RFRRH vs. Traditional Base Stations: A Comparison
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This article explores the differences between Remote Radio Head (RRH) based base stations and traditional base station architectures, commonly used in cellular communication systems. With the advent of RRHs, base station design has evolved, offering several advantages over the conventional approach.
Introduction
Traditional base stations have been a staple in cellular networks for years. However, the introduction of Remote Radio Heads (RRHs) has brought significant changes to base station architecture. RRHs separate RF processing from baseband processing, utilizing two distinct modules: Radio Equipment (RE) and Radio Equipment Control (REC). In contrast, traditional base stations house both baseband and radio transceiver functionalities at a single cell site.
Traditional Base Station Architecture
Figure 1 illustrates a typical traditional base station setup.
Key characteristics include:
- Tower Mounted Amplifier (TMA): TMAs are often deployed near antennas.
- BTS/BSC: This unit contains both RF and baseband processing capabilities.
- RF Coaxial Cables: Used to connect the amplifier to the BTS/BSC unit.
- Function of TMA: TMAs boost radio sensitivity on the cell site by mitigating uplink feeder losses, thereby enhancing cell coverage and service quality.
- Connectivity: The BTS connects to the TMA on one side and the backhaul network on the other.
RRH-Based Base Station Architecture
Figure 2 showcases the architecture of an RRH-based base station.
Here are the key features:
- Centralized Baseband Unit (BBU): The baseband unit is located centrally.
- Remote Radio Units (RRUs): These units, along with antennas, are located at the cell sites.
- Fiber Optic Cables: High-speed fiber optic cables connect the BBU to the RRUs (RE part).
- Signal Transmission: The optical signals carry data, control, management, and synchronization information.
- Topology: The BBU and multiple radio heads can be connected in cascade or star configurations.
The rise in popularity of RRH technology stems from numerous benefits, including improved network performance, reduced signal loss, flexibility, scalability, low power consumption, cost-effectiveness, ease of maintenance, support for 5G and beyond, and a reduced site footprint.
Key Differences: RRH vs. Traditional Base Stations
The following table highlights the core differences between RRH-based and traditional base stations:
| Parameters | RRH-based Base Station | Traditional Base Station |
|---|---|---|
| Radio Frequency (RF) Front End Location | Brought very close to the antennas | Located at the cell site but not close to the antenna; requires coaxial RF cables to connect the RF unit with antennas. |
| Baseband Unit (BBU or REC) | Centralized at the core network side and interfaced using fiber optic cables with radio heads (RE). | Located at the cell site or nearby. |
| Signal Loss | Lower as it uses fiber optic cables for connectivity between the BBU and RF units; moreover, RF units are very close to the RF antennas. | Higher as it requires long coaxial cables to connect the farthest BTS hardware to the RF antennas. |
| Deployment Flexibility | More flexibility in antenna placement and coverage expansion. | Less flexibility due to the fixed co-location structure. |
| Network Scalability | Easier; it is easy to add more RRH units, and it is possible to upgrade the software of the BBU (Baseband Unit) as per changing requirements. | Scalability is limited by space and power constraints; it is difficult to upgrade the baseband unit as it is integrated into one unit. |
| Deployment Examples | Small cells, densification projects, 5G mmWave sites. | Traditional 2G/3G/4G Base stations. |
Conclusion
RRH-based base station architecture presents several advantages over its traditional counterpart. These advantages include improved network performance, enhanced coverage and capacity, cost efficiency, infrastructure sharing, lower power consumption, flexible network scaling, and rapid network deployment.
Furthermore, RRH-based base station architectures are designed to support multiple generations of wireless technologies, facilitating easier upgrades to support the latest standards like 5G NR and beyond. This architecture is well-suited to support MIMO, beamforming, and advanced antenna configurations.
