Huawei Remote radio unit (RRU) applies to distributed base stations and macro+distributed scenarios, and radio frequency unit (RFU) applies to macro base stations. They are used to transmit and receive baseband signals, modulate and demodulate RF signals, process data, and amplify the power of signals.

The RRU performs the following functions:

* Receives downlink baseband data from the BBU and sends uplink baseband data to the BBU.
* Receives RF signals from the antenna system, down-converts the signals to intermediate
frequency (IF) signals, amplifies the IF signals, performs analog-to-digital conversion, and up-converts RF signals to the
transmit (TX) band.
* Multiplexes receive (RX) and TX signals on the RF channel so that these signals can share the same antenna channel, and filters the RX and TX signals.
* Provides a built-in Bias Tee (BT). Both the internal calibration and external calibration modes are supported. The RRU outputs OOK signals through the CAL port. * In versions earlier than SRAN16.1, the RRU supports only the external calibration mode.
* In SRAN16.1 and later versions, the RRU can be configured to work in internal or external calibration mode through software setting.
* The RRU can work with the Monitoring Extension Box (MEB). The MEB can transmit
external RS-485 communication signals and dry node monitoring signals into the RRU, implementing information monitoring and reporting. For details about the MEB, see the corresponding MEB User Guide.
* DC RRUs can use external power modules (such as OPM50M(Ver.B)) to support AC scenarios. For details about the external power modules, see user guides of the corresponding models.

Blade RRUs are as follows: RRU3971, RRU3959, RRU3959w, RRU3953, RRU3953w, RRU3952m, RRU3952, RRU3939, RRU3938, RRU3936, RRU3838, RRU3839, RRU3958, RRU3832, RRU3824, RRU382 6, RRU3668, RRU3281, RRU3269, RRU3268, RRU3262, RRU3260, RRU3249, RRU3276, RRU3853, RRU3962, and 5000 series RRUs.