O-RAN will transform and virtualise the radio access network infrastructure

As 5G NR O-RAN networks are being introduced, it is essential to understand how they differ from 4G LTE networks. This blog will explore some of these differences and help you better understand this new technology that has many implications for future telecommunications.

To understand the mission, you need to understand the driving forces

The wireless industry is approaching an inflexion point where the open radio access network – Open RAN or just O-RAN for short – is a significant interrupter. O-RAN will transform and virtualise the radio access network infrastructure. With it, you’ll be able to mix and match components and work together with specialists to create unique solutions and agile services with advanced capabilities. You’ll be able to combine embedded intelligence with the increasing infrastructure virtualisation.

Many different organisations help to define radio access network standards. These include industry alliances and well-structured, formal groups that work together for a common goal of improving the quality of wireless networks.

Open RAN is appealing for its ability to allow users the freedom of choosing hardware and software from different vendors. It also provides businesses with a way out against supplier lock-in where one has to keep buying products only available by few large suppliers. O-RAN will directly impact the foundation of the next-generation wireless infrastructure. Increasing RAN virtualisation and data-driven intelligence. Quicker innovation and reduced complexity will also positively impact deployment and operational costs.

 

O-RAN Alliance membership is open

The O-RAN ALLIANCE, which is at the forefront of defining the next generation RAN architecture, was started by operators in early 2019. They wanted to accelerate product delivery by supporting an open architecture and standardised interfaces. Soon, major OEM component manufacturers joined in.

Today, the O-RAN Alliance counts over 300 members: at least 29 operators and a broad group of vendors. Big names like AT&T, China Mobile, Deutsche Telekom, NTT DoCoMo, and Orange can be found among its founders. The membership is open to all mobile operators, all vendors, and any research and academic institution that wants to contribute to the O-RAN effort in a significant way.

 

Efficient use of resources

With 5G, the network will be undergoing a densification process. Operators are pushing for this because standardised structures will help increase resource utilisation in their networks.

Because the traditional fronthaul technology does not scale well to support the increased demand and bandwidth required by the 5G network, new technologies like virtualisation are now available at a level of maturity that allows integration into the radio access network. O-RAN will leverage these new technologies to maximise performance and to optimise capital and operating expenditures.

New split levels, like the LLS split option 7-2, will help optimise the bandwidth on the fronthaul interface. It will also allow for better scalability. The fronthaul, which was earlier based on proprietary protocol and transport, is now evolving to switched Ethernet-based network.

 

New specifications are being released

The evolution of the O-RAN alliance specifications shows that we are dealing with a vibrant, developing ecosystem. As companies build equipment, they discover where the specifications need improvement. When ambiguities or interoperability issues crop up in the specifications, they submit change requests to O-RAN to refine the specifications. They also spot the needs for new capabilities to improve performance and optimise the network bandwidth. It’s like any software code that goes through iterations and gets optimised over time.

 

Does O-RAN create any technical challenges?

O-RAN has many technical challenges to overcome. Some experts predict that O-RAN will become more complicated as wireless technology moves forward. It’s also possible that O-RAN could create new issues if not implemented correctly, such as increased interference or poor bandwidth efficiency.

Network specialists must take into account these new demands on speed and bandwidth when designing their networks. The first challenge is how to provide a high quality of service (QoS) for diverse data types; this means ensuring that all data types get the same level of service despite different priorities. For example, voice will need a higher QoS than text messages or pictures because it needs to be delivered in real-time with less latency than other data types.

Overall success comes down to whether or not these challenges can be successfully addressed by engineers and developers alike.

 

Challenges in virtualisation

With O-RAN, there is a push to virtualise as many things as possible. However, virtualisation leads to performance impacts, which one must consider when transitioning from physical servers into software-based systems.

The CU is perfect for virtualisation. While it looks like a typical data centre, it has the added benefit of hardware assistance in performing complex signal processing tasks. Whether the hardware assist should be ASIC, FPGA, or GPU is still under much discussion.

 

Challenges in network

In 4G, the fronthaul is a dedicated fibre running a proprietary protocol CPRI. Everything, including the zeros, is sent to the radio unit, which means that the scale of the fronthaul network depends on how many antennae you have and the sampling rate. So even when there’s no traffic, there’s still a lot of bandwidth on the fronthaul.

In 5G O-RAN, it is ethernet with the new 7-2 split. The bandwidth is needed only when there’s traffic. The radio receives only the data that is going to be transmitting the actual data. Nothing gets sent during quiet time. The ethernet also allows virtualisation, which means that you can switch traffic from one node to another and spin up new instances as you need. This is not possible in the 4G network.

That ethernet has many switches – many low-cost switches – can be a real challenge because 5G is a time-sensitive network, and you need low latencies.

 

Challenges in interoperating

The O-RAN network can consist of radios from one vendor, DUs from a second vendor, BUs from a third vendor, RICs from yet another vendor, and all these pieces will have to work together. The O-RAN Alliance’s work is to define interfaces and protocols to make it possible that all these different pieces from different vendors can work together.

The specifications are, however, still very much a work in progress. The challenge is that there’s always room for interpretation, even for basic things like data transfer and data format, even with detailed specs. As a result, one vendor may interpret a feature one way and another vendor in another way. This is why testing the network will be even more critical in O-RAN than it was with 4G.

 

Challenges in the management plane

The management plane is vital for the fronthaul. It is the system element that configures, monitors, and provides management, monitoring, and configuration services to all layers of the network stack and other system parts.

Often, the management plane is the last thing to be put in, which can mean that it lags behind the real-time parts of the network. The DEU must be tightly synchronised with the radio unit, down to micro- or even nanoseconds. The specifications state that this is done with precision time protocol and synchronised ethernet. Because real switches in real networks are involved, it can sometimes be tricky to get these through, especially when some of the implementations are still not mature.

Timing is probably one of the biggest challenges for getting all the “bits and bobs” to interwork.

 

Conformance testing vs interoperability testing

Conformance testing takes each component in isolation. Any supported feature is looked at and exercised to ensure that it is conforming, doing what it says it’s going to do. Conformance testing is one of two types of tests conducted on mobile devices, such as smartphones or tablets used by consumers. It is not to be confused with compliance testing, which ensures that an individual device meets all applicable regulatory requirements when manufactured and distributed for sale in a particular country or market region.

Interoperability testing is a process in which network equipment from different vendors is tested to ensure compatibility with each other.

Both conformance testing and interoperability are needed: conformance testing to make sure the individual components work in isolation and interoperability testing to ensure that things work as a group.

 

 

The responsibility is shifting from the vendor to the service provider

For 4G, doing the interoperability testing was enough because everything came from one vendor. Now, it’s up to the service provider to put things together. This means they are also responsible for making sure that all these different parts work together as intended.

Going with interoperability testing alone would be like using untested parts to put together a space shuttle. At the start, the shuttle would function ok. But, when the going got tough, you’d start seeing parts caving in or blowing out – not doing their bit for the whole – with disastrous consequences.

As 5G networks are being developed, service providers will have to take on more responsibility for implementing new technologies into their networks. This shift from vendor-developed to service provider-developed solutions is a trend that will likely continue in the future as 5G networks are deployed in response to increasing demand for faster connection speeds and increased network capacity.

The benefits of this shift include:
• Shorter deployment timeframes.
• Reduced risk of vendor lock-in.
• Less dependence on third-party hardware suppliers.

The challenges with this shift include higher upfront costs due to the capital investment required when building out infrastructure.

 

Importance of testing

Open radio access network development will make testing how everything works together increasingly vital. Running realistic simulations covering all aspects of network communication will help identify potential issues before deployment or during field trials and avoid costly mistakes and poor customer ratings.

You’ll need network emulation tools that can be applied at any stage of development to see what your final product will look like with real-world conditions in mind.

Our team has been developing network emulating tools since the early days of LTE design. As a result, we’ve seen first-hand how they save precious time and prevent costly fixes later down the line.

If you’re looking to take your development one step further by addressing all possible issues before deployment, see how to get ready for real-life challenges with our network emulation tools and request a demo.