As we usher in the 5G era, radio access networks (RAN) become a key enabler of the next-generation wireless communications revolution. RAN is at the heart of connectivity, bridging the gap between countless devices and the core network, and is critical to unlocking the transformative potential of 5G - lightning speeds, near-zero latency and ubiquitous coverage. This article aims to reveal the role of RAN in 5G networks, clarify its operating principles and advantages, and help us better understand how RAN is at the forefront of driving a hyper-connected future.

What is a wireless access network?

RAN is the part of the telecommunications system that connects individual devices such as smartphones, laptops, and IoT devices to other parts of the network through radio connections. RAN is a key element in mobile telecommunications system architecture, acting as a channel for transmitting information between user equipment (UE) and the core network. This network component equates to the necessary infrastructure needed to provide wireless communications in a variety of environments, including dense urban areas, suburbs and remote rural areas.

What parts does RAN in 5G consist of?

Unlike 4G, 5G RAN includes antennas, remote radio units (RRUs), and baseband units (BBUs). Instead, it was rebuilt into three operating units, known as the Centralized Unit (CU), the Active Antenna Unit (AAU) and the Distributed Unit (DU):

CU: CU is responsible for information aggregation and tasks with low real-time requirements. It also supports protocols higher up the stack, including RRC, PDCP, and SDAP.

AAU: AAU is a wireless communication device that integrates RRU functions and antenna arrays. Used to simultaneously handle the sending and receiving of wireless signals. Due to hardware integration, the base station architecture can be simplified and signal processing efficiency can be improved.

DU: DU supports the lower layers of the protocol stack, including MAC, RLC and physical layers, and is responsible for autonomous, demanding tasks that must be completed in real time. The CU regulates the operation of the logical node that contains a subset of eNB/gNB functions based on the function splitting option.

How does RAN work?

The wireless access network is a key component of the mobile communication system and is responsible for managing the wireless link between user equipment and the network. In RAN, RRU plays a vital role. It is connected directly to the antenna and is responsible for sending, receiving and converting digital radio signals. After receiving the signal, the RU communicates with the BBU through CPRI (Common Public Radio Interface). The BBU further processes the signal to ensure that the information enters the core network smoothly and performs necessary scheduling and management. Just like blood, data flows forward or backward to the user through this transmission mechanism, completing the process of calls and data exchange.

What wireless technologies and advantages does RAN have?

In 5G RAN, a number of key wireless technologies support the high speed, large capacity, and low latency of 5G networks. Let’s take a look at the important technologies in 5G RAN.

Massive MIMO (Massive Multiple Input Multiple Output): By installing a large number (sometimes dozens or even hundreds) of antennas on the base station, more users can be served simultaneously, greatly improving spectrum efficiency and network capacity.

Beamforming: This is a signal processing technique that focuses wireless communications onto "beams" targeted at specific people or objects. Beamforming and massive MIMO combine to significantly increase transmission range

Network slicing: Although not a pure wireless technology, network slicing allows operators to provide virtual network architecture to meet the special needs of different user groups, such as different speeds, capacities, number of connections, latency, etc.

Ultra-Dense Network (UDN): 5G uses a denser base station layout than 4G. Large-scale deployment of small base stations can improve coverage and capacity, and is particularly suitable for densely populated urban environments.

Together, these technologies form the technical foundation of 5G RAN, enabling 5G networks to support a large number of user devices and provide services for various applications, such as enhanced mobile broadband (eMBB) and massive machine type communications (mMTC). and ultra-reliable low-latency communications (URLLC).

As the backbone of 5G, wireless access networks not only enhance user experience through improved broadband and connectivity solutions, but also open up rich possibilities for industry-wide innovation, such as smart cities, autonomous vehicles and the Internet of Things (IoT). With its advanced capabilities, RAN is critical to realizing the overall vision of a hyper-connected future where seamless and powerful communications are a foregone conclusion, marking a major leap forward in our journey towards a connected world.