The telecoms industry is full of acronyms. But onlookers should take note of one in particular, which experts said we’ll be hearing a lot more about in the coming months and years as 5G rollouts move ahead: dynamic spectrum sharing (DSS).
What is DSS?
Part of the 3GPP’s Release 15 specifications, DSS is rapidly becoming one of the stars of the 5G show.
In April, T-Mobile US and Verizon both revealed plans to deploy the technology in 2020, with the latter’s CEO Hans Vestberg declaring it “one of the most important features” of the operator’s 5G strategy. European operator Swisscom similarly highlighted DSS as a key part of its plan to achieve nationwide 5G coverage in 2020.
But what is DSS?
Historically, multiple cellular technologies could not be deployed simultaneously on the same chunk of spectrum: each technology (2G, 3G, 4G) was deployed in its own designated block. When operators wanted to upgrade from one technology to another in a given block, they needed to push the old users off that spectrum and reserve either the whole or a portion of the block for the new, regardless of whether the latter had fewer users.
This process made recycling spectrum both time-consuming and inefficient.
However, Paul Challoner, VP of network product solutions for Ericsson North America, explained to Mobile World Live DSS changes the game by allowing operators to deploy both 4G and 5G in the same block, and dynamically allocate the right amount of spectrum to each based on demand.
Using the technology, he said operators can avoid setting aside large chunks of precious LTE spectrum for 5G before it is fully needed, and instead gradually load 5G users onto their LTE bands.
“Imagine I have a fully deployed network with lots of subscribers and now I have my first 5G subscriber. If I can’t share the band, I would have to put up a new radio or allocate a new radio channel on an existing radio just for that user. If you are in a spectrum crunch situation in the lower and mid bands, which many operators are, that’s really wasting capacity. So that’s the problem that DSS solves.”
Daryl Schoolar, practice leader for Ovum’s Intelligent Networks team, noted the technology represents an attractive option for operators looking to rapidly roll out broad 5G coverage.
“Generally, we think this is how many operators around the globe are going to get 5G into lower bands. This gets you into low-band without having to buy more spectrum, or spend money trying to move people out of spectrum.”
Indeed, Challoner said Ericsson had seen a huge amount of interest in DSS, particularly from operators in spectrum-constrained markets. He noted North American operators have led the charge, followed by operators in Asia and Europe.
Challoner said DSS software for the network will be ready by the end of 2019, but added compatible handsets won’t become broadly available until the first half of 2020.
Even as operators charge ahead, GlobalData principal analyst Lynette Luna noted DSS is a temporary solution:
“The overall advantage is that a carrier without lots of spectrum dedicated to 5G can get it to market…For a company like Verizon, it really has no choice but to play up DSS as it’s waiting for the C-band to open up.”
She noted operators will still need dedicated 5G spectrum in low-, mid- and mmWave-bands to rollout a complete 5G network. “You need a broad swathe of spectrum to accomplish the data speeds and capacity required, and this will eventually include refarmed 3G and 4G spectrum.”
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