Clearwire doesn't have much time left before its promised LTE rollout goes live in early 2013, so it's with some relief that we know the deployment is getting underway. CFO Hope Cochran told those at Goldman Sachs' Communacopia Conference this week that construction of the first cell sites starts this month, with efforts truly swinging into full gear during the fall. The executive also reminded us of a very pragmatic reason why many of the 5,000 LTE sites due by June 30th will target high-traffic areas -- as Clearwire is only selling the faster data access to other providers, it should pocket more money in any regions where Sprint needs all the help it can get. Call it a virtuous cycle. Cochran certainly does: while Clearwire is free to make deals with others, Cochran says her company weighs any alliances against what it still considers a very special pact with Sprint. No doubt the 4G pioneer is hoping that it's making the right choices, as other carriers aren't waiting around.