Investigation of 4-ASK modulation with digital filtering to increase 20 times of direct modulation speed of white-light LED visible light communication system

Abstract

In this demonstration, we propose and experimentally investigate the quaternary-amplitude-shift-keying (4-ASK) modulation with digital filtering to enhance the direct modulation speed of white-light lightemitting-diode (LED) in visible light communication (VLC) system. Here, an ordinary LED commercially available for lighting application with a direct modulation speed of 1 MHz is used. Data rate of 20 Mbit/s can be achieved in a 1 m free space transmission without using optical blue filter. In the previous studies, the transmission rate of LED VLC could only be increased by 2 to 10 times of the direct modulation speed of the white-light LED if using electrical equalization only. Moreover, the adaptive-controlled FIR filter makes the system closer to the matched filtering condition for reducing the inter-symbol-interference (ISI) for the LED VLC. A recorded 20 times enhancement of the direct modulation speed of white-light LED VLC system is demonstrated by using digital filter only and without using optical blue filter.

Line-of-Sight Visible Light Communications With InGaN-Based Resonant Cavity LEDs

“…In addition, the banspass filter reduces the influence of ambient light noise on the received optical signals. The performance of white-light LED communications could be further improved by using a quaternary-amplitude-shiftkeying modulation technique, combined with a digital filter (adaptively-controlled FIR equalizer) to achieve high-speed data transmissions [11].…”

Reproducing Single-Carrier Digital Modulation Schemes for VLC by Controlling the First Switching Harmonic of the DC–DC Power Converter Output Voltage Ripple

“…4). This modulation family has already been proposed for VLC and their benefits have been demonstrated in [23] and [50]- [57]. Since the method presented in this work is fully based on the use of DC-DC power converters (i.e., power efficient approach), the target is to improve the results achieved in [37] and [39] (i.e., power efficient approach reproducing an inefficient modulation scheme).…”

A perspective perception on the applications of light‐emitting diodes

“…Researchers discovered the potential of LEDs to provide free‐space optical wireless VLC for both indoor and outdoor applications. However, use of phosphor‐converted W‐LED suffers from poor modulation bandwidth and hence it is essential to undertake measures to overcome this for a better VLC data transmission rate; the use of different types of analogy equalizers at both the transmitter (Tx) and receiver (Rx) sides has been proposed . Another proposal is the use of a blue filter at the receiver side to remove the phosphorescent component, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) .…”