Visible light communication for intelligent transportation in road safety applications.
ABSTRACT 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.
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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). · 0.81 Impact Factor
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ABSTRACT: This paper presents the experimental results for a cooperative system that uses Infrastructure-to-Vehicle (I2V) and Vehicle-to-Vehicle (V2V) communication to increases the traffic safety, efficiency and adaptability. The wireless communication technique chosen to enable the data transmission is Visible Light Communication (VLC) due to its numerous advantages. The system consists of a commercial LED-based traffic light as a Road-Side-Unit (RSU) emitter, a transceiver that receives the message from the traffic light and retransmits it to the vehicle behind by using the tail lights, and also a second receiver that receives the message from the transceiver. Measurements exhibit a Bit Error Ratio of 10-7, both for the I2V and V2V, without using any complex error correction codes, which is considered good, even for traffic safety applications. The tests results show that the proposed cooperative system allows the RSU to communicate with vehicles outside the service area by using multi-hop communication.2013 IEEE 20th Symposium on Communications and Vehicular Technology in the Benelux (SCVT); 11/2013
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ABSTRACT: The predicted ubiquity of light-emitting diodes (LEDs) suggests great potential for dual-use systems with visible light communications (VLC) capabilities. One class of LEDs employs multiple emitters at different wavelengths, making them appropriate for applications requiring colored output and providing multiple channels for communication. We present a design framework for optimizing the signaling constellation of VLC systems employing an arbitrary number of such LEDs, each with an arbitrary number of emitters. In particular, by considering the design of constellation-symbol locations jointly across LED emitters, the framework provides for the precompensation of linear channel distortions arising from, for example, cross-channel leakage, noise correlation, or wavelength-dependent received-signal and/or noise power, as well as the incorporation of design constraints for color-shift keying, dimming, and/or perceived color. Simulation results demonstrate the design approach and the potential performance enhancement that can be achieved for particular system scenarios. Experimental measurements using a prototype VLC system confirm such performance enhancements, providing real-world evidence of the benefit of applying the proposed framework to VLC channel precompensation.IEEE Transactions on Communications 01/2014; 62(6):1995-2005. · 1.98 Impact Factor