T-Mobile says dynamic spectrum sharing needs low- and midband spectrum

Dynamic spectrum sharing (DSS) is the hot new technology du jour in wireless communications. Top executives from both Verizon and T-Mobile mentioned it recently on their quarterly earnings calls. With DSS, an operator doesn’t have to split a band of spectrum between 4G LTE and 5G. Instead, as the name implies, it can share that spectrum between the two technologies. 

Verizon CEO Hans Vestberg said, “One of the most important features that I have talked about is of course the dynamic spectrum sharing that will come during next year … and then you don't need to allocate certain spectrum to certain technology,” according to a Seeking Alpha Transcript.

But, on T-Mobile’s earnings call a few days later, CEO John Legere poked holes in Vestberg’s DSS comments. Legere said, “The interesting piece is to get to dynamic spectrum sharing, you’ll deploy new radio. So, I am yet to hear anybody in Verizon declare that they are deploying new radio in low-band or midband. There’s some very limited backwards compatibility on very recently deployed radio for DSS. And if you want to use DSS, you are effectively committing in the same breath to rolling out 5G in mid- and low band. I haven’t heard that yet as a declared strategy for a Verizon.”

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Legere was pointing out that Verizon has been deploying some 5G New Radio (5G NR) equipment, but it’s doing so in the millimeter wave (mmWave) spectrum, which has never been used for 4G LTE. So, in that spectrum, there is no need for “spectrum sharing.”

Verizon, which is an Ericsson customer, began installing 5G NR equipment before the 3GPP Release 15 so that it could move from pre-standard 5G to standardized equipment with a software upgrade.

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BTIG analyst Walter Piecyk said in an interview with FierceWireless, “All of the 5G NR RF they’ve deployed is in mmWave spectrum. We’re still early stage."

Lack of midband 

Piecyk is concerned about the lack of midband spectrum in the United States. “Typically when new technologies are rolled out, operators have used new spectrum rather than potentially negatively impacting their existing networks by taking away existing spectrum," he said.

But, he added that given the limited amount of spectrum that US wireless operators have, it’s going to be very important for them to use DSS in order to roll out 5G. “DSS can flip back and forth,” he said. “It’s the only way to make this work, unless they can get mmWave to travel greater distances. Otherwise, you’ll be taking away a vital LTE resource.”

Piecyk has blogged that the FCC needs to move on midband items. He said the agency is sitting on several spectrum concerns: CBRS, Ligado Networks, Dish Networks and C-band. “None of these are finalized,” he said.