Project EXCELL-FR3

Overview

EXCELL-FR3 aims to develop reconfigurable, multi-beam radiating surfaces for the FR3 band (7.2-8.4 GHz), both at the mobile terminal side and at the access point side, in support of a new Cell-Free Massive MIMO network architecture. The project combines innovative antenna design, dosimetric studies, and PHY/MAC layer development on the open-source OpenAirInterface platform, aiming for an integrated demonstrator validating the real-world performance of the proposed architecture. Coordinated by the LEAT laboratory (Université Côte d’Azur), it brings together CEA-LETI and EURECOM, with an End-User Committee including Nokia and Orange.

📅 October, 1st 2026

⏳ 42 months

• Aliou Diallo, LEAT, Université Côte d’Azur : porteur du projet / responsable scientifique
• Christophe Delaveaud, CEA-LETI
• Antonio Clemente, CEA-LETI
• Florian Kaltenberger, EURECOM
• Raymond Knopp, EURECOM
• Robert Staraj, LEAT
• Philippe Le Thuc, LEAT
• Marylène Cueille, LEAT
• Jean-Lou Dubard, LEAT

Current mobile telecommunications architectures, based on a cellular model with base stations, face critical limitations: only 15-25% of supplied power is effectively radiated (700 MHz-6 GHz range), omnidirectional antennas needlessly emit radiation toward users’ heads, and network densification worsens intercellular interference.

The recently released FR3 band (7.2-8.4 GHz) offers an opportunity to rethink these transmission principles, with wider bandwidth allocations (400 MHz per operator vs. 100 MHz in FR1), reduced antenna size, and a better coverage/capacity trade-off than millimeter-wave (FR2) bands.

EXCELL-FR3 proposes replacing the conventional cellular structure with a dense mesh of distributed access points cooperating to ensure homogeneous connectivity (Cell-Free Massive MIMO paradigm), coupled with intelligent radiating surfaces able to:

• steer the radiation lobe away from the user to reduce electromagnetic exposure;
• perform adaptive angular scanning of a reconfigurable beam toward the most relevant access point;
• generate multiple simultaneous beams (about four) for multi-access or multi-stream connectivity.

The project is organized into six work packages: use cases and specifications (WP0), radiating surfaces for mobile terminals (WP1, led by LEAT), Cell-Free access point antenna systems based on superdirective transmitarrays (WP2, led by CEA-LETI), multi-scale dosimetric studies compliant with ICNIRP 2020 guidelines (WP3, led by LEAT), re-architecture of OpenAirInterface PHY/MAC layers for Cell-Free MIMO (WP4, led by EURECOM), and system integration and demonstration (WP5, led by EURECOM).

The project builds upon the complementary expertise of the three partners: miniaturized multi-antenna systems, advanced isolation techniques and dosimetry at LEAT; superdirective transmitarray architectures at CEA-LETI; and the open-source 5G OpenAirInterface platform at EURECOM.