I'm currently working on a project, involving a Raspberry PI and a tablet. Now the tablet should be able to communicate with the Raspberry PI, even though it does not have internet. I was thinking on Bluetooth first, but that's not really an option either, is there something you can suggest me?
Many thanks.
If you make the raspberry pi a wifi access point, the tablet can connect to the pi, however unless the pi has a connection using ethernet you will have no wifi whatsoever. Adafruit has a reasonable guide to actually getting setup. I havent tried it, i had just looked it up earlier this week and it was still an open tab.
https://learn.adafruit.com/setting-up-a-raspberry-pi-as-a-wifi-access-point/what-youll-need
If you havent got a wifi usb, nor a bluetooth, youre kinda out of luck, you could if you have the skills, hook up the audio output from your tablet to the pi's io (may require more then just wire, im not sure the amps, voltage, etc), and write an app that translates data into the signal to tx/rx over the audio cable, to make it wireless you could use ir transmitter/receiver pair, but again this is a lot more work.
Update from comment: alternately the tablet could be made a hotspot, and you can connect to its wifi using the pi, however, since the fastest speed of your whole setup is your 3g/4g connection itll not get better then that regarding speeds, im not sure if its possible to connect to wifi with tablet and push out hotspot for the pi to connect through, but you could try that out as well