xRAN Forum releases open fronthaul spec in move to transform RAN industry

In a move that will have some operators and smaller vendors rejoicing, the xRAN Forum announced the approval and public availability of the xRAN Fronthaul Specification Version 1.0, the first specification to come from the group since xRAN launched in October 2016. The spec is available for download on the forum’s website.

In particular, the specification defines open interfaces between the remote radio unit/head (RRU/RRH), the baseband unit (BBU) and the operation and management (OAM) interface to simplify interoperability between suppliers. It’s significant because traditionally, the RRU and BBU had to come from the same vendor.

What xRAN did was define an interoperable interface between these two units so that an operator can buy an RRU from one vendor and a BBU from another and they'll work together, opening it up to more competition. Some say it's going to bust up the old "cartel" of RRU/BBU suppliers.

The forum puts it more subtly, saying it fosters a growing ecosystem of interoperable RAN products catering to the various needs of its operator members. The new spec is a win for companies like AT&T, Verizon and Deutsche Telecom, which have been active in the xRAN Forum Front Haul Working Group, chaired by Verizon Communications.

“The release of the xRAN Fronthaul Specification is a groundbreaking advancement toward enabling an open RAN architecture to support next-generation products and services,” said Bill Stone, vice president, Network Technology Development and Planning at Verizon, in a press release. “xRAN compliant radios coupled with virtualized basebands provide much needed flexibility to support rapid development and deployment of RAN products. By adopting xRAN specifications, we will be able to speed innovation, increase collaboration and be more agile to a quickly evolving market.”

The xRAN Forum announced at Mobile World Congress 2018 in Barcelona that it was merging with the C-RAN Alliance to form a worldwide, carrier-led effort to drive new levels of openness in the radio access network. Called the ORAN Alliance, one of its key principles is to lead the industry toward open, interoperable interfaces, RAN virtualization and big data enabled RAN intelligence.

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Andre Fuetsch, CTO and president AT&T Labs, said xRAN's initial release creates the first wave of a positive sea change for the industry, transforming the way next-generation RAN infrastructure will be built, managed and optimized. “Equipment that supports open specifications from xRAN (and ORAN in the future), combined with increasing RAN virtualization and data-driven intelligence, will allow carriers to reduce complexity, innovate more quickly and significantly reduce deployment and operational costs," he said in a statement.

Sachin Katti, professor at Stanford University and director of the xRAN Forum, told FierceWirelessTech that operators increasingly are involved in specifying what they need in greater detail, as opposed to the traditional environment where vendors peddled their products and operators had to choose among them.

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The xRAN Fronthaul Specification addresses several key operator-defined requirements, including efficient bandwidth scaling and support for LTE, New Radio and Massive MIMO beamforming antenna systems.

Besides AT&T, Verizon and Deutsche Telekom, the xRAN Forum includes KDDI, NTT DoCoMo, SK Telecom and Telstra.

The xRAN Forum also had to get a few big vendors to the table, and Katti gave kudos to the likes of Nokia and Samsung for making contributions these past months. The vendor and academic community is also represented in the xRAN Forum by AltioStar, Amdocs, Aricent, ASOCS, Blue Danube, Ciena, Cisco, CommScope, Fujitsu, Intel, Mavenir, NEC, Netsia, Radisys, Stanford University, Texas Instruments and University of Sydney.

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Notably absent from the contributions is longtime infrastructure vendor Ericsson, which is involved in standards-setting through 3GPP but is not jumping into the xRAN, ORAN or open source initiatives.

Asked about its potential interest in ORAN, the company provided this statement: “Ericsson welcomes all discussions around openness. However, we currently have no public statement on the ORAN Alliance. We are in continuous contact with our operator customers and other stakeholders in the industry, including the ones currently associated with ORAN, to ensure we continue to develop the right products that make operators successful in their markets and satisfy their end-users’ needs in the best way possible.”

Mavenir Business Development SVP John Baker characterized the xRAN Forum’s new spec as an area that’s been locked down by the biggest radio infrastructure players the past 10 to 15 years due to the Common Protocol Radio Interface (CPRI). He believes this is a point where the industry will look back years from now and say it changed the entire paradigm.

But he added it’s still not a slam dunk because operators need to incorporate it in their RFIs or RFPs to vendors. “Unless the operators apply it, it’s meaningless,” he said. But there are advantages for operators, such as keeping costs down, putting competition back into the network and differentiating themselves with a new set of partners.

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Of course, Mavenir aims to benefit. The new spec will make it easier for the company to compete on a level playing field from a technical perspective; it’s already working with more than 300 operators around the world, he said.  

“We’re right at the beginning,” Baker said. “I believe this is a game changer. I think the marketplace is going to change.”