Paper outlines possible solutions for testing and optimising disaggregated small cell radio and distributed units of the RAN.
The Small Cell Forum released a paper outlining the key test configurations for 3GPP TS38.141 compliance testing of split 6 products using the SCF nFAPI 2.0 interface.
The effort was led by Forum members Keysight Technologies and Picocom to inform operators and integrators on how split 6 products can be tested, with specifications derived from 3GPP standards.
Within and between products
The Forum's suite of 5G FAPI/nFAPI specifications are intended to stimulate innovation and competition across the small cell ecosystem by supporting multi-vendor interoperability both within products and between different products in small cell networks.
It is architected within the 3GPP defined disaggregated functional split framework.
Trends identified in the Forum’s 2021 Market Forecast showed plans for Open RAN disaggregated networks – with considerable interest in split 6 for shorter range indoor enterprise, campus, and private networks.
Operators and systems integrators will need to integrate disaggregated network components including the central units (CUs), distributed units (DUs) and radio units (RUs) from different vendors, and for integration/testing these need to be compliant with 3GPP test specification TS38.141.
However, the units need to be able to be tested individually as well as part of an integrated system and this paper lays out how this can be done.
The paper provides an overview of 5G split 6 S-RU and S-DU products and architectures, and examines the impact of split 6 on compliance testing for 5G base stations.
It also develops options and proposes different solutions for testing S-RU and S-DUs, and has an overview of TS38.141 test approach for split 6 products.
“Open RAN disaggregated networks facilitate vendor diversification with radio units and distributed units supplied by different vendors. It is imperative that vendors can be confident their units are compliant when tested as a complete system, and a test solution particularly for S-RU needed developing.” said Vicky Messer, Director Product Management at Picocom.
“The test methodology recommended in this paper enables vendors to perform conformance testing without requiring any specialised test mode on their S-RU, thus removing a major pain point in the development and deployment process.” added Balaji Raghothaman, Chief Architect at Keysight Technologies.
“The [Small Cell Forum's] standardized nFAPI interface is an Open RAN interface that can be used across the ecosystem of S-RU vendors and S-DU vendors, but it is essential that it can also be used by test equipment vendors,” said Prabhakar Chitrapu, Chair of Small Cell Forum.