Finding a way to create a WLAN between tablet and phone
Android, starting from 4.0, does officially support a form of p2p wifi networking called Wifi Direct. A Wifi Direct-capable device can create an access point which any other Wifi-capable device can access. I don't know about Nexus 7 specifically, but Galaxy Nexus does support Wifi Direct so I'd presume that so is Nexus 7.