iDim: Practical Implementation of Index Modulation for LiFi Dimming

This paper introduces a novel dimming method for Light Fidelity (LiFi) based on time-domain sample index modulation (TIM), called indexed (iDim). The aim is to provide wide brightness range, while maintaining high signal-to-noise ratio (SNR) performance and transmission rate. Direct current optical orthogonal frequency division multiplexing (DCO-OFDM) used line codes are presented. system experimentally validated by an implementation NI PXIe-1085 NI-7966R Field Programmable Gate Array (FPGA). Implementation results show that the proposed iDim jointly offers multiple benefits compared existing methods such as amplitude (AM) dimming. Specially, lowest power of measured at $20~\mu \text{W}$ , which 10 times lower than limit AM provides SNR 22.5 dB all levels, AM-dimming dramatically reduces its when light dimmed. rate also higher DCO-OFDM. in up 40% reduced per bit sDim, pulse-width-modulation (PWM)-inspired method. Therefore, promising applications targeting extremely low illumination levels.