Performance evaluation of neural network assisted motion detection schemes implemented within indoor optical camera based communications

This paper investigates the performance of the neural network (NN) assisted motion detection (MD) over an indoor optical camera communication (OCC) link. The proposed study is based on the performance evaluation of various NN training algorithms, which provide efficient and reliable MD functionality along with vision, illumination, data communications and sensing in indoor OCC. To evaluate the proposed scheme, we have carried out an experimental investigation of a static indoor downlink OCC link employing a mobile phone front camera as the receiver and an 8 x000D7; 8 red, green and blue light-emitting diodes array as the transmitter. In addition to data transmission, MD is achieved using a camera to observe userx02019;s finger movement in the form of centroids via the OCC link. The captured motion is applied to the NN and is evaluated for a number of MD schemes. The results show that, resilient backpropagation based NN offers the fastest convergence with a minimum error of 10x02212;5 within the processing time window of 0.67 s and a success probability of 100 x00025; for MD compared to other algorithms. We demonstrate that, the proposed system with motion offers a bit error rate which is below the forward error correction limit of 3.8 x000D7; 10x02212;3, over a transmission distance of 1.17 m

The first tests of smartphone camera exposure effect on optical camera communication links

In this paper, we study the effect of smartphone camera exposure on the performance of optical camera communications (OCC) link. The exposure parameters of image sensor sensitivity (ISO), aperture and shutter speed are included. A static OCC link with a 8×8 red, green and blue (RGB) LED array employed as the transmitter and a smartphone camera as the receiver is demonstrated to verify the study. Signal-to-noise ratio (SNR) analysis at different ISO values, the effect of aperture and shutter speed on communication link quality is performed. While SNRs of 20.6 dB and 16.9 dB are measured at 1 m and 2 m transmission distance, respectively for a ISO value of 100, they are decreased to 17.4 dB and 13.32 dB for a ISO of 800. The bit error rate (BER) of a 1 m long OCC link with a camera’s shutter speed of 1/6000 s is 1.3×10 −3 (i.e., below the forward error correction BER limit of 3.8×10 −3 ) and is dropped to 0.0125 at a shutter speed of 1/20 s. This study provides insight of the basic smartphone settings and the exposure adjustment for further complex OCC links

Flicker-free Multi-channel Transmitter Orientation in Camera based Optical Wireless Communications

We demonstrate the camera based optical wireless communications using flicker-free multi-channel transmitter orientation that provide 100 % success of reception over orientation angle of up to 30° at 200 and 400μs camera shutter speed

Spatial frequency-based angular behavior of a short-range flicker-free MIMO–OCC link

In this paper, we provide a solution based on spatial frequency fsf to study the angular behavior of a flicker-free, short-range indoor multiple–input multiple–output (MIMO) optical camera communications (OCC) link. We focus on the experimental investigation of OCC’s performance for the transmitters (Txs) [i.e., light-emitting diode (LED) based arrays] located at the same and different distances from the receiver (Rx) with the off-axis rotation angle θ. We have used two 8 × 8 distributed LED arrays and a commercial low-cost complementary metal-oxide-semiconductor (CMOS) Raspberry Pi camera with the rolling-shutter capturing mode as the Tx and Rx, respectively. The image and the respective communications link quality metrics are measured in terms of the peak signal-to-noise ratio (PSNR) and the rate of successfully received bits with respect to fsf for different camera shutter speeds (SS). A CMOS image sensor noise characterization is carried in terms of the signal-to-noise ratio (SNR) and PSNR. The proposed study provides a 100% success rate in data reception at the optimum θ of 50◦ at lower captured values of fsf, which is projected onto the image sensor in the form of pixels. Moreover, the effect of channel saturation over fsf is studied with respect to θ and SS and we show that, for θ exceeding the optimum value along transmission range, the fsf area of the Txs reduces to less than ∼50% of the captured Tx units at θ of 0◦, where no data can be fully recovered

Optical Camera Communications for IoT–Rolling-Shutter Based MIMO Scheme with Grouped LED Array Transmitter

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

The First Study of MIMO Scheme Within Rolling-shutter Based Optical Camera Communications

In this paper, we propose the first study of MIMO (multiple-input multiple-output) scheme using a simplified design of MIMO transmitter (Tx) based on grouping of light-emitting diodes (LED) within an array for flicker-free transmission in optical camera based communications (OCC) link. We carried out an initial experimental investigation of indoor static downlink OCC using a Raspberry Pi camera as the receiver with rolling-shutter capturing mode and a 7.2 cm × 7.2 cm small 64-neopixel LED array as the Tx. The initial study suggests that, despite the small area of the display, communication links from 20 up to 60 cm can be established

Experimental Investigation of Neuron Based Motion Detection in Internet of Things using Optical Camera Communications

This paper experimentally investigates the performance of visible light based optical camera communications (OCC) link with motion detection (MD) for the optical Internet of things applications. This efficient MD can be considered another functionality of OCC in addition to traditional features of vision, illumination data communications and sensing. The experiments were conducted in an indoor static downlink OCC system employing a mobile phone front camera is employed as the receiver and an 8 × 8 red, green, and blue (RGB) light-emitting diode array as the transmitter. The motion is detected by observing the user's finger movement in the form of centroid through the OCC link via a camera. The experiment results demonstrate that, the proposed scheme can detect all considered motions accurately with acceptable bit error rate (BER) performances at a transmission distance of up to 80 cm. We show a BER of 1.7 × 10-3 below the forward error correction limit of 3.8 × 10-3 over a transmission distance of up to 1 m. The proposed neuron based MD combined together with OCC can be considered an efficient system, which provides illumination, communications, and motion detection in a convenient smart home environment

Optical Internet of Things within 5G: Applications and Challenges

International audienceThe fifth generation (5G) telecommunications standards are being developed to meet the growing demands for high-speed wireless networks (i.e., few tens of Gigabits per second). The 5G standard stems largely from an increasing number of users and plethora of different devices, collectively referred to as smart devices, connecting to a network as part of Internet-of-Things (IoT). A few potential technologies have emerged for 5G such as millimeter waves, massive multiple-input multiple-output, and small cell communications. Although these technologies would satisfy the requirements of 5G, there is a complementary alternative wireless technology of optical wireless communications (OWC), which is being considered. As part of OWC, visible light communications (VLC) and optical camera communications (OCC) are the most attractive options for 5G networks and beyond. VLC with huge frequency spectrum integrated with IoT can open up a wide range of indoor and outdoor applications as part of future smart environments. This paper provides an overview of the all-optical IoT (OIoT) focusing on VLC and OCC based potential applications and challenges as part of 5G standards. Keywords-Optical wireless communications (OWC); visible light communications (VLC); optical camera communications (OCC); Internet of things (IoT); light emitting diodes (LEDs)

Spatial frequency-based angular behavior of a short-range flicker-free MIMO–OCC link

International audienceIn this paper, we provide a solution based on spatial frequency f sf to study the angular behavior of a flicker-free, short-range indoor multiple-input multiple-output (MIMO) optical camera communications (OCC) link. We focus on the experimental investigation of OCC's performance for the transmitters (Txs) [i.e., light-emitting diode (LED) based arrays] located at the same and different distances from the receiver (Rx) with the off-axis rotation angle θ. We have used two 8 × 8 distributed LED arrays and a commercial low-cost complementary metaloxide-semiconductor (CMOS) Raspberry Pi camera with the rolling-shutter capturing mode as the Tx and Rx, respectively. The image and the respective communications link quality metrics are measured in terms of the peak signal-to-noise ratio (PSNR) and the rate of successfully received bits with respect to f sf for different camera shutter speeds (SS). A CMOS image sensor noise characterization is carried in terms of the signal-to-noise ratio (SNR) and PSNR. The proposed study provides a 100% success rate in data reception at the optimum θ of 50 • at lower captured values of f sf , which is projected onto the image sensor in the form of pixels. Moreover, the effect of channel saturation over f sf is studied with respect to θ and SS and we show that, for θ exceeding the optimum value along transmission range, the f sf area of the Txs reduces to less than ∼50% of the captured Tx units at θ of 0 • , where no data can be fully recovered

Optical camera communications link using an LED-coupled illuminating optical fiber

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