Back in February we announced the open-nfapi project, a set of libraries and simulators that implement the Small Cell Forum’s nFAPI MAC/PHY split base station architecture. We described the need for many of the verticals identified as targets for new 5G use cases to be able to serve all employees, contractors, partners and visitors, irrespective of their carrier affiliation. We went on to examine the current capabilities for active network sharing to deliver multi-operator solutions, and cautioned that those were ill equipped to accelerate the deployment of the wide range of indoor use cases. And we concluded that the Small Cell Forum’s multi-vendor nFAPI split architecture, together with its neutral host management model, offered a new approach to active sharing of an LTE RAN based on a multi-vendor CU-DU implementation.

Shortly afterwards, GSMA released its report on 5G,  describing new models for infrastructure ownership and which reported the results of their survey of 750 operator CEOs. The results of that survey highlighted that the operator CEOs thought that the widespread adoption of network sharing, including active sharing, will be the most common structure for the mobile industry in the 5G era.

Now moving forward, even though Cisco has licensed the nFAPI libraries under the permissive Apache 2.0 license, enabling them to be integrated by the widest possible set of stakeholders, including closed source proprietary RAN products, we do not underestimate the real challenges in getting such capabilities implemented. With this in mind, we are pleased to announce that Cisco has joined the Open Air Interface (OAI) open source ecosystem. We will use our membership of OAI to demonstrate how to integrate the open-nFAPI libraries into an existing LTE RAN protocol stack; the integration between the lower nFAPI libraries and the PHY layer implemented on a Software Defined Radio platform as well as the integration between the upper nFAPI libraries and the MAC and RRC layers.

Like GSMA, we are convinced that 5G will need to focus on lowering the barriers for deploying active sharing in order to support multi-operator deployments. This naturally means addressing the thorny issue of multi-vendor interoperability of internal RAN interfaces. With a combination of SCF’s published nFAPI specification, together with open source libraries and simulators to test implementations already available in the open-nfapi project, Cisco is now working with OAI to reduce the risks and effort associated with realising an nFAPI based multi-vendor LTE solution derived from a pre-existing protocol and hardware platform. Cisco welcomes other OAI members, SCF members, 3rd party developers, other open source ecosystems and researchers to help contribute to this effort.


Mark Grayson

Cisco Fellow

Cisco’s Emerging Technologies & Innovation Group