• Electronics and Telecommunications Trends
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• v.22 no.3 s.105
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• pp.20-28
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• 2007

본 고에서는 텔레매틱스/LBS용 실내외 연속측위를 위해 무선통신 기반 실내측위 및실외측위 기술에 대하여 동향을 분석한다. 위치기반서비스에서 측위기술은 핵심.기반기술로 오늘날 GPS가 그 중심을 차지하고 있지만 실내와 같은 음영지역에서는 새로운방식의 측위기술을 필요로 하고 있으며, 무선통신 인프라 기반의 측위 기술이 연구되어 오고 있다. 실외에서는 CDMA 기반 무선측위 기술, 실내에서는 WLAN, UWB, 적외선, 초음파, RFID 등의 인프라를 이용한 무선측위 기술이 연구되고 부분적으로 상용화되고 있다. 그러나 아직 실내외 연속측위를 위한 기술은 개념적으로 설계만 되고 있으며 상용화를 위한 기반기술이 연구중에 있다. 본 고에서는 실내외 연속측위를 위해 실내측위와 실외측위로 나누어 각각의 기술 동향을 분석하고 이 기술을 구현하기 위한 무선측위 기술을 분류, 설명한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9A
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• pp.852-858
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• 2010

In this paper, the compensation algorithm for radiodetermination error using a concept of determination coordinator value of equivalent distance rate (CADE) is proposed, and the performance of the proposed algorithm is analyzed. As a result of the experiments, CADE improves the performance of the algorithm accuracy about 37.5% and 69.8% each in the inside and outside of 4 beacon nodes. Furthermore, the CADE is 76.3% excellent enough to compensate 2m or more of the radiodetermination error. It also confirms that CADE can be adapted to the wide range by installing only 4 beacon nodes according to the excellence of compensation performance besides the ranges of 4 beacon nodes. From the results, it is strongly considered that the proposed algorithm CADE can be used to the performance enhancement of radiodetermination systems using SDS-TWR.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.72-78
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• 2011

Localization information of an object can be a very useful element for many application areas. Presently, GPS is typically used for it, but many researches on the wireless localization technology are going on recently actively using mobile communication network, wireless sensor network, and ad hoc network in order to overcome the limitations of the GPS such as indoor, cost, power consumption, and etc. Therefore, this article surveys the most representative wireless localization techniques, which can be deployed in the wireless networks, and their principles and performances are analyzed based on the researched papers. In a conclusion, selection of a localization technique should consider the key design elements to a given application from the design elements such as localization environment, accuracy, time to fix, computation amount, implementation ease, and etc.

• The Magazine of the IEIE
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• v.38 no.1
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• pp.68-74
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• 2011

이동단말기의 위치기반서비스가 핵심 무선인터넷서비스로 부상하고 있다 위치기반서비스는 정확하고 신뢰성 있는 단말기의 위치추정을 기반으로 한다. 이를 위하여 현재 GPS가 광범위하게 사용되고 있지만 기술적인 한계점으로 인하여 최근 RF 무선신호를 이용하는 RF 무선측위기술이 대체기술로 대두되고 있다. 이에 따라 최근 타 RF 기술에 비해 측위기술과 네트워크 인프라의 경쟁력을 보유한 WiFi 기반 무선측위기술이 부각되고 있다. 국내 또한 WiFi 기반 무선측위에 대한 연구를 활발히 수행 중이지만 시스템 개발에 따른 해외특허의 회피전략 또한 중요 관심사이다. 따라서 본고는 국내 위치기반서비스에 대한 국가 정책 및 사업화 방향의 전략결정에 유용하게 할용 될 수 있도록 WiFi 기반 무선측위기술의 기반기술 및 요소기술들을 정의하고 출원특허들의 선행조사와 분석을 통하여 이들 기술들에 대한 출원특허들의 기술계통도를 작성한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11C
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• pp.1098-1105
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• 2009

In this paper, we propose an asynchronous UWB (Ultra Wide Band) Positioning scheme that can provide precise positioning performance with low complexity and low power consumption. We also present the residual test to improve the positioning performance in multipath channels having heavy NLoS (Non-Line of Sight) components. As compared to conventional ToA (Time of Arrival) positioning scheme that requires round-trip transmissions as many as the number of beacons, the proposed UWB positioning scheme effectively decrease power consumption and processing delay since a single round-trip transmission is only required. Also, as compared to conventional TDoA (Time Difference of Arrival) positioning scheme requiring precise synchronization among the beacons, asynchronous nature of the proposed scheme achieves very low system complexity. Through simulations in LoS (Line of Sight) channel models, we observe that the proposed scheme requires low system complexity, low power consumption, while providing positioning performance of almost the same accuracy as the conventional ToA and TDoA positioning schemes. In addition, the proposed scheme by employing the residual test achieves accurate positioning performance even in multipath channels having heavy NLoS components.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.87-95
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• 2010

In this paper, we propose an improved TDoA (Time Difference of Arrival) localization scheme using PSO (Particle Swarm Optimization) in UWB (Ultra Wide Band) systems. The proposed scheme is composed of two steps: re-estimation of TDoA parameters and re-localization of a tag position. In both steps, the PSO algorithm is employed to improve the performance. In the first step, the proposed scheme re-estimates the TDoA parameters obtained by traditional TDoA localization to reduce the TDoA estimation error. In the second step, the proposed scheme with the TDoA parameters estimated in the first step, re-localizes the tag to minimize the location error. The simulation results show that the proposed scheme achieves a more superior location performance to the traditional TDoA localization in both LoS (Line-of-Sight) and NLoS (Non-Line-of-Sight) channel environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.573-580
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• 2011

WSNs (Wireless Sensor Networks) are becoming more widely used in various fields, and improving localization performance is a crucial and essential issue for sensor network applications. In this paper, we propose a low-complexity localization mechanism for WSNs that operates in 3D (Three-Dimensional) space. The basic idea is to use aerial vehicles or flying objects that are deliberately equipped with the anchor nodes. These anchor nodes periodically broadcast beacon signals containing their current locations, and the unknown nodes receive these signals as soon as they enter the communication range of the anchors. We estimate the locations of the unknown nodes based on the proposed scheme that transforms the 3D problem into 2D computations to reduce the complexity of 3D localization. Simulated results show that our approach is an effective scheme for 3D self-positioning in WSNs.

• Journal of KIISE:Information Networking
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• v.34 no.5
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• pp.389-395
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• 2007

It is necessary to research on wireless position determination technology that enables location based services on Portable Internet. In this paper, I consider the position determination technology based on TDOA belong to trilateration method. That is using the difference of relative distance between base stations and terminal due to the time difference of arrival of downlink signal. In order to design the positioning server, This paper reviews the related research on current status of wireless position determination technology based on TDOA on Portable Internet. And then, it is suggested that system architecture, network interface, the calculation model for position determination, which are adapted to circumstance of portable Internet. Through this research on the positioning server, it is expected to guarantee that low cost and high efficiency of wireless positioning server on Portable Internet will be developed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6B
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• pp.888-894
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• 2010

For the indoor positioning, wireless fingerprinting is most favorable because fingerprinting is most accurate among the technique for wireless network based indoor positioning which does not require any special equipments dedicated for positioning. The deployment of a fingerprinting method consists of off-line phase and on-line phase and more efficient and accurate methods have been studied. This paper proposes a bayesian algorithm for wireless fingerprinting and indoor location determination using fuzzy clustering with bayesian learning as a statistical learning theory.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3049-3051
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• 2005

본 논문은 UWB(Ultra Wide Band) 펄스 기반의 단일 송수신을 통한 근거리 무선측위 시스템 및 방법에 관한 것으로서, UWB 펄스의 높은 시간 분해능을 이용하여 근거리에서 높은 정밀도를 가지고 태그의 위치를 획득할 수 있다. 특히, 마스터-슬레이브 형태로 구성된 비콘(beacon)들 간의 사전 설정을 통해 마스터 비콘과 무선측위 대상인 태그 사이의 단일 송수신만으로 ToA(Time of Arrival) 및 TDoA(Time Difference of Arrival) 기법을 적용할 수 있도록 하며, 이로써 태그의 신호 송신을 최소화하여 태그의 저전력 동작을 가능케하는 UWB기반 단일송수신을 통한 근거리 무선측위 시스템이다.