The U.S. Federal Communications Commission expects a major auction of low-frequency airwaves to be pushed back to early 2016 from mid-2015 because of its complexity and a pending court challenge, an FCC official said in a blog post on Friday. The FCC is working on rules for the so-called incentive auction, in which wireless carriers would get the first opportunity since 2008 to purchase airwaves that are considered the “beach-front property” of radio spectrum for their reach and strength.