Ericsson says driving Open Fronthaul evolution in O-RAN Alliance

Ericsson backs new work item to evolve uplink capabilities of O-RAN Open Fronthaul.

Ericsson has confirmed that it is working within O-RAN Alliance’s Open Fronthaul (OFH) Working Group to drive evolution of the Alliance’s fronthaul specifications.

Until now, Ericsson has not supported O-RAN OFH, which is based on an implemenation of the lower layer 3GPP functional split known as 7.2x. It has argued that the OFH interface, which connects the open Distributed Unit (O-DU) of a radio baseband to the Radio Unit (O-RU), does not meet performance and energy use requirements of its customers.

That has meant that one of the largest Radio Access Network suppliers in the market effectively remained “closed”, so confirmation that the company is contributing to an “evolution” of OFH could be a significant moment. Especially if it follows through on its implication it will extend support across its Cloud RAN portfolio.

We are very clear want to make sure it can scale across our solutions

Mårten Lerner, Head of Product Line Cloud RAN, Ericsson, told TMN that the company has engaged in a new work item within the OFH Working Group at the O-RAN Alliance, with the aim of improving performance of the lower layer split that forms the basis of O-RAN OFH.

Lerner said, “We are driving that enhancement of the lower layer split, to improve the uplink of that split that is today sub par.” He added that Ericsson was “working very hard to develop the lower layer split to make sure it’s capable of handling a high performing network.”

“Today we are in the position where 7.2 has a sub par performance, which is why we want to enhance the specification as part of the work that is now on the table, to create a split that we can leverage for the [Ericsson’s] full portfolio. We are very clear want to make sure it can scale across our solutions.

Ericsson later confirmed that this work is part of the O-RAN Alliance Working Group 4: WG4-2022.001 “Improved 7-2x UL Performance for mMIMO”. It said in a statement (bold text is TMN’s):

“Today’s O-RAN LLS (Lower Layer Split) specifications are not competitive for most of operators in cost and performance (network reliability and energy use). We are working on evolving the open fronthaul interface in order to address concerns especially with regards to the uplink radio performance for Massive MIMO, as spectrum efficiency and performance for 5G mid-band are essential for the industry. We have been driving this together with other industry players in the O-RAN Alliance.”

As Lerner said, Ericsson wants a fronthaul connection that can support Massive MIMO and higher performing uplink requirements. Its contributions to the OFH WG coincide with an expansion of the market-readiness of its Cloud RAN portfolio. At MWC 22, the company was demonstrating a midband Cloud RAN solution, operating on an Intel-based HPE ProLiant DL 110 server.

Ericsson’s midband Cloud RAN demo deployment at MWC22.

Lerner said, “After starting with the low band, where there’s a smaller carrier and compute requirement, we are now at stage where can do midband, and Massive MIMO solution for the midband carrier. Where we are right now is we focus very much on the DU, making sure our vDU is capable of handling all requirements. We have come quite far which is why we are comfortable today we can realise a Massive MIMO deployment with Intel.”

Lerner said that Ericsson’s plan is to be able to support Cloud RAN DU-CU workloads on COTS hardware, without specific L1 accelerators in the DU. In the RU, it maintains its architecture of moving part of the L1 into the RU on its architecture, to support massive MIMO. As an example, the company said that one of its most recent remote radios, the dual band 4T/R, 24kg Radio 4490, is “Cloud-RAN ready”, with support for  eCPRI fronthaul.

However, Lerner then added that the company is also positive on evolving that lower layer split, which is where it is engaging in the new work item.

“Today we are in the positon where the technical specifications are not as mature as we want to build a solution for the highest performance that we can do on our split today. That’s whey we are driving that enhancement of the lower layer split, to improve the uplink of that split that is today sub-par. There’s a fairly strong consensus that improvements are needed.” 

Lerner said the end goal is to offer Cloud RAN with parallel capabilities to its purpose built solutions, being able to access the entire range of its radios. That includes Ericsson’s definition of Bluefield, where it can add Cloud RAN to radios that are already deployed in the field. The decision for operators then becomes which deployment scenario suits them best. Cloud RAN enables them to take advantage of a more CI/CD operational model, and the potential for automation. Ericsson is also committed to open upper layer Service Management and Orchestration, specified as the non real time RIC within O-RAN.

Lerner added that the Cloud RAN Business Unit now has full strategic support within the company. “I would say at this point in time there is fantastic support in the company. Some of the ones who have been through this journey see it changing it a little bit, from people doubting us, and a few heated dicsiossions. But the fact Cloud RAN is a large proportion of the (MWC) floor this year shows what the company believes, and that this is a very viable solution.”