Virtualizing the RAN is getting a lot of attention from operators because it promises to lower operator capex and opex costs as well as make it possible for them to add new capabilities to the network more quickly. It’s likely that all that interest is behind the creation of three different groups —the xRAN Forum, the Telecom Infra Project’s OpenRAN Group, and Cisco’s Open vRAN initiative. Although all these groups say they are working on the same thing, which is basically to make the RAN more open using standardized interfaces and white box network elements, on closer examination there are some differences. According to John Baker, SVP of business development at Mavenir, which is a member of all three groups, there is no overlap between the groups because each one has a different focus.
The xRAN Forum was formed in 2016 with the goal of standardizing an open alternative to the traditional hardware-based RAN. The group focuses on three areas —decoupling the RAN control plane from the user plane, building a modular eNodeB software stack that uses COTS hardware, and publishing open north- and south-bound interfaces.
The group has a very operator-centric membership, including AT&T, Verizon, Deutsche Telekom, KDDI, NTT Docomo, SK Telecom, Telstra, and Verizon. According to Sachin Katti, a Stanford University professor and the director of the xRAN Forum, the group is focused on network architecture and developing specifications. “We are focused on taking apart the stack and defining interfaces that are interoperable,” he said.
The xRAN Group just released its first specification dedicated to virtualizing the fronthaul portion of the network. (Fronthaul is the interface that delivers traffic from the baseband units (BBUs) and the remote radio heads). The specification is intended to drive interoperability between baseband units and the remote radio heads, even if they are from different vendors.
Cisco’s Open vRAN
At the Mobile World Congress 2018 conference in February, Cisco announced a new open virtualized Radio Access Network (vRAN) initiative, called Open vRAN. The goal of Open vRAN is to assemble an open and modular RAN architecture, based on general purpose processing platforms (GPPP) and disaggregated software, that will support different use cases.
Indian operator Reliance Jio was the only carrier involved in the group when it was announced. However, Cisco said it believed other operators, including U.S. carriers, would back the initiative. According to Mavenir’s Baker, today’s mobile networks use a lot fiber and point-to-point connectivity for fronthaul. But with the xRAN Group’s release of the fronthaul specification, new types of routing and IP connectivity will be possible.
The Open vRAN Group was formed to support these types of new deployment architectures. “Cisco’s Open vRAN is about how to deploy and structure IP networks in carrier networks for fronthaul,” Baker said.
The Telecom Infra Project was co-founded in 2016 by Facebook, along with Intel, Nokia, Deutsche Telekom, and SK Telecom. Its mission is the disaggregation of software and hardware, and its members include more than 500 Internet companies, telcos, vendors, and system integrators.
In November 2017, Vodafone contributed its software-defined RAN project to TIP and created the OpenRAN Group. The goal of the group is to develop RAN technologies based on GPPP and disaggregated software.
xRAN Forum’s Katti said that the OpenRAN Group is focused on implementation and how to build the software and the hardware while the xRAN Group is more focused on specifications. Nevertheless, the two groups do talk to each other, and they share many of the same members.
“We make sure we stay complementary to their efforts. We don’t want to redo the same work,” Katti explained.
Mavenir’s Baker agrees, noting that TIP’s OpenRAN is focused on use cases and building the network using fronthaul algorithms rather than developing specifications. He also said that because of the hundreds of companies that are TIP members, many are just observers and not playing an active role in the development.