Remote Radio Head (RRH) Advantages and Disadvantages

This page covers the advantages and disadvantages of Remote Radio Head (RRH) and its basics. It mentions the benefits and drawbacks of using RRH technology.

Introduction

Remote Radio Head (RRH) is a technology used in wireless communication systems, particularly in cellular mobile networks. It separates the radio frequency (RF) functionality and baseband processing into two separate modules, known as the Radio Equipment (RE) and Radio Equipment Control (REC) respectively.

The RE module (also known as the radio front end module) is typically placed very close to the RF antennas. The REC is installed farther away from the base station cell site and connects to the core network.

Both RE and REC modules are connected using fiber optic cables. CPRI (Common Public Radio Interface) and eCPRI (Enhanced CPRI) are widely used interface protocols in RRH deployments, especially in 4G LTE and 5G networks.

Base station with RRH

The figure above depicts a base station with RRH. CPRI carries digitized baseband signals, including IQ data, control & management fields, and synchronization information, over fiber optic cables at high data rates. As shown, three fiber optic cables are laid out to carry information from a single Baseband Unit (BBU) to three Remote Radio Units and RF antennas.

An example of one such RRH is the Ericsson Radio 2219, which can be installed close to the antenna. It can be located up to 40 km from the Baseband Unit (BBU). A fiber optic cable is used between a single baseband unit and multiple radio units connected in cascade or star configuration. It supports GSM, WCDMA, and LTE with up to 8 carriers and requires a -48V DC power supply for operation. There are other Remote Radio Head (RRH) models available from Ericsson as well.

Benefits or Advantages of RRH

Following are the benefits of RRH:

• By locating radio heads closer to the antennas and using fiber optic cables between the BBU and the radio end, signal loss is minimized compared to traditional base stations. This results in improved signal quality and better overall network performance.
• RRH allows for easier installation of antennas in various locations, including hard-to-reach areas and densely populated urban regions. This flexibility helps to expand coverage and increase network capacity.
• Radio heads are placed closer to the RF antennas, hence less power is required to transmit the signals due to low signal loss. This reduces energy consumption and operational costs.
• Centralized baseband processing allows efficient resource allocation and interference management, leading to improved network performance and reduction in co-channel interference.
• RRH technology enables easier upgrades and modifications to the Baseband Unit (BBU). Moreover, changes in remote radio heads or antennas are not always required. RRH-based base stations are scalable and future-proof against technological advancements and changes in network standards.
• With RRH, a single Baseband Unit can serve multiple remote radio units or antennas. This consolidation of equipment reduces the physical footprint of cell sites, making it easier to install and maintain RRH-based network infrastructure in congested urban areas.
• CPRI and eCPRI protocols are vendor-agnostic protocols that define the interface between the Baseband Unit (BBU) and remote radio units. Hence, BBUs and remote radio units from different manufacturers or vendors can be installed at a single cellular site without any interfacing or interoperability issues.
• The technology used in Remote Radio Head (RRH) development is compatible with various advanced wireless cellular technologies such as 4G LTE, 5G, and beyond. This makes it suitable for future network evolutions.

Drawbacks or Disadvantages of RRH

Following are the limitations or drawbacks of RRH:

• RRHs require high-speed fiber optic cables between the BBU and RRHs. The deployment of fiber infrastructure can be costly, especially in remote or challenging terrains.
• Remote management solutions are used for maintenance of RRHs, but it still requires skilled personnel for on-site troubleshooting and repairs.
• The distance between the BBU and radio units needs to be within a certain range to maintain optimal signal quality. Longer distances may require signal repeaters or additional equipment.
• RRHs installed in outdoor environments must withstand various weather conditions such as extreme temperatures, rain, and humidity.
• As the network expands, more RRHs are added. This can lead to increased fiber requirements and potential capacity constraints in the fiber network, which requires careful scalability planning.

Conclusion

Overall, RRHs (Remote Radio Heads) play a vital role in WiMAX, 4G LTE, and 5G NR cellular systems. They enable efficient RF processing, improved network coverage, and enhanced network performance to meet the growing demands of wireless communication services. Moreover, software upgrades to Physical layer-1 as per changes in existing standards or during the introduction of any new standards have become much easier. Hence, new products can be launched quickly.