Quantized Feedback-based Space Shift Keying in Visible Light Communication

Abstract

This work proposes a novel feedback-based space shift keying (SSK) to overcome the lim itations of conventional SSK in visible light communication (VLC). The limitations of con ventional SSK are the symmetric nature of VLC channel and fixed spatial constellation. The symmetric nature of the VLC channel makes two or more channel gains equal at many loca tions. This causes a high bit error rate (BER). In addition, the fixed spatial constellation may not follow gray mapping into real-line constellation for all locations and this leads to high BER. Due to these limitations, the BER performance of SSK is poor. To overcome all these limita tions, the proposed scheme gives unequal power allocation (PA) between LEDs and uses an adaptive spatial constellation based on the knowledge of channel gain ordering. The proposed scheme requires only a finite number of feedback bits to transfer the information of channel gain ordering at the transmitter side. Since it requires few feedback bits, hence the proposed scheme named as quantized feedback-based SSK (QFSSK) scheme. It is observed from analy sis that the proposed QFSSK scheme significantly improves BER performance at all locations compared to conventional SSK with very finite feedback bits.