BERLIN — In the 1989 movie “Field of Dreams,” a farmer builds a baseball park in an Iowa cornfield, believing that “if you build it, he will come.” In a way, the global mobile industry is making the same leap of faith with Long Term Evolution, the technology behind the super-fast wireless broadband networks now being switched on around the world.

In October, mobile operators are building 174 LTE networks in 64 countries, according to the GSA Association, an industry group of network equipment makers based in Zurich. With its faster speed and greater capacity to handle the explosive growth in mobile data traffic, operators are wagering that LTE will be critical to future profitability.

This year, operators are spending $3 billion to install LTE base stations and related equipment, according to ABI Research, an industry analyst in Scottsdale, Arizona. By 2016, ABI forecasts annual LTE spending will be $16.5 billion.

It is a big wager — and one largely made on speculation. Much of this initial investment is being made before the release of a single LTE-capable cellphone, the first of which are not supposed to reach consumers in bulk until next year.