When i was looking for a method to use my mobile as a Wi-fi for connecting internet, i found this and i like to share it.
Tethering is the use of a mobile device with Internet access such as 3G or 4G cellular service to serve as an Internet gateway or access point for other devices. Other devices may connect to the gateway via Bluetooth, Wi-Fi or by Universal Serial Bus (USB) cabling.
Tethering uses mobile applications or software depending on the mobile's operating system. A popular application is Joikuspot that works on Nokia, Samsung (Symbian) and Windows Mobile phones.
There are advantages and disadvantages to tethering.
I hope it would be some how useful to you.