O-RU
O-RAN Radio Unit: performs low-PHY, RF processing, and beamforming at the antenna site, connected to O-DU via the open fronthaul interface.
The O-RU is the box bolted up on the tower or wall — the part that actually radiates. It handles the RF front end (power amplifiers, filters, the antenna array) plus low-PHY: the FFT/iFFT, cyclic prefix handling, digital beamforming, that lower edge of the physical layer the 7.2x split assigns to it. Keeping low-PHY on the radio is a deliberate compromise. Push too little down and the fronthaul has to carry raw time-domain samples (the old CPRI problem, enormous bitrates); push too much down and the O-RU gets expensive and vendor-specific again.
The whole reason the O-RU matters commercially is the open fronthaul interface beneath it. Standardise that link and an operator can buy radios from one vendor and the O-DU from another — breaking the lock-in that came with classic integrated RAN. In practice this is also where a lot of O-RAN interoperability pain shows up, because getting a third-party O-RU and O-DU to agree on timing, beamforming descriptors, and the M-plane management details is harder than the spec makes it sound.
Related terms
Want to truly understand O-RU? Learn it in context.
A free account opens all 13 courses — 404 video lessons, labs and full practice exams — for 7 days, no card. Prime Membership keeps them and adds the certification exam and a verifiable certificate.
- 7 days of every course
- Then the first module, free
- No card needed
- TELCOMA since 2009
Get one 5G/LTE engineering deep-dive a fortnight
One thing explained properly every other Tuesday — a real failure, and the lab or trace where you work it yourself. No spam, no marketing, just engineering. Unsubscribe in one click.