• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8C
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• pp.806-813
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• 2009

This paper presents a modem chip design for high-speed wireless communications. Among the high-speed communication technologies, we design the UWB (Ultra-Wideband) modem SoC (System-on-Chip) Chip based on a MB-OFDM scheme which uses wide frequency band and gives low frequency interference to other communication services. The baseband system of the modem SoC chip is designed according to the standard document published by WiMedia. The SoC chip consists of FFT/IFFT (Fast Fourier Transform/Inverse Fast Fourier Transform), transmitter, receiver, symbol synchronizer, frequency offset estimator, Viterbi decoder, and other receiving parts. The chip is designed using 90nm CMOS (Complementary Metal-Oxide-Semiconductor) procedure. The chip size is about 5mm x 5mm and was fab-out in July 20th, 2009.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.224-231
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• 2003

In this paper we proposed system parameter values of ultra-wideband Impulse Radio systems for the frequency band(3.1~10.6GHz), which is allocated by Federal Communications Commission(FCC). We also analyzed performance of the proposed system in the multiple access interference environment. According to result, application of possible pulse duration($t_{n}$) is very limited by 0.04~0.0326 ns in permission frequency range that establish in FCC. In the case of the same pulse signal power, we could know that system performance was changed by pulse repetition number($N_{s}$ ) regardless of pulse duration. Thus, We could know that we have to need duration of monocycle pulse and setting of frame un it time(Τ$_{f}$ ) according to multi user numbers and design proper pulse repetition number by transfer rate in multiple access systems design. In the IR system that needs high speed transmission more than 50 Mbps in multiple access interference environment, we could know that very serious performance decrease by multiple access interference happens. Therefore, as the design of high speed multiple access IR system, it should be designed to additional improvement techniques that can remove multiple access interference at the same time.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.60-66
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• 2008

In this paper, the CPW-fed Ultra-wideband antenna is designed and fabricated for UWB communications. To achieve ultra-wide bandwidth of the antenna, we propose the mutual coupling of two planar monopole antennas. The mutual coupling of monopole pair of the proposed antenna is optimized by adjusting the parameters, the widths of the planar monopoles and the space between two monopoles. Two UWB antennas with different horizontal sections of the CPW-fed monopole antenna are fabricated and measured to examine the mutual coupling effects on the monopole pair antenna. The measured result show that two antennas are satisfied with UWB communication band(3.1$\sim$10.6Ghz).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.189-193
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• 2005

In this paper, we propose a direct conversion double-balanced down-converter fer MB-OFDM W system, which is implemented using $0.18\;{\mu}m$ CMOS technology and its measurement results are shown. The proposed down-converter adopts a resistive current-source instead of general transconductance stage using MOS transistor to achieve wideband characteristics over RF input frequency band $3\~5\;GHz$ with good gain flatness. The measured conversion gain is more than +3 dB, and gain flatness is less than 3 dB for three UWB channels. The dc consumption of this work is only 0.89 mA from 1.8 V power supply, leading to the low-power W application.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.64-71
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• 2017

In this paper, Kalman filter and RRWA algorithm are used to estimate the accurate target in IR-UWB (Impulse-Radio Ultra Wideband) radar system, which enables accurate location recognition of indoors and outdoors with low cost and low power consumption. In the signal reflected by the target, unnecessary signals exist in addition to the target signal. We have tried to remove unnecessary signals and to derive accurate target signals and improve performance. The location of the targets is estimated in real time with one transmitting antenna and one receiving antenna. The Kalman filter was used to remove the background noise and the RRWA algorithm was used to remove the reflected signal. In this paper, we think that it will be useful to study the accurate distance estimation and tracking in future target estimation.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.81-88
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• 2016

In this paper, we propose an adaptive multi-target estimation algorithm using the characteristics of signals in the IR-UWB(Impulse-Radio Ultra Wideband) radar system, which is attracting attention because it has good transparency, robustness to the indoor environment, and high precision positioning of tens of centimeters. We proposed an algorithm that estimates multiple peaks with the characteristic that the signal reflected by the target has a peak. To verify the performance of these algorithms, multiple targets were placed in front of the radar and the existing technique and the multi - target estimation algorithm were compared. The location of the targets is estimated in real time with one transmitting antenna and one receiving antenna. The number of estimates can be increased compared with the existing peak signal derivation method, and multiple targets can be derived. The conventional technique estimates only one target, which results in a mean square error of 1 while a multi - target estimation algorithm yields a result of about 0.05. The proposed method is expected to be able to apply multiple targets to the estimation and application in one IR-UWB module environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.47-54
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• 2007

Since impulse-radio-based ultra wideband (IR-UWB) do not use carrier frequency but use very short pulse to transmit data it sends data not continuously but discretely and this feature gives the potential to reduce collision in multi-user environment. In this paper, we analyse characteristic of IR-UWB and propose a new collision paradigm, Collision Distribution which changes collision level from packet to pulse. In Collision Distribution mechanical each node sends data with its own pulse interval in random time, distributed manner. It prevents packet drop due to packet collision. We show that Collision Distribution can reduce packet error and can provide real time packet transmission with analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7C
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• pp.443-450
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• 2011

Recently, various transmission techniques for communication and broadcasting systems have been developed to meet the dramatically increasing requirement of consumers. Because UWB (Ultra-Wideband) is a wireless communication technique that supports high data rate with low power, it can satisfy the requirement and can be applied to various wireless communication services. The multi-band orthogonal frequency division multiplexing (MB-OFDM) system, one of UWB system, is the wireless communication system that satisfies the transmission characteristic for UWB and so it can be used for various wireless communication services. In this paper, we propose a scheme that uses hierarchical modulation which is applied in digital video broadcasting system at the source and adaptive modulation based on the channel quality at the relays. The simulation results have shown that the proposed scheme has both the advantages of the increased throughput by 33% and similar BER performance to conventional scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.381-391
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• 2013

Wireless transmission of uncompressed video guarantees higher quality with lower latency than compressed video transmission. Although current wireless technologies cannot fully cover required data rates of about a few Gb/s for full high definition resolution, some wireless technologies such as ultra-wideband (UWB) provide 1 Gb/s data rate which is adequate for uncompressed video transmission in portable devices. In this paper, we propose an uncompressed video transmission system for wireless mirroring services in portable devices. We firstly simulated the performance of uncompressed video transmission using single or multiple 1 Gb/s UWB technology. Then we implemented hardware-based uncompressed video processing block and Gb/s wireless MAC accelerator. Finally, we show the implementation result and the demonstration of uncompressed HD video transmission using multiple 1 Gb/s UWB PHYs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.547-554
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• 2010

Recently, the multi-band orthogonal frequency division multiplexing(MB-OFDM) system, one of UWB system, can satisfy the requirement and can be applied to various wireless communication services because ultra-wideband(UWB) is a wireless communication technique that supports high data rate with low power. In this paper, the method applying Alamouti's space time block code(STBC) and cyclic delay diversity(CDD) is proposed. The proposed method can be easily applied with arbitrary number of relays and only needs two time slots of quasi stationary assumption. And it is applied to the MB-OFDM system. Second, an optimal relaying scheme based on decode-and-forward(DF) method is proposed which is provides good error performance compared to conventional schemes.