Accelleran: Blogs & Insights

The latest articles and insights from Accelleran. This section also features our jointly published whitepapers, videos and other related material.


Looking for something else?

Back to HomeContact Us

Understanding the DU and CU in Open RAN Architecture

Open RAN has ushered in a fresh chapter for telecommunications. By championing flexibility, interoperability, and cost efficiency,

Open RAN is a progressive approach to network architecture. Central to this vision are two primary components: the Distributed Unit (DU) and the Central Unit (CU).

This article provides an in-depth exploration of these integral units within the Open RAN ecosystem. This is a simplified and accessible guide to these contepts. If you would like a more in-depth discussion, feel free to contact us.

Distributed Unit (DU)

The Distributed Unit (DU) handles the lower layers of the protocol stack, which includes the Upper Physical, MAC, and RLC layers. Its chief responsibilities are:

Data Organisation and Management: The DU is tasked with preparing data for transmission. It structures the data, ensuring it’s in the right format for efficient radio transmission.

Interaction with the Radio Unit (RU): The DU directly manages data communication with the Radio Unit, translating the organised data into radio waves for transmission and vice versa.

Latency Reduction and Efficiency: Being in closer proximity to the RU and managing the lower protocol layers, the DU assures minimal latency, especially crucial for real-time data exchange applications.

Metaphorically, think of the DU as the skilled technician of a symphony, tuning the instruments to perfection before the performance.

Central Unit (CU)

The Central Unit (CU) oversees the higher layers of the protocol stack, particularly the SDAP, PDCP, and RRC layers. Its primary roles encompass:

Network Management: The CU manages broader aspects of data flow within the network, dictating how data packets journey through the infrastructure.

Coordination with DUs: To ensure coherent communication between the core network and the Radio Units (RUs), the CU liaises with the DUs, guiding them on data management tasks.

Strategic Decision-making: For overarching network decisions, such as user mobility management and establishing user-specific communication bearers, the CU plays a pivotal role.

To draw a parallel, the CU is akin to a symphony conductor, ensuring each section comes together harmoniously for a flawless performance.

Integration and Openness

A primary advantage of the Open RAN model is its vendor-neutral design. The F1 interface, standardised by 3GPP, enables seamless communication between the DU and CU, irrespective of the equipment or software supplier.

This is extended and enhanced by the E2 interface defined in O-RAN Alliance which together with O1 and O2 enable a standardized approach to the management, orchestration and support for real time telemetry exposure and control of the CU and DU nodes to bring AI/ML network intelligence in the RAN.  

This vendor neutrality gives network operators the flexibility to integrate best-in-class solutions without being tethered to one provider.

Would you like to know more?

As we stand on the brink of a new era in telecommunications, Open RAN emerges as a game-changer. Its potential to redefine, reshape, and revitalise the industry is immense. If you’re keen to delve deeper and understand how Open RAN can revolutionise your operations or if you have queries about its implementation, we’re here to assist.