Minnetonka-based Carlson Cos. has taken some modest steps to rejuvenate its Radisson Hotels brand. But Carlson executives say much larger upgrades are in the works. A marketing campaign aimed at Gen X and Y travelers, free high-speed Internet access, breakfast for business rewards package travelers and a Sleep Number bed have been key elements of the formula that Carlson Cos. has put in place in recent years to revive its Radisson Hotels brand. The aim is to regain market share, particularly among business travelers, who make up the majority of its customers. Serious planning has been under way to reinvigorate the Radisson brand since Hubert Joly took over March 1 as Carlson Cos. chief executive. More details might be revealed in 60 to 90 days, according to Paul Kirwin, president of Carlson Hotels Worldwide for the Americas.