In addition to new devices at Mobile World Congress this year, Sony is also showcasing Xperia Link, a solution for mobile on the go professionals to allow access to their company network whenever they have the need when away from the office. Xperia Link allows users to tether their laptop or tablet to their Xperia smartphone for a connection to high speed mobile data on the go.
Essentially this is just a Sony specific feature to tether WiFi enabled devices like a laptop or Sony tablet to a smartphone's mobile data. While there are likely some Sony specific features here, any Android device has mobile internet tethering these days and you'll find those features in the device settings. Check out some of the hands images of Xperia Link below.