arXiv subjects

Roberto C. G. Porto

Publications and source records attributed to Roberto C. G. Porto.

5 recordsLinked to original sources

arXiv2026

Study of Code-Aided Channel Estimation for Metasurface-Based Holographic MIMO Systems

This work proposes an iterative code-aided detection, decoding, and channel estimation scheme for metasurface-based holographic MIMO systems employing stacked intelligent metasurfaces (SIM-RIS) and their fully connected counterparts (BD-SIM-RIS). A novel channel estimation strategy is developed by exploiting low-density parity-check (LDPC) coding in the uplink, enabling both pilot and parity bits of the encoded packet to contribute to the iterative refinement of the channel. In addition, closed-form expressions for the metasurface parameter design are derived and incorporated into an alternating-optimization (AO) procedure. Numerical results demonstrate substantial gains in normalized mean square error (NMSE) and bit error rate (BER), with particularly strong improvements observed for BD-SIM-RIS architectures.

cs.IT↗

arXiv2025

Iterative Channel Estimation, Detection and Decoding for Multi-Antenna Systems with RIS

This work proposes an iterative channel estimation, detection and decoding (ICEDD) scheme for the uplink of multi-user multi-antenna systems assisted by multiple reconfigurable intelligent surfaces (RIS)}. A novel iterative code-aided channel estimation (ICCE) technique is developed that uses low-density parity-check (LDPC) codes and iterative processing to enhance estimation accuracy while reducing pilot overhead. The core idea is to exploit encoded pilots (EP), enabling the use of both pilot and parity bits to iteratively refine channel estimates. To further improve performance, an iterative channel tracking (ICT) method is proposed that takes advantage of the temporal correlation of the channel. An analytical evaluation of the proposed estimator is provided in terms of normalized mean-squared error (NMSE), along with a study of its computational complexity and the impact of the code rate. Numerical results validate the performance of the proposed scheme in a sub-6 GHz multi-RIS scenario with non-sparse propagation, under both LOS and NLOS conditions, and different RIS architectures.

cs.IT↗

arXiv2025

Study of Iterative Dynamic Channel Tracking for Multiple RIS-Assisted MIMO Systems

The use of multiple Reconfigurable Intelligent Sur- faces (RIS) has gained attention in 6G networks to enhance coverage. However, the feasibility of deploying multiple RIS relies on efficient channel estimation and reduced pilot overhead. To address these challenges, this work proposes an iterative channel estimation scheme that exploits low-density parity-check (LDPC) codes, channel coherence time, and iterative processing to improve estimation accuracy while minimizing pilot length. Encoded pilots are used to strengthen the iterative processing, leveraging both pilot and parity bits, while previous estimates are incorporated to further reduce overhead. Simulations consider a sub-6 GHz scenario with non-sparse channels and multiple RIS under both LOS and NLOS conditions. The results show that the proposed method outperforms existing approaches, achieving significant gains with substantially lower pilot overhead.

cs.IT↗

arXiv2025

Study of Iterative Detection, Decoding and Channel Estimation for RIS-Aided MIMO Networks

This work proposes an iterative detection, decoding and channel estimation scheme for multiple-antenna systems assisted by multiple reflective intelligent surfaces (RIS). A novel channel estimation technique that exploits low-density parity-check (LDPC) codes and iterative processing is developed to enhance estimation accuracy while reducing the number of required pilot symbols. The key idea is to exploit encoded pilots to improve the iterative process, enabling the use of not only pilot bits but also parity bits from the coded packet to refine channel estimation. Simulations analyze a sub-6 GHz scenario where the channel propagation is not sparse and multiple RIS are deployed, considering both LOS and NLOS conditions. Numerical results show significant performance gains for the proposed scheme and estimator over competing approaches.

cs.IT↗

arXiv2022

Wireless Connectivity of a Ground-and-Air Sensor Network

This paper shows that, when considering outdoor scenarios and wireless communications using the IEEE 802.11 protocol with dipole antennas, the ground reflection is a significant propagation mechanism. This way, the Two-Ray model for this environment allows predicting, with some accuracy, the received signal power. This study is relevant for the application in the communication between overflying Unmanned Aerial Vehicles (UAVs) and ground sensors. In the proposed Wireless Sensor Network (WSN) scenario, the UAVs must receive information from the environment, which is collected by sensors positioned on the ground, and need to maintain connectivity between them and the base station, in order to maintain the quality of service, while moving through the environment.

cs.NI↗