A system for performing indoor positioning using a Light Emitting Diode (LED) lighting unit is provided. The system includes the LED lighting unit for determining whether transmission packet data exists in a frame to be transmitted, modulating the transmission packet data in accordance with a predetermined method in order to maintain a uniform brightness of the LED lighting unit when the transmission packet data exists, and transmitting the frame including the modulated transmission packet data. The system also includes a mobile terminal for receiving the frame, demodulating the modulated transmission packet data to determine the transmission packet data, and performing indoor positioning by using the demodulated transmission packet data and information included in the frame.