To clarify this question in order to use AIRPRINT you need either a wifi net work ie modem wifi router, a portable MYFI 3G or 4g device (supports 5 devices inc printers) and a wifi printer that supports AirPrint (look for AirPrint logo on box).
A second option if you do not have a wifi network at home is to purchase a wifi DIRECT printer which not only supports the first option but can also be used as a wifi hotspot allowing one to print direct from any iPhone, iPod or iPad or any computer. Android devices require an app to be installed to use this type of solution. Currently HP has I believe 3 or 4 printers that have print direct feature that does not require a PC or a network. These printers are AIRPRINT friendly.
This is an ideal solution for some one mobile however the printers are not as one would say portable.
One can use other apps to print but I personally have not tested them.
Hope this helps
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