from Apple doc:
Learn the system requirements for Personal Hotspot on your iPhone, iPad, and iPad Mini.
To use this feature, your wireless carrier must offer Personal Hotspot and your devices must meet certain system requirements.
The table below lists the iPhone and iPad (Wi-Fi + Cellular models) capable of Personal Hotspot and which connections they can use to share cellular data with another device:
| USB | Bluetooth | Wi-Fi |
| iPhone 4 or later | ✓ | ✓ | ✓ |
| iPhone 3GS and iPhone 3G* | ✓ | ✓ |
| iPad (3rd generation or later) Wi-Fi + Cellular | ✓ | ✓ | ✓ |
| iPad mini Wi-Fi + Cellular | ✓ | ✓ | ✓ |
| * On iPhone 3G, Personal Hotspot is referred to as Internet tethering. |
To connect to a Personal Hotspot, your device requires:
- Wi-Fi: Support for 802.11g/n using WPA2 encryption.
- USB: Mac or PC with iTunes 9.2 or later installed.
- Bluetooth: Mac OS X v10.4.11 or Windows.
Verify that your carrier supports Personal Hotspot for your device and that you have Personal Hotspot enabled on your cellular plan:- iPhone: View a list of carriers that support Personal Hotspot on the iPhone.
- iPad and iPad mini: Check with your carrier for availability.
Find more information on using Personal Hotspot.