Quantized Feedback-based Space Shift Keying in Visible Light Communication

This work proposes a novel feedback-based space shift keying (SSK) scheme to remove the limitations of the conventional SSK scheme in the visible light communication (VLC) system. The proposed scheme requires finite feedback bits to transfer the knowledge of channel gain ordering at the transmitter side and therefore termed as quantized feedback-based SSK (QF-SSK) scheme. Due to the symmetric nature of the channel gain in the VLC system, there are many locations where two or more channel gains become the same, which leads to the very high bit error rate (BER) performance for the SSK scheme. Furthermore, the fixed spatial constellation of the SSK scheme in the VLC system may not follow the gray mapping for real-line constellation points at every location, which is another reason for high BER. To overcome these limitations, the proposed QF-SSK scheme provides uneven power allocation between LEDs and uses an adaptive spatial constellation based on the information of channel gain order. It is noticed from the analysis that the proposed QF-SSK scheme significantly improves BER performance over all locations in VLC system as compared to conventional SSK scheme with very small feedback bits.