Chang Hyun Hong

High-speed asynchronous Optical Camera Communication using LED and rolling shutter camera

This paper introduces the asynchronous Optical Camera Communication (asynchronous OCC) using LED and rolling shutter camera as a pair of wireless communication. Aiming to enhance the capacity of unidirectional wireless link, the response of camera is measured, and then the operating frequency range, system architecture, decoding procedure and algorithm are proposed. The frame and super-frame structure are also considered especially for OCC using rolling shutter camera. The performance of implemented system is evaluated and discussed.

Effect of blur Gaussian in MIMO optical camera communications

MIMO is popular technique which can improve the reliability and spectral efficiency of RF communication system by using the spatial link dimensions. It is also an attractive option solution for achieving high data rate. Optical Camera Communication (OCC) is considered for revision specification of visible light communication standard. One of the most consideration disadvantages of OCC is data rate limitation. With traditional modulation scheme, the throughput can achieve a few bits per second. MIMO is promising technique to overcome this limitation. Independent streams of light transmitter array will be sent over optical channel and decoded over a group of camera pixels. However with the effect of blur, two transmit element images may not be resolvable by overlap pixels. In this paper we analyze and evaluate the performance of the blur Gaussian in MIMO OCC.

Color transmission in image sensor communications using display and camera

Intention for using color in image sensor communication (ISC) has become trendy issue due to its specific limitations. This paper suggests a color transmission technology to minimize the blur effects in the ISC. We propose an asynchronous communication using display as a transmitter and rolling shutter camera as a receiver to measure the blur effect. The interruption due to the blur effects in the communication system has been analyzed. The performance of implemented system has been illustrated with respect to signal to noise ratio (SNR) as well as bit error rate (BER) with a view to estimating the effects of blur on the communication system.

Mathematical modeling for calibrating illuminated image in image sensor communication

Image sensor communication (ISC) has become more imperative for the technology lover by virtue of the development of image sensors in the camera. Lately, Digital signage technology has become one of the most flourished industry for ISC technology as it has uncovered a lot of opportunities such as interactivity, dynamic content provisioning and so on. Granting all this opportuneness, there are some major issues in the case of ISC technology when the communication system specifies the communication by means of steganography process (Inserting data in the video image). Geometric and photometric transformations of the image are among them while the display and the camera act as a transmitter and a receiver in ISC, respectively. Due to this effect, the data can be changed or noise can be even more influential than the required signal. To achieve a relevant communication method, the influence of these transformational issues need to be taken into care. We proposed a mathematical modeling to figure out the photometric effects created by illumination from the light source of the environment in this paper. The channel model is used as non-Lambertian model. The novelty of this work implies the unification of computer vision and proposed channel model to remove the photometric transformational effects due to illumination in an image.

Hybrid modulation scheme for indoor image sensor communication system using smartphone and LEDs

This paper shows a layout for a newly proposed hybrid modulation scheme for image sensor communication, especially for indoor image sensor communication using smartphone and LEDs. The proposed system infers compatibility support for frame rate variation too whereas the compatibility is performed by inserting asynchronous data bit with the original data bit. We propose the modulation scheme considering both frequency domain and phase domain of the communication signal. The scheme contains M-FSK and N-PSK schemes where M and N stand for the number of frequencies and the number of phases, respectively. The M-FSK scheme, a scheme for sharing frequency bandwidth to multiple transmitters, can be useful for rolling shutter cameras while most of the smartphones use rolling shutter functionality for the camera. The N-PSK (only 2-PSK is discussed in the work) method is applied along with M-PSK scheme to achieve higher data rate as well far distant transmission. The higher data rate is very supportive of bringing compatibility in case frame rate variation because the use of asynchronous bit causes a decline in data rate.

Channel modeling and system analysis for seaside image sensor communications

This paper presents an Image Sensor Communications (ISC) concept in maritime environments. The proposed concept is a cost-effective method of implementation by using existing infrastructures including a lighthouse or a ship LED lamp and typical rolling-shutter cameras. Through the content of paper, a complete channel modelling based on practical experiment results is introduced in which a model of light beam and imaging operation of camera are considered under seaside medium. The communication analysis is also given.

Flicker-free spatial-PSK modulation scheme for vehicular image sensor communications

This paper proposes a 2-Phase Shift Keying (2-PSK) based modulation scheme for Image Sensor Communications. The considered communication system on a car uses a couple of LED light sources for transmitting data (either two rear light sources or two front light sources) and a typical-frame-rate camera (i.e. 30fps frame rate) which is either a global shutter camera or a rolling shutter camera for receiving data; therefore a flicker-free is required. Taking advantage of a dual light-source on a car, our spatial modulation approach allows a camera decoding a complete symbol from an image. Compared to a temporal approach, our scheme avoids a data decoding procedure that a symbol is demodulated from different images at which there is a high possibility of noise difference exposed by those two images especially in vehicular movement environment. Moreover, besides being compatible to both shutter types, global shutter and rolling shutter, our additional contribution on the paper is the ability to support a camera that has a wide frame-rate variation (i.e. a camera drops the frame rate to even less than 20fps) which was considered on the Technical Consideration Document (TCD) of the on-going IEEE 802.15.7r1 Task Group. Later, some analysis and experiment results are addressed to show the performance of the proposed modulation scheme.