• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.36-43
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• 2012

Ultra-wideband propagation measurement results for body area network scenarios are presented. We assumed several different scenarios for around-body and on-body propagations, and for each scenario, we conducted both time domain and frequency domain measurements in an anechoic chamber. For the around-body case, we investigated the effects of human body parts blocking line-of-sight, which could be accounted for by diffraction. On-body measurement results indicate a more complicated propagation mechanism exists in on-body propagation than in around-body propagation and antenna characteristics are affected.

• The Journal of Korea Robotics Society
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• v.11 no.3
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• pp.127-132
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• 2016

For a practical mobile robot team such as carrying out a search and rescue mission in a disaster area, the localization have to be guaranteed even in an environment where the network infrastructure is destroyed or a global positioning system (GPS) is unavailable. The proposed architecture supports localizing robots seamlessly by finding their relative locations while moving from a global outdoor environment to a local indoor position. The proposed schemes use a cooperative positioning system (CPS) based on the two-way ranging (TWR) technique. In the proposed TWR-based CPS, each non-localized mobile robot act as tag, and finds its position using bilateral range measurements of all localized mobile robots. The localized mobile robots act as anchors, and support the localization of mobile robots in the GPS-shadow region such as an indoor environment. As a tag localizes its position with anchors, the position error of the anchor propagates to the tag, and the position error of the tag accumulates the position errors of the anchor. To minimize the effect of error propagation, this paper suggests the new scheme of full-mesh based CPS for improving the position accuracy. The proposed schemes assuring localization were validated through experiment results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.703-722
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• 2016

Passive wireless devices have increasing civilian and military applications, especially in the scenario with wearable devices and Internet of Things. In this paper, we study indoor localization of a target equipped with radio-frequency identification (RFID) device in ultra-wideband (UWB) wireless networks. With known room layout, deterministic multipath components, including the line-of-sight (LOS) signal and the reflected signals via multipath propagation, are employed to locate the target with one transmitter and a single inaccurate receiver. A factor graph corresponding to the joint posterior position distribution of target and receiver is constructed. However, due to the mixed distribution in the factor node of likelihood function, the expressions of messages are intractable by directly applying belief propagation on factor graph. To this end, we approximate the messages by Gaussian distribution via minimizing the Kullback-Leibler divergence (KLD) between them. Accordingly, a parametric message passing algorithm for indoor passive localization is derived, in which only the means and variances of Gaussian distributions have to be updated. Performance of the proposed algorithm and the impact of critical parameters are evaluated by Monte Carlo simulations, which demonstrate the superior performance in localization accuracy and the robustness to the statistics of multipath channels.

• Journal of Digital Contents Society
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• v.18 no.4
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• pp.787-793
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• 2017

This paper proposes the IoT based monitoring system to reservoir and erosion control dam that measure amount of contained water and amount of sediment by real time through unit volume block object modeling and support the related image. The proposed system is more effective in establishing a more accurate dredging plan and effectively managing efficient water management plans, and effectively preventing accidents such as landslides, etc.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.504-507
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• 2005

차세데 홈네트워크 환경하에서는 다양한 데이터 통신 무선기기들이 홈/오피스에서 공존할 것이다. 예를들어 무선랜, 블루투스(Bluetooth), 지그비(Zigbee), 무선 USB, UWB(Ultra Wideband) 등이 함께 주파수를 공유하게 될 것이며, 특히 ISM 대역은 서비스, 산업, 의료용 등으로 다양한 응용이 가느하기 때문에 전파 간섭이 예상된다. 본 논문에서는 IEEE 802.11b 무선랜(WLAN)과 IEEE 802.15.4 저전력 저속 무선팬(WPAN) 무선기기에 대하여 간섭실험을 하였으며 두 무선기기가 상호 공존할 수 있는 공유 조건에 대해 분석하였다. 무선랜(WLAN)과 무선팬(WPAN)의 주파수 대역이 완전히 오버랩된 경우 간섭 레벨과 무선팬의 패킷 전송 횟수를 변화 시켜 상호간의 간섭 영향 저도를 측정하고 상호 무선기기간의 간섭 결과를 바탕으로 상호 무선기기간의 주파수 공유 조건을 제시하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.315-321
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• 2011

Since the MB-OFDM(Multi-Band Orthogonal Frequency Division Multiplexing) is an ultra wideband communication system operated on ISM(Industrial, Scientific and Medical) band, DAA(Detect-And-Avoid) is required for co-existence with the other communication service. In this paper we propose the new detection algorithm based on decision-feedback, which shows faster convergence time and less complexity than previous works. The proposed algorithm detects interference above -20dB in AWGN(Additive White Gaussian Noise) and LOS(Line-Of-Sight) channel, and close to AWGN in non-LOS channel under appropriate channel clipping.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.8
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• pp.117-124
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• 2009

This paper describes a 3 to 5 GHz frequency synthesizer for MB-OFDM (Multi-Band OFDM) UWB (Ultra- Wideband) application using 0.13 ${\mu}m$ CMOS process. The frequency synthesizer operates in the band group 1 whose center frequencies are 3432 MHz 3960 MHz, and 4488 MHz. To cover the overall frequencies of group 1, an efficient frequency planning minimizing a number of blocks and the power consumption are proposed. And, a high-frequency VCO and LO Mixer architecture are also presented in this paper. A new mixed coarse tuning scheme that utilizes the MIM capacitance, the varactor arrays, and the DAC is proposed to expand the VCO tuning range. The frequency synthesizer can also provide the clock for the ADC in baseband modem. So, the PLL for the ADC in the baseband modem can be removed with this frequency synthesizer. The single PLL and two SSB-mixers consume 60 mW from a 1.2 sV supply. The VCO tuning range is 1.2 GHz. The simulated phase noise of the VCO is -112 dBc/Hz at 1 MHz offset. The die area is 2 ${\times}$ 2mm$^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.5
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• pp.418-426
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• 2019

Recently, many studies on vital sign detection using a radar sensor related to Internet of Things(IoT) smart home systems have been conducted. Because vital signs such as respiration and cardiac rates generally cause micro-motions in the chest or back, the phase of the received echo signal from a target fluctuates according to the micro-motion. Therefore, vital signs are usually detected via spectral analysis of the phase. However, the probability of false alarms in cardiac rate detection increases as a result of various problems in the measurement environment, such as very weak phase fluctuations caused by the cardiac rate. Therefore, this study analyzes the difficulties of vital sign detection and proposes an efficient vital sign detection algorithm consisting of four main stages: 1) phase decomposition, 2) phase differentiation and filtering, 3) vital sign detection, and 4) reduction of the probability of false alarm. Experimental results using impulse-radio ultra-wideband radar show that the proposed algorithm is very efficient in terms of computation and accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.561-570
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• 2009

Ultra-wideband communication systems based on impulse radio have merits that are possible for the high data rate transmission, high resolution ranging are positioning system. Conventionally, in order to accomplish these features, the high-speed ADC (Analog to Digital Convertor) is necessary to apply radio determination system operating in time domain. However, considering low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces a low complex AR (Auto Regressive) model based non-coherent ranging scheme operating in frequency domain with using low-speed ADC utilizing analog Voltage Control Oscillator (VCO) mode for the frequency domain transformation. To verify the superiority of the proposed ranging and location algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.441-444
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• 2018

In this paper, a microstrip antenna for LTE / WiMAX is designed for UWB communication. The proposed antenna is designed for FR-4 (er = 4.3), 29[mm] x 45[mm], and can be used in the LTE frequency band of 1.82[GHz] and the WiMAX frequency band of 3.5[GHz]. Studio 2014 was used. The simulation results show 1.785[dB] at 1.82[GHz] and 1.720[dB] at 3.5[GHz]. S-parameters were also found to be less than -10dB (WSWR2: 1) in the desired frequency band. In order to achieve broadband, miniaturization, low cost and low loss, Width, length, width of transmission line, etc. were calculated. Therefore, it is considered that the applicable antenna can be applied satisfying the desired condition.