Theoretical and experimental optimization of DMT-based visible light communication under lighting constraints

Abstract

High spectral efficiency is a key element that drives research for future wireless communication systems in order to meet the increasing demand for ubiquitous connectivity despite a limited radio frequency spectrum. Visible light communications (VLC) that allow exploiting the existing infrastructure for both lighting and communications could be an effective and economic solution. Thanks to the revolution in the field of solid-state lighting and the accelerated development of light-emitting diodes (LED), VLC becomes one of the most promising new technologies for the next generation of wireless communication systems. However, the limited bandwidth of the LEDs remains a major challenge that is limiting VLC from achieving very high data rates. In this paper, we propose to adapt the discrete multi-tone (DMT) modulation scheme of indoor VLC communications for data rate enhancement. With the help of bit and power-loading algorithms, a transmission bandwidth much larger than the 3-dB bandwidth of the LED could be exploited. We firstly present the typical lighting requirements for indoor applications and investigate the maximal bit-rate of DMT-based VLC. Then, with a regular luminance level for normal office work, an overall optimization of DMT configuration scheme in terms of modulated bandwidth, subcarrier number, cyclic prefix length, and clipping level is proposed. Theoretical analysis and verifications by experiments are simultaneously carried out. Based on the proposed configuration, we demonstrate a 100-Mbps VLC wireless transmission employing low-cost components under realistic lighting constraints.

Experimental Comparison of PAM and CAP Modulation for Visible Light Communication Under Illumination Constraints

“…where * denotes the convolution operator and G b and G p are the power gains associated with the blue light response and the phosophor layer response respectively. Under the assumption that most of the received optical power stems from the yellow photons [15], we have G p ≫ G b and a simplified model of the LED response can be derived from (10), such that…”

“…In a previous study from 2020 [10], an experiment was carried out with DMT under identical conditions and using the same experimental setup. Without compensating LED nonlinearity, a ∼ 100 Mbps transmission rate was successfully achieved at a BER of 10 −3 , which is significantly less than the achievable transmission rates demonstrated in this study with PAM and CAP.…”

“…It is reasonable to assume that modulations with higher peak-to-average power ratio (PAPR) will suffer more degradation due to nonlinearity. In previous work by our team [10], DMT was optimized under lighting constraints with the same experimental VLC setup and a 100 Mbps transmission was achieved at a targeted bit error rate of 10 −3 .…”

A Seamless Broadband PLC-VLC Transmission: Performance Evaluation and Dimensioning

“…Based on the Deutsche Institut fur Normung (DIN) standard, the required illuminance of a normal office room is 500 lux [15]. The total luminous flux can be calculated as a function of the horizontal illuminance (E h ) by the following expression [16]:…”

VLC Modelization for VLC-PLC System: Evaluation of Optical, Electrical, and Frequency Behavior

“…Although, all the curves presented in the LED data sheet are normalized to this value. However, it can be calculated using the luminous flux expression [17] as following:…”