arXiv subjects

Demos Serghiou

Publications and source records attributed to Demos Serghiou.

3 recordsLinked to original sources

arXiv2026

Coexistence of 5G NR and Wi Fi 6E/7 at 6 GHz: Experimental Interference Measurements

This paper presents the first conducted-interference measurements of a commercial Very Low Power (VLP) Wi-Fi 6E/7 device into both the gNB uplink and UE downlink receiver chains of a live 5G New Radio (NR) system, using a complete O-RAN/SDR stack with 5G core in band~n102 (6\,GHz). We use a Software-Defined Radio (SDR) testbed built on OpenAirInterface with band~n102 support (40 MHz, 30 kHz Subcarrier Spacing). We sweep the injected Wi-Fi power and record throughput, block error rate, and signal-to-noise ratio on both the gNB uplink and UE downlink paths. Neither receiver shows measurable degradation below 75 dBm. Above this threshold, performance degrades progressively. The UE is more resilient at lower data rates and unaffected by beacon-only transmissions. A complementary link-budget analysis maps these measured thresholds to equivalent VLP-to-victim distances. These distances fall well inside the 545--685 Listen Before Talk (LBT) exclusion zone, confirming that a compliant VLP device would vacate the channel before its emissions could harm either receiver.

cs.NI↗

arXiv2026

Experimental Sensitivity Enhancement of a Quantum Rydberg Atom-Based RF Receiver with a Metamaterial GRIN Lens

We experimentally demonstrate enhanced sensitivity of an atom-based Rydberg radio frequency (RF) receiver integrated with a gradient refractive index (GRIN) Luneburg-type metamaterial lens. By analyzing the electromagnetically induced transparency (EIT) effect in Cesium vapor, we compare receiver performance with and without the GRIN lens under a 2.2~GHz and a 3.6~GHz far-field excitation. Our measurements reveal a significant amplification of the EIT window when the lens is introduced, consistent with the theoretical prediction that the local E-field enhancement at the vapor cell reduces the minimum detectable electric field and improves the microwave electric field measurement sensitivity of the Rydberg atom-based RF receiver over an ultrawide bandwidth of the lens. This experimental validation demonstrates the potential of metamaterial-enhanced quantum RF sensing for a wide range of applications, such as electromagnetic compatibility (EMC) testing, quantum radar, and wireless communication.

quant-ph↗

arXiv2026

Multi-Functional RIS-enabled Radar and Communication Coexistence: Channel Modeling and a Sub-6 GHz Indoor Measurement Campaign

In this work, we analyze a multi-functional reconfigurable intelligent surface (MF-RIS)-enabled radar and communication coexistence (RCC) system, detailing the key aspects of its phase synthesis codebook generation and the implemented localization algorithm for real-time user tracking based on density-based spatial clustering of applications with noise (DBSCAN), which features a Kalman filter for the prediction of user mobility. We derived a 3GPP-compatible radar cross-section (RCS) and re-radiation pattern-based channel model for the described MF-RIS system, supplementing it with channel measurements. We obtained large and small-scale characteristics, including path loss, shadow fading, Rician K-factor, cluster powers, and RMS delay spread. The study finds that Sub-6 GHz indoor propagation is largely free of blind spots, even with a blocked line-of-sight (LoS) path. Therefore, the proposed channel model includes non-line-of-sight (NLoS) paths, including the ones created by the MF-RIS. We also performed an experimental evaluation of the channel throughput in a fifth generation (5G) new radio (NR) single user multiple-input-multiple-output (SU-MIMO) system, reporting a 74\% reduction in throughput variance and a 12.5\% sum-rate improvement within the MF-RIS near-field compared to the no-RIS setup. This result shows that the MF-RIS can minimize delay spread and increase the coherence bandwidth by creating virtual-LoS (vLoS) path for the moving user, thereby effectively hardening wireless MIMO channels.

eess.SP↗