About the project
The National Arena in Bucharest - Romania’s largest stadium, with over 50,000 seats - hosts international matches, concerts and events where tens of thousands of spectators use the mobile network at the same time - from the stands and, at concerts, from the pitch as well. For one of the leading mobile network operators, in the summer of 2025 Claritech implemented the upgrade and extension of the stadium’s radio system - from the existing 4G network to 5G massive-MIMO, with a complete resizing of capacity and improved radio coverage.
Project requirements
A full stadium is a demanding radio environment: maximum user density on a compact footprint, a massive steel structure, and every job executed at height, on the roof catwalks, without affecting the event schedule. The existing system was reconfigured without interrupting service, with a new sectorization able to carry the high traffic of event days. During concerts, splitting the pitch into separate sectors provides coverage for tens of thousands of spectators, alongside the sectorization of the stands - across multiple technologies.
Project type
Reconfiguration and extension of the stadium’s radio system: iBwave design, installation, commissioning and optimization.
Location
The National Arena, Bucharest - a stadium with over 50,000 seats and a retractable roof on a steel structure.
Technologies
4G and 5G with active massive-MIMO antennas, sectorized for capacity.
The solution
We built the coverage of the entire stadium - the ring of stands and the pitch - from 24 antenna positions: 12 on the northern ring, 12 on the southern one, mounted on the catwalk under the roof membrane, next to the floodlighting system.
Eight 5G massive-MIMO units
Four existing active units were complemented with four new ones - one at the middle of each side - for uniform 5G coverage across all the stands.
Sectorization for capacity
The stands are divided into radio sectors on 1800 and 2600 MHz, and the pitch has its own cells - at concerts, the field is itself a spectator area. The handover zones between cells are planned from the simulation stage, reducing interference.
New fiber-optic backbones
Two new runs of 350 m each of 24-fiber optical cable, from the technical rooms up to the floodlight catwalk - north and south - feed the radio units on the roof.
Multiband through dual combiners
New radio units on 1800/2100 and 2600 MHz, combined onto each antenna group - more capacity on the same antenna infrastructure.
An active 5G massive-MIMO unit mounted on the roof catwalk.
One of the new spherical lens radio antennas, installed for better isolation between cells and improved radiation characteristics.
What we delivered
| Component | Details |
|---|---|
| Area covered and sectorized | The full ring of stands and the pitch |
| Antenna positions around the stands | 24 (12 north + 12 south) |
| Active 5G massive-MIMO units | 8 (4 existing + 4 new) |
| New fiber-optic backbones (24 fibers) | 2 × 350 m, up to the floodlight catwalk |
| New 1800/2100 and 2600 MHz radio units | On every sector, with dual combiners |
| Technical rooms equipped | 4, with 42U racks |
| New electrical panels and routes | Resized for the new equipment |
Simulation and measurements
Before installation, coverage was simulated for the entire stadium - stands and pitch: signal levels, the handover zones between sectors and the interference margins. For 2600 MHz LTE, the simulation showed a handover margin of over 4 dB across 83% of the covered area already at the design stage, with the borders between cells placed along planned corridors. After installation, the system was measured and optimized up to the designed parameters.
The results
5G coverage in the stands and on the pitch. Eight massive-MIMO units cover the ring of stands, and the field has its own cells - for matches and concerts at full capacity.
Capacity through sectorization. Dedicated cells across the stand zones and on the pitch - traffic is split across zones instead of overloading a single cell.
No service interruption. The reconfiguration was executed on a system in operation, coordinated with the stadium’s event calendar.
Expansion capacity. The new fiber backbones and the resized power supply carry the next extensions without major works.
Why Claritech
We have been designing radio-coverage systems in iBwave since 2012, with our own RF lab and over 40,000 antennas installed - including on Romania’s largest stadiums. See the DAS project portfolio →