Nokia Strengthens Commitment to OpenRAN

Confronting the paradigm-changing implications of the growing Open Radio Access Network (OpenRAN) movement has forced Tier-1 vendors to reevaluate their respective roles in the mobile network infrastructure supply chain. Should they continue selling End-to-End (E2E) proprietary equipment and software in the midst of this burgeoning trend? Or should they choose to adapt by embedding flexibility and interoperability within their interfaces to allow operators to deploy customized multi-vendor networks? The combination of reduced vendor diversity due to geopolitical tensions and the continued progress of new OpenRAN players such as Altiostar (Rakuten’s fully virtualized network) and Mavenir (Vodafone UK’s 4G OpenRAN sites) is incrementally changing the industry sentiment on the OpenRAN movement.

In the face of the increasing global demand of more open standards-based RAN, Nokia is committing to implementing OpenRAN-defined interfaces in its Airscale RAN portfolio that would facilitate interoperability. Nokia has announced that “an initial set of open RAN functionalities will become available this year, while the full suite of ORAN-defined interfaces is expected to be available in 2021.” Nokia is already supplying its services to U.S. carriers with deployment in the C-Band (3.3 to 4.2 GHz) through its 5G Airscale Cloud RAN solution in vRAN2.0 configuration. This involves a fully virtualized baseband configuration with a Radio Intelligent Controller (RIC), virtualized Central Unit (vCU) and virtualized Distributed Unit (vDU). This virtualized, disaggregated Baseband Unit (BBU) will run on general-purpose processor-based (x86) architecture.

The key benefit of an OpenRAN architecture lies in how it unbundles traditionally E2E solutions from Tier-1 vendors and provides more autonomy to operators in their respective network deployments. The uncoupling of hardware and software and priority toward virtualized network functions can ideally help operators reduce both Capital and Operational Expenditures (CAPEX and OPEX). This can be done by eliminating vendor dependencies and having more supplier diversity (thereby enhancing vendor ecosystem market efficiency) while leveraging OpenRAN’s embedded network intelligence layers to enable more network automation to reduce operational tasks. A crucial aspect in designing a fully modularized virtual network running on Commercial Off-the-Shelf (COTS) servers is establishing OpenRAN-compliant interface protocols.

The fronthaul interface, Common Public Radio Interface (CPRI) protocol, facilitates data communication between the Remote Radio Unit (RRU) and the BBU. The problem with CPRI is that it is based on vendor-specific proprietary technology—operators would therefore be relegated to relying on a single vendor in their procurement for more BBU/RRUs in their network due to the reliance on the inflexible proprietary interface. The introduction of the open interface Enhanced CPRI (eCPRI) will allow operators to have more options in complementing their RRU/BBU equipment from different vendors. Notably, the OpenRAN-compliant eCPRI 7.2x ether-based interface is utilized by Nokia’s 5G Airscale Cloud RAN.

Another interface that is dominated by proprietary technology is the connecting X2 interface that bridges communication between different base stations in networks. Among many things stipulated by the X2-AP standards, the X2 interface supports the exchange of information between vendor-diverse Evolved Universal Terrestrial Access Network (E-UTRAN) Node B (eNB) base stations that allows for data traffic/load management, interference coordination, and Coordinated Multi-Point (CoMP) transmission/reception. The opening of this interface is especially critical for Non-Standalone (NSA) 5G networks that rely on the coexistence between 4G and 5G baseband units. A closed, vendor-specific X2 interface restricts operators’ NSA 5G network development to only their existing 4G vendor. The OpenRAN X2 specifications solves this issue as it establishes interoperability between 4G eNBs and 5G next-generation Node Bs (gNB) provided by multiple vendors in NSA 5G.

Lastly, the Small Cell Forum (SCF) is also furthering the OpenRAN conversation by extending the Functional Application Platform Interface (FAPI) and network FAPI (nFAPI) interfaces of small cells to 5G. The FAPI uses a common set of APIs for the interoperability of the hardware, software, and application elements of small cells. The nFAPI, on the other hand, is pertinent to the context of the more virtualized 5G network as it is an open network interface between the vDU and vCU.

As mentioned, Nokia is spearheading the Tier-1 vendor foray into OpenRAN with its addition of open-air interfaces in its products, voluntarily unlocking its proprietary technologies and interfaces to allow operators flexibility in adding solutions from rival vendors in its deployments. Ericsson is currently contributing its expertise in the O-RAN Alliance working groups through its work on Non-Real-Time RAN Intelligent Controller (Non-RT RIC) and A1 interface which allow operators to use both RAN and non-RAN data to streamline network performance. Ericsson is adopting a more pragmatic view, balancing its ambitions of being the first to market in rolling out OpenRAN kits with the awareness of the current cost and performance limitations of OpenRAN-specified equipment.

OpenRAN-driven networks should realistically have a longer timeline to achieve widespread industry adoption. There have to be concrete examples of commercial viability, a more mature ecosystem of software and hardware vendors, and more experienced, qualified Systems Integrators (SIs) for OpenRAN to fully be embraced by the operator community. With that said, this protracted timeline of OpenRAN development should not severely impact the market share of Tier-1 vendors in the short term and would provide these vendors with more leeway in developing the right strategies for adapting to the long-term upward momentum of OpenaRAN.