The FCC is delaying a highly anticipated spectrum auction for TV broadcasters to sell airwaves for use in mobile broadband.

The spectrum-incentive auction was originally set to be held in 2015 and will now take place in 2016. It involves TV broadcasters giving up airwaves to mobile carriers to meet demand for smartphones, tablets and other devices. The decision to delay the auction is reportedly due to legal challenges from broadcasters over the auction.

"We are confident we will prevail in court, but given the reality of that schedule, the complexity of designing and implementing the auction, and the need for all auction participants to have certainty well in advance of the auction, we now anticipate accepting applications for the auction in the fall of 2015 and starting the auction in early 2016," said Gary Epstein, chair of the FCC's Incentive Auction Task Force.

The National Association of Broadcasters has denied the legal challenge is to blame for the delay, but it says it welcomes the opportunity to resolve issues prior to the auction.

"As NAB has said repeatedly, it is more important to get the auction done right than right now," said Dennis Wharton, a spokesperson for the NAB. "We reject suggestions that our narrowly-focused lawsuit is cause for delay. We look forward to a speedy resolution of our legal challenge and a successful auction."

Some experts say the auction is the most complex undertaking attempted by the FCC and there is a lot of uncertainty over exactly how many television stations will decide to participate. A pitch from the FCC for TV stations to take part involves high-end estimates for how much money stations could make, some reaching hundreds of millions of dollars. Ultimately, the auction is expected to affect up to 80 markets. Stations located in urban areas are expected to make the most money from the auction.

While a number of large mobile carriers are expected to take part, AT&T is so far the only one to pledge a specific amount, saying it will spend at least $9 billion.

Some analysts suggest the delay could reopen the door for Sprint and T-Mobile to secure a place as the third-largest mobile carrier, especially now they have abandoned plans to merge.

This is not the first time the auction has been pushed back. It was originally planned to take place in 2014 and was pushed to 2015.