• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.4C
• /
• pp.395-400
• /
• 2010

This paper proposes a novel two-stage detection scheme based on combining multiple correlator outputs to enhance the detection performance in ultra-wideband (UWB) signal acquisition. Due to the rich multipath of UWB channels, the signal energy spreads over multiple correlator outputs, which makes each correlator output have only a portion of the signal energy, and thus, degrades the detection performance of the conventional scheme where a single correlator output is used as the decision variable for detection. In the proposed two-stage detection scheme, the decision variable is formed by combining multiple correlator outputs, making it possible to collect the signal energy spread by the multipath. Simulation results show that the proposed scheme can provide a better detection performance over the conventional scheme in various UWB channel environments.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.2C
• /
• pp.109-116
• /
• 2006

Many application scenarios of ultra-wideband(UWB) radio assume non-line-of-sigit(non-LoS) signal propagations. Through-material propagation of UWB signal introduces a distortion of the waveform as well as attenuation, which will introduce a decrease of the correlation coefficient between the correlator template and the received signal. A hypothesis test approach to selection of the template waveform for UWB rake receivers is posed. Linde-Buzo-Gray(LBG) algorithm is used to select the candidate waveforms which are used to setup the hypothesis test. The performance of the algorithm is tested using a set of indoor non-LoS propagation measurement data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.2
• /
• pp.159-168
• /
• 2012

In this paper, we designed the antipodal vivaldi antenna for IR-UWB systems application and evaluated IR-UWB antenna performance for the ultra wideband impulse signal transmission in the time- and frequency-domain. The designed antipodal vivaldi antenna was fabricated using FR-4 substrate which thickness 1.6 mm, dielectric constant ${\epsilon}_r=4.7$ and $tan{\delta}=0.002$. We measured the return loss, far filed radiation pattern at the anechoic chamber in the frequency-domain. We also performed the pulse fidelity analysis in the time-domain using nano-second impulse signal transmission and demonstrated the feasibility of ultra wideband signal stable transmission in the UWB band. The designed and fabricated antipodal vivaldi antenna could be emitting and receiving the IR-UWB signal while preserving low pulse distortion and good radiation pattern in time- and frequency-domain.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1421-1423
• /
• 2003

Ultra Wideband is a new technology from commercial or civilian application viewpoint. It uses already allocated radio spectrum without causing significant interference to other users. It uses very low power, which is below the thermal noise of the receiver and is inherently difficult to detect by un-intentional users. Since, FCC approved the regulation for the commercial use of UWB in February 2002, the development of UWB technology is drastically gaining momentum. However, the technology itself is not new. It has already been used in military applications. UWB has three basic areas of applications, which are communication, positioning and imaging (UWB Microwave). The main commercial application will be for communication since it has very high data transfer rate for short distance. It can also be used for both indoor and outdoor 3-D positioning. Another important application is imaging like microwave remote sensing. An UWB sensor can pass through doors and walls and hence detect the objects inside the room. In this paper, we will introduce about UWB technology along with it’s various possible applications. We will also present some models to generate UWB signal and it’s analysis using signal-processing tools.

• 한국정보통신설비학회:학술대회논문집
• /
• 2005.08a
• /
• pp.141-145
• /
• 2005

In this paper, UWB system did research about effect that interference effect with neighborhood single equipment or nearby group equipment gets In DMB service. 2.6425GHz satellite digital multimedia broadcasting service(SDMB) that electric wave interference special quality is contiguity frequency-band including interference of signal by unnecessary radiation level that is radiated in UWB system, and 3.4125GHz broadcasting relay net that is In-band frequency-band and interference effect degree that get in service did comparative analysis. SDMB system was BER $1{\times}10^{-4}$ that interference effect happens from 6.5m point and broadcasting signal reception is possible at 4m point. Also, it was BER $1{\times}10^{-4}$ that interference effect begins to happen from 5.0m point about center frequency 3.4126GHz and broadcasting signal reception is possible at 2m point. And, confirmed that UWB system of impulse method is less interference effect about 2 dB than UWB system of OFDM method, to electric wave of UWB system that is small output

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.2C
• /
• pp.199-205
• /
• 2004

This paper presents a method of UWB channel modeling, which includes the phase characteristics of the UWB channel. This is accomplished by decomposing a UWB pulse into several narrowband signal components. We show the ray-tracing algorithm can be used to acquire the amplitude and the phase of each signal component. Finally, it is shown that the received pulses simulated can have various shapes due to frequency-dependent reflectivity coefficient resulting from the intrinsic nature of ultra-wide bandwidth of a UWB pulse.

• Journal of Positioning, Navigation, and Timing
• /
• v.11 no.1
• /
• pp.45-49
• /
• 2022

In this paper, we propose a method for estimating the error of the Ultra-Wideband (UWB) distance measurement using the channel impulse response (CIR) of the UWB signal based on machine learning. Due to the recent demand for indoor location-based services, wireless signal-based localization technologies are being studied, such as UWB, Wi-Fi, and Bluetooth. The constructive obstacles constituting the indoor environment make the distance measurement of UWB inaccurate, which lowers the indoor localization accuracy. Therefore, we apply machine learning to learn the characteristics of UWB signals and estimate the error of UWB distance measurements. In addition, the performance of the proposed algorithm is analyzed through experiments in an indoor environment composed of various walls.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.127-128
• /
• 2006

In this paper, we propose a novel signaling method using chirp signals in UWB radio with satisfaction of FCC regulation. Chirp signals have been used in many ranging systems such as radar because of its good correlation properties. Because it is important to use broader signal bandwidth in order to get higher precision of the ranging, according to the Cramer-Rao Lower Bound, UWB radio is extremely good as the ranging systems. But, it is very difficult to apply existing chirp signals to UWB, because FCC regulates that the systems operating in UWB radio must occupy signal bandwidth more than 500MHz on the condition of stopping the frequency sweeping. So, we propose multiple chirp signals which can satisfy the regulation of FCC while maintaining chirp signal's properties. The multiple chirp signals which are composed of the sub-chirps modulated by sub-carriers can expand the signal bandwidth with the same principle of OFDM systems. The simulation results show that the BER performance of the proposed multiple chirp signals is identical to that of conventional OFDM when it is applied to data communication, and that the correlation properties of the proposed signals are almost the same with properties as those of single chirp signals whose sweeping bandwidth is the same value with the proposed one.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.3
• /
• pp.19-26
• /
• 2008

We propose a selective detection scheme based on pulse repetition considering the BER (Bit Error Rate) performance and complexity of coherent IR-UWB (Impulse Radio-Ultra Wide Band) systems. To take system complexity into account, the proposed scheme transmits the UWB signals by pulse repetition at the transmitter, like conventional PRC (Pulse Repetition Coding). However, to effectively improve BER performance of the system, the proposed scheme performs selective detection by estimating the SNR (Signal-to-Noise Ratio) of the received pulse-repeated signal at the UWB receiver. Hence, the proposed scheme effectively improves BER performance of the coherent IR-UWB systems without increasing system complexity, as compared to the conventional PRC algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.3
• /
• pp.384-390
• /
• 2008

Chaotic OOK modulation method can be used in LDR(Low Data Rate) UWB systems. In this paper, UWB chaotic-OOK transmitter system is designed and verified using TSMC 0.18 um CMOS process. A transmitter system is composed of Quasi-chaotic signal generator, OOK Modulator, and driving amplifier. The traditional chaotic signal generators using analog feedback method is weak to process variation. In order to solve this problem, a quasi-chaotic signal generator using digital feedback technique is get wide band signal and OOK Modulator using T-type switching structure is used to enhance the isolation characteristic. A driving amplifier has differential to single structure to avoid an external balun for low cost communication. The measured output power spectrum of the transmitter meet the FCC regulation and the result of the modulation test at data rate of 20 Kbps, 200 Kbps, 2 Mbps, and 10 Mbps is conformed to LDR UWB system. It is shown that the transmitter in this paper can be used for the UWB chaotic-OOK system.