Wireless users in the U.S. could gain new blocks of unlicensed wireless spectrum as several high-profile auctions are completed over the next 18 months, the chairman of the Federal Communications Commission said on Wednesday. Major wireless technologies such as Wi-Fi and Bluetooth currently operate in such spaces -- blocks of the radio spectrum that are open to use by any technology and do not require formal FCC licensing -- but some of those spaces are now crowded with signals.