What is RRH?
An RRH (Remote Radio Head) is a radio transceiver unit located at or near the antenna (typically on the tower top or rooftop), connected to a centralised BBU via a fronthaul link. The RRH handles the conversion between digital baseband signals and analog RF signals — including digital-to-analog conversion (DAC), up-conversion, power amplification, filtering, and antenna interfacing. By separating the radio unit from the baseband processing, the RRH architecture reduces cable losses, improves efficiency, and enables C-RAN deployments.
How Does RRH Work?
The RRH receives digitised baseband IQ samples from the BBU via a CPRI or eCPRI fronthaul interface (over fibre). It converts these to analog, up-converts to the target RF frequency, amplifies using power amplifiers, filters, and feeds the antenna. In the receive direction, the RRH performs the inverse: amplification (LNA), filtering, down-conversion, and analog-to-digital conversion (ADC), sending digitised uplink IQ samples back to the BBU. Modern RRHs integrate multi-band, multi-technology support in a single compact unit. In 5G, the RRH concept evolves into the RU (Radio Unit) or O-RU, with potentially more PHY processing moved to the radio unit (lower-layer split) to reduce fronthaul bandwidth requirements.
Use Cases
Tower-top radio deployment for macro cell sites, C-RAN architectures with centralised BBU, distributed antenna systems (DAS) using RRH nodes, multi-band multi-technology radio consolidation, and migration path to 5G O-RU.
3GPP / Standards Reference
CPRI Specification (RRH interface), 3GPP TS 38.104 (NR BS radio requirements), O-RAN WG4 (Open fronthaul for O-RU)
Related Terms
BBU | CPRI | RU | O-RU / O-DU / O-CU | Fronthaul
Learn More
This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
