rru

Remote Radio Unit, or RRU, is a component of modern wireless networks located at or near the cell site antenna. It houses the RF front-end functions required to transmit and receive wireless signals and is connected to a centralized baseband unit (BBU) via a fronthaul interface. The RRU typically includes RF transceivers, power amplifiers, low-noise amplifiers, filters, and RF switching elements, performing upconversion and downconversion, amplification, filtering, and signal routing. The BBU handles baseband processing, resource management, and higher-layer control.

The connection between the RRU and BBU is usually implemented over digital interfaces such as CPRI, OBSAI, or eCPRI, using fiber or specialized copper links. This arrangement enables distributed deployment, placing RF functions closer to the antennas to reduce feeder losses, support multi-band operation, and accommodate simultaneous multiple-input multiple-output (MIMO) configurations.

In LTE and 5G networks, RRUs are deployed in both macro and small-cell environments. Modern RRUs can support multiple RF paths, several frequency bands, and a range of MIMO configurations. They are designed for outdoor or indoor use and often include environmental protection and cooling features to endure harsh conditions.

Terminology in the field varies: the term RRU is sometimes used interchangeably with Remote Radio Head (RRH). In practice, both describe the remote RF front-end portion of the radio access network, while the BBU or centralized unit handles baseband processing.