• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제15권2호
• /
• pp.404-420
• /
• 2021

In this paper, an automatic system of locating the indoor area with weak or no mobile signal was proposed and demonstrated experimentally by using the Internet of Things (IoT) technology. Nowadays, the technicians of mobile services providers need to go along with numerous heavy equipment to measure and record the mobile signal strength at outside environment. Recently, there are systems proposed to do such measurement at outdoor area by using the IoT technology automatically. However, these works could not be applied in the indoor area since there are difficulties to do the indoor mapping and positioning. In this work, the Bluetooth Low Energy (BLE) was used to tackle these two difficulties. After a proper placement of BLE in the testing site, while the technician walk around with a handheld analyzer, the data can be obtained accordingly for further analysis in the proposed system which includes the construction of floor plan, detection of mobile signal strength and suggestion of indoor base stations. The gift wrapping and centroid algorithms were used during the analysis. The experimental results showed that the proposed system successfully demonstrated the indoor mapping, positioning of weak mobile signal area and suggestion of indoor base stations for the normal rectangular rooms with an area of 100 m² on single floor.

• 제어로봇시스템학회논문지
• /
• 제12권10호
• /
• pp.975-981
• /
• 2006

This paper shows a feasibility analysis results on RFID for car positioning system. Usually, a car navigation is mainly based on GPS combined with map-matching. However, in the case of poor visibility of satellites, GPS can not supply accurate position information continuously. In recent years, RFID has been considered to be one of key technologies in positioning and localization area. But its application and research results in the area of vehicular positioning are not popular. RFID system consists of tag, reader, antenna and software such as drivers and middleware. The main function of RFID system in a vehicular positioning is to retrieve ID recorded position information from tags which set on the center of road. We propose a positioning method for vehicles using RFID and we present some indoor and outdoor experiment results to show that the proposed method is available in vehicle operational environments.

• 제어로봇시스템학회논문지
• /
• 제17권6호
• /
• pp.610-618
• /
• 2011

For improved localization around the indoor/outdoor transit area of buildings, this paper proposes an efficient algorithm combining the measurements from the WLAN (Wireless Local Area Network) and the GPS (Global Positioning System) for. The proposed hybrid localization algorithm considers both multipath errors and NLOS (Non-Line-of-Sight) errors, which occur in most wireless localization systems. To detect and isolate multipath errors occurring in GPS measurements, the propose algorithm utilizes conventional multipath test statistics. To convert WLAN signal strength measurements to range estimates in the presence of NLOS errors, a simple and effective calibration algorithm is designed to compute conversion parameters. By selecting and combining the reliable GPS and WLAN measurements, the proposed hybrid localization algorithm provides more accurate location estimates. An experiment result demonstrates the performance of the proposed algorithm.

• 한국인터넷방송통신학회논문지
• /
• 제22권3호
• /
• pp.117-123
• /
• 2022

인공위성 기반의 실외 측위 시스템과는 달리 실내 측위 시스템은 BLE, Wi-Fi, UWB 등 다양한 무선 기술을 활용한다. BLE 기반 비컨 기술은 일정 주기로 사전에 정의된 장치 ID와 위치 정보를 제공하고 이를 수신한 장치에서 RSSI를 활용하여 실내에서 사용자의 위치를 측정할 수 있다. 기존의 BLE 기반 실내 측위 시스템 연구들은 단일 지점에서 사용자의 실제 위치와 계산된 위치의 오차를 비교하는 연구가 많았다. 본 논문에서는 엔트로피 분석 모델을 적용하여 이동 경로나 구역에 따른 측위 정확도를 평가하는 기법을 제안하였다. 또한 시뮬레이션을 통해 서로 다른 경로에 대한 엔트로피 결과값을 추출하고 이를 비교하여 어느 경로가 더 정확한지에 대해 평가할 수 있음을 검증하였다.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
• /
• pp.83-88
• /
• 2006

Many applications in the area of location-based services and personal navigation require nowadays the location determination of a user not only in outdoor environment but also indoor. To locate a person or object in a building, systems that use either infrared, ultrasonic or radio signals, and visible light for optical tracking have been developed. The use of WiFi for location determination has the advantage that no transmitters or receivers have to be installed in the building like in the case of infrared and ultrasonic based location systems. WiFi positioning technology adopts IEEE802.11x standard, by observing the radio signals from access points installed inside a building. These access points can be found nowadays in our daily environment, e.g. in many office buildings, public spaces and in urban areas. The principle of operation of location determination using WiFi signals is based on the measurement of the signal strengths to the surrounding available access points at a mobile terminal (e.g. PDA, notebook PC). An estimate of the location of the terminal is then obtained on the basis of these measurements and a signal propagation model inside the building. The signal propagation model can be obtained using simulations or with prior calibration measurements at known locations in an offline phase. The most common location determination approach is based on signal propagation patterns, namely WiFi fingerprinting. In this paper the underlying technology is briefly reviewed followed by an investigation of two WiFi positioning systems. Testing of the system is performed in two localization test beds, one at the Vienna University of Technology and the second at the Hong Kong Polytechnic University. First test showed that the trajectory of a moving user could be obtained with a standard deviation of about ${\pm}$ 3 m.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2022년도 춘계학술대회
• /
• pp.89-91
• /
• 2022

실내에서 측위를 위해 주로 사용되는 무선 센서 네트워크(WSN)는 수신 신호 강도(RSSI)의 정확성에 의존한다. 이 RSSI는 간섭을 유발하는 여러 요인에 민감하며, 그 중 온도가 실내/외 환경에서 RSSI에 큰 영향을 미친다는 국외 연구 사례가 있다. 실내에서는 열원이나 공조 시스템으로 인해 실내 공간의 온도가 고르지 않으며, 특정 위치에서는 잦은 온도 변화가 발생한다. 특히, 실내 화재 상황 시 대피 경로 안내를 위해 정확한 측위 시스템이 요구되지만 Receiver 주변에서의 화재로 인해 국부적으로 높은 온도가 형성되어 RSSI 값에 영향을 미칠 수 있다. 본 논문에서는 SoC 내부 및 국부 온도와 RSSI의 상관관계 분석을 통해 RSSI에 미치는 영향을 연구하고자 한다.

• 한국산업정보학회논문지
• /
• 제17권4호
• /
• pp.1-7
• /
• 2012

본 논문에서는 ZigBee와 GPS를 이용한 실내 위치 인식 시스템을 설계하였다. 본 연구에서 설계한 위치 인식 시스템은 실외 위치 인식에 대표적으로 사용되는 GPS 값을 실내 위치인식에 사용함으로서 기존 실내와 실외로 구분되던 위치 인식 기술을 하나로 통합하였다. 개발된 시스템은 노드간의 거리를 이용하여 위치를 구하는 방식으로 노드 간의 거리는 ZigBee의 수신 신호 세기를 이용하여 거리를 계산하는 방식을 사용하였다. 그러나 ZigBee의 수신 세기의 경우 거리에 따라 달라지나 그 값이 정확하지 않아 오차가 크다. 이 오차를 줄이기 위하여 개발 시스템에서는 ZigBee의 출력 파워를 5단계로 조절하여 거리에 따른 수신 신호 세기를 세분화하였다. 이동 노드가 신호를 발생하면 고정 노드에서는 수신된 신호의 세기와 자신의 GPS 정보를 고정 노드로 전송을 한다. 이동 노드에서는 수신된 정보를 이용하여 자신의 위치를 구하는 방식을 제안하였다.

• Journal of Positioning, Navigation, and Timing
• /
• 제3권2호
• /
• pp.63-69
• /
• 2014

In this study, due to the necessity of the equipment for inspecting an anti-jamming function depending on the expansion of the development of anti-jamming systems, an array antenna hood that can inspect the anti-jamming function of an anti-jamming system while being installed at the system was designed and manufactured. The manufactured array antenna hood plays a role in radiating GNSS signals and jamming signals. Based on an experiment, it was demonstrated that using a near-field radiation method, the manufactured array antenna hood could be used for examining the normal operation of an anti-jamming system function in outdoor or indoor environments rather than an anechoic chamber.

• 제어로봇시스템학회논문지
• /
• 제20권11호
• /
• pp.1098-1102
• /
• 2014

Localization of aerial vehicles and map building of flight environments are key technologies for the autonomous flight of small UAVs. In outdoor environments, an unmanned aircraft can easily use a GPS (Global Positioning System) for its localization with acceptable accuracy. However, as the GPS is not available for use in indoor environments, the development of a SLAM (Simultaneous Localization and Mapping) system that is suitable for small UAVs is therefore needed. In this paper, we suggest a vision-based SLAM system that uses vision sensors and an AHRS (Attitude Heading Reference System) sensor. Feature points in images captured from the vision sensor are obtained by using GPU (Graphics Process Unit) based SIFT (Scale-invariant Feature Transform) algorithm. Those feature points are then combined with attitude information obtained from the AHRS to estimate the position of the small UAV. Based on the location information and color distribution, a Gaussian process model is generated, which could be a map. The experimental results show that the position of a small unmanned aircraft is estimated properly and the map of the environment is constructed by using the proposed method. Finally, the reliability of the proposed method is verified by comparing the difference between the estimated values and the actual values.

• 한국멀티미디어학회논문지
• /
• 제22권2호
• /
• pp.186-193
• /
• 2019

Visible light communication technology is being studied and developed in various ways due to advantages such as high transmission speed, excellent positioning and higher security. However, existing visible light communication systems have difficulties in entering the market because they use special transmitters and receivers. We will overcome the difficulty if we develope a VLC system that uses a conventional LED light as a transmitter and a smartphone camera as a receiver. What matters is that LED lights include a scatter filter to prevent glareness for human eyes, but the existing VLC(Visual Light Communication) method can not be applied. In this paper, we propose a method to encode data with On / Off patterns of LEDs in the lighting with $M{\times}N$ LEDs. We defined parameters like L-off-able and K-seperated to facilitate the recognition of On / Off patterns in the diffused Lights. We conducted experiments using an LED lighting and smart phones to determine the parameter values. Also, the maximum transmission rate of our encoding technique is mathematically presented. Our encoding scheme can be applied to indoor and outdoor positioning applications or settlement of commercial transactions.