Remote Radio Units (RRU/RRUS): Bands, Power and Fronthaul
In a distributed base station the radio is split from the baseband. The RRU sits at the top of the mast next to the antenna; the baseband unit stays in the shelter, connected by a fibre fronthaul link. Keeping the radio near the antenna removes most of the feeder loss — which is the whole point of the architecture.
The three numbers that define an RRU
- Band. Which frequency range the unit transmits in, expressed as the standard band number. A unit for one band cannot be re-tuned to another — the band is the first thing to match, before anything else.
- Output power per path. Quoted as power per transmit path (for example 2×60 W for a two-path unit). This sets the cell size together with the antenna gain.
- Fronthaul rate and generation. The CPRI line rate, and which baseband generation the unit is designed to work with. A radio that is electrically perfect but speaks to the wrong baseband generation is still the wrong radio.
What to confirm before buying
- Band and bandwidth — including whether the unit covers the specific sub-band your licence uses.
- RF connector type. Din 7/16 and 4.3-10 are both common; they are not interchangeable and the jumper set has to match.
- Number of transmit paths (MIMO order) the site plan assumes.
- Optical interface and rate — single or multi-rate CPRI, and the SFP type the unit expects.
- Mechanical fit. Pole and wall mount brackets differ per generation and are frequently the item that is missing from a second-hand sale.
- Condition and provenance. Radios work outdoors for years; whether a unit has been in service, and for how long, matters more here than for indoor equipment.
We deal in RRU/RRUS units across generations with the band, power and connector stated explicitly on the quotation, plus the mounting hardware where we have it.