As 5G networks continue to spread across the world — faster than some predicted, but slower than others might prefer — physically upgrading existing 4G towers has proved to be a significant bottleneck, leading to massive expenses, permitting controversies, and shortages of cell tower climbers. Today, Nokia released an alternative that will help carriers rapidly convert 4G infrastructure to 5G: a software update that can convert 5 million existing 4G tower radios to 5G without the need for tower climbs or site revisits.

According to the company, the software update is available now for approximately 1 million 4G radios, and will expand to 3.1 million by the end of 2020, then over 5 million in 2021 — big numbers that should enable country-scale 5G deployments. To put those numbers in perspective, China expects that 600,000 5G base stations will cover most of the major cities in its huge landmass by year’s end, so physically smaller countries could offer edge-to-edge 5G with far fewer radios. Nokia estimates carriers’ savings from the software update to be tens of billions of euros, coupled with reduced time for “immediate” and “seamless” 5G deployments that will help businesses and consumers start using 5G right away.

If there’s any issue with the software upgrade, it’s a fairly obvious one: The upgraded Nokia radios aren’t magically gaining new frequency support for the fastest flavor of 5G, millimeter wave transmissions in the 24-39GHz range. Instead, their existing 4G radio frequencies — think 2.5GHz and below — are going to be re-farmed for 5G, either entirely or in a dynamic spectrum sharing (DSS) arrangement between 4G and 5G. Notably, AT&T was among the earliest carriers to suggest that it would turn on 5G via tower software updates “when it’s ready for prime time.”

The re-farming process will enable both 5G where 4G already exists, Nokia says, and enhanced 5G performance in areas with early dedicated 5G infrastructure. “Most” of the 4G frequency division duplex (FDD) radio units previously purchased by Nokia’s 359 existing 4G customers can be upgraded to 5G, which will spur rapid development of lower band 5G infrastructure. Moreover, the new software will support carrier aggregation, enabling 5G devices to simultaneously use two radio frequencies at once for higher speeds — one frequency might be purely low band 5G, while the other could be split between 4G and 5G with DSS, but together they’ll outperform 4G by a non-trivial margin.

Nokia isn’t disclosing the cost of the software upgrade, but says it’s “cost-effective” and offers “high value” to existing customers, cutting the need for expensive site engineering and re-visiting. Assuming the updating process is as straightforward as claimed, low band 5G could begin rolling out for some carriers in the very near future, and expanding with others — such as T-Mobile — that have already started offering low-frequency 5G service across multiple cities.

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