Xiaomi works on simple fundamental that each phone will be market for 15-24 months while other target period is 12-18 months. So here Xiaomi makes handsome profit for its R & D activity from same while others have to keep on launching new phones at higher price. Also Xiaomi sells only online, there also its saves 10-15% on margin. Also xiaomi has not invested heavily on service centres whereby saving cost. So cost vs benefit is main factor for xiaomi sells in Asia.