• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.185-190
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• 2020

The rapid aging is increasing as the shortage of medical facilities and the resulting of decline in the quality of public health. In order to ease the burden of rising medical expenses, advanced medical institutions are expanding their remote medical care to lower the cost of services. U-healthcare detects the changes in physical and chemical phenomena occurring in the human body and converts them into electrical signals that can be processed and feeds back to the results through analytical and visualization processes to select only the desired information from the measured signals. The service is provided through a process of providing an alarm to a user. However, traditional biometric methods of attaching sensors directly to the body can be annoying and rejected in daily life. Therefore, there is a need for a method of continuously measuring biometric information without causing inconvenience to daily life. In this paper, we propose an IR-UWB-based non-contact and non-responsive respiratory measurement system that can continuously monitor biological information without any inconveniences to daily life.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1307-1313
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• 2014

In this paper, we have proposed a tapered slot antenna for IR-UWB communication system suitable of indoor positioning in the building. The designed tapered slot antenna is designed using Ansys Inc. HFSS and its standing wave ratio, return loss, and radiation pattern is analyzed. In 2.36 GHz ~ 5.51 GHz and, the designed antenna shows satisfactory return loss at -10 dB and meets the requirement of $VSWR{\leq}2$. The presented designed showed a higher sensitivity for the end-fire propagation characteristics in a specific direction across all bands of the radiation pattern.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.27-32
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• 2008

Impulse Radio Ultra Wide Band (IR-UWB) system can be used to wireless position location system because of its unique very short pulse in the order of nanosecond. A few algorithms have been proposed to calculate location of sensors or tags. In this paper, we compare these algorithms and propose 'TDoA with wireless synchronization' as practical solution. Earlier algorithms need special logic to fix the duration to receive and send pulse or assume synchronization with wire. In proposed method, beacons synchronize each other using impulse and nodes can be made simple and cheap. We evaluated the performance and it shows 50% improved accuracy at the error range of 50cm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.98-105
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• 2007

In this paper, we propose a timing detector using suboptimal maximum likelihood method. The proposed method has an simple reference signal generator. Additionally, timing detector's gain of the proposed method is the same to Early-Late gate and ML method. We reveal that tracking range of time tracker is narrow because of using data-decision, that is, tracking range is ${\pm}0.06ns$ for the 4-order Gaussian monocycle with 0.7ns pulse width. Therefore we can find that searcher must have very accurate acquisition procedure. When estimating a performance of time tracker, we consider a jitter in transmitter and receiver's pulse generation process as well as background noise. By using computer simulation, we propose mean/variance of timing detector and tracking process. Also we consider a mobility in tracking process, i.e., timing error modeled ramp function. In order to propose a performance of time tracker, we consider only one correlation demodulator.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.3
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• pp.105-116
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• 2017

Several wireless localization algorithms are evaluated for the IR-UWB-based indoor location with the assumption that the ranging measurements contain the channelwise Non-Calibration Error (NCE). The localization algorithms can be divided into the Model-free Localization (MfL) methods and Model-based Kalman Filtering (MbKF). The algorithms covered in this paper include Iterative Least Squares (ILS), Direct Solution (DS), Difference of Squared Ranging Measurements (DSRM), and ILS-Common (ILS-C) methods for the MfL methods, and Extended Kalman Filter (EKF), EKF-Each Channel (EKF-EC), EKF-C, Cubature Kalman Filter (CKF), and CKF-C for the MbKF. Experimental results show that the DSRM method has better accuracy than the other MfL methods. Also, it demands smallest computation time. On the other hand, the EKF-C and CKF-C require some more computation time than the DSRM method. The accuracy of the EKF-C and CKF-C is, however, best among the 9 methods. When comparing the EKF-C and CKF-C, the CKF-C can be easily used. Finally, it is concluded that the CKF-C can be widely used because of its ease of use as well as it accuracy.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.38-44
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• 2008

In this paper, we introduce an low complexity and low power IR-UWB (impulse radio ultra wideband) baseband transceiver for wireless sensor network. The proposed baseband, implemented by TSMC 0.18um CMOS technology, has a simple structure in which a simplified packet structure and a digital synchronizer with 1-bit sampler to detect incoming pulses are used. Besides, clock gating method using gated clock cell as well as customized clock domain division can reduce the total power consumption drastically. As a result, the proposed baseband has about 23K digital gates with an internal memory of 2Kbytes and achieves about 1.8mW@1Mbps power consumption.

• Journal of the Korea Convergence Society
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• v.12 no.9
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• pp.31-37
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• 2021

Recently, in the market of home appliances, the technical differentiation of products using convergence technology has been receiving a lot of response to satisfy consumer demand. However, air-conditioner products are an area that requires research and development in the early stages of convergence technology. In this paper, it is developed that a non-contact bio-signal(respiration, movement) collection technology using IR-UWB(Impulse-Radio Ultra Wideband) technology, which controls the air-conditioner direction according to the user's location and also monitors sleep to provide an optimal sleep environment. In addition, emotional lighting and ASMR are developed to provide a comfortable and emotional place of life. Finally, based on the developed convergence technology, we develop intelligent smart air-conditioning services for the convenience of daily life and a comfortable resting space.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.415-424
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• 2016

This paper describes a high data rate proximity transmitter design for high resolution smartphone-mirrored display applications. A 2 Gb/s transmitter is designed with a low transmission power of -70 dBm/MHz and a wide bandwidth of nearly 3 GHz. A digital pre-correction method is employed in the transmitter to mitigate the inter-symbol interference problem. A carrier-based digital pulse shaping and a reconfigurable digital envelope generation methods are employed for robust operation by utilizing 20 phases from a 2 GHz phase-locked loop. A 6.5-9.5 GHz transmitter implemented in 65 nm CMOS achieves the maximum data rate of 2 Gb/s, consuming only 7.6 mW from a 1 V supply.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.784-790
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• 2012

In this paper, an all-digital CMOS ultra-wideband(UWB) pulse generator for high band(6~10 GHz) frequency range is presented. The pulse generator is designed and implemented with extremely low power and low complexity. It is designed to meet the FCC spectral mask requirement by using Gaussian pulse shaping circuit and control the center frequency by using CMOS delay line with shunt capacitor. Measurement results show that the center frequency can be controlled from 4.5 GHz to 7.5 GHz and pulse width is 1.5 ns and pulse amplitude is 310 mV peak to peak at 10 MHz pulse repetition frequency(PRF). The circuit is implemented in 0.13 um CMOS process with a core area of only $182{\times}65um^2$ and dissipates the average power of 11.4 mW at an output buffer with 1.5-V supply voltage. However, the core consumes only 0.26 mW except for output buffer.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.622-633
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• 2015

The coexistence among different systems is a major problem in communications. Mutual interference between different systems should be analyzed and mitigated before their deployment. The paper focuses on two aspects that have an impact on the system performance. First, the coexistence analysis, i.e. evaluating the mutual interference. Second aspect is the coexistence techniques, i.e. appropriate system modifications that guarantee the simultaneous use of the spectrum by different technologies. In particular, the coexistence problem is analyzed between ultra-wide bandwidth (UWB) and narrow bandwidth (NB) systems emphasizing the role of spectrum sensing to identify and classify the NB interferers that mostly affect the performance of UWB system. A direct sequence (DS)-time hopping (TH) code design technique is used to mitigate the identified NB interference. Due to the severe effect of Narrowband Interference on UWB communications, we propose an UWB transceiver that utilizes spectrum-sensing techniques together with mitigation techniques. The proposed transceiver improves both the UWB and NB systems performance by adaptively reducing the mutual interference. Detection and avoidance method is used where spectrum is sensed every time duration to detect the NB interferer's frequency location and power avoiding it's effect by using the appropriate mitigation technique. Two scenarios are presented to identify, classify, and mitigate NB interferers.