It’s not secret that the explosive growth of mobile broadband has forced wireless providers to search for more spectrum due to looming capacity constraints. For Verizon, that search has led to a proposed deal with cable companies, but as Diane Bartz of Reuters reports, the company’s road to regulatory approval is a rocky one:

Verizon Wireless may need to agree to tough conditions to win approval for its deals to buy spectrum from cable companies and market each others’ products, according to three sources knowledgeable about the negotiations.

The Justice Department and Federal Communications Commission are reviewing plans by Verizon Wireless, the biggest U.S. mobile provider, to buy spectrum from a consortium of cable providers, including Comcast (CMCSA.O) and Time Warner Cable (TWC.N), for about $3.9 billion. The transactions were proposed in December.

While the Justice Department and FCC appear prepared to approve the spectrum portion of the deals with minor adjustments, antitrust regulators have sought strict limits on controversial side deals.