Visible Light Communication Channel Research Articles

Evaluation of visible light communication channel delay profiles for automotive applications

Abstract In this article, we present channel delay profiles based on simulated data regarding the practical conditions for the use of visible light communication (VLC) in automotive applications such as Intelligent Transportation Systems (ITS). Practical vehicular LED headlamp and street lamp that consider the lighting regulation for transportation are used to design the ITS scenarios based on VLC. We modeled two usage scenarios, crossroad and metropolitan street, using the CATIA V5 tool. Measurements for the VLC channel delay profile evaluation were then gathered by using a ray-tracing scheme employing commercial LightTools software under the vehicle-to-vehicle and vehicle-to-infrastructure (V2I) communication links. From the obtained channel impulse responses from both scenarios, we derived the VLC channel delay profiles. From them, we found that the common property of the delay profile was composed of dominant multiple line of sight (LOS) links and a less number of non-LOS delay taps. However, the channel delay profile for the V2I link and metropolitan scenario show more dispersive channel characteristics due to the reflection and diffusion of the visible light.

Traffic light to vehicle visible light communication channel characterization

Outdoor visible light communication (VLC) between an LED traffic light and an automobile has been proposed for intelligent transportation system development. An unobstructed line-of-sight (LOS) channel has to be guaranteed for this communication system. In this paper, an analytical LOS path loss model is proposed and validated by the measurement results. Commercial-off-the-shelf (COTS) LED traffic lights are characterized for use as transmitters and possible interference sources are studied, such as background solar radiation and artificial lighting. Accordingly, the performance of an outdoor VLC system is evaluated using different modulation schemes.

Indoor positioning algorithm using light-emitting diode visible light communications

This paper proposes a novel indoor positioning algorithm using visible light communications (VLC). The algorithm is implemented by preinstalled light-emitting diode illumination systems. It recovers the VLC channel features from illuminating visible light and estimates receiver locations by analytically solving the Lambertian transmission equation group. According to our research, the algorithm is able to provide positioning resolution higher than 0.5 mm, in a practical indoor environment. The performance significantly exceeds conventional indoor positioning approaches using microwaves.

Performance study of an OFDM visible light communication system based on white LED array

By introducing orthogonal frequency division multiplexing (OFDM) technology, a visible light communication (VLC) system using a 5×5 white LED array is studied in this paper. The OFDM transmitter and receiver are modeled through MATLAB/Simulink tool. The electrical-optical-electrical (EOE) response of the VLC channel, which is also the response of the detector, is derived based on Lambert’s lighting model. Then the modeling on the overall OFDM/VLC system is established by combining the above three models together. The effects of the factors which include the digital modulation, Reed-Solomon (RS) coding, pilot form, pilot ratio (PR) and communication distance on the bit error rate (BER) of the system are discussed. The results show that through the use of RS coding, block pilot, quadrate phase shift keying (QPSK) modulation and a suitable pilot ratio about 1/3, under the communication rate about 550 kbit/s, the BER can be dropped to below 10–5, and the communication distance can reach 0.9 m.

사용자 위치 기반의 VLC 채널 모델 도출에 관한 연구

본 논문에서는 실내 환경에서 LED(Light Emitting Diode)를 이용한 가시광 통신(VLC : Visible Light Communication) 채널의 특성을 모델링 및 분석하였다. LED에서 방사된 광 입자(Photon)의 일부는 직접(LOS : Line Of Sight) 또는 반사(NLOS : None Line Of Sight)의 경로를 거쳐서 PD(PhotoDiode)에 도달하며, 이것은 수신 부에서 시간 지연(delay profile)과 감쇠(attenuation)를 가진 다중 수신 신호 특성을 나타낸다. 가로, 세로, 높이의 크기가 20*8*2.3m로 가정된 실내 환경에서 2개의 LED와 3개의 PD를 사용하여, 각 PD에서 직접파, 반사파에 의한 채널 특성을 컴퓨터 모의실험하고 분석하였다. 채널 모델별 특성은 BPSK 기반의 통신 모의실험을 통하여 그 유용성을 입증하였다. In this paper, channel modeling and analysis of wireless visible light communication(VLC) were studied in indoor circumstance. Photons emitted from LED straightly moved and navigated within indoor, after that a part of photons reached on PD via LOS(Line Of Sight) or NLOS(None Line Of Sight). These received signals had characteristics of delay profile and attenuation, which was multiple-path fading. In this paper, computer simulation of VLC channel was executed under the condition that two LEDs were used for transmitter and three PDs were located at different positions of the 20*8*2.3m sized indoor. BER performance simulation was excuted based on the characteristics of each VLC channel.

A new indoor VLC channel model based on reflection

In this paper the indoor visible light communication (VLC) multipath channel model is analyzed. A new reflection model based on the Lambert-Phong pattern is presented by investigation of the reflection characteristics. Through the Monte-Carlo ray tracing simulation based on the Lambert-Phong pattern, the VLC optical channel models are set up, including the single source and multiple-source systems. The simulation results show that using the Lambert-Phong reflection pattern, the calculation becomes linear to the number of reflections and the computation complexity is decreased.

Independent reflecting element interaction characterization for indoor visible light communication based on new generation lighting

Indoor visible light communication (VLC) based on next generation environmentally friendly lighting is important in energy conservation. However, at present, the efficient characterization of VLC channels, including sophisticated reflection, has not yet been proposed. In this letter, we present a fast and comparably accurate channel characterization algorithm called independent reflecting element interaction characterization (IREIC), which can be used to describe optical power, illuminance, and impulse response.