Open RAN is transforming the way network equipment manufacturers and mobile network operators design, build and operate cellular networks. Open RAN is an open and disaggregated radio access network (RAN) architecture that allows operators to leverage best-in-class components for greater flexibility and competitiveness.
Open RAN adoption by mobile operators is accelerating fast. This article will walk you through the most frequently asked questions about Open RAN and help you understand the Open RAN architecture and resultant testing considerations.
1. What is Open RAN?
Open RAN is the movement by mobile network operators from closed, proprietary RANs to disaggregated RANs with open interfaces and hardware and software from multiple vendors.
Open RAN enables more open, virtualized, and fully interoperable RANs. Operators gain the flexibility to mix and match RAN components from different vendors. A more competitive supplier ecosystem also helps control capital expenditures.
Open RAN’s open architecture and standards drive innovation in the wireless industry by allowing more companies to participate in the RAN ecosystem. In addition to providing greater flexibility and fostering innovation, the new architecture also addresses issues legacy architectures failed to address, such as security.
2. Why is Open RAN important for 5G?
5G networks require agile, flexible, and scalable deployment and management capabilities. The high complexity of 5G networks calls for a virtualized solution that is easy to integrate, automate, and upgrade. Legacy proprietary network architectures make it difficult for operators to scale network coverage and capacity. Open RAN implements software-centric principles that fundamentally solve the problems created by legacy network architectures.
4. What are the key components of an O-RAN architecture?
The O-RAN architecture splits RAN functions into four key components:
a. O-RAN radio unit (O-RU) for processing the lower part of the physical layer.
b. O-RAN distributed unit (O-DU) for baseband processing, scheduling, radio link control, medium access control, and the upper part of the physical layer.
c. O-RAN central unit (O-CU) for the packet data convergence protocol layer.
d. RAN intelligent controller (RIC) to gather information from the network and perform the necessary optimization tasks.
Figure 1 depicts the Open RAN architecture with user equipment (UEs) and the 5G core network.
5. What are the important tests required for 5G O-RAN networks?
Testing for conformance and interoperability is crucial for 5G O-RAN networks because Open RAN brings more components and interfaces into the RAN architecture and these components can come from different vendors. Making sure individual component conforms to the standards requires isolating each component and simulating the rest of network. Ensuring all network elements interoperate seamlessly requires testing each component from various angles.
Testing the fronthaul interface is the most important and difficult part of the O-RAN conformance test process. 5G Open RAN networks transmit time-sensitive messages at extremely high data rates between O-RUs and O-DUs. The testing equipment needs to operate at an extremely high speed to deliver adequate results. Fronthaul conformance testing requires a test sequencer to automate hundreds of tests and analyzing the RF response of the O-RU to determine if it understands the O-DU correctly.
Operators also need to simulate many UEs with different data types to understand the true performance of their network. The tests need to cover different radio conditions and take into consideration key techniques used in 5G networks such as multiple-input and multiple-output (MIMO) and beamforming.
To learn more about Open RAN testing, enroll for the O-RAN demo course at Keysight University. This course goes through the different steps to take to test different components, interfaces, and integrated RANs with real-world examples.
You can also visit the Keysight Open RAN Architect (KORA) web page to learn more about the solutions we offer to overcome the test challenges brought by O-RAN to the entire ecosystem, from chip designers and network equipment manufacturers to mobile network operators and Open Testing and Integration Centers (OTIC).
Learn more about Keysight’s 5G device testing solutions:
Keysight Open RAN Architect (KORA)
The Essential Guide for Understanding O-RAN eBook
5G RAN Testing
O-RAN Next-Generation Fronthaul Conformance Testing white paper
Pre-Silicon Validation of Next Generation O-RAN Compliant Radio Units Chipsets white paper