• ETRI Journal
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• v.29 no.4
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• pp.518-520
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• 2007

In this letter, we propose an impulse series for an ultra-wideband-based cognitive radio system which can utilize the spectrum dynamically by controlling the impulse positions and thus reduce the system complexity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1371-1379
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• 2010

This paper presents an analysis of impulse dispersion for impulse radio ultra-wide band(IR-UWB) antenna. A set of antenna structure configurations are highlighted with verification based on the STFT(Short Time Fourier Transform) in 3.1~5.1 GHz: first, a taper-slotted antenna allowing the optimal impulse transmission, and second, 4 types of the omni-directional IR-UWB antenna using different feed structures(microstrip line, and CPW(Coplanar Waveguide)). The proposed STFT allows the analysis of the IR-UWB antenna's dispersion characteristic.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.42-47
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• 2008

In this article a novel constant amplitude precoding for impulse UWB system is proposed. According to IEEE 802.15.4a, impulse UWB can be used in indoor localization and sensor data transmission. Most USN(ubiquitous sensor networks) needs multiple access. However impulse UWB system has a limited capability to detect superpositioned signal induced by multiple access. To overcome this problem we have adopted the concept of CAMC(Constant Amplitude Multi-Code) deviced by Wada and Kim. The proposed system consists of systematic constant amplitude precoding and LDPC decoding. And this system shows a good BER performance in computer simulation.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.67-73
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• 2015

This paper presents a fully integrated 3 - 5 GHz IR-UWB(impulse radio ultra-wide band) RFIC for Location based system. The receiver architecture adopts the energy detection method and for high speed sampling, the equivalent time sampling technique using the integrated DLL(delay locked loop) and 4 bit ADC. The digitally synthesized UWB impulse generator with low power consumption is also designed. The designed IR-UWB RFIC is implemented on $0.18{\mu}m$ CMOS technology. The receiver's sensitivity is -85.7 dBm and the current consumption of receiver and transmitter is 32 mA and 25.5 mA respectively at 1.8 V supply.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.61-66
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• 2005

In this paper, we implemented a impulse generator, the one of the part in UWB(Ultra Wide Band) system using step recovery diode(SRD) and gain-switced semiconductor laser. The impulse generator was consisted of four stages; The first stage used SRD to generate the first impulse for gain switching. The second stage controled current for the suitable gain switching condition. The third was the second impulse generator to generate gaussian pulse. For gain switching, the first impulse was applied to semiconductor laser. In the last stage the gain switched impulse was converted into mono-gaussian pulse. The measured mono-gaussian pulse was 360 psec pulse-width and $-70mV \~ +50mV$ amplitude in time domain. In frequency domain its magnitude and bandwidth was, respectively, -41dBm and 3.6GHz. Accordingly, the impulse generator that we suggested was suitable for UWB systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.165-170
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• 2005

In this paper, influences of a ultra wideband (UWB) antenna on impulse channel measurement are investigated in time domain (TD) and frequency domain (FD) as well. Firstly, impulse response of an UWB antenna is obtained and then using the result of impulse response of the UWB antenna, influences of the antenna on impulse radio channel is analyzed. Furthermore, using the impulse response of the UWB anenna, method of impulse radio channel analysis is presented by excluding the effect of the antenna from an impulse radio channel. For verifying the theory, a modified conical monopole antenna is designed for measuring impulse radio channel and its impulse response is obtained. After that, in order to investigate the effects of the UWB antenna on an impulse radio channel, multipath environments are set up in an anechonic chamber and transmission coefficient for each multipath environment is measured with an aid of vector network analyzer. Data measured in frequency domain is transformed into those in time domain by way of signal processing. Measurement shows that such properties of the antenna as dispersion and ringing affect impulse radio channel. Moreover, using the impulse response of the antenna, impulse response of only multipath channel is obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.287-294
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• 2006

In the paper, characterization and analysis of UWB(Ultra Wide Band) antennas in time domain are described. The impulse propagation channel including UWB antennas is proposed for the analysis in time domain. Using the proposed propagation channel, the technique of obtaining impulse response of UWB antenna is proposed. Also, ringing, peak value of the impulse response, and the width of the impulse response are introduced as parameters for characterizing a UWB antenna in time domain. A modified UWB conical monopole antenna, a UWB TEM horn antenna, and a UWB stepped fat monopole antenna were fabricated. From the measurement of reflection coefficients, three antennas had bandwidth more than 3 GHz. The impulse responses of the antennas were measured in an anechoic chamber. The results showed that the TEM horn with highest gain has the highest peak amplitude and the stepped fat monopole antenna with narrowest bandwidth for reflection coeffcient had the widest width of the impulse response. Also, ringing in the stepped fat monopole antennas and the UWB conical monopole antenna were observed.

• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.1
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• pp.29-34
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• 2009

In this paper, we design RF transceiver architecture and building blocks for impulse radio UWB system. Impulse radio UWB signal occupies the wide frequency band which is very low transmission power. So, it can minimize the interference effect with the other system. Using UWB technology, we obtain position awareness service. Therefore, we describe the RF transceiver architecture of direct conversion receiver and define the requirement of RF transceiver. Moreover, we implement a prototype RF transceiver based on the presented standard and verify a function and performance through the wireless data communication and ranging test.

• Journal of Advanced Navigation Technology
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• v.10 no.1
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• pp.13-19
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• 2006

In this paper, Gaussian impulse generator for DS-UWB was proposed and fabricated so that the frequency band allocated to WLAN, around 5 GHz, was suppressed in accordance with the regulation of radiation spectrum limitation defined by FCC. In order to transform an unipolar rectangular signal to a Gaussian impulse, the proposed impulse generator consists of two stage impulse generation parts; the first stage using dual SRD and the second stage using gain switching of semiconductor laser diode. The result shows a gaussian impulse as narrow as 180 psec in width. In addition, high order derivative Gaussian filter with a structure of 4 stage ring resonators was designed and fabricated so that DS-UWB impulse generator could reduce the frequency spectrum of WLAN by 25 dB compared to the spectral power of th adjacent UWB band.

• Journal of Advanced Navigation Technology
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• v.9 no.1
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• pp.1-8
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• 2005

In this paper, an impulse generator for UWB(Ultra Wide-band) technique with great possibility to be adopted as a next generation indoor WLAN(Wireless Local Area Network) has been designed by using SRD(Step Recovery Diode). Design goal is to design an impulse generator with simple structure, low cost, small size, and high performance. The impulse generator satisfied by FCC's regulation ( frequency range: 3.1~10.6 GHz, limit of power level: -41.25 dBm ) has been simulated by using ADS(Advanced Design System) which is the trade name of the Agilent Technologies. The output power of the impulse generator has been explained separately for single and multi band purposes, respectively.