A very high bit rate is required if we use analog-to-digital conversion (ADC) for the video transmission. For example, with an 8-bit ADC, the sampling rate must be 10 MS/s and the resulting output data rate from the ADC for video transmission will be 80 Mb/s. The maximum modulation frequency of the ordinary high-brightness LED is around 20 MHz, Which is not sufficient to support 80 Mb/s. Therefore, one solution would be to employ pulse time modulation schemes such as PWM, pulse fre-quency modulation (PFM), square wave FM, etc. [26]