thanks for the answer.
we have big network , with about 70 APs, internet speed is about 10 mbps, windows, linux and mac laptops are using this traffic mostly. android and IOS devices need much less traffic, in most cases they are used for social networking, voip and e-mail. so i need to give priority to mobile devices per OS.
i know that i can use rate limit, or use solution as you wrote, But i think this will be a good feature for ruckus APs.