Communication technology has improved exponentially over the past decade, and the current level of smartphone proliferation would have been hard to predict when the devices first emerged. In addition to the boom in devices being used, there has been an increase in the number of communication networks through which data can travel. But these networks are in competition with each other, and it could slow down your devices, according to research from the University of Chicago.
Wi-Fi uses a shared spectrum band that is “unlicensed” and nearly anyone can use it if they follow the Federal Communications Commission’s transmission rules. Cellular phone systems operate on a different band of spectra that the FCC licenses for use exclusively by the cellular operators who purchase them, such as AT&T, T-Mobile, or Verizon.
Because of their exclusivity, the licensed bands experience little interference and offer fast, reliable service. But the number of cellular network users and the amount of data they use has increased significantly in the last five years, and service providers are using up their available licensed bands, said Monisha Ghosh, research professor at the University of Chicago. Purchasing more is extremely expensive, so service providers have started migrating to the unlicensed spectrum via a mode called licensed assisted access, or LAA.
LAA operates on the same bands used for Wi-Fi. The researchers aimed to figure out how this coexistence on the unlicensed spectrum affects both Wi-Fi and cellular users.
They spotted an outdoor LAA station on the University of Chicago campus where Wi-Fi is also in use and set up an experiment there to see how the LAA and Wi-Fi coexistence works. They set up numerous devices to access the different networks and used multiple types of data — low data consumption activity like looking at a website to high-consumption activity like streaming video.
The researchers found that each system’s performance decreased when the two are used simultaneously. Negative effects include slower data transmission, less data transmitted, and reduced signal quality. However, the effects were not observed equally.
“What we were surprised by was how much more Wi-Fi suffered in comparison to LAA,” Ghosh said.
When LAA was used at the same time as Wi-Fi, users’ Wi-Fi data transmission decreased by up to 97%. LAA data transmission decreased 35% when Wi-Fi was also in use.
As more devices continue to access these networks and use larger amounts of data, users increasingly could experience slower operating speeds and reduced data use. The problem is not yet prevalent, though, because this is such a new, evolving realm using new technologies, Ghosh said.
“Right now, not too many people have the newer phones that can take advantage of the newer systems … and LAA usage right now is not very heavy,” Ghosh said. “We probably won’t see an effect on Wi-Fi right away. But just looking at the increase in LAA deployments and people buying new phones all the time … we expect this type of scenario will be played out more in the future.”
This research could help to inform regulations and standards for communication and unlicensed spectrum coexistence.
“The objective of this research is to evaluate the current parameters and offer guidance on how these can change to make coexistence better in the future,” Ghosh said.
Coexistence is expected to first be an issue in urban areas because that’s where LAA currently is being employed most widely and where Wi-Fi deployment also is widespread, Ghosh said.
The research could prompt places like universities to examine how to improve their Wi-Fi coverage. Plus, last year the FCC released a 6 GHz spectrum band for unlicensed use; the coexistence lessons learned on the 5 GHz spectrum could influence the future of the 6 GHz band.
Future research also could examine whether coexistence affects energy consumption and if there are opportunities for increasing energy efficiency.
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