  Visible light communication (VLC), which uses LEDs for both illumination and
communication purposes, has recently emerged as either an alternative or a
support system for radio frequency (RF) communication. VLC channel inside a
room is highly variable since it is pretty much depends on optical line of
sight (LOS) and field of view (FOV) and it causes the received signal to vary
dramatically. Therefore, to achieve spectral efficient communication, using
rate adaptation methods are essential. In this study, we propose a rateless
codes based rate adaptation method which adjusts transmission rate at receiver
side and does not require channel state information (CSI) at the transmitter
side. Spectral efficiency of proposed method is analyzed and compared with
adaptive modulation and coding (AMC) rate adaptation method widely used in
literature. For simulation work, we consider a realistic communication system
model by using commercially available LEDs and also fulfilling illumination
requirements. To overcome multi-path effects, optical orthogonal
frequency-division multiplexing (OFDM) is used. Simulation results indicate
that proposed rate adaptive method can achieve seamless rate adaptation and has
higher spectral efficiency compared to AMC in presence of significant signal
quality variations caused by mobility in a model room.
