Commercial wireless operators will have an opportunity in June to bid on 90 MHz of spectrum that is expected to be used for 3G services, but many large carriers likely will have to pay more for making the same bids as in previous auctions.

Bidding on frequencies in the 1710-1755 MHz band—airwaves vacated by government agencies, including the military—and the 2110-2155 MHz band is scheduled begin on June 29, according to the FCC’s wireless bureau. The auction will feature new rules regarding so-called “designated entities”—smaller wireless operators—that would alter bidding by large carriers such as Cingular Wireless.

Designated-entity rules were established to let small wireless providers bid for spectrum against deep-pocketed incumbents by granting bidding credits to the small operators. But a more common practice was for large carriers such as Cingular to contract with a designated entity to acquire the spectrum via auction with its bidding credit, then sell the spectrum license to the large carrier after network-buildout milestones were met five years later, according to an FCC source. The maneuver effectively let the large carrier obtain spectrum for less than it would have paid had it bid on the airwaves itself.

In a notice of proposed rulemaking (NPRM) released Friday, the FCC tentatively concluded that designated entities should not receive bidding credits during the auction if it has a “material relationship” with a “large, in-region incumbent carrier.”

FCC Chairman Kevin Martin expressed support for the NPRM but said he believed its scope should be extended beyond large wireless carriers.

“While I think [it] is a good step, I believe we should consider going further, applying the same rule to all large communications service providers,” Martin said in a prepared statement. “Why single out large wireless carriers alone for this kind of treatment and allow large wireline carriers, cable companies, satellite providers, and other communications companies to continue to participate in a program for small businesses?”