On March 14, Industry Minister Christian Paradis unveiled the rules for the federal government’s wireless spectrum auction, which will allow Canada’s telecommunications companies to bid on some prime new electromagnetic real estate. On the auction block in early 2013 will be the 700-MHz band, which was freed up by the switch to digital television. Lower frequencies are generally more valuable than higher ones, since they travel farther and easily penetrate buildings. This makes 700 MHz a blue-chip frequency that should allow cellphones to work in elevators and underground garages, while supporting the newest wireless high-speed technology, LTE. The auction could generate $3.5 billion in revenue—and that may be conservative, given that the 2008 auction brought in $4.3 billion, far exceeding expectations. Here’s a look at previous auctions, how much they raised and who the biggest spenders were.