Under the campaign's General tab, select the option you want to target from the Mobile Connection Types found under the Advanced settings.
There are three options available: Wi-Fi only, Wi-Fi excluded (i.e. mobile carrier), or unknown Wi-Fi status.
Wi-Fi can be excluded on all mobile campaigns (e.g., App, mobile web and hyperlocal campaigns). In the General settings tab of the campaign, scroll down to Advanced > Mobile Connection Types and uncheck the box for "Wi-Fi".
Please note: Unknown connection types may include either Wi-Fi or Mobile Data connections.