Optical Camera Communications: Principles, Modulations, Potential and Challenges

Optical wireless communications (OWC) are emerging as cost-effective and practical solutions to the congested radio frequency-based wireless technologies. As part of OWC, optical camera communications (OCC) have become very attractive, considering recent developments in cameras and the use of fitted cameras in smart devices. OCC together with visible light communications (VLC) is considered within the framework of the IEEE 802.15.7m standardization. OCCs based on both organic and inorganic light sources as well as cameras are being considered for low-rate transmissions and localization in indoor as well as outdoor short-range applications and within the framework of the IEEE 802.15.7m standardization together with VLC. This paper introduces the underlying principles of OCC and gives a comprehensive overview of this emerging technology with recent standardization activities in OCC. It also outlines the key technical issues such as mobility, coverage, interference, performance enhancement, etc. Future research directions and open issues are also presented

Design and Implementation of a Novel Compatible Encoding Scheme in the Time Domain for Image Sensor Communication

This paper presents a modulation scheme in the time domain based on On-Off-Keying and proposes various compatible supports for different types of image sensors. The content of this article is a sub-proposal to the IEEE 802.15.7r1 Task Group (TG7r1) aimed at Optical Wireless Communication (OWC) using an image sensor as the receiver. The compatibility support is indispensable for Image Sensor Communications (ISC) because the rolling shutter image sensors currently available have different frame rates, shutter speeds, sampling rates, and resolutions. However, focusing on unidirectional communications (i.e., data broadcasting, beacons), an asynchronous communication prototype is also discussed in the paper. Due to the physical limitations associated with typical image sensors (including low and varying frame rates, long exposures, and low shutter speeds), the link speed performance is critically considered. Based on the practical measurement of camera response to modulated light, an operating frequency range is suggested along with the similar system architecture, decoding procedure, and algorithms. A significant feature of our novel data frame structure is that it can support both typical frame rate cameras (in the oversampling mode) as well as very low frame rate cameras (in the error detection mode for a camera whose frame rate is lower than the transmission packet rate). A high frame rate camera, i.e., no less than 20 fps, is supported in an oversampling mode in which a majority voting scheme for decoding data is applied. A low frame rate camera, i.e., when the frame rate drops to less than 20 fps at some certain time, is supported by an error detection mode in which any missing data sub-packet is detected in decoding and later corrected by external code. Numerical results and valuable analysis are also included to indicate the capability of the proposed schemes

Design and Implementation of a Novel Compatible Encoding Scheme in the Time Domain for Image Sensor Communication

This paper presents a modulation scheme in the time domain based on On-Off-Keying and proposes various compatible supports for different types of image sensors. The content of this article is a sub-proposal to the IEEE 802.15.7r1 Task Group (TG7r1) aimed at Optical Wireless Communication (OWC) using an image sensor as the receiver. The compatibility support is indispensable for Image Sensor Communications (ISC) because the rolling shutter image sensors currently available have different frame rates, shutter speeds, sampling rates, and resolutions. However, focusing on unidirectional communications (i.e., data broadcasting, beacons), an asynchronous communication prototype is also discussed in the paper. Due to the physical limitations associated with typical image sensors (including low and varying frame rates, long exposures, and low shutter speeds), the link speed performance is critically considered. Based on the practical measurement of camera response to modulated light, an operating frequency range is suggested along with the similar system architecture, decoding procedure, and algorithms. A significant feature of our novel data frame structure is that it can support both typical frame rate cameras (in the oversampling mode) as well as very low frame rate cameras (in the error detection mode for a camera whose frame rate is lower than the transmission packet rate). A high frame rate camera, i.e., no less than 20 fps, is supported in an oversampling mode in which a majority voting scheme for decoding data is applied. A low frame rate camera, i.e., when the frame rate drops to less than 20 fps at some certain time, is supported by an error detection mode in which any missing data sub-packet is detected in decoding and later corrected by external code. Numerical results and valuable analysis are also included to indicate the capability of the proposed schemes

Design and Implementation of a Novel Compatible Encoding Scheme in the Time Domain for Image Sensor Communication

Abstract: This paper presents a modulation scheme in the time domain based on On-Off-Keying andproposes various compatible supports for different types of image sensors. The content of this article isa sub-proposal to the IEEE 802.15.7r1 Task Group (TG7r1) aimed at Optical Wireless Communication(OWC) using an image sensor as the receiver. The compatibility support is indispensable forImage Sensor Communications (ISC) because the rolling shutter image sensors currently availablehave different frame rates, shutter speeds, sampling rates, and resolutions. However, focusing onunidirectional communications (i.e., data broadcasting, beacons), an asynchronous communicationprototype is also discussed in the paper. Due to the physical limitations associated with typicalimage sensors (including low and varying frame rates, long exposures, and low shutter speeds),the link speed performance is critically considered. Based on the practical measurement of cameraresponse to modulated light, an operating frequency range is suggested along with the similar systemarchitecture, decoding procedure, and algorithms. A significant feature of our novel data framestructure is that it can support both typical frame rate cameras (in the oversampling mode) as wellas very low frame rate cameras (in the error detection mode for a camera whose frame rate is lowerthan the transmission packet rate). A high frame rate camera, i.e., no less than 20 fps, is supported inan oversampling mode in which a majority voting scheme for decoding data is applied. A low framerate camera, i.e., when the frame rate drops to less than 20 fps at some certain time, is supportedby an error detection mode in which any missing data sub-packet is detected in decoding and latercorrected by external code. Numerical results and valuable analysis are also included to indicate thecapability of the proposed schemes