Search for: All records

The directionality of optical signals provides an opportunity for efficient space reuse of optical links in visible light communication (VLC). Space reuse in VLC can enable multiple-access communication from multiple light emitting transmitters. Traditional VLC system design using photo-receptors requires at least one receiving photodetector element for each light emitter, thus constraining VLC to always require a light-emitter to light-receptor element pair. In this paper, we propose, design and evaluate a novel architecture for VLC that can enable multiple-access reception using a photoreceptor receiver that uses only a single photodiode. The novel design includes a liquid-crystal-display (LCD) based shutter system that can be automated to control and enable selective reception of light beams from multiple transmitters. We evaluate the feasibility of multiple access on a single photodiode from two light emitting diode (LED) transmitters and the performance of the communication link using bit-error-rate (BER) and packet-error-rate (PER) metrics. Our experiment and trace based evaluation through proof-of-concept implementation reveals the feasibility of multiple LED reception on a single photodiode. We further evaluate the system in controlled mobile settings to verify the adaptability of the receiver when the LED transmitter changes position. 

The increasing use of light emitting diodes (LED) and light receptors such as photodiodes and cameras in vehicles motivates the use of visible light communication (VLC) for inter–vehicular networking. However, the mobility of the vehicles presents a fundamental impediment for high throughput and link sustenance in vehicular VLC. While prior work has explored vehicular VLC system design, yet, there is no clear understanding on the amount of motion of vehicles in real world vehicular VLC use–case scenarios. To address this knowledge gap, in this paper, we present a mobility characterization study through extensive experiments in real world driving scenarios. We characterize motion using a constantly illuminated transmitter on a lead vehicle and a multi–camera setup on a following vehicle. The observations from our experiments reveal key insights on the degree of relative motion of a vehicle along its spatial axis and different vehicular motion behaviors. The motion characterization from this work lays a stepping stone to addressing mobility in vehicular VLC. 

Theoretical models estimate visible light communication (VLC) data capacity to be of the order of Tera-bits-per-second (Tbps). However, practical limitations in receiver designs have limited state-of-the-art VLC prototypes to (multiple) orders of magnitude lower data rates. This paper explores a new architecture to realize ultra-high data rates in visible light communication systems by dramatically improving the Signal-to-Interference-Noise-Ratio (SINR) at the receiver. The key idea is to leverage the fast sampling rates of photodiode receivers and integrate a shutter mechanism that filters noise and interference thus creating a high-speed imaging receiver effect. Through adaptive selection of the exact receiver area over which the transmitted light is detected, the SINR can be dramatically increased yet not compromising the high sampling rate achievable using state-of-the-art photoreceptors. In addition to introducing the new hybrid architecture for high SINR reception, in this paper, we study the feasibility of noise and interference reduction through a proof-of-concept experimentation.