The principle of Open RAN is to build an open, multi-vendor interoperable RAN system for a more flexible and enabling future network architecture. On one side of the coin, hardware and software disaggregation of RAN infrastructure brings the so desired supply chain diversity and technology innovation back to the industry. On the other side of the coin, network complexity rises as a consequence of a multi-vendor environment. Thus, it is crucial to ensure network equipment interoperability among vendors before implementing an end-to-end system integration. As an industry-leading O-RU radio vendor who actively collaborates with O-RAN Alliance and Telecom Infra Project (TIP), Comba has gained extensive integration experience working with multiple DU software vendors. Below are the highlights of best practices for achieving successful integration.
In its specification effort, O-RAN Alliance has been extending RAN standards with open interfaces and intelligent RAN functions, and they continue bringing new or updated features to all parts of the O-RAN architecture, allowing vendors to progress with improved O-RAN based implementations.
Among a list of specifications, given that O-RAN Alliance fronthaul specifications are widely adopted and recognized as the common standard of O-DU and O-RU interface, applying this unified standard for Open RAN radio integration is recommended. The integration usually starts with the alignment of the Interoperability Testing (IOT) profile, comprised of a complete set of specifications and parameters. With the chosen CUS-Plane and M-Plane profiles, both O-DU and O-RU vendors would better understand the integration features and then exchange the packet captured in the fronthaul interface to verify the correctness of IOT profile. After that, the actual IOT test will be carried out according to the clear and well-communicated test plan with test cases.
The above process seems fairly straightforward. However, considering the limited processing resources of the O-RU, the alignment between O-DU and O-RU vendors on the optional features within the IOT profile, such as IQ data compression, synchronization modes, and etc., could be quite challenging.
To meet the expected KPI, vendor alignment applies to the interface integration and the system as a whole. Taking the timing advance as an example, continuous tunability of time delay is crucial for the overall system performance. The alarm is another example as its definition varies from vendor to vendor as it is hardware-dependent.
In conclusion, the best practices for O-RAN radio integration should include pre-integration planning of the detailed IOT testing. Besides, the automatic plug-n-play radio in an O-RAN system has not existed yet, so both O-DU and O-RU vendors must work closely together to optimize the Open RAN solution performance.