5G RAN Architecture: Nodes and Components

One of the key components of 5G is the Radio Access Network (RAN) architecture, which is responsible for managing the wireless connections between devices and the network.

This article will provide a technical overview of the 5G RAN architecture, including its various nodes and components.

It will explain the functionality of each node and component, their roles in the network, and how they work together to provide seamless connectivity to you as a user.

By understanding the technical workings of the 5G RAN architecture, you would be able to gain a deeper insight into the technology that powers mobile devices and the infrastructure that enables high-speed data transfer, low latency, and improved network efficiency.

5G RAN Architecture

The 5G RAN architecture is composed of multiple nodes and components that work together to provide seamless connectivity to users. These nodes include the User Equipment (UE), the Base Station (BS), the Central Unit (CU), and the Distributed Unit (DU).

The 5G RAN architecture also includes several key components, including the Radio Frequency (RF) Front End, the Digital Signal Processor (DSP), and the Antenna System.

The RF Front End is responsible for transmitting and receiving signals between the UE and the BS, while the DSP processes the signals to extract useful information. The Antenna System is responsible for directing the signals to and from the UE and the BS.

The DSP (Digital Signal Processor) is responsible for processing the signals received from the RF Front End to extract useful information.

It includes various algorithms and techniques like beamforming, interference cancellation, and modulation schemes that improve signal quality and reduce latency.

The DSP is an essential component of the 5G RAN architecture, as it enables advanced features like massive MIMO, dynamic spectrum sharing, and network slicing.

The UE is the end-user device that communicates with the network through the BS, which acts as the access point for the wireless connection.

The CU is responsible for managing multiple BSs and controlling the network resources, while the DU is responsible for processing and forwarding data between the UE and the CU.

5G RAN Components

The 5G Radio Access Network (RAN) components are key elements that enable high-speed, low-latency wireless communication. These components include the Radio Frequency (RF) Front End, the Digital Signal Processor (DSP), and the Antenna System.

5G RAN Components Lists:

  • Base Station (BS)
  • Central Unit (CU)
  • Distributed Unit (DU)
  • User Equipment (UE)

1. Distributed Unit (DU)

The Distributed Unit (DU) is in charge of managing certain protocols that relate to the lower levels of the OSI model, which is a framework for understanding how networks operate.

These protocols include radio link control (RLC), medium access control (MAC), and the PHY protocol.

The PHY protocol is named after its interaction with the network’s physical layer, typically working with the node’s radio unit.

Regarding the radio unit, it is made up of an antenna and specific software. The antennas send and receive radio frequencies through the air.

The accompanying software takes the data from these frequencies and converts it into a format that the other parts of the RAN can understand.

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In 5G RANs, antennas are being upgraded to a more advanced type called multiple input, multiple output (MIMO) antennas, which are specifically known as massive MIMO in 5G networks.

Massive MIMO involves several antennas within one unit, with the size of the unit corresponding to the frequency it supports. Additionally, MIMO technology includes a greater number of transmission ports, which boosts the network capacity and data transfer speed.

The Antenna System is responsible for directing the signals to and from the UE and the BS. It includes several antennas that can be arranged in different configurations like beamforming, MIMO, and phased array.

2. Control Unit (CU)

The Central Unit (CU) efficiently orchestrates network resources and manages base stations, playing a critical role in enhancing 5G RAN performance and adaptability.

One of the key functions of the CU is to establish and release connections between user equipment and the network.

It is also responsible for handling data transfer, executing quality of service functions, and compressing and decompressing IP data streams, among other tasks.

By ensuring seamless connectivity and efficient resource allocation, the CU greatly contributes to improved user experience and overall network efficiency.

Furthermore, the CU can have its functions disaggregated using software-defined networking (SDN) principles. This approach allows the CU control plane (CU-CP) and user plane (CU-UP) to handle different sets of protocols that execute various functions.

For instance, the CU-CP hosts the radio resource control (RRC) protocol as well as the control plane portion of the packet data convergence protocol (PDCP). In contrast, the CU-UP hosts the service data adaptation protocol (SDAP) and the user plane portion of the PDCP.

3. User Equipment (UE)

User Equipment (UE) refers to the end-user devices, such as smartphones, tablets, or IoT devices, that connect to the 5G Radio Access Network (RAN) for wireless communication.

The UE communicates with the network infrastructure through the base station, which serves as the access point for wireless connections.

In the context of 5G RAN, UE devices benefit from enhanced data transfer speeds, low latency, and improved network efficiency.

These improvements enable better user experiences, supporting advanced applications like augmented reality, mobile gaming, and autonomous vehicles, as well as expanding the possibilities for IoT deployments.

4. Base Station

Base Station (BS) is a key component of the 5G Radio Access Network (RAN) architecture that serves as an access point for wireless connections between user equipment (UE) and the network.

It consists of a radio unit and an antenna system that transmits and receives signals to and from the UE.

The BS is responsible for establishing, maintaining, and releasing wireless connections to the network, enabling seamless connectivity for the UE.

In 5G RAN, BS nodes can also support multiple input, multiple output (MIMO) antennas, increasing the network capacity and data throughput for improved performance.

5G RAN Architecture Nodes/Components

The basic hardware of a RAN node includes the antennas, radio units, and baseband units.

1. RAN Antennas

RAN antennas play a crucial role in capturing signals emitted by user devices and forwarding the information to the radio unit. In advanced RAN generations, certain nodes are equipped with multiple input, multiple output (MIMO) antennas, which enhance overall network capabilities.

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This innovative antenna design allows for the concurrent transmission and reception of several data streams, optimizing network performance.

2. Radio Units

To ensure the efficient reception of signal data from antennas, radio units can be strategically placed at the base of the RAN tower or in the vicinity of the antennas.

This placement helps to mitigate signal loss caused by extensive cabling, thus maintaining optimal signal strength and network functionality.

3. Baseband Unit (BBU)

The baseband unit (BBU) plays a vital role in transmitting data from the RAN node to the core network and relaying data received from the core network to the radio unit for further transmission.

BBU connections to the core network are established through fiber optic cables, which also facilitate the execution of management functions.

A BBU can either be situated on-site at the tower or housed at a centralized location. The latter configuration is often found in cloud RAN (C-RAN) or centralized RAN architectures.

This setup exemplifies how virtualization is transforming RANs. In C-RAN architectures, BBU resources are consolidated at a data center and can be deployed within virtual machines (VMs).

These centralized BBUs maintain connections to the towers they support through optical fibers.

RANs Virtualization

The evolution of Radio Access Networks (RANs) has seen a significant shift towards virtualization. Virtual RANs (vRANs), which include 5G RANs, Cloud RANs (C-RANs), and Open RANs (O-RANs), are characterized by the separation of network functions from the underlying hardware.

This separation enables function disaggregation, which facilitates greater network flexibility and efficiency.

RAN Virtualization Key Points

Below are the RAN Virtualization Key Points:

Function Disaggregation in vRAN

Function disaggregation is exemplified by the division of a hardware-based Baseband Unit (BBU) into a Central Unit (CU) and a Distributed Unit (DU). Both units are responsible for different BBU functions and can be deployed independently or together. This arrangement is reminiscent of C-RAN architectures.

vRAN Central Unit (CU)

The CU is responsible for a variety of tasks, including information broadcasting, establishing and releasing connections to user equipment, data transfer, executing quality of service functions, and compressing and decompressing IP data streams.

Utilizing software-defined networking (SDN) principles, the CU’s functions can be further disaggregated into the CU control plane (CU-CP) and the CU user plane (CU-UP). Each plane handles different sets of protocols and functions.

For instance, the CU-CP hosts the radio resource control (RRC) protocol and the control plane portion of the packet data convergence protocol (PDCP).

Conversely, the CU-UP hosts the service data adaptation protocol (SDAP) and the user plane portion of the PDCP.

vRAN Distributed Unit (DU)

The DU manages the radio link control (RLC) and medium access control (MAC) layers, in addition to some aspects of the physical layer at a base station.

By bringing compute resources closer to the RAN edge, the DU plays a crucial role in improving user experience, reducing latency, and enhancing network efficiency and capacity.

Virtualization and Next-Generation RANs

Virtualization is vital for the development of next-generation RANs, particularly 5G RANs, as it increases network flexibility and reduces costs.

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Integrating edge computing into RANs offers substantial advantages for various applications, including autonomous vehicles, mobile gaming, and IoT deployments.

Network Slicing and Multi-Tenancy

One of the key benefits of RAN virtualization is the ability to implement network slicing, which allows operators to divide a single physical network into multiple virtual networks.

Each virtual network, or “slice,” can be tailored to the specific requirements of different use cases or customer segments.

This flexibility enables multi-tenancy, where multiple operators or service providers can share the same RAN infrastructure, leading to more efficient resource utilization and reduced operating expenses.

Orchestration and Management

RAN virtualization requires efficient orchestration and management systems to ensure seamless operation.

The management and orchestration (MANO) framework, defined by the European Telecommunications Standards Institute (ETSI), can be applied to RANs. Several organizations are developing MANO tools for use in RAN environments.

Orchestrators are responsible for provisioning network functions, configuring them to work together, managing their lifecycles, and deploying updates as needed.

In an O-RAN architecture, MANO tools exist within the service management and orchestration framework present in the Open Cloud (O-Cloud).

The O-Cloud comprises physical RAN nodes hosting network controllers, CUs, and DUs; software components such as operating systems and runtime environments; and the service management and orchestration (SMO) system.

Interoperability and Open Standards

Another advantage of RAN virtualization is the promotion of interoperability and open standards. Open RAN (O-RAN) architectures encourage the use of standardized interfaces and protocols, which enable communication between components from different vendors.

This openness fosters innovation, competition, and a diverse ecosystem of suppliers, ultimately driving down costs and improving overall network performance.

The O-RAN Alliance, a global organization of mobile network operators and technology providers, is spearheading the development and adoption of open RAN architectures.

The Alliance focuses on defining open interfaces, creating reference designs, and promoting the use of common data models to ensure interoperability between components.

vRAN Security Considerations

As RANs become more virtualized and open, security becomes an increasingly important concern.

Ensuring the integrity, confidentiality, and availability of network functions and data is paramount for both operators and end-users.

To address these challenges, security mechanisms must be implemented at various levels, including the physical infrastructure, the virtualized network functions, and the management and orchestration systems.

Techniques such as encryption, authentication, and access control can help protect against unauthorized access, data tampering, and other security threats.

Moreover, ongoing monitoring and threat detection are essential for maintaining a secure network environment.

Network operators should implement security information and event management (SIEM) systems, which collect and analyze security data from across the network to identify potential threats and respond to incidents in real-time.

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Som D

Som is Network and Cloud Security expert with 12+ years of experience in the field and years of experience into 5G Security. She has researched, tested and written hundreds of articles on a variety of topics such as Network Security, Cloud Security, Wireless Security, Networking Basics, Mobile Operators services guides and 5G Security. In addition to her professional pursuits, Som is also a passionate into researching and publishing the content on other education platforms surrounding network security, cloud security and 5G security. She also creates guides, walkthroughs, solutions and more to help others with their progression in the same field.