Visible light communications (VLC) can utilize light-emitting diodes (LEDs) to provide illumination and a safe and low-cost broadcasting network simultaneously. In the past decade, there has been a growing interest in using organic LEDs (OLEDs) for soft lighting and display applications in public places. Organic electronics can be mechanically flexible, thus the potential of curved OLED panels/displays devices. This paper provides unique characteristics of a flexible OLED-based VLC link in a shopping mall. We show that, for curved OLED the radiation pattern displays a symmetry, which is wider than Lambertian. A number of scenarios of VLC system with flexible OLED are analyzed. Numerical models for the delay spread and optical path loss are derived, which followed a 2-term power series model for both empty and furnished rooms. We show that using a full-circular OLED for both empty and furnished rooms offers a uniform distribution of emitted power for the same transmission link spans. The link performance using full and half-circular OLED in an empty room shows that the average optical path losses are lower by 5 and 4 dB, compared with the furnished room.
Visible light communication (VLC) employs light emitting diodes (LEDs) to provide illumination and data communications simultaneously. Organic LEDs (OLEDs) employing small molecules and long-chain polymers PLEDs, have been gaining attention within the VLC research community due to their inherent advantages such as flexible substrates and low-cost manufacturing. However, the carrier mobility of organic semiconductors is much slower than the devices composed of metal alloys, such as gallium nitride, thus leading to a restriction in the OLED modulation bandwidth. The manufacturing processes, materials and the photoactive size of the devices can affect the raw bandwidth of OLEDs. To increase the transmission speeds, novel approaches have been proposed including equalization techniques, signalling schemes and the optimum driver circuits. The paper provides a survey on the evolution of OLED-based VLC systems, and the respective challenges and recent progresses.
Organic light emitting diodes (OLEDs) have recently received growing interest for their merits as soft light and large panels at a low cost for the use in public places such as airports, shopping centers, offices, and train or bus stations. Moreover, the flexible substrate-based OLEDs provide an attractive feature of having curved or rolled lighting sources for the use in wearable devices and display panels. This technology can be implemented in visible light communications (VLC) for several applications such as visual display, data communications, and indoor localization. This article aims to investigate the use of flexible OLED-based VLC in indoor environments (i.e., office, corridor and semi-open corridor in shopping malls). We derive a two-term power series model to be match with the root-mean-square delay spread and optical path loss (OPL). We show that, for OLED positioned on outer-wall of shops, the channel gain is enhanced in contrast to them being positioned on the inner-wall. Moreover, the channel gain in empty environments is higher compare with the furnished rooms. We show that, the OPL for a 10 m link span are lower by 4.4 and 6.1 dB for the empty and semi-open corridors compared with the furnished rooms, when OLED is positioned on outer-wall of shops. Moreover, the channel gain in the corridor is higher compared with the semi-open corridor. We also show that, in furnished and semi-open corridors the OPL values are 55.6 and 57.2 dB at the center of corridor increasing to 87.6 and 90.7 dB at 20 m, respectively, when OLED is positioned on outer-wall of shops.
The potential use of flexible substrate-based organic light emitting diodes (OLEDs) as curved or rolled lighting sources offers news opportunities for the implementation of visible light communications (VLC) in indoor environments. This paper outlines the use of such a system in a furnished office and investigates the impact of the beam pattern of OLED, which is symmetrical and wider than Lambertian, on the VLC system. We present new results of the VLC system performance in terms of the root-mean-square delay spread and the bit error rate (BER) for the link using both flat and half-circular OLEDs. We demonstrate a data rate of 4 Mb/s using both the curved and flat OLEDs for the transmitter's half-angle within the range of ±90° and ±53°, respectively with a BER below the forward error correction BER limit.
The use of organic light emitting diodes (OLEDs) is being growing in public places, mobile phones, and wearable smartwatches and computers, which facilitate simultaneous illumination, display, and data communications. Therefore, there is a high demand to model the OLED-based visible light communications (VLC) channel in device-to-device (D2D) communications. This paper proposes D2D communications where the information data is transmitted via the smartphone's display pixels and received using the built-in cameras of another smartphone. The impact of the receiver orientation on the channel characteristics is investigated, where two static users face each other and the receiver is intentionally oriented towards the transmitter. It is shown that, in an empty room, the range of delay spreads are around 6 to 7.5 ns and 6 to 10 ns when the distances of the transmitter from the wall are 1.5 and 7.5 m, respectively. Furthermore, in a furnished room, there is a drop in the delay spread at the cost of increased optical path loss compared to the empty room.
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