Hi! This is my first post here, I search for that answer to my problem in the forum but I didn't find it.
I'm making a quadcopter for my final exam as project, I want to control it by my phone even outdoor(so non through a WiFi router).
The question is: how can I make my phone communicate with Arduino? I find the xbee and I was wondering if they can be used for my problem, if yes how?
Thanks for help, sorry for English 
if your phone has bluetooth you can use it to communicate with an arduino
I know that but I found out that bt is not stable as WiFi or radio and for a quadcopter is very important the stability
I suspect the range of bluetooth or WiFi from a phone will be very limited.
...R
What about radio signal?
How can I make my phone use it?
Ooze:
What about radio signal?
How can I make my phone use it?
You can easily connect radio transceivers to an arduino.
However, the only way I can think of to do the same on the phone would be to use Bluetooth or WiFi as an intermediary medium.
In other words you need an arduino to talk to the phone with BT from one port and relay everything to the RF transceiver on another board.
Ie Use serial1 for BT and Serial2 on Radio (Serial2 being SoftwareSerial and Serial1 hardware serial if you choose an ATMEGA32U4 based board such as the arduino micro)
You could communicate between a ground-based Arduino and your 'copter using nRF24L01+ wireless modules and you could communicate between your phone and the ground-based Arduino using Bluetooth or WiFi.