Barcelona braces for Mobile World Congress (pictures)

With the rising importance of smartphones, the Mobile World Congress show has become an important event on the annual trade show circuit. It's mostly devoted to mobile phones and the networks that support them, but it's expanded to include tablets, connected cars, the Internet of things, and wearable computing. Samsung bought advertising space around the entrance to the Fira Gran Via in Barcelona, where Mobile World Congress takes place.

Mobile World Congress, a big show with tens of thousands of attendees, has barriers set up to channel attendees toward the registration area.

Chinese phone and network gear manufacturer Huawei entertained Barcelona residents and visitors at the Placa Catalunya with music on Saturday, two days before Mobile World Congress officially began.

Samsung is expected to unveil its new flagship Android phone, the Galaxy S5, during Mobile World Congress on Monday at one of its "Unpacked" events. The company also likely will show new smartwatches.

Sony purchased much of the advertising space between the train station and the Fira Gran Via, where Mobile World Congress takes place. Here, it shows off its wearable computing device, the Core.

The Mobile World Congress show moved to Barcelona's Fira Gran Via in 2013, a more spacious venue than the earlier site downtown.

For travelers coming to Mobile World Congress, the show begins at the airport with plenty of advertising -- in this case for Samsung's Knox security technology for Android.

A cyclist rides past the Mobile World Congress entrance, still empty before the throngs of attendees arrive Monday.

Barcelona in 2012 had to bid against other European cities to keep Mobile World Congress. It won, and now brags that it's the "mobile world capital."

The Fira Gran Via in Barcelona, home of Mobile World Congress, features a vast building clad with curvaceous concrete.

Mobile World Congress already has hundreds of people on site -- but they're mostly wearing hard hats and fluorescent safety vests.

The Fira Gran Via in Barcelona, home of Mobile World Congress.