Google renewed speculation Tuesday about plans to build a "Google X" phone and tablet after executives referred to the impending fruition of Motorola Mobility's 12- to 18-month product pipeline. Separately, analysts mused whether Google was preparing to build an array of dense and high-speed wireless networks that would greatly expand mobile access to the Internet following a move by the company last week asking the Federal Communications Commission to approve a license for an "experimental radio service" surrounding its Mountain View, Calif., offices.