The influence of driving current on the LED modulation bandwidth indoor VLC

Abstract

This paper discusses the effect of driving current on frequency response of the two types of light emitting diodes (LEDs), namely, phosphor-based LED and single color LED. The experiments show that the influence of the change of driving current on frequency response of phosphor-based LED is not obvious compared with the single color LED(blue, red and green). The experiments also find that the bandwidth of the white LED was expanded from 1MHz to 32MHz by the pre-equalization strategy and 26Mbit/s transmission speed was taken under Bit Error Ratio of 7.55×10-6 within 3m by non-return-to-zero on-off-keying modulation. Especially, the frequency response intensity of the phosphor-based LED is little influenced by the fluctuation of the driving current, which meets the requirements that the indoor light source needs to be adjusted in real-time by driving current. As the bandwidth of the single color LED is changed by the driving current obviously, the LED modulation bandwidth should be calculated according to the minimum driving current while we consider the requirement of the VLC transmission speed.