• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.4
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• pp.180-187
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• 2014

In this paper, a extension of a fixed-complexity sphere decoder (FSD) to perform interference signal detection and cancelling is proposed for downlink multiuser multiple input-multiple output (MIMO) communication system. It is based on the application of channel matrix expansion on generalized sphere decoder (GSD), and modification of the channel matrix ordering scheme to a FSD algorithm for interference detection. A Monte Carlo simulation shows that the proposed algorithm improves the receiver performance by 3 dB as compared to maximum likelihood detection without interference cancelling at 10% packet error rate in configuration of 702 Mbit/s datarate for four users respectively on IEEE802.11ac.

• Journal of IKEEE
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• v.23 no.3
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• pp.1046-1053
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• 2019

In a multi-channel single-ended system, the far-end crosstalk (FEXT) due to mutual inductance and mutual capacitance between two adjacent channels critically limit the bandwidth. FEXT causes crosstalk-induced jitter (CIJ) and crosstalk-induced glitch (CIG) which leads to timing margin and voltage margin degradations, respectively. Therefore, FEXT must be compensated in order to increase eye opening and achieve high data-rate. It can be compensated in transmitter by controlling the timing of the data or reshaping the waveform of the signal. Also, FEXT can be compensated in receiver by generating mimicked FEXT using high-pass filter. In this paper, recent techniques to compensate FEXT are investigated, with discussions of their pros and cons.

• Journal of Broadcast Engineering
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• v.11 no.3 s.32
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• pp.302-310
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• 2006

ITU-R B.O. 1130-4 Digital System E adopted for Korean satellite DMB service is a multimedia broadcasting system based on DS-CDM-QPSK technique which broadcasts audio and video contents via the satellite or terrestrial gap-filler. However, Digital System E can not provide full loading services because the multi-channel interference (MCI) is increased due to the loss of orthogonality between signature waveforms in multipath fading channels. In this paper a chip equalizer using tap selection algorithm that enhances the receiving performance is proposed and compared to the conventional rake receiver for the satellite DMB system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1618-1622
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• 2004

In this paper, the linearly interpolated PRC(Pseudo Range Correction) regenerating algorithm was applied to improve the DGPS(Differential Global Positioning System) positioning accuracy at user's spot by using the various PRC information obtained from multi-DGPS reference stations. The PRC information of each GPS satellite is not varying rapidly; it is possible to assume that the variation of PRC information of each GPS satellite is linear. So the linearly interpolated PRC regenerating algorithm can be applied to improve the DGPS positioning accuracy at user's spot by using the various PRC information obtained from multi-DGPS reference stations. To test the performance of the linearly interpolated PRC regenerating algorithm, maritime DGPS reference stations' PRC data was used in RTCM format. 11 maritime DGPS reference stations are in service providing DGPS information to public since 1999. Two set of 3 DGPS reference stations are selected to compare the performance of the linearly interpolated PRC regenerating algorithm. The DGPS positioning accuracy was dramatically improved about 40%. Linearly interpolated PRC regenerating algorithm adopted multi-channel DGPS receiver will be developed in near future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.4
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• pp.1-9
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• 2003

Many CDMA systems provide pilot channels in order to help channel estimation process. Especially in wideband CDMA systems, the number of receive diversity paths can be large due to small chip duration and high multi-path resolution capability. Hence, the received signal power of each path is small for a given total SNR (signal-to-noise ratio) and the pilot power of each path may not be sufficiently large for accurate channel estimation. When the pilot power is small, one can use decision-directed channel estimation to utilize more energy of the received data. However, the decision errors can deteriorate the quality of decision-directed channel estimation. This paper proposes a novel channel estimation method that optimally utilizes receiver decisions as well as pilot symbols with the help of estimated SER (symbol error rate) and SNR. The proposed method computes two channel estimates using the pilot and the data channel filters and optimally combines them. The simulation results show that the proposed method is robust and outperforms the conventional pilot-symbol-aided channel estimation method.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.49-52
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• 2000

The Multi-Code CDMA systems that are proposed as an effective transmission methodology in the IMT-2000 systems allow higher rate services under the IS-95 CDMA infrastructure. The Multi-Code CDMA systems convert the higher rate data into the lower rate by serial to parallel operation and spread the converted data streams by the multiple walsh codes, and its mobile receiver needs multiple walsh generators and data correlators to demodulate simultaneously multiple walsh code channels. Therefore, the number of data correlators is increased as the number of traffic channels increases. In this paper, we proposed the new structure of the data correlators using walsh overlay coding, the shared accumulator, and FWHT(Fast Walsh Hadamard Transform) algorithm for reducing the bottle-neck effect resulting the increase of the number of data correlators.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.33-38
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• 1996

A multi-media binary DS/CDMA system with variable processing gain and coherent correlation receivers are considered under additive white Gaussian noise channels. Two types of information sources with different rates and transmitting powers are assumed to be transmitted simultaneously in the same channel. Average signal-to-noise ratios at the correlation receiver outputs for each type of information sources are analytically derived as functions of discrete partial cross-correlations between spreading code sequences. The analysis is expected to provide analytical tools for use in preliminary system design and spreading code selection.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.1-7
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• 2008

As a clean fuel, LNG or LPG is widely used in large restaurants or plants instead of coal. These fuels are easy to use and cheap. However, they are inflammable very much and easily exploded at the worst. So there are many laws and regulations legislated for the handling and usage of the gas facilities. Nevertheless, very harsh explosions occurred in several domestic or foreign places. In this paper a gas detection and alarm system was developed for large facilities. A new concept for connecting many gas detectors was proposed and based upon that a system including hardware and software have been developed and tested. Although up to 16 gas detectors apart 1 km from main controller can be connected currently, this system can be easily expanded for more detectors because each gas detector receiver communicates with main controller using industrial standard RS-485 multi drop technique. Furthermore several additive functions was included for the installation and maintenance convenience.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.9
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• pp.1198-1206
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• 1997

The flow characteristics of an intermittent fuel injection into a stationary ambient air were investigated using gasoline. The measurements were made by two-channel, air cooling type Phase Doppler Anemometer(PDA) system (DANTEC, 750 MW). And a pintle type injector of MPI (Multi-point Port Injection) system was utilized as a fuel injector. The PDA receiver optic was set up in a 60.deg. C forward scatter arrangement to obtain the optimum scattering signal of fuel droplets. The data were obtained by synchronizing PDA system with the fuel injection period, and the axial and radial velocity and turbulent components of fuel droplets were mainly measured for the analysis of temporal and spatial distribution depending upon the fuel injection pressures.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.433-448
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• 2012

A source-synchronous receiver based on a delay-locked loop is presented. It employs a shared global calibration control between channels, yet achieves channel expandability for high aggregate I/O bandwidth. The global calibration control accomplishes skew calibration, equalizer adaptation, and phase lock of all the channels in a calibration period, resulting in the reduced hardware overhead and area of each data lane. In addition, the weight-adjusted dual-interpolating delay cell, which is used in the multiphase DLL, guarantees sufficient phase linearity without using dummy delay cells, while offering a high-frequency operation. The proposed receiver is designed in the 90-nm CMOS technology, and achieves error-free eye openings of more than 0.5 UI across 9-28 inch Nelco4000-6 microstrips at 4-7 Gb/s and more than 0.42 UI at data rates of up to 9 Gb/s. The data lane occupies only $0.152mm^2$ and consumes 69.8 mW, while the rest of the receiver occupies $0.297mm^2$ and consumes 56.0 mW at the 7- Gb/s data-rate and supply voltage of 1.35 V.