planes and directions). The developed architecture has demonstrated the expected high level of reconfigurability despite its simplicity. The results have been collected in a paper recently accepted in the IEEE Journal on Wireless Power Technologies
Project details
Unibo Team Leader: Diego Masotti
Unibo involved Department/s:
Dipartimento di Ingegneria dell'Energia Elettrica e dell'Informazione "Guglielmo Marconi"
Coordinator:
ALMA MATER STUDIORUM - Università di Bologna(Italy)
Total Eu Contribution: Euro (EUR) 166.332,00
Total Unibo Contribution: Euro (EUR) 116.121,00
Project Duration in months: 24
Start Date:
28/09/2023
End Date:
28/02/2026
