J.P. Linnartz, Thiago Bitencourt Cunha, Diego Vargas Romero, Xiong Deng, “Throughput optimization for IR-LEDs in an optical wireless link,” IEEE International Conference on Communications (ICC 2022)

Abstract: This paper addresses the question of whether an optical wireless communication (OWC) LiFi system preferably uses LEDs near their most efficient operating point, which is preferred for environmentally-friendly highly efficient illumination, or that one should preferably drive the LED into its droop regime to speed up its response. In fact, additional non-radiative recombination speeds up the LED response to modulation but spoils efficiency. We introduce the differential (Internal and External) Quantum Efficiency (dIQE; dEQE), as a particular derivative of quantum efficiencies. It quantifies the efficiency at which a current modulation translates into an optical signal.We optimize the current density, thus how deeply the LED is to be driven into droop, using DC-offset (DCO) OFDM throughput expressions for the first–order low-pass LED response. Short-range small-coverage systems prefer high current densities to achieve very high throughputs. LiFi with wide opening angles, e.g. covering tens of square meters are better off with a high dIQE, thus lower current densities.