The mobile industry body says coverage is set to increase from 27% at the end of last year to 35% by the end of this year.
GSMA expects the number of LTE connections to rise from 490 million to 875 million by the end of 2015.
As of the end of January 2015, the number of 4G operators stood at 352 globally.
"GSMA Intelligence forecasts that global 4G connections will grow at more than 30 per cent a year (CAGR) from 2014 to 2020," said Hyunmi Yang, chief strategy officer at the GSMA.
"There is a tipping point we typically see when 4G grows to account for more than 20% of a market that drives adoption of new services. This 20% threshold has already been reached in some markets, and is forecast to happen by 2017-18 on a global basis, which will have a huge transformational impact."
In terms of geographic reach, Asia-Pacific has the largest number of 4G connections at 232 million, followed by North America at 157 million and Europe at 69 million.
China is on track to reach 300 million 4G connections by the end of the year, overtaking the US to become the world’s largest 4G market.
