What is Fronthaul?
Fronthaul is the network segment connecting the Radio Unit (RU/RRH) at the antenna site to the Distributed Unit (DU) in a C-RAN or Open RAN architecture. It replaces the traditional co-located base station connection and must handle significant data volumes with very strict latency constraints.
How Does Fronthaul Work?
Traditional CPRI fronthaul transports raw IQ samples over dedicated dark fibre with round-trip latency under 100 µs. O-RAN’s enhanced fronthaul (eCPRI, Option 7-2x split) reduces bandwidth by processing more functions at the RU before transmission. O-RAN defines open U-plane, C-plane, S-plane, and M-plane interfaces for the fronthaul link between O-RU and O-DU.
Use Cases
C-RAN architectures with centralised BBU pools, Open RAN multi-vendor deployments, small cell and DAS (Distributed Antenna System) connectivity.
3GPP / Standards Reference
O-RAN Alliance CUS-Plane Specification (WG4), eCPRI Specification v2.0, CPRI Specification v7.0
Related Terms
Midhaul | C-RAN | Open RAN | RRH | CPRI | O-RAN
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
