Transceiver Characteristics and Additional Data Transmission Scheme for LED-ID Systems

In this paper, characteristics of transmission and receive of RGB (Red/Green/Blue) light emitting diodes (LEDs) are analyzed for LED identification (LED-ID) systems. LED is considered as a future light technology because of advantages of LED such as the long life time, low power consumption and high power efficiency. Moreover, LED is used to lighting device also, it can be used a communication device, because LED has high frequency response of a few MHz. For LED communication systems, each red, green and blue LED has different transmission / receive characteristic. The red LED has good transmission characteristic in the transmission power and distance aspects. Similarly, the blue LED has good transmission characteristic in the data rate aspects. However, the green LED has low SNR (Signal-to-noise ratio) characteristic in comparison with red and blue LEDs. So, LED communication systems take in SNR to make the green LED. In this case, system performance such as data rate, transmission power and bit error rate (BER) are deteriorated for LED communication systems. For this reason, in this paper, we use optical filter to separate RGB colors and then, send the main data (image, video, etc.) using red and blue LEDs. And an additional data (simple text, location information, etc.) is transmitted by greed LEDs. Using this method, we obtain the SNR gain for main data transmission and receive, in additional, without increase of system complexity, we transmit additional data. From simulation results, it is confirmed that the proposed scheme is very effective to enhance system performance of LED-ID communication systems.