LED 조명 기반 가시광 무선 통신을 이용한 실내 위치 인식 실험 및 분석

Visible light positioning (VLP) is an emerging positioning technique that utilizes indoor light sources to broadcast archer locations through visible light communication (VLC). Benefited by the densely deployed light lamps, VLP holds the promise for more accurate positioning accuracy than RF based approaches, and thus enables interesting applications such as retail navigation and shelf-level advertising in supermarkets and shopping malls. However, we observe that in existing VLP systems, receiving devices are heavily burdened in handling light flickering for VLC. In order to prevent human from being disturbed, the VLC transmitter lamps have to transmit pulses in a high rate (over 1kHz). Since the pulse rate far exceeds the cameras' sampling capability (30fps), receiver design either requires customized light sensor with cumbersome calibration on receiving signal strength [2] or processing high resolution images to leverage rolling shutter effect of the CMOS camera to decode message [1]. The heavy burden on receiving devices motivated us to try getting rid of light flickers. Since human eyes normally can not perceive changes in polarization, the idea is to modulate polarization instead of intensity for communication. In this demo, we demonstrate the VLC system in our VLP design [3] which realizes this idea. It enables lightweight VLC that is even affordable in wearables (Google Glass), without incurring hardware modification or computation off-loading. Moreover, it also makes other types of illuminating light beyond LED light (even sun light) possible to construct communication, therefore eliminates the barrier for deploying future VLC-based applications. As detailed in the full paper [3], our design was inspired by the liquid crystal display (LCD), from which we borrowed polarizer and liquid crystal. Liquid crystal has the property to change the polarization of bypassing polarized light according to the applied voltage. We use polarizer to polarize illuminating light and leverage liquid crystal to modulate bits through changing the light's polarization. The receiver can thus detect changes in polarization with a polarizing film, through which different polarizations result in different intensities. Since the SNR of such communication channel may significantly vary with the mobility of receiving device, we propose to add a dispersion filter to the transmitter. The dispersion filter can cast different frequency of lights into different polarization directions so that SNR in different receiving directions are evened. With the above techniques, VLC transmitter generates signal in low baud rate and mobile devices can perform VLC through camera directly. The communication is long in distance and lightweight enough for resource-constrained devices since the information is carried in intensity changes rather than certain image patterns in rolling shutter approaches. In this demo, we will illustrate the prototype implementation of the VLC communication system. We use incandescent lamps as illuminating light sources. The transmitter consists of a polarizing film, a liquid crystal layer, a dispersor and a control board. The receiver is demonstrated in Android smartphone with polarizing film in front of the camera.

Visible light communication technology is a wireless optical communication technology based on LED lighting. [1] Making use of the high speed response characteristic of LED, visible light communication technology can realize the dual functions of lighting and communication. As a new way of data access and a supplement to radio frequency communication, visible light communication has been widely concerned. This paper is based on the development of application-oriented visible light communication system based on intelligent terminal, in order to accelerate the practical process of visible light communication. By changing the traditional visible light receiving scheme and using smart phone as the receiving device of the visible light system, a visible light communication system based on intelligent terminal is built [2]. Through the research on the existing receiving algorithm, a new receiving algorithm is proposed to improve the adaptability and BER performance of the system.

Location-Based Services (LBS) are technologies that utilize user location data to provide relevant location-based information. This study aims to examine various LBS applications in smart systems through a review of previous literature. LBS are applied in both outdoor and indoor environments. Outdoor LBS typically use Global Positioning System (GPS) technology for applications such as attendance systems, local business searches, transportation, and healthcare services. Meanwhile, indoor LBS use technologies like Pedestrian Dead Reckoning (PDR) and Simultaneous Localization and Mapping (SLAM) to navigate environments where GPS signals are obstructed. This study also identifies the use of hybrid systems that integrate both indoor and outdoor LBS to ensure consistent service. In addition, challenges related to accuracy, privacy, and energy efficiency in LBS applications across various sectors are discussed. The findings of this research highlight the significant potential of LBS in supporting smart systems while emphasizing the need for further research to address existing challenges, particularly in technology integration and privacy improvements. The implementation of hybrid systems combining indoor and outdoor technologies is expected to provide a more comprehensive solution for future development.

Modern smartphones and location-based services and apps are poised to transform our daily life. However, current smartphone-based localization solutions are limited mainly to outdoor, mostly missing practical, robust and accurate indoor location solutions. Despite significant efforts on indoor localization in both academia and industry in the past two decades, highly accurate and practical smartphone-based indoor localization remains an open problem. To enable indoor location-based services (ILBS), e.g., step-by-step navigation for the Blind and visually impaired, there are several stringent requirements: highly accurate (foot-level); no additional hardware components or extensions on users’ smartphones; scalable to massive concurrent users. Current GPS, Radio RSS (e.g. Wi-Fi, Bluetooth, ZigBee), or Fingerprinting based solutions can only achieve meter-level or room-level accuracy. In this paper, we propose a practical and accurate solution that fills the long-lasting gap of smartphone-based fine-grained indoor localization. Specifically, we design and implement an indoor localization ecosystem Guoguo. Guoguo consists of an anchor network with a coordination protocol to transmit modulated localization beacons using high-band acoustic signals, a realtime processing app in a smartphone, and a backend server for indoor contexts and location-based services. We further propose approaches to improve its coverage, accuracy, and location update rate with low-power consumption. Our prototype shows centimeter-level localization accuracy in several typical indoor environments. Such precise indoor localization is expected to have high impact in the future ILBS and our daily activities.

With the recent successful standardization of broadband power line communication (PLC) (IEEE 1901, ITU-T G.9960/61) and visible light communication (VLC) (IEEE 802.15.7), there is an excellent opportunity to consider their integration. In particular, there is inherent benefit to leveraging existing power line infrastructure to provide connectivity while exploiting energy-efficient LED illumination systems for wireless downlink. The ubiquity of LED lighting together with power line networks leads us to conclude that VLC will be a strong complementary wireless technology to indoor PLC much in the way that Wi-Fi currently supports broadband Ethernet connections. This paper will survey some aspects of both PLC and VLC and present new proposals for their integration.

Accurate and fast indoor Location-Based Services (LBS) is very important for daily life and emergency response. Indoor map is the basis of indoor LBS. The model construction and data organization of indoor map are the key scientific problems that urgently need to be solved in the current indoor LBS application. In recent years, hybrid models have been used widely in the research of indoor map, because they can balance the limitations of single models. However, the current studies about hybrid model pay more attention to the model accuracy and modeling algorithm, while ignoring its relationship between positioning and navigation and its practicality in mobile indoor LBS applications. This paper addresses a new indoor map model, named Building Information Modeling based Positioning and Navigation (BIMPN), which is based on the entity model and the network model. The highlight of BIMPN is that it proposes a concept of Step Node (SN) to assist indoor positioning and navigation function. We developed the Mobile Indoor Positioning and Navigation System (MIPNS) to verify the practicability of BIMPN. Results indicate that the BIMPN can effectively organize the characteristics of indoor spaces and the building features, and assist indoor positioning and navigation. The BIMPN proposed in this paper can be used for the construction of indoor maps and it is suitable for mobile indoor positioning and navigation systems.

Visible Light Communication (VLC) holds a great potential to solve the spectrum crunch problem and to provide scalable connectivity to zillions of mobile and IoT devices. However, VLC commonly requires LED lights to be on, which fundamentally limits the applicable scenarios of VLC and makes VLC less attractive to mobile and IoT devices with tight energy budget. We present DarkVLC, a new VLC primitive that allows the VLC link to be sustained even when the LED lights appear dark or off. The key idea is to encode data into ultra-short light pulses imperceptible to human eyes yet detectable by devices equipped with photodiodes. Realizing DarkVLC faces several challenges to generate and deal with the ultra-short light pulses reliably. We describe our preliminary efforts to tackle these challenges and build a DarkVLC prototype using off-the-shelf LEDs and low-cost photodiodes. DarkVLC fundamentally broadens the application scenarios of VLC and provides a new ultra-low power, always-on connectivity affordable for mobile and IoT devices.

Indoor visible light positioning becomes attractive due to the increasing demands of location-based services. In this paper, we presented a model of an indoor positioning system based on visible light communication technology firstly. The system uses white light emitting diodes (LED) as light sources, so it has the dual role of communication and lighting. Then, the transmitter and receiver of visible light communication in the system have been designed and realized. Next, a coding protocol was designed and implemented, which can be used to transmit ID of each light source. Finally, the error performance in experiments of the proposed system is analyzed and several suggestions on future research of indoor positioning based on visible light communication were given.

With the development of indoor positioning methods, such as Wi-Fi positioning, geomagnetic sensor positioning, Ultra-Wideband positioning, and pedestrian dead reckoning, the area of location-based services (LBS) is expanding from outdoor to indoor spaces. LBS refers to the geographic location information of moving objects to provide the desired services. Most Wi-Fi-based indoor positioning methods provide two-dimensional (2D) or three-dimensional (3D) coordinates in 1–5 m of accuracy on average approximately. However, many applications of indoor LBS are targeted to specific spaces such as rooms, corridors, stairs, etc. Thus, they require determining a service space from a coordinate in indoor spaces. In this paper, we propose a map matching method to assign an indoor position to a unit space a subdivision of an indoor space, called USMM (Unit Space Map Matching). Map matching is a commonly used localization improvement method that utilizes spatial constraints. We consider the topological information between unit spaces and moving objects’ probabilistic properties, compared to existing room-level mappings based on sensor signals, especially received signal strength-based fingerprinting. The proposed method has the advantage of calculating the probability even if there is only one input trajectory. Last, we analyze the accuracy and performance of the proposed USMM methods by extensive experiments in real and synthetic environments. The experimental results show that our methods bring a significant improvement when the accuracy level of indoor positioning is low. In experiments, the room-level location accuracy improves by almost 30% and 23% with real and synthetic data, respectively. We conclude that USMM methods are helpful to correct valid room-level locations from given positioning locations.

Using smartphones for accurate indoor localization opens a new frontier of mobile services, offering enormous opportunities to enhance users' experiences in indoor environments. Despite significant efforts on indoor localization in both academia and industry in the past two decades, highly accurate and practical smartphone-based indoor localization remains an open problem. To enable indoor location-based services (ILBS), there are several stringent requirements for an indoor localization system: highly accurate that can differentiate massive users' locations (foot-level); no additional hardware components or extensions on users' smartphones; scalable to massive concurrent users. Current GPS, Radio RSS (e.g. WiFi, Bluetooth, ZigBee), or Fingerprinting based solutions can only achieve meter-level or room-level accuracy. In this paper, we propose a practical and accurate solution that fills the long-lasting gap of smartphone-based indoor localization. Specifically, we design and implement an indoor localization ecosystem Guoguo. Guoguo consists of an anchor network with a coordination protocol to transmit modulated localization beacons using high-band acoustic signals, a realtime processing app in a smartphone, and a backend server for indoor contexts and location-based services. We further propose approaches to improve its coverage, accuracy, and location update rate with low-power consumption. Our prototype shows centimeter-level localization accuracy in an office and classroom environment. Such precise indoor localization is expected to have high impact in the future ILBS and our daily activities.

Nowadays, with the incursion of solid state lighting technology in our daily life, visible light communication (VLC) systems are becoming more important. This fact has generated a lot of attention on VLC to provide solutions on multiple applications where this technology can be exploited. At the same time, the growing of automation processes has created the necessity of knowing the localization of different objects and devices. Indoor localization based on radio frequency signals is one of the most used techniques (Wi‐Fi, Bluetooth, UWB, RFID, etc); however, VLC is a new and interesting method, which is gaining enormous research attention. Moreover, there are environments where the use of RF technologies is restricted or even prohibited. In such cases, VLC technology becomes an interesting alternative to solve this problem. In this paper, we design and implement a novel VLC‐based indoor localization system that combines the application of a VLC scheme for downlink and an ultrasonic communication for the uplink. Practical localization experiments are carried out in an actual office room environment, and results show a localization accuracy of 4 cm on average for direct links and 10 cm for indirect links.

Visible-light wireless communication is an optical communication technology rising with the development of white LED lighting technology. Based on the analysis of current visible light communication technology, the paper aims at the application requirement of m-ary modulation communication system, and designs the component of APD receiving circuit. Firstly, this article specifies the operating principle of APD detection circuit, secondly, the paper designs and analyzes circuit structure and function of each part of the system of high voltage circuit, lastly, the detection module of m-ary visible light communication (VLC) receiving circuit's relevant test is carried out. The results show that the design is valid and feasible and the APD receiving circuit has the advantages of high gain, wide bandwidth, good stability, which has good application value on m-ary visible light communication and provide the basis for the further studies of m-ary VLC.

Visible Light Communication (VLC) is a way of communication that uses visible light as information carrier to transmit optical signal in the air without wired channels. VLC is attracting more and more attention from the industry because of its good performance in electromagnetic radiation, environment and safety. However, it’s still a tough challenge to achieve high accuracy in real applications, due to the complexity of the environment and the limitations of devices and technology of VLC system. In this paper, the VLC systems’ developments and applications in indoor positioning are summarized, providing a reference to the further study of VLC systems.

This study presents a method for analyzing workers’ behavior using indoor positioning technology and field test in the workplace. Recently, various indoor positioning methods, such as Wi-Fi, Bluetooth low energy (BLE), visible light communication, Japan’s indoor messaging system, ultra-wide band (UWB), and pedestrian dead reckoning (PDR), have been investigated. The development of these technologies allows tracking of movement of both people and/or goods in indoor spaces, people and/or goods behavior analysis is expected as one of the key technologies for operation optimization. However, when we use these technologies for human tracking, there are some problem as follows. 1) Many cases need to use dedicated facilities (e.g. UWB). 2) When we use smartphone as sensing device, battery depletion is one of the big problem (especially using PDR). 3) the accuracy is instability for tracking (e.g. Wi-Fi). Based on these matters, in this study we designed and developed an indoor positioning system using BLE positioning. And, we adopted smartphone for business use as sensing device, developed a smartphone application runs on android OS. Moreover, we conducted the field test of developed system at Itoki Corporation’s ITOKI Tokyo Innovation Center, SYNQA, office (Tokyo, Japan). Over 40 workers participated in this field test, and worker tracking log data were collected for 6 weeks. We analyzed the characteristics of the workers’ behavior using this log data as a prototyping.

Precise indoor positioning is a widely researched topic currently. Many existing or new radio devices and standards are being explored for this purpose. Existing infrastructure or technology is always advantageous as it might reduce the cost and at the same time can be used for other purposes. The emerging visible light communication (VLC) is another technology being researched for precise positioning, especially in the indoor environment. VLC can be designed on existing infrastructure or slightly modified systems, and positioning using VLC would find usage in real-life scenarios. In this positioning system, an object whose location needs to be determined must have a VLC receiver. In this work, a comparative study is performed for popular algorithms through simulation as well as hardware demonstration. Thorough analysis and simulation are performed for circular lateration, hyperbolic lateration, differential detection, and angulation; the hardware implementation and demonstration as a proof of concept (POC) is completed for circular lateration and differential detection. Both these models use received signal strength (RSS) to calculate distances. We use a single photodetector for implementing circular lateration whereas two photodetectors for demonstrating differential technique. We observe that the differential detection performs relatively better compared to circular lateration, that is, the error is reduced in differential detection.