Bluetooth Trasmitter
A basic way of doing this is to go the Arduino route. You can purchase bluetooth modules that are compatible with the serial lines of an Arduino. The bluetooth module will already have its own ID and to transmit data all you need to do is send serial to the bluetooth module from the Arduino board. 

This is a simple method that will be very easy to implement. All the components you need are an Arduino, (an Arduino Uno would suffice) and a bluetooth 4.0 Arduino compatible module.