Can my phone automatically turn on its Wi-Fi hotspot when it no longer has a Wi-Fi connection?

I carry both an iPhone and a Nexus tablet. Normally they are both connected to a WiFi network, but when no WiFi networks are in range I would really like my tablet to be able to automatically switch over to a new network connection (just like my phone automatically begins using cellular data.) I thought I could accomplish this if my iPhone automatically enabled its WiFi hotspot feature when no WiFi networks were in range, but I haven't had any luck finding documentation on how to do this.

Is this possible, and if so how?