The purpose of this study is to evaluate the superiority in terms of efficacy and evaluate the safety of QMF149 (indacaterol (acetate) / mometasone (furoate)) compared to budesonide in children from 6 to less than 12 years of age with asthma. * The study duration will be up to 37 weeks including an investigational treatment duration of 12 weeks and a comparator treatment duration of 12 weeks. * The visit frequency will be 3 weeks for screening, run-in and wash-out period, 6 weeks interval for visits during each treatment period, 30 days for safety follow-up.