By Peter Cohen

The rollout of 5G continues globally. The next step for carriers is the transition from Non-Standalone (NSA) 5G to Standalone (SA) 5G. 5G SA promises operators a telco cloud with the flexibility and scalability to create new services and new revenue opportunities. But 5G SA implementation is rife with technical and operational challenges.

Globally, Communication Service Providers (CSPs) are in different stages of 5G SA implementation. There are already lessons to learn. Dave Bolan, analyst with Dell’Oro Group, explored some of these topics as moderator of a panel of 5G SA stakeholders for RCR Wireless News’ recent Telco Cloud Forum 2022. Bolan spoke with representatives from Intel, AT&T and NTT DoCoMo to explore 5G NSA to SA migration issues.

First, do no harm

Director of RAN Engineering at AT&T, Sinan Akkaya cautioned carriers to consider standalone 5G’s Dynamic Spectrum Sharing (DSS) carefully. There’s work to be done figuring out the appropriate load balance between 4G and 5G traffic. “We generally don’t think about the spectrum,” he said.

“You need to think about optimizing your dynamic spectrum sharing features in such a way that you should not hurt the customer who’s on a 4G platform,” said Akkaya.

Carriers need to keep their focus on satisfying all customers, not just ones making the 5G transition themselves.

“Customer experience is not necessarily only about 5G and SA. We have a mix of customers. Probably 70 to 80 per cent globally, maybe even more subscribers today, do not have SA-compatible phones,” Akkaya said.

DSS enables carriers to deliver more 5G services to compatible equipment, but under peak network conditions may hurt 4G LTE performance.

“This is pretty much the only challenge in front of us right now,” said Akkaya, describing it as “a RAN problem.” Akkaya said that AT&T is working through the problem with new RAN features and optimization techniques.

“There’s going to be quite a lot of optimization effort going into this,” he added.

Get more from dual-core

Senior Business United Director of 5G and Wireless Core Infrastructure, Network and Edge Group, Intel, Chandresh Ruparel noted the trend towards dual mode architectures which enable 4G LTE and 5G SA cores to work side by side.

“The vendors are coming up with some very innovative solutions,” he said. “You can have elasticity, in terms of the capacity you can handle for 4G and 5G subscribers.”

The switch to a cloud-native standalone 5G core requires carriers to rethink key performance indicators beyond user plane and control plane performance, he said.

“All the capabilities in the infrastructure need to available to address the KPI [key performance indicator] around performance,” he said.

Security, automatic network resource failure recovery and other factors must be exposed, observed, measured and optimized, he said.

Reduce latency everywhere

Latency isn’t just a problem to solve at the near and far edge, advises General Manager of Radio Access Network Development, NTT DoCoMo, Sadayuki Abetta. The company activated 5G SA service for its enterprise customers in 2021 and will activate 5G SA service for consumers this year, he said.

Abetta sketched out in detail how NTT DoCoMo’s SA network is set up.

“We have two sub-six bands: 3.7 and 4.5, with 100 megahertz [mHz] bandwidth for each. So we can provide more than 1 Gbps in single-band operations. This is much higher than LTE single-band,” he said.

Reducing end-to-end latency is a pressing challenge for NTT DoCoMo, said Abetta. There isn’t a single roadblock — the company is taking a holistic approach. It’s looking at ways to improve latency in transport, core network and processing between the server and terminal, he said.

NTT DoCoMo is investing resources to reduce latency throughout the network to optimize 5G SA performance. “We need to improve end-to-end latency,” he said.

“So not only to improve the radio side if it’s not ok, but we need to improve the processing to provide good applications,” he said.

Standards and a strong ecosystem

AT&T’s Akkaya had the last word. He encourages carriers to get the most out of network automation. We’re not going back to the 1990s, he warned, with “hundreds of engineers working behind the curtain.”

Akkaya also thinks transparency is important to carriers when it comes to security. Transparency enables problems to be identified and resolved that much faster.

“The most secure system is the open system,” said Akkaya. “I’d rather have an open system, an open platform that is challenged every single day, so that I have the most secure system.”

Akkaya also told carriers to mind the environment. The massive scale of distributed standalone 5G telco cloud architectures needed to power the near and far edge may create power-hungry “BBU farms.”

“We’re not only living in the age of AR, VR and autonomous vehicles but we’re living in age of climate change,” he said. “Power consumption models need to be under control. We need to be very smart about it.”

The third is for the industry to organize around strong, meaningful standards.

“We need a strong ecosystem, and a strong ecosystem will definitely rely on standards,” said Akkaya.