Can any one tell me how to redirect oxwall site to subdomain ..

What i want is when a user open a site from loptop/computer he should be able see normal url example abc.com but when he is on mobile he should be redirected to m.abc.com .

What actually i want to do through this is when a user is on laptop/computer i will show him simplicity theme but when he is on mobile i would be redirecting him to m.abc.com where i would be placing my customised responsive theme