What Is an RRU?

An RRU (Remote Radio Unit) is one of the most important components of a modern mobile base station.
Its main function is to transmit and receive wireless radio signals between mobile devices and the telecom network.

Whenever you make a phone call, browse the internet, or stream a video, your device communicates with the network through an RRU.

In simple terms:

The RRU is the part of the base station that handles wireless radio signals.

Where Is the RRU Installed?

In modern 4G and 5G networks, RRUs are usually installed close to the antenna, such as:

• On telecom towers

• On rooftops

• On poles or outdoor sites

This is very different from older base stations, where radio equipment was placed inside indoor cabinets.

Why install the RRU near the antenna?
Because shorter RF cables mean less signal loss and better network performance.

Main Functions of an RRU

An RRU performs several key tasks:

1. Radio Signal Transmission and Reception

• Sends radio signals to mobile phones

• Receives radio signals from user devices

2. Signal Conversion

• Converts digital signals from the BBU into RF signals

• Converts received RF signals back into digital signals

3. Signal Amplification

• Boosts signal power

• Extends coverage and improves signal quality

4. Multi-Band Support

RRUs can operate on different frequency bands, such as:

• 900 MHz

• 1800 MHz

• 2100 MHz

• 2600 MHz

• 3.5 GHz (5G)

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RRU and BBU: How They Work Together

An RRU cannot work alone.
It must be connected to a BBU (Baseband Unit).

They are connected via optical fiber using CPRI or eCPRI links.

A simple way to understand this relationship:

The BBU is the brain, and the RRU is the mouth and ears of the base station.

RRU vs AAU: What’s the Difference?

In 5G networks, you may also hear about AAU (Active Antenna Unit).

• RRU: Radio unit + external antenna

• AAU: Radio unit and antenna integrated into one device

AAUs are commonly used for 5G Massive MIMO deployments,
while RRUs are still widely used in 4G networks and low-band 5G sites.

Common RRU Brands and Models

RRUs are manufactured by major telecom vendors, including:

• Ericsson: RRU 2219, RRU 2217, RRU 4415

• Nokia: FRGX, FRGT, FXED

• Huawei: RRU 5904, RRU 3971, RRU 5301

• ZTE: Multi-band RRU series

These devices are widely deployed in macro base stations worldwide.

Why Refurbished RRUs Are in High Demand

As operators upgrade their networks, large numbers of RRUs enter the secondary market.

Refurbished RRUs offer several advantages:

• Up to 50–70% cost savings

• Fully tested and reliable performance

• Faster delivery compared to new equipment

• Environmentally friendly reuse

That’s why refurbished telecom equipment is popular in regions such as Africa, the Middle East, Latin America, and Eastern Europe.

Key Takeaways

• An RRU is the radio unit responsible for wireless signal transmission

• It is installed close to the antenna to reduce signal loss

• RRU works together with the BBU via optical fiber

• RRUs are essential for both 4G and 5G networks

• Refurbished RRUs provide a cost-effective and sustainable solution