What Is Open RAN (ORAN)?

An Open Radio Access Network (ORAN) is a nonproprietary version of the Radio Access Network (RAN) system that allows interoperation between cellular network equipment provided by different vendors.

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What is the future goal for Open RAN?

The future goal for ORAN is for any hardware and software in the cellular network to interoperate both seamlessly and securely regardless of its originating vendor.

ORAN today may have multiple vendors, but the radio unit (RU) software comes from the same company that manufactures the antennae, while the Distribution Unit (DU) and Centralized Unit (CU) could originate from another company.

Also, as noted above, RAN traditionally has been a proprietary (closed) segment of the network. Currently, it is the last remaining portion of the network that is predominantly proprietary.

What are split options with ORAN?

ORAN is based on interoperable lower layer splits, but where best to perform this split is a complex question requiring a compromise between RU simplification, support for advanced multipoint radio frequency capabilities, and requirements of the front haul transport.

Splits have been assigned numbers to assist in comparing the many available options. The higher number assignments represent splits that reside lower in the protocol stack, with less functionality deployed below the RU split.

Lower layer splits are centered in the protocol stack below the Medium Access Control (MAC) layer. Options for this include a location between the MAC and Physical (PHY) layers (Split 6), within the PHY layer (Split 7), and between the PHY layer and RF functionality (Split 8).

What is a virtualized RAN (vRAN)?

The disaggregation of hardware and software for the radio access network is known as vRAN. It involves the separation of traditional hardware from the software that operates the base stations, RU, DU, and CU.

Because it evolves hardware-driven functions into virtualized (or software-based) functions, vRAN is often seen as the next step in cellular network evolution—most notably in the advancement of 5G. That said, a vRAN can still be a proprietary solution requiring both hardware and software to be provided by the same vendor (which maintains vendor lock-in).

Below is a high-level illustration of a virtualized proprietary (closed) RAN:

What is Open virtualized RAN (OvRAN)?

OvRAN is a nonproprietary RAN that has disaggregated hardware from software—that is, it's an open and virtualized RAN.

With OvRAN, service providers aren’t locked into a single solution and have the freedom to choose their own (best-of-breed) components based on their specific needs. Enabling this flexibility in choice is the overall goal for OvRAN.

Following is a high-level illustration of a virtualized open (nonproprietary) RAN:

What is a Radio Access Network (RAN)?

A RAN is a key segment of a mobile telecommunications system that uses cellular radio connections to link individual devices to other parts of a network.

A RAN serves different generations of mobile networking evolution beginning with the first generation of the technology, known as 1G, and culminating today in 5G, which is the fifth generation of cellular technology.

Radio access technology is the first segment in the cellular network, interconnecting end devices such as mobile phones, tablets, computers, or Internet of Things (IoT) machines to each other and to services through the mobile packet core.

Here is a high-level illustration of a traditional proprietary (closed) RAN:

More about OvRAN

Most nationwide networks deploy RAN technology from multiple vendors (typically two or three vendors). The challenge with this closed environment is that it often forces the mobile service provider to settle for the lowest common denominator when it comes to features that they can offer to their customers.

If a mobile service provider has two proprietary RAN vendors, they need to ensure that all features are common across the networks to prevent inconsistent customer experiences—for example, if the feature only works in some regions and not in others.

Additionally, OvRAN allows the service provider to be in the driver’s seat by avoiding vendor lock-in. Open solutions also offer the possibility of implementing better security.

Here is some other key information to know about OvRAN:

OvRAN management

Automation and orchestration tools are essential elements for managing OvRAN. They instantiate and perform lifecycle management of RAN in a zero trust environment in an easy and cost-effective manner.

For example, the first commercial service provider of OvRAN was able to deploy a completely open vRAN environment using a multi-tier automation and orchestration solution. As a result, they successfully instantiated radios in 8 minutes with zero touch as opposed to the traditional 6 hours with multiple, costly truck rolls.

OvRAN security

Securing the radio network is of critical importance to service providers.

There is ongoing debate as to whether an OvRAN environment invites security issues not otherwise found in closed, proprietary systems. However, the debate points out that OvRANs enable the user to select from a much broader basket of security solutions.

OvRAN also provides greater opportunity for visibility throughout the RAN network, which is critical because when it comes to security "you can't protect what you can't see."

For this reason, most RAN security experts agree that OvRAN is more secure than traditional proprietary RAN.

Status of OvRAN support for 4G and 5G

Different vendors support different technologies. Some offer only 4G, others offer 5G, and some may offer both.

Also, these vendors are creating radio offers suitable for different scenarios—for example, internal vs. external or micro vs. macro.

OvRAN is creating opportunities for greater competitiveness that, in turn, generates greater diversity of choice.

Current commercial deployment of OvRAN

Rakuten in Japan is the first carrier to commercially deploy networkwide OvRAN as opposed to limited test cases. Rakuten initially started with 4G and is now introducing 5G services.

Several Tier 1 and Tier 2 carriers have followed Rakuten's lead and have either initiated rollouts or announced their intention to implement OvRAN as they build out their 5G networks.

It is generally understood that "open" is the preferred direction of the mobile service provider industry.