The data can be encoded in the light by varying the
flickering rate at which the LEDs flicker on and off to
generate different strings of 1s and 0s.The LED intensity is
modulated so rapidly that human eye cannot notice, so the
light of the LED appears constant to humans [13].
Light-emitting diodes (commonly referred to as LEDs and
found in traffic and street lights, car brake lights, remote
control units and countless other applications) can be switched
on and off faster than the human eye can detect, causing the
light source to appear to be on continuously, even though it is
in fact 'flickering'. The on-off activity of the bulb which seems
to be invisible enables data transmission using binary codes:
switching on an LED is a logical '1', switching it off is a
logical '0'. By varying the rate at which the LEDs flicker on
and off, information can be encoded in the light to different
combinations of 1s and 0s. This method of using rapid pulses
of light to transmit information wirelessly is technically
referred to as Visible Light Communication (VLC), though it
is popularly called as Li-Fi because it can compete with its
radio-based rival Wi-Fi. Figure 5 show