Teenagers are the major consumers of data for smartphone video streaming be it over Wi-Fi or through cellular data, according to a new study.

Use of cellular data among teenagers for smartphone videos grew by 127% in just 15 months (2014-15), according to the latest edition of the Ericsson Mobility Report.

“Over a period of four years (2011-15) there has been a 50% drop in the time teens spend watching videos on a TV screen, and in contrast an 85% increase in those viewing videos on smartphones,” says the study.

The survey also predicted that the Internet of Things (IoT) was likely to overtake mobile phones as the largest category of connected device by 2018.

IoT is a system of interrelated computing devices, mechanical and digital machines, objects, that are provided with unique identifiers and the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction.

According to the study, between 2015 and 2021, the number of IoT connected devices is expected to grow by 23% every year, of which cellular IoT is forecast to have the highest growth rate.

Of the 28 billion total devices that will be connected by 2021, close to 16 billion will be IoT devices, it said.

“IoT is now accelerating as device costs fall and innovative applications emerge. From 2020, commercial deployment of 5G networks will provide additional capabilities that are critical for IoT,” Rima Qureshi, senior vice president, chief strategy officer, Ericsson, said.

The study also pointed an increase in the subscription for smartphones, which is predicted to surpass that of basic phones by the third quarter of this financial year.

Meanwhile, there has been a phenomenal growth of mobile technology in a relatively short period of time, with 5 billion “unique users” across the globe.

“By 2021, smartphone subscriptions will almost double from 3.4 billion to 6.3 billion,” the study said.

The increase in subscription accelerates data consumption per subscriber, which in turn results in rising mobile data traffic.

“Mobile data traffic in India is expected to grow fifteen times by 2021,” the study said.