arXiv subjects

Pedro H. C. de Souza

Publications and source records attributed to Pedro H. C. de Souza.

4 recordsLinked to original sources

arXiv2026

Tree Search Algorithms Applied to the BD-RIS Configuration in MU-MISO Communication Systems

The reconfigurable intelligent surface (RIS) has attracted considerable attention from both academia and industry in recent years, given its capacity to dynamically manipulate the reflection of incident electromagnetic waves. Although the research developed for the RIS may have reached its maturity, there are still contentious aspects and limitations regarding its potential benefits for the next generation of wireless communications. In order to improve upon the RIS technology, the beyond diagonal reconfigurable intelligent surface (BD-RIS) was recently proposed as a promising alternative. The BD-RIS boasts a more sophisticated circuit topology that is capable of providing more combinations of different adjustments or configurations for signal reflection. However, to aptly reap the benefits of the BD-RIS, the added degrees-of-freedom of its configuration must be leveraged accordingly. Therefore, in this work we propose a depth-first tree search algorithm for configuring the BD-RIS in multi-user multiple-input single-output (MU-MISO) communication systems. Taking advantage of the tree search exploration, the proposed algorithm achieves a remarkable trade-off between channel strength maximization performance and computational complexity scalability.

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arXiv2026

PAPR Reduction in OFDM Systems Using Neural Networks: A Case Study on the Importance of Dataset Generalization

In [1], we introduced a NN designed to reduce the PAPR in OFDM systems. However, the original study did not include explicit generalization tests to assess how well the NN would perform on previously unseen data, which prevented a comprehensive evaluation of the model's robustness and applicability in diverse scenarios. To address this gap, we conducted additional generalization assessments, the results of which are presented in this case study. These results serve both to complement and to refine the original analysis reported in [1]. Most importantly, the overall conclusions of the initial study remain valid: the NN is still able to reduce the PAPR level to a desired reference value, also with a lower computational cost, confirming the effectiveness and practical applicability of the proposed method across a more generalized setting.

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arXiv2025

Lightweight Gradient Descent Optimization for Mitigating Hardware Imperfections in RIS Systems

Ongoing discussions about the future of wireless communications are reaching a turning point as standardization activities for the sixth generation of mobile networks (6G) become more mature. New technologies must now face renewed scrutiny by the industry and academia in order to be ready for deployment in the near future. Recently, reconfigurable intelligent surfaces (RISs) gained attention as a promising solution for improving the propagation conditions of signal transmission in general. The RIS is a planar array of tunable resonant elements designed to dynamically and precisely manipulate the reflection of incident electromagnetic waves. However, the physical structure of the RIS and its components may be subject to practical limitations and imperfections. It is imperative that the hardware imperfections (HWIs) associated with the RIS be analyzed, so that it remains a feasible technology from a practical standpoint. Moreover, solutions for mitigating the HWIs must be considered, as is discussed in this work. More specifically, we introduce a gradient descent optimization for mitigating HWIs in RIS-aided wideband communication systems. Numerical results show that the proposed optimization is able to compensate for HWIs such as the phase-shift noise (PSN) and RIS surface deformations.

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arXiv2025

Frequency Selective Reflection of Wideband Signals with Reconfigurable Intelligent Surfaces

Recently, the reconfigurable intelligent surface (RIS) technology has ushered in the prospect of control over the wireless propagation environment. By establishing alternative propagation paths for the transmitted signals, and by reflecting them in a controllable manner, the RIS is able to improve the signal reception. However, an aspect often overlooked is the potential bandwidth restrictions on the wideband signal reflected by the RIS. If not carefully considered, this can become an impediment for the adoption of the RIS in the next generation of communications systems. Therefore, in this work we propose a RIS configuration method that provides frequency selective signal reflection for wideband signals.

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