Appropriate RLL coding scheme for effective dimming control in VLC

In visible light communication (VLC), on-off keying (OOK) is able to achieve the best BER performance as compared with variable pulse position modulation. However, OOK has a significant defect that the dimming levels (i.e. brightness) of illumination are greatly affected by the input ratio of 0 and 1 bits. To overcome this drawback, OOK with run length limited (RLL) line codes such as Manchester code or 8B10B block code has been studied in IEEE 802.15.7 VLC standard. However, those mechanisms cannot support the dimming levels more than 50%. Also, spectral efficiency of those mechanisms is reduced and then it is causative of BER performance degradation. An effective RLL line coding scheme is proposed in order to enhance the brightness and BER performance as compared with conventional RLL coding schemes. The simulation results demonstrate that the proposed coding scheme is superior to Manchester code and 8B10B block code in terms of the brightness and BER performance.