• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.2
• /
• pp.202-207
• /
• 2015

A CMOS relaxation oscillator, with high robustness over process, voltage and temperature (PVT) variations, is designed in $0.18{\mu}m$ CMOS. The proposed oscillator, consisting of full-differential charge-discharge timing circuit and switched-capacitor based voltage-to-current conversion, could be expanded to a simple open-loop frequency synthesizer (FS) with output frequency digitally tuned. Experimental results show that the proposed oscillator conducts subcarrier generation for frequency-modulated ultra-wideband (FM-UWB) transmitters with triangular amplitude distortion less than 1%, and achieves frequency deviation less than 8% under PVT and phase noise of -112 dBc/Hz at 1 MHz offset frequency. Under oscillation frequency of 10.5 MHz, the presented design has the relative FS error less than 2% for subcarrier generation and the power dissipation of 0.6 mW from a 1.8 V supply.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.2
• /
• pp.194-201
• /
• 2015

A frequency modulated ultra-wideband (FM-UWB) transmitter with a high-robust relaxation oscillator for subcarrier generation and a dual-path Ring VCO for RF FM is proposed, featuring low power and low complexity. A prototype 3.65-4.25 GHz FM-UWB transceiver employing the presented transmitter is fabricated in $0.18{\mu}m$ CMOS for short-range wireless data transmission. Experimental results show a bit error rate (BER) of $10^{-6}$ at a data rate of 12.5 kb/s with a communication distance of 60 cm is achieved and the power dissipation of 4.3 mW for the proposed transmitter is observed from a 1.8 V supply.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.10 no.2
• /
• pp.57-64
• /
• 2015

In this paper, we propose structures and power spectral densities of UWB radar transmitters of Short Range Automobile. While the conventional transmitters did not consider interferences from self and other automobiles, the proposed method of this paper can minimize interferences. First, we compare a structure of the proposed method with pulse train and pulse compression method. Then, by using mathematical analysis and computer simulations, we show that the proposed method is superior to others. Also we can set proper parameters in UWB radar's transmitter through the numerical method of mathematical results.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.1
• /
• pp.220-226
• /
• 2004

Ultra-wideband(UWB) communication applications is a recent innovation due to high transmission rate and low power emission. Therefore, it is important to research UWB signal's characteristics and modulation methods to apply to various UWB communication technologies. In this paper the characteristics of Gaussian monopulse which is capable of using UWB communication was analyzed and we compared the performance of PPM and PAM modulation method. Also we analyzed the interference effect of QPSK system with different center frequencies in the present of various UWB noises and simulated simple UWB transceiver system.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2012.07a
• /
• pp.225-227
• /
• 2012

무선 사운드 스피커는 서로 다른 위치에 배치되어 송신기와의 채널 환경이 서로 다르게 되어 송신기와의 거리가 상대적으로 먼 후방 스피커의 경우 사람이나 구조물에 의해 채널 환경이 열악하게 되어 전방 스피커에 비해 데이터 오류 발생 확률이 높다. 본 논문은 Multi-band orthogonal frequency division multiplexing (MB-OFDM) 기반의 무선 오디오 전송 시스템에서 무선 채널 환경이 우수한 스피커에서 무선 채널 환경이 열악한 스피커로 데이터를 전달하는 스피커 릴레이 기법을 사용할 때, packet error ratio (PER) 성능을 향상시키며 전송 시간을 감소시킬 수 있는 효율적인 스피커 릴레이 기법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.12A
• /
• pp.1177-1184
• /
• 2008

Non-line-of-sight (NLOS) propagation can severely weaken the accuracy of ranging and localization in wireless location systems. NLOS bias mitigation techniques have recently been proposed to relieve the NLOS effects, but positively rely on the capability to accurately distinguish between LOS and NLOS propagation scenarios. This paper proposes an energy-capture-based NLOS identification method for LDR-UWB systems, based on the analysis of the characteristics of the channel impulse response (CIR). With this proposed energy capture method, the probability of successfully identifying NLOS is much improved than the existing methods, such as the kurtosis method, the strongest path compare method, etc. This NLOS identification method can be employed in adaptive modulation scheme to decrease bit error ratio (BER) level for certain signal-to-noise ratio (SNR). The BER performance with the adaptive modulation can be significantly enhanced by selecting proper modulation method with the knowledge of channel information from the proposed NLOS identification method.

• 한국항공운항학회:학술대회논문집
• /
• 2015.11a
• /
• pp.83-87
• /
• 2015

미국 국방부에서 군사용으로 사용되던 수 GHz 대역의 초 광대역 주파수 스펙트럼을 미국연방통신위원회(FCC)에서 민간에 개방하면서 여러 활용 기술이 개발 되고 있다. 소비전력이 적고, 고속통신 및 방해 전파에 강하다는 특성을 갖고 있으며 또한 작은 위치 검출 오차로 정밀도가 높으나 거리가 길어지면 급속도록 떨어지는 속도로 인하여 근거리 통신으로 활용 검토 되고 있다. 따라서 공항 및 항공기내 지역에서 초 광대역 주파수 특성을 활용하여 적용 가능한 항공기 익단충돌방지시스템, 항공기와 고속 데이터 전송, 항공기 내의 무선 백본 시스템 활용 및 공항 지역의 이동체 위치 정보 관리 등 다양한 항공 서비스 업무에 적용 가능함을 알 수 있었다.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.2
• /
• pp.928-935
• /
• 2018

In this paper, a compact fully printable bandpass filter is suggested for a low-frequency channel 3.2 GHz ~ 3.7 GHz in the Ultra-Wideband (UWB) communication system. It is featured with a small geometry of $0.5{\lambda}_g/15$ and a low insertion loss despite using FR4 as a cheap substrate of a high dielectric loss. This is made possible by generating zeroth-order-resonance (ZOR) from one cell comprising two series resonances obviously separated from one shunt resonance as a third-order bandpass filter. Especially, the series resonance elements are combined with spur-lines bent by 90 degrees, which makes the port-impedance matched well and eliminates spurious hikes in the stopband, while the overall size remains almost unchanged. The design is carried out by setting up the equivalent circuit and the circuit simulation is checked by the full-wave EM analysis. The structure is manufactured and measured to show that the circuit modeling and EM simulation results agree with the measured data.

• Journal of Digital Contents Society
• /
• v.5 no.3
• /
• pp.171-175
• /
• 2004

In this paper, We applied CCI canceller to remove multi-user interference in co-channel environment and improved performance of TH PPM UWB-IR system. As a result, We could get reception performance that data transmission of high speed is available in small reception power applying CCI canceller. Also, We could get permission available channel capacity to maximum access number 40 in high speed transmission environment more than 100Mbps.

• ETRI Journal
• /
• v.29 no.1
• /
• pp.1-7
• /
• 2007

In this paper, we analyze the performance of double-dwell hybrid initial acquisition in a direct sequence ultra-wideband (DS-UWB) system via detection, miss, false alarm probabilities, and mean acquisition time. In the analysis, we consider the effect of the acquisition sequence as well as the deployment scenario of the abundant multipath components over small coverage of the piconet in the DS-UWB system. Based on the simulation, we obtain various performance measures for the mean acquisition time by varying parameters such as the total number of hypotheses to be searched, subgroup size, and dwell time. We thereupon suggest the optimum parameter set for the initial acquisition in the DS-UWB system.