In this Letter, we develop a novel technique, to the best of our knowledge, to increase the link span ( L s ) of a rolling shutter (RS)-based optical camera communications (OCC) system by reducing the spatial bandwidth of the camera in the out-of-focus regions. We demonstrate a 400 m line-of-sight RS-based OCC link, which is to date the longest L s reported in these systems, and develop a detection method to extract the information out of the video frames, successfully. The proposed system relaxes the condition of a large surface area for the transmitter light source. Consequently, we show that at 400 m L s and exposure times of 100–80 µs, a data rate of 450 bps is achieved successfully.

In optical camera communications (OCC), the provision of both flicker-free illumination and high data rates are challenging issues, which can be addressed by utilizing the rolling-shutter (RS) property of the image sensors as the receiver (Rx). In this paper, we propose an RS-based multiple-input multiple-output OCC scheme for the Internet of things (IoT) application. A simplified design of multi-channel transmitter (Tx) using a 7.2 × 7.2 cm² small 8 × 8 distributed light emitting diode (LED) array, based on grouping of LEDs, is proposed for flicker-free transmission. We carry out an experimental investigation of the indoor OCC system by employing a Raspberry Pi camera as the Rx, with RS capturing mode. Despite the small area of the display, flicker-free communication links within the range of 20–100 cm are established with data throughput of 960 to 120 bps sufficient for IoT. A method to extend link spans up to 1.8 m and the data throughput to 13.44 kbps using different configurations of multi-channel Tx is provided. The peak signal-to-noise ratio of ~14 and 16 dB and the rate of successfully received bits of 99.4 and 81% are measured for the shutter speeds of 200 and 800 µs for a link span of 1 m, respectively.

Optical camera communications (OCC) research field has grown recently, aided by ubiquitous digital cameras; however, atmospheric conditions can restrict their feasibility in outdoor scenarios. In this work, we studied an experimental OCC system under environmental phenomena emulated in a laboratory chamber. We found that the heat-induced turbulence does not affect our system significantly, while the attenuation caused by fog does decrease the signal quality. For this reason, a novel strategy is proposed, using the camera’s built-in amplifier to overcome the optical power loss and to decrease the quantization noise induced by the analog-digital converter of the camera. The signal quality has been evaluated using the Pearson’s correlation coefficient with respect to a reference template signal, along with the signal-to-noise ratio that has been empirically evaluated. The amplification mechanism introduced allows our system to receive the OCC signal under heavy fog by gradually increasing the camera gain up to 16 dB, for meteorological visibility values down to 10 m, with a correlation coefficient of 0.9 with respect to clear conditions.

Visible-light communication (VLC) is an emerging technology utilizing light-emitting diodes and photodetectors (PDs) and cameras [i.e., image sensors (ISs)] as the transmitter and receivers (Rx), respectively, for simultaneous data communications, illumination, localization, and sensing in the indoor optical Internet of Things. We propose a single-input–multiple-output (SIMO) hybrid VLC system using PD-based and IS-based Rxs for simultaneous high-speed and low-speed (i.e., $R_{b-{\mathrm{ High}}}$ and $R_{b-{\mathrm{ Low}}}$ ) data transmission. In addition, we propose amplitude overlapping ${A} _{\mathrm{ OL}}$ in the modulation format to increase $R_{b}$ and reduce the attenuation due to the high-pass filter effect of the bias-T. We experimentally evaluate the performance of the proposed scheme considering the interlink impacts. Results show that at ${A} _{\mathrm{ OL}}$ of 0–0.2: 1) the measured bit error rate for the PD-based VLC is below the forward error correction limit of $3.8 \times 10^{-3}$ for $R_{b-{\mathrm{ Low}}}$ of 2.5 and 5 kb/s at $R_{b-{\mathrm{ High}}}$ of 35 and 60 Mb/s, respectively, and 2) for the IS-based VLC link with the camera gain of 4 dB and $R_{b-{\mathrm{ High}}}$ of up to 70 Mb/s, the reception success rates are >96 and 90% at $R_{b-{\mathrm{ Low}}}$ of 2.5 and 5 kb/s, respectively.

In this Letter, we propose and demonstrate a novel wireless communications link using an illuminating optical fiber as a transmitter (Tx) in optical camera communications. We demonstrate an indoor proof-of-concept system using an illuminating plastic optical fiber coupled with a light-emitting diode and a commercial camera as the Tx and the receiver, respectively. For the first time, to the best of our knowledge, we experimentally demonstrate flicker-free wireless transmission within the off-axis camera rotation angle range of 0–45° and the modulation frequencies of 300 and 500 Hz. We also show that a reception success rate of 100% is achieved for the camera exposure and gain of 200 µs and 25 dB, respectively.

This paper outlines the concept of a multilevel bipolar on-off keying hybrid optical wireless communication (OWC) system using a single light-emitting diode (LED) as a transmitter as well as photodiode and camera-based receivers for versatile indoor Internet of Things applications. The proposed system offers simultaneous high- and low-speed transmission capabilities using visible light communication (VLC) and optical camera communication (OCC) links, respectively. By means of experimental implementation, we show that the hybrid OWC system employing a chip LED modulated with a multilevel signal improves the data rate Rb as well as the bit error rate and reception success rate of VLC and OCC links, respectively, by doubling the bandwidth. We show that the proposed scheme can provide an independent link performance, irrespective of significant differences between the operating Rb of VLC and OCC over a range of transmission spans L. We demonstrate that the throughput of the VLC link is improved by up to ~100 Mb/s, which corresponds to twice the LED bandwidth, using direct modulation, different amplitude levels, and optimizing the received optical power of the hybrid OWC link. Error-free data transmission for the OCC link is achieved for all values of Rb, amplitude overlap of 0 and 0.3, and a range of L.