Putting it on the first floor should not be a problem. I would recommend trying to use the "3 wall rule"... Don't assume that your wireless connection will work beyond 3 walls... Simple. Of course, it might work with 4 or more, but when planning, always assume the worst. In your case, the ceiling would be considered the first "wall". Of course, insulation barriers can possibly have an adverse affect also, but hopefully that will not be an issue in your case.