This paper discusses the implementation of a light emitting diode based visible light communication system, for intelligent transportation in road safety applications. The signal processing of both, transmitter and receiver are realized in a field programmable gate array using two Spartan-3E development kits. The implemented modulation scheme is based on direct sequence spread spectrum techniques. The performance of the overall system is evaluated and results are presented. It is found that the system is well suited for traffic broadcast at low data rate and medium range. The simulation results also show that spread spectrum modulation techniques mitigate the effect of noise produced by ambient artificial light sources.
[Show abstract][Hide abstract] 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.
EURASIP Journal on Wireless Communications and Networking 01/2012; 2012(1). DOI:10.1186/1687-1499-2012-370 · 0.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper presents a Visible Light Communication (VLC) system architecture suitable for outdoor applications. VLC usages in outdoor scenarios are facing new opportunities raised by the increasing trends on the usage of LEDs. Traffic light signals and public illumination systems are two application examples, where VLC can show its merits. These scenarios pose several challenges due to the fact that it is difficult to control environmental conditions. Thus, VLC systems able to operate under these conditions need to employ robust modulation schemes. This paper proposes the usage of direct sequence spread spectrum to combat noise and interference. The implemented prototype demonstrates that it is feasible to achieve more than 40m communication range for low data rate applications even in the presence of significant optical noise levels.
8th IEEE, IET International Symposium on Communication Systems, Networks and Digital Signal Processing; 01/2012
[Show abstract][Hide abstract] ABSTRACT: In this paper, we provide simulated channel models reflecting practical conditions for the usage of visible light communications (VLC) in intelligent transportation system (ITS). Practical vehicular LED Head Lamp and Street Lamp considering the lighting regulation for transportation is used to design ITS scenario based on VLC. We model vehicle-to-vehicle (V2V) and vehicle-to-infra (V2I) communication links in two usage scenario (crossroad and metropolitan scenario) by using CATIA V5 tool. Then, measurements for VLC channel modeling are gathered by using Ray-Tracing scheme with commercial LightTools software. From the obtained channel impulse response in both scenario, we found that VLC channels for ITS has dominant multiple LOS links and less multipath components. However, we can notice that V2I link and metropolitan scenario show more dispersive multipath channel characteristics than others.
2012 15th International IEEE Conference on Intelligent Transportation Systems - (ITSC 2012); 09/2012
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