A new standard for Dynamic Spectrum Sharing

Software bugs are part and parcel of product development. You identify it, fix it, move on. However, what happens when you discover a bug in the 5G specification at the eleventh hour of 3GPP standardization? And when that very bug can affect performance of a business-critical product by up to 15 percent? In this blog, Mattias Frenne, a principal researcher and an Ericsson RAN1 delegate for 3GPP, reveals exactly what happens next.

Ericsson in the lead

Principal Researcher

Principal Researcher

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This blog entry is part of Ericsson's Standardization Stories series.

My position as an Ericsson delegate for 3GPP takes me across the world – from Busan in South Korea, via Athens in Greece, to Vancouver, Canada – to help secure the best possible standards across telecom. It's a coming-together of hundreds of actors from across industry, government and other sectors to jointly develop the best possible technologies into a shared global standard.

Last year, as with many of the previous years, I was part of the Ericsson RAN1 delegation (comprising approximately 25 expert delegates) quietly working on, among other things, Ericsson's business-critical Dynamic Spectrum Sharing solution as part of the upcoming 3GPP Release 15. The outcome would ultimately form the final specifications for the 5G standard and would follow years of daily technical debate and discussion across hundreds of stakeholders.

In mid-autumn 2018, I received a phone call from a colleague in an Ericsson product development team that was looking into the fine details needed to support Dynamic Spectrum Sharing. By this stage, the 5G New Radio (NR) specifications were all but complete, the hardware design all but settled and the standard all but good to go.

I took the call, spoke for a couple of minutes and then hung up.

We had a problem.

The how and why of Dynamic Spectrum Sharing

To gauge the scale of the problem, it’s important that you know a little more about the strategic importance of Dynamic Spectrum Sharing as part of the migration story from 4G LTE to stand-alone 5G. 

Dynamic Spectrum Sharing is a unique piece of Ericsson innovation and the piece in the puzzle which makes it easier for our customers to be first to market with nationwide 5G coverage through only a single software upgrade. It allows them to dynamically switch between both LTE and 5G NR coverage on existing 4G assets. In fact, the technology is so intuitive that it would be easy to overlook the years of complex research and development which went into the product. 

From the early stages of our research into 5G NR, when we began to map 5G transmissions to time-frequency resources, we created the possibility for holes in the 5G transmission grid which could be used for 4G LTE transmissions. This means that, by simultaneously sharing frequency bands which are already available today, service providers can fire up 5G on existing LTE bands without actually shutting off LTE. This means that, as well as having the option to roll out 5G on existing Ericsson 4G hardware, operators can keep the LTE network up and running while starting 5G. This can truly make it easier for thousands of operators to transition to 5G in the coming years.

To find out more about the technology, visit Ericsson’s Spectrum Sharing page.

An unprecedented challenge awaits

Back to that phone call.

During the systemization phase, we identified a specification bug which led to some 5G reference signals colliding with those of 4G, meaning that a 5G terminal would not be able to receive the data transmission. A potential workaround for this bug would likely result in a huge 15 percent drop in expected NR downlink throughput whenever Dynamic Spectrum Sharing was used. The stakes couldn’t have been higher. With such a drop, the full potential of Dynamic Spectrum Sharing would never be realized.

However, the real challenge wasn’t the fix itself. This was swiftly identified and resolved by our standardization team, following consultation with the major chipset vendors. I won’t get too technical, but we found a solution which would allow the 5G devices to receive the data transmission without the need for the 15% throughput drop. The real challenge would be in persuading all other stakeholders to push through such an amendment so late in the game – something unprecedented in the history of 3GPP. 

Release 15 completion was literally weeks away. Actually, the NR completion date had already passed in June 2018 and specification work was now in maintenance mode whereby only very minor non-critical fixes were allowed. The spec was “frozen” to prevent any delay to eventual product launches. A consensus to modify the specifications would require extensive negotiations and convincing of many different stakeholders across vendors, customers and the major 3GPP stakeholders. Yet, even so, there would still be no guarantee of a desirable outcome for our team.

Securing a consensus at the eleventh hour

And so, with commitment and conviction, our delegation got to work.

Drawing on Ericsson's wider trust in the 3GPP domain, our delegates began an extensive campaign across several fronts together with our product management team. With the right solution in place, and following weeks of intense technical discussions with major 3GPP partners, the 3GPP RAN1 working group agreed by consensus to our late change request on the specification. Approved just a matter of weeks before the final close of implementation of Release 15 NR in products, this unprecedented feat looks set to secure a significantly easier migration to 5G for thousands of operators – and, by extension, consumers and industries alike – over the coming years.

For me, achieving such a feat was a clear demonstration of the credibility, trust and integrity which Ericsson is known for across the wider telecom industry.

Here's to many more successes on the forthcoming 3GPP Release 16.

About Ericsson and 3GPP standardization

3GPP is the body responsible for global standardization of 2G, 3G, 4G and 5G mobile networks. As a technology leader with an extensive patent portfolio, Ericsson places strategic importance in leading 3GPP initiatives so as to align new telecom standards with our vision for the future. In our series of Standardization Stories, we showcase that, through leadership and innovation, Ericsson plays a leading role in building today's and tomorrow's global eco-system of Core and Radio Access Networks.

Want to find out more?

Read our previous standardization blog articles to explore Ericsson's role in paving the way for 5Ghow new mobile generations are created and, more specifically, the origins of 5G standardization.

Gain a broader view on Ericsson’s role in shaping future telecom standards.

Read more about Ericsson’s Dynamic Spectrum Sharing solution.

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