Color-and-Intensity Shift Keying for Visible Light Communication

In this letter, a modulation technique referred to as color-and-intensity shift keying (CISK) is proposed for visible light communication systems. The new scheme amalgamates conventional color shift keying (CSK) and non-zero-level unipolar pulse amplitude modulation (NZL-UPAM) for efficiently exploiting the degrees of freedom in both the color and the intensity domains. Specifically, it relaxes the constant power constraint for CSK, but maintains a constant average transmit power to fulfill the non-flickering requirement for the normal illumination. In addition, the optimal theoretical NZL-UPAM intensity levels are derived for achieving the best symbol error rate performance of the proposed system. Simulations verify our analytical results, showing that CISK largely outperforms the conventional CSK and NZL-UPAM in high-data-rate scenarios.