xRAN Forum updates methods for delivering RRU, BBU interoperability

When the xRAN Forum announced the xRAN Fronthaul Specification Version 1.0 in April, that represented a major step in the industry’s objective of defining open interfaces between the remote radio unit/head (RRU/RRH) and the baseband unit (BBU).

But the group at that time knew there were some gaps, and its latest release is designed to address that.

Specifically, the xRAN Forum announced the public availability of the xRAN Fronthaul Control, User and Synchronization (CUS) Plane Specification Version 2.0 and the xRAN Fronthaul Management Plane (MP) Specification Version 1.0. Previously, the management plane wasn't well defined.

The second major version of CUS-plane specification incorporates several enhancements over the first version, including support for two radio categories, A and B, to enable both simple (A) and more complex (B) functionality leveraging largely the same interface specification. It also includes support for LTE features like LAA and NB-IoT.

The first version of M-plane specification is also a significant milestone for the industry, providing an open multivendor M-plane model for radios based on standardized modern protocols like NETCONF/YANG. It includes key capabilities, such as a comprehensive YANG model developed for LTE and 5G radio. 

The group said the specifications have been designed to allow a wide range of vendors to develop innovative, best-of-breed RRUs and BBUs for various deployment scenarios, which can be easily integrated with virtualized infrastructure and management systems using standardized data models.

All of which is to say, the industry is closer to being able to deliver RRUs and BBUs that are interoperable so that operators don’t have to continue to deal with vendor lock-in, the way they’ve been doing the past 10 or 15 years due to the Common Protocol Radio Interface (CPRI). It’s significant because traditionally, the RRU and BBU had to come from the same vendor.

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Sachin Katti, professor at Stanford University and director of the xRAN Forum, told FierceWirelessTech that he couldn’t speculate as to when the first commercial products will be ready. Some vendors have said it could be as early as six months from now.

The xRAN Forum is still in the midst of merging with the ORAN Alliance, which was announced at Mobile World Congress 2018 in Barcelona. More recently, O-RAN kicked off its first board meeting at MWC Shanghai 2018, where seven new operator members were announced, joining the original co-founders, AT&T, China Mobile, Deutsche Telekom, NTT DoCoMo and Orange. The seven new members are Bharti Airtel, China Telecom, KT, Singtel, SK telecom, Telefonica and Telstra. 

RELATED: Verizon committed to Open RAN efforts despite not being in O-RAN Alliance

Verizon told FierceWirelessTech at that time that it was not an O-RAN forum member but was waiting to see final governance documents from the organization.

Those types of documents are being distributed to potential new members for their review. Things are still going as planned and xRAN's combination with O-RAN is expected to wrap up around the end of August, according to Katti.  

Katti will co-chair the technical board in ORAN. Operators are on the general board, but vendors will be welcome to join and participate in the technical board and working groups.

John Baker, SVP of business development at xRAN member Mavenir, previously characterized the xRAN spec as a game changer poised to change the industry significantly. It’s not a slam dunk because operators need to incorporate it in their RFIs or RFPs to vendors, but it's certainly a major change in how business is done.

The first Mavenir products are due, approximately, in the first quarter of 2019. Mavenir does expect to become a member of ORAN, but specific details are still being sorted out, according to Baker.