SAN JOSE, Calif. – The 3GPP released a set of at least eight change requests for its specification for 5G cellular networks. The updates are not expected to delay commercial rollouts expected in the next few weeks and months, but they underscore the intensity of the engineering going on quietly in the background as carriers race to turn on their first 5G networks.

The 3GPP marked the eight change requests released this month as non-backwards compatible. So, carriers and their suppliers will have to agree whether they will standardize on the 3GPP’s 5G spec released at its June 2018 plenary, the new spec from the September plenary or a hybrid.

The changes come at a time when carriers are already deploying and testing infrastructure that will make up commercial offerings. In parallel, handset makers are finishing work on smartphones supporting the wide variety of bands from 600MHz to 39GHz expected to be used by 5G services turning on before April.

“We have not announced which version [of the 3GPP spec] our products will be based on… these changes are relevant to both base stations and [handsets], but there is no need for any new chip sets,” said Lorenzo Casaccia, who oversees 3GPP standards work for Qualcomm.

The eight changes are all marked ASN.1 which means they are at the software layer, Casaccia said. At least five of the eight are marked as coming from 3GPP’s RAN-2 group that typically defines functions implemented in software, he added.

“No spec is bug free. I can guarantee there will still be small corrections in the next version of spec, however we are reasonably confident there will not be any critical ones,” he said, suggesting most carriers and suppliers probably will base initial rollouts on the September spec.

A representative of one other chip company who asked not to be named agreed the latest 3GPP changes could be handled in software or firmware.

Separately, a Nokia executive described carriers demands for 5G systems as “extremely aggressive” with all four top U.S. carriers now planning to turn on 5G networks in the first quarter or even before the end of this year. “I get almost daily updates with numbers of sites that have air interfaces working even though launches have not happened yet,” said Mike Murphy, chief technologist for Nokia in North America.

As part of the rush to market, the 3GPP “tried to push the [5G New Radio] spec too quickly, targeting December last year, and as a side effect a lot of change requests are coming through. People thought all the non-backwards compatible ones would be finished in June," he said.

3GPP 5G specification changes September 2018

A list of eight 5G spec changes the 3GPP released this month. Click to enlarge. (Source: Nokia)

The outlook for 5G smartphones and mmwave

Murphy of Nokia expects by April handsets will ship supporting U.S. 5G networks at 600MHz (for T-Mobile), 2.5GHz (for Sprint) and 28- and 39GHz (for Verizon and AT&T).

Whether any of the smartphones ship before the end of the year “is touch and go,” Murphy said. In addition, supporting both low and high bands for roaming in first-generation handsets “seems to be challenging at the moment… depending on the manufacturer, you get different answers,” he added.

Qualcomm and Ericsson announced earlier this month they made successful 5G links using an Ericsson base station and a Qualcomm smartphone reference design.

“There is really solid progress. I think we will see mmwave handsets next year, but which bands they will support is an OEM decision,” said Casaccia of Qualcomm.

New bands are still emerging. The U.S. Federal Communications Commission said earlier this year it will auction spectrum for both 28GHz and a new 24GHz band that may require new RF front-end chips.

Outside the U.S., many carriers are focusing their first 5G launches on the 3.5GHz band. However, in the U.S. only a 3.55-3.7GHz slice of that band is available, and so far it is reserved for LTE. The U.S. may approve 5G at 3.7- and 4.2GHz, but “probably not until 2020 or 2021,” Murphy said.

For carriers, one challenge is getting approvals to set up small-cell base stations needed to support mmwave frequencies, typically in crowded urban environments, he added.

— Rick Merritt, Silicon Valley Bureau Chief, EE Times