• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1697-1703
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• 2014

In this paper, we propose an indoor RSSI (received signal strength indication)-based localization method that uses virtually overlapped visible light with an indoor LED lighting system. In our system, a photodiode (PD) measures the RSSI from LED lamps that blink in one row or column units. Subsequently, the RSSI is used to obtain the horizontal distances between the LED lamps and the receiver with the predetermined characteristics curve, R-D curve, that represents the relation between the RSSI and the horizontal distances. When the controlled LED lamps blink in one row or column units, the R-D curve at the border of the LED lamps is different because of the weak lighting, which results in the position sensing error of the receiver. The deviation of the optical power of each LED also causes the error. To solve these problems, we propose a method that overlaps the visible light through the numerical operation at the receiver side without any modification of the light source side. Our proposed method has been simulated in a room measuring $1.2{\times}1.2{\times}1.8m^3$ considering the effect of the error on the optical power of the LED. The simulation result shows that the proposed method eliminates the error condition with the R-D curve and achieves an average positioning error of 13.4 mm under the error rate 3% of the optical power.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.348-353
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• 2008

Despite the increasing popularity of wireless sensor network, indoor positioning using low power IEEE 802.15.4 compliant radio had attracted an interest of many researchers in the last decade. Old fashionable indoor location sensing information has been presented in dull and unpleasant 2D image standard. This paper focused on visualizing high precision 3 dimensional RSSI-based (received signal strength indication) spatial sensing information in an interactive virtual reality on PDA. The developed system operates by capturing and extracting signal strength information at multiple pre-defined reference nodes to provide information in the area of interest, thus updating user's location in 3D indoor virtual map. VRML (Virtual Reality Modeling Language) which specifically developed for 3D objects modeling is utilized to design 3D indoor environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.69-76
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• 2017

Bluetooth Low Energy (BLE), also known as Bluetooth Smart, has ultra-low power consumption; in fact, BLE-enabled devices can run on a single coin cell battery for several years. In addition, BLE can estimate the approximate distance between two devices using the Received Signal Strength Indication (RSSI) feature, enabling relatively precise navigation in indoor and small outdoor areas where GPS is not an option. In this paper, an experimental setup is presented in which BLE is used for navigation within a small outdoor area. BLE-based beacons are installed in fixed positions, which periodically transmit a universally unique identifier (UUID). A smart device receives the UUID and sends it to a database server using cellular or Wi-Fi technology. The server returns fixed position information corresponding to the received UUID codes, and the smart device uses that information to compute its current position based on relative signal strengths, and display it on a map. These results demonstrate the successful application of BLE technology for navigation in small outdoor areas. This system can be implemented for indoor navigation as well.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.758-760
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• 2012

The wireless sensor network is used to get information that location tracing or data of surrounding areas. Unnecessary retransmission request or many energy consumption because the transmission over the wireless links. In order to select the link of reliable and energy efficient to estimate the quality of radio link technique is required using RSSI, LQI, and so on. In this paper, each path between the sensor nodes, a small in the path within standard deviation of shall be determined the priority. Each path a high priority of the node values, respectively LQI is accumulated. Node can be selected the high LQI value path. Among them the less hop count to select the path is proposed. The proposed algorithm is removed the paths of shorten life using high the LQI value of the entire and high hop count even less variation. So its advantage that the sensor nodes can be selected more reliable path.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2414-2434
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• 2015

Among numerous localization schemes proposed specifically for Wireless Sensor Network (WSN), the range-free localization algorithms based on the received signal strength indication (RSSI) have attracted considerable research interest for their simplicity and low cost. As a typical range-free algorithm, Approximate Point In Triangulation test (APIT) suffers from significant estimation errors due to its theoretical defects and RSSI inaccuracy. To address these problems, a novel localization method called FIAPIT, which is a combination of an improved APIT (IAPIT) and a fuzzy logic system, is proposed. The proposed IAPIT addresses the theoretical defects of APIT in near (it's defined as a point adjacent to a sensor is closer to three vertexes of a triangle area where the sensor resides simultaneously) and far (the opposite case of the near case) cases partly. To compensate for negative effects of RSSI inaccuracy, a fuzzy system, whose logic inference is based on IAPIT, is applied. Finally, the sensor's coordinates are estimated as the weighted average of centers of gravity (COGs) of triangles' intersection areas. Each COG has a different weight inferred by FIAPIT. Numerical simulations were performed to compare four algorithms with varying system parameters. The results show that IAPIT corrects the defects of APIT when adjacent nodes are enough, and FIAPIT is better than others when RSSI is inaccuracy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3889-3903
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• 2017

Fast and accurate localization of randomly deployed nodes is required by many applications in wireless sensor networks (WSNs). However, mobile nodes localization in WSNs is more difficult than static nodes localization since the nodes mobility brings more data. In this paper, we propose a Range-based Monte Carlo Box (RMCB) algorithm, which builds upon the Monte Carlo Localization Boxed (MCB) algorithm to improve the localization accuracy. This algorithm utilizes Received Signal Strength Indication (RSSI) ranging technique to build a sample box and adds a preset error coefficient in sampling and filtering phase to increase the success rate of sampling and accuracy of valid samples. Moreover, simplified Particle Swarm Optimization (sPSO) algorithm is introduced to generate new samples and avoid constantly repeated sampling and filtering process. Simulation results denote that our proposed RMCB algorithm can reduce the location error by 24%, 14% and 14% on average compared to MCB, Range-based Monte Carlo Localization (RMCL) and RSSI Motion Prediction MCB (RMMCB) algorithm respectively and are suitable for high precision required positioning scenes.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.27-38
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• 2019

Sensors collect information for Internet of Things (IoT)-based services. However, indoor construction sites have a poor communication environment and many interfering elements that make it difficult to collect sensor information. In this study, a network was constructed between a Bluetooth Low Energy (BLE)-based IoT device based on a serverless IoT framework and a router. This experimental environment was applied to large- and small-scale indoor construction sites. Experiments were performed to test the communication performance of BLE-based IoT devices and routers at indoor construction sites. An analysis of the received signal strength indication (RSSI) graph patterns collected from the communication between the BLE-based IoT devices and routers for different testbed site situation revealed areas with good communication performance and poor communication performance due to interfering factors. The results confirmed that structural components of the building as well as the materials, equipment, and temporary facilities used in indoor construction interfere with the communication performance. Construction project managers will require improved technical knowledge of IoT, such as optimizing the router placement and matching communication between the router and workers, to improve the communication performance for large-scale indoor construction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.9
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• pp.763-773
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• 2012

본 논문에서는 Wi-Fi를 이용한 RSSI (Received Signal Strength Indication)기반의 측위 시스템에서 전파환경변화에 민감한 시스템의 문제를 보완하기 위하여 랜드마크 발신기 기반의 측위 시스템을 제안한다. 이를 위하여 핑거프린팅 알고리즘 및 랜드마크 발신기를 구현 하였으며 간단한 측위 정확도 예측모델을 만들어 수신된 전파세기를 기반으로 측위 정확도를 예측하였다. 이를 바탕으로 실내 TEST BED를 구축하였고 주요 지점에 랜드마크 발신기를 부착하여 시스템의 효용성을 검증하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.185-186
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• 2016

안전사고 발생 위험요소가 산재한 사업장 내에서의 이상 징후를 파악할 수 있는 안전관리 시스템의 구축이 필요하다. 또한 사람이 직접 안전관리를 하는 것이 어려운 장소와 사업장 환경의 변화가 중요한 경우까지 고려하고, 실시간으로 정보를 관리하고 대처할 수 있는 방법이 요구된다. 본 연구에서는 유해가스 누출에 열악한 작업환경에서 인명보호 및 안전사고 예방을 위한 작업자 중심 사고 예방을 위한 다중센서 BLE 디바이스개발과 스마트폰 서비스를 연계방법에 대한 시스템을 제안한다. 제안된 시스템은 AQ, AP, Motion, SmartPhone App, Server로 구성하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1381-1384
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• 2006

실내 위치인식 기술은 유비쿼터스 구현의 기반이 되는 중요기술요소 중 하나이다. 특히 병원의 환자 관리, 실버타운의 노인관리, 스마트 홈의 구현을 위해서는 실외의 광역범위보다는 실내에서의 사용자 위치인식에 대한 기술이 필요하다. 본 논문에서는 무선랜기기 및 통신기술을 이용한 실내 위치 인식 시스템의 설계 및 구현에 관해 기술하고자한다. 사용자 위치인식을 위한 기반기술로 무선랜의 전파신호강도(Received Signal Strength Indication, RSSI)를 이용한 삼변측량 기법을 이용하였다. 구현될 시스템은 무선랜기기와 지형 맵핑서버, Access Point(AP)로 구성되며, 시스템의 개발 및 실제 환경에 서의 테스트를 통하여 실생활 응용에 대한 가능성을 확인할 수 있었다.