Channel Capacity Evaluation of Digital Color Shift Keying with Spatial Modulation Technique

Abstract

Digitally controlled color shift keying (DCSK) can accurately represent multilevel optical intensities by turning multiple RGB-LEDs on and off. On the other hand, the channel capacity per LED of DCSK is lower than that of the conventional color shift keying (CSK), although the number of RGB-LEDs is increased. Therefore, we propose a spatially modulated DCSK (SDCSK) scheme to realize a higher channel capacity. This SDCSK combines DCSK and a generalized space shift keying (GSSK) scheme. GSSK is a unique form of spatial modulation (SM). We also consider the new DCSK constellation for increasing the amount of SM data of the SDCSK scheme. As a result of numerical analysis, the channel capacity of SDCSK increased by 3 bit/s/Hz compared with that of DCSK when the received SNR was larger than 57 dB.