The scope of performance benchmarking is to cover Open RAN Full Stack testing, which includes DU (L1-HighPhy + L2-Schedular) and CU (L3) along with E2E 3GPP compliant test tools from vendors like Keysight and Viavi. In this Open RAN architecture, running the performance tests required end-to-end calls through the simulated UEs. The typical test tools are the UE Traffic Generator, Emulated 5G Core, and O-RAN 7.2 compliant Radio Unit (RU).
The 5G Open RAN architecture is more flexible, scalable, and efficient than previous generations of mobile networks. It promotes cloud-based technologies, SDN, and NFV to automate and streamline the network management including new services for real-time network optimizations to achieve better quality and user experience. Unlike previous generations, it is also designed to provide higher data rates, lower latency, and improved network efficiency, all of which helps reduce the network TCO.
This white paper highlights the ongoing improvements in the next generation of platforms that are capable of hosting Open RAN components at scale and have a noticeable contribution in TCO reduction.
The following list provides an overview of a 5G Open RAN architecture:
- Radio Units (RUs): RUs are the hardware components that transmit and receive radio signals to and from endpoint devices. The radio implements the lower PHY and can send IQ samples coming from DU over the fronthaul to the UE through RF either wired in simulated environment or over-the-air (OTA) in real environment. RU is usually deployed on cell towers or other elevated locations to provide wider coverage. In 5G, RUs are more energy-efficient and support higher data rates.
- Distributed Units (DUs): DUs are responsible for controlling and managing multiple RUs in a given area and are typically located closer to the RUs because of latency constraints. Normally, it consists of L1 (High PHY) and L2 (RLC, MAC). The following list describes DU components.
- L1 (High PHY) of DU runs in real-time mode with time slots (for TTI/Symbol boundaries) using the HW clock.
- Time Synchronization on DU and RU is done by Linux ptp4l service using PTPv2 packets coming as boundary clock from the network.
- L2 Stack (MAC and RLC) of DU runs on CPU as service and integrated with FlexRAN™ over WLS. It communicates with CU over F1 interface.
- Centralized Units (CUs): CUs are responsible for managing multiple DUs and coordinating the flow of data between the RAN and the core network. They are usually located in a centralized data center and can be shared by multiple operators. CUs use software-defined networking (SDN) and network function virtualization (NFV) to provide more flexible and efficient network management. CU does talk to 5G Core (in SA mode) using NG interfaces over the backhaul.
- Core network: The core network is responsible for managing user authentication, traffic routing, and other functions that are not directly related to the RAN. In 5G, the core network is designed to be more flexible and scalable than previous generations of cellular networks. It uses cloud-based technologies to provide more efficient network management and support new services such as network slicing and edge computing.
The 5G RAN architecture includes typically a 7.2 split between the RU and the DU. It simplifies the packet transmission between DU and RU over cost effective standard Ethernet network. It also enables more efficient processing and transmission of data packets, resulting in improved network performance.
The 7.2 split architecture provides several benefits, including:
- Minimized transport bandwidth: The 7.2 split between DU and RU helps minimize the Transport Bandwidth required for centralizing the RAN processing functions, the CU, and DU.
- Scalability: This architecture enables more flexibility and a better scalability in the 5G network. The DU and CU components can be independently scaled based on the network requirements. This flexibility allows more pooled resources more efficient, secure agile as per demand.
- Improved efficiency: The split architecture enables more efficient use of network resources, which can result in lower costs and better performance.
- More flexible deployment: The split architecture enables more flexible deployment of network infrastructure, which can be customized to meet the needs of specific use cases.