Bi-directional Visible Light Communication System Research Articles

Bidirectional Visible Light Communication System Using a Single VCSEL With Predistortion to Enhance the Upstream Remodulation

The demand of higher data rates has made it attractive to consider a low-cost laser diode (LD), such as vertical-cavity-surface-emitting laser (VCSEL) for use in visible light communication (VLC) transmitters (Tx) due to their higher electrical-to-optical modulation bandwidth, beam convergence, and energy efficiency. Many reported LD-based VLC systems only had a solitary downstream transmission. We demonstrate a 3-m bidirectional signal remodulated VCSEL-based VLC system using visible-light modulator to produce the upstream signal. The visible-light external modulator usually has limited modulation bandwidth. By using the predistortion, the upstream remodulated data rate is enhanced by ∼2.8 times. Hence, the VCSEL-based VLC system with 10.64-Gb/s downstream signal and 5-Mb/s upstream remodulated signal can be achieved. We also analyze via numerical simulations how the predistorted signal can enhance the transmission data rate by mitigating the intersymbol interference introduced by the bandwidth limitation of the upstream modulator.

Power analysis based side-channel attack on visible light communication

Visible light communication (VLC) technology has emerged as a significant and necessary improvement to the wireless communication technologies; VLC systems are considered to be more secure than wireless fidelity (Wi-Fi) systems by design, since light cannot penetrate most walls and obstacles. This paper presents a design for a bidirectional VLC system, and it also introduces a method to jeopardize the security aspect of this system. The methodology in this paper is side-channel attack which is defined as exploiting data based on the information gained from physical implementation. It is not a cyber attack on the theoretical weaknesses in the algorithms, but rather is a sideway approach to a fully-functioning physical system. Thus, the authors became the attackers and implemented a current sensor on the power lines from the power supply to the VLC system; the instantaneous power consumed by the communication system has become their main source to obtain the binary data transmitted by visible light. The work has resulted in effective attacks which could successfully extract the information and it has demonstrated side channel attacks on VLC systems through their instantaneous power consumption analysis.

LED作为收发元件的双向可见光通信系统方案及实现

LED作为收发元件的双向可见光通信系统方案及实现

A high-speed bi-directional visible light communication system based on RGB-LED

In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats (QAM-OFDM), advanced digital signal processing, pre- and post-equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes (LEDs), of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios (BERs) for all channels after 0.7 m indoor delivery are below pre-forward-error-correction (pre-FEC) threshold of 3.8×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.