The telecoms and digital technologies sectors are notoriously jargonised. Eavesdrop on any conversation at an industry conference (remember those?) and you’d be treated to a parade of acronyms, initialisms and technical terms that would sound like ancient Greek to an outsider.
However, with new technologies being developed and deployed at an accelerated rate, staying on top of terminology can be challenging for even seasoned professionals. This is nowhere as apparent as in the evolving debate around Open RAN and its applications. Open RAN and its variations became the next “big thing” in wireless and I thought I’d try and help clarify some of the related terms that often get confused.
People often mean different things when they talk about Open RAN. Some are referring to network specifications, others are describing a philosophy. Add to this mix the different industry Open RAN groups, a multiplicity of spellings (often within the same article) and creative hashtags that populate social media, and it’s easy to see how conversations on this topic quickly become confused.
What follows is a lexicon of Open RAN-related terms and definitions that will hopefully help you cut through the noise. But first, some background:
The radio access network (RAN) is a critical part of network infrastructure. It is also one of the most expensive. Traditional RAN setups are hardware heavy and require major CapEx to build the foundation of a wireless network.
But the costs are not only significant in capital investment. RAN operating expenses are also high, unnecessarily so according to a growing number of network operators and suppliers. Theoretically, a radio access network built by a particular vendor to 3GPP standards should be interoperable with devices or components produced by any other vendor satisfying the same specifications.
In practice, though, vendors usually construct RAN setups with proprietary software and interfaces built on top of hardware developed by the same vendor. For the telecoms operator, the long-term cost of this inflexibility can be punitive. Many find themselves locked-in to unfavourable vendor contracts with little to no control over the upgrades and security of their RAN components.
The movement towards Open RAN has grown primarily in response to the gated nature of legacy RAN deployment and management. The cause is driven by operators hungry for the cost benefits of greater competition and prospective suppliers currently unable to break into a market dominated by a handful of monolithic vendors.
Open RAN refers to a disaggregated approach to deploying and managing radio access network functions, by using open interfaces between network elements. This aims to increase interoperability through vendor-neutral hardware and software-driven technology developed according to community-agreed standards.
Perhaps because Open RAN encourages a less restrictive and more accessible approach it is often conflated with open source, but they are not the same thing.
Some people also use Open RAN more generally, as an umbrella term to describe a collection of technologies, including vRAN and C-RAN (see below), that support the disaggregation of RAN elements.
OpenRAN (one word) is seen regularly online and is employed in one of three ways:
- Used interchangeably with the term Open RAN
- Used in social media posts, often with a hashtag: #OpenRAN to refer to any Open RAN-related technology
- Used to describe the OpenRAN Telecom Infra Project tasked with defining and building 2G, 3G, 4G and 5G RAN solutions based on general-purpose, vendor-neutral hardware and software-defined technology
Refers to the O-RAN Alliance, an industry group working to develop new standards for open and intelligent RAN, provide open software development for the RAN, and support member organisations in testing and integrating O-RAN implementations.
The global O-RAN Alliance was born from a merger of the C-RAN Alliance and xRAN, and brings together more than 160 mobile operators, vendors, and research and academic institutions.
According to the group, O-RAN focuses on technical aspects of the RAN and stays neutral in any political, governmental or other areas of any country or region. O-RAN does not get involved in any policy-related topics.
In addition to the O-RAN Alliance and the above-mentioned Facebook-backed Telecom Infra Project (TIP) other Open RAN-related industry groups have started forming and influencing the development and deployment of open, disaggregated, and standards-based RAN approaches. One interesting to mention is the newly-formed Open RAN Policy Coalition that promotes policies to advance the adoption of open and interoperable RAN solutions
oRAN or ORAN
Often used as shorthand for the Open RAN movement in general.
On social media, however, #oRAN or #ORAN may refer to either the Open RAN movement or the O-RAN Alliance.
In Virtual RAN (vRAN) the RAN functions of the baseband unit (BBU) are virtualised on a commercial-off-the-shelf (COTS) server. Theoretically, this allows different components of the baseband and radio software and hardware to be supplied by different vendors.
However, in practice, the interfaces between the BBU at the bottom of the cell tower and the remote radio unit (RRU) at the top of the tower often remain proprietary, meaning that an RRU from one vendor can require software from the same vendor to run on the COTS-based BBU. As a result, vRAN can still lead to vendor lock-in.
So, even though vRAN is a more open and flexible architecture and the virtualisation of network functions is a key principle of Open RAN, virtual RAN does not equal Open RAN.
In Open RAN, the proprietary interfaces between the baseband unit and the remote radio unit are replaced with open interfaces. So, any vendor’s software can work on any open RRU.
Cloud RAN or Centralised RAN. Staring about 10 years ago, this was an important first step towards disaggregating the radio access network. C-RAN sees the baseband unit relocated from the radio site to a data center where it is combined with other BBUs to form a pool of centralized resources that function as a cloud.
C-RAN relies on a fibre-based fronthaul – the connection layer between a BBU and RRU (or multiple RRUs) – and, as a result, has traditionally been limited to high-density or urban areas.
C-RAN has many benefits over legacy RAN and, like vRAN, has contributions to make to Open RAN, but it is not open in the Open RAN sense and is still susceptible to vendor lock-in.