Nearly two years ago, U.S. regulators proposed opening up 100 MHz chunk of federal airwaves for commercial use, creating a shared spectrum band between the government, mobile carriers and the ordinary public. The proposal languished as carriers weren’t too hot on the idea of sharing the airwaves, but the Federal Communications Commission seems to be making it a renewed priority under new chairman Tom Wheeler. The FCC on Wednesday approved a new notice for proposed rulemaking to establish how the 3.5 GHz spectrum could be used.