BARCELONA, A move by cellphone operators to use airwaves freely available in the same bandwidth as Wi-Fi networks has raised concerns that consumers' home Internet service could be disrupted, along with connected devices such as security monitoring systems.
For the operators, who have spent billions of dollars on acquiring licensed frequencies, using the new LTE-unlicensed (LTE-U) technology to tap into higher-frequency Wi-Fi spectrum could prove a relatively cheap way to cope with the explosive growth in data traffic, particularly within buildings.
"It is the Wild West at the moment. Anyone can use it and the parameters change a lot more quickly than when you use licensed spectrum," said Todd Mersch, co-founder of start-up XCellAir, which helps telecoms companies to make use of Wi-Fi.
But the risk of a clash can still be avoided, he says, as only around 15 percent of the Wi-Fi spectrum, which is in the 5 gigahertz (GHz) range, is currently being used.
The technology to use Wi-Fi spectrum for mobile on a large scale is far from ready but the first operational connections could be in place in less than two years, industry experts say.
U.S. network operator Verizon is currently running tests with chipmaker Qualcomm and Deutsche Telekom completed a trial last year in the German city of Nuremberg.
Deutsche Telekom says the Nuremberg test using a technology known as LTE-Licence Assisted Access (LAA) showed no problems with interference.
"It would be bad if we created something new that ended up pushing others out, wouldn't it?" Bruno Jacobfeuerborn, chief technology officer Deutsche Telekom, told Reuters.
But if there was interference the symptoms could go beyond simply disrupting a connection, says XCellAir's Mersch, pointing to an incident he encountered in his own work involving Wi-Fi signals.
"Interference caused the home security system to increase its power transmission to each of the little sensors on the windows and doors," he said.
"Their batteries were dying faster, so our customer constantly had these false alarms and battery alarms."
In the early days of Wi-Fi, consumers faced similar issues as some household electronics including microwave ovens, baby monitors, cordless phones and even some older Bluetooth devices interfered with the home Wi-Fi network.
Watching a streaming movie over the Internet would, for instance, be interrupted when the cordless phone rang.
Nest, the wireless home security company owned by Google's parent Alphabet, still warns users that microwave ovens and other appliances can interfere with its systems. Certain television sets, even when turned off, can also affect Wi-Fi signals, it cautions.
The only solution has been for consumers either to buy a new dual-band Wi-Fi router or to replace their existing consumer electronics with more Wi-Fi friendly devices.
U.S. digital civil rights organization Electronic Frontier Foundation says nobody knows how LTE-U and Wi-Fi will coexist if LTE-U is deployed on a large scale.
Google last year voiced concerns in a white paper to the Federal Communications Commission (FCC) that LTE over unlicensed spectrum had the potential to crowd out unlicensed services.
"Holders of licensed spectrum shouldn't be able to convert the unlicensed 5 GHz band into a de-facto licensed spectrum band, and certainly they should not have the ability to drive out other unlicensed users," Google said.
However, with monthly global mobile data traffic expected to reach 30.6 exabytes by 2020, telecoms operators are desperate to find more capacity to satisfy users of data-guzzling smartphones.
Global mobile data traffic increased by 74 percent in 2015, reaching 3.7 exabytes per month at the end of the year, up from 2.1 exabytes per month at the end of 2014, according to networking company Cisco.
But while LTE-U offers some sort of a solution within buildings the very fact that the spectrum is freely available could lead to overcrowding on these frequencies, making the networks as well as home Wi-Fi unreliable.
And if cash-starved governments decide to regulate Wi-Fi spectrum, operators could end up with stranded investments.
Tony Brand, director of marketing and industry development at the Wireless Broadband Alliance - which seeks to promote interoperability between operators in the Wi-Fi industry and improve the user experience, sums up the operators' dilemma.
"The good thing about unlicensed spectrum is that is unlicensed. The bad thing is, it is unlicensed."
(Additional reporting by Eric Auchard and Peter Maushagen; Editing by Greg Mahlich)