Its Easy , Simply set up a sub domain
Example Main Domain : abc.com
Sub-domain for Mobile : m.abc.com
Install the plugin Mobile Redirect . This plugin detects when a mobile device is being used and sends the user to another website address specified by you.
Go Responsive With by use a responsive theme for your website.
Hire a professional designer or developer to design (or convert your design) to a responsive layout, or learn how to do it yourself..
For better Understanding Find it With Post