• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.296-298
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• 2009

In this paper, we are performance analysis of IEEE 802.15.4b LR-WAPN(Low-Rate Wireless Personal Area Network; Zigbee) system noncoherent receivers at 915MHz under Jamming. IEEE 802.15.4b concerns itself with devices at 915MHz, which employ a higher data rate of up to 250 kbps, and which use O-QPSK(Offset Quradrature Phase Shift Keying modulation with DSSS(Direct Sequence Spread Spectrum). Communication between devices can still be hampered by the presence of interferers outside the network, whether the interference be intentional or not. Hence the receivers can not have stable receiving condition due to worse BER. To solve this problem, we present a mere stabilized receiver system of using noncoherent detection. In this paper, we look instead at the effect of jamming, i.e. intentional interference, on the BER performance of IEEE 802.15.4 devices.

• ETRI Journal
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• v.34 no.4
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• pp.617-620
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• 2012

The denoising mapping with the closest-neighbor clustering (CNC) method in denoise-and-forward two-way relay channels is studied. Specifically, the symmetry of the constellations in source terminals A and B is utilized to reduce the complexity of the CNC method. The specific case considered first to illustrate how the constellation symmetry works in the CNC method is the quadrature phase-shift keying constellation in A and B and the single-antenna deployment in all terminals. This case study shows that an enormous complexity reduction can be achieved. Next, the result is extended to multiple-antenna scenarios and square quadrature amplitude modulations.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.32-41
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• 1996

We propose the improved GMSK (gaussian-filtered minimum shift keying) quadrature modulator using the FIR(finite impulse response )filter whose coefficients are obtained form the differnce of phase response, and design its ASIC (applicaton specific integrated circuit) which can be used for GSM (global system for mobile communication) digital cellular system and DCS 1800 (digital cellular system at 1800MHz) personal communication system. Input data become quantized I and Q channel 10 bit signal through cosine and sine ROM mapping after being filtered by the FIR filter whose normalized bandwidth is 0.3 and designed by considering intersymbol interference as well as sampling ratio. These two signals become the GMSK modulated I and Q channel signal through DAC (digital-to-analog converter) and 7th order analog chebyshev LPF(low pass filter) respectively. The difference between the ideal analog signal and its digitized signal is analyzed in terms of sampling noise, quantization noise, truncation noise and coefficient noise. And the effect of the LPF following the DAC is considered. The ASIC design of the GMSK quadrature modulator is also confirmed by an experiment.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.398-402
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• 2003

In this paper, we have analyzed the performance enhancement of OFDM/QPSK-DMR(Orthogonal Frequency Division Multiplexing/Quadrature Phase Shift Keying Modulation-Digital Microwave Radio)system using BL-PSF(Band Limited-Pulse Shaping Filter) over the microwave channel. For performance enhancement, we apply the one-tap adaptive equalizer for OFDM/QPSK-DMR system and compare with the BER performance of single carrier DMR system. Computer simulations confirm that the OFDM/QPSK-DMR system using one-tap adaptive equalizer has the same BER performance for the single carrier DMR system.

• Journal of information and communication convergence engineering
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• v.14 no.4
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• pp.227-232
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• 2016

In this study, the performance of a 32-quadrature amplitude position modulation (QAPM) system is analyzed under a Rician fading channel condition when the maximal ratio combining (MRC) diversity technique is used in the receiver. The fading channel is modeled as a frequency non-selective slow Rician fading channel corrupted by additive white Gaussian noise (AWGN). QAPM is available to improve BER performance without amplifying transmit power, and MRC diversity makes the performance improvement of QAPM system even bigger by intentionally maximizing SNR. Error performances are shown for the 32-QAPM system and a 32-phase silence shift keying (PSSK) system in order to examine the effects of fading severity, for various values of the Rician parameter, K. The dependence of error rates on MRC diversity is also analyzed. The simulation results show that the BER performance of the 32-QAPM system is better than that of the 32-PSSK system under the above mentioned conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1948-1959
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• 1999

The error rate performance of the proposed $\pi$/4-differential quadructure phase shift keying( $\pi$/4-DQPSK) with nonredundant multiple error correction is analyzed for Nakagami fading channel. The scheme for differential detection of $\pi$/4-QPSK with nonredundant multiple error correction utilizes the output that employ the received signal delayed by more than two time slots. It was observed that the performance increased as the error correction capability increased.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.165-168
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• 2006

최근 디지털 변복조 방식에서 추가적인 전송률 증가를 통하여 기존 시스템의 성능개선 및 서비스의 유연성 확보를 위해 계층변조에 대한 연구가 활발하다. 기존의 QAM(quadrature amplitude modulation)계열의 계층변조 방식은 이미 많은 연구를 통해 분석되고 응용되고 있지만 차분변조 방식을 취하고 있는 DQPSK(differential quadrature phase shift keying) 방식에 대한 계층변조 기법은 아직까지 선행연구가 활발히 진행되지 않았다. 본 논문에서는 DQPSK방식에 가능한 계층변조기법을 성상에 따라 분석하고 DQPSK방식에 가장 적합한 계층변조기법을 도출한다.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3E
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• pp.99-108
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• 2005

To investigate the equalizer performance in underwater acoustic communication m the presence of intersymbol interference (ISI) due to multipath, computer simulations are carried out in discrete multipath shallow water channels for three different horizontal ranges. For the purpose of computation simplicity, least mean square (LMS) algorithm is adopted both in linear equalizer and nonlinear equalizer, decision feedback equalizer (DFE) to cancel out ISI effects. Binary phase shift keying (BPSK) signals have been transmitted with high data rate of 2000bps through the use of equalization technique. The results demonstrate that equalization is an efficient way to achieve high transmission data rate in the shallow water channel.

• ETRI Journal
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• v.32 no.3
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• pp.464-467
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• 2010

In this letter, we analyze the error performance of a mobile communication system with microdiversity and macrodiversity reception in gamma-shadowed Rician fading channels for a binary differential phase-shift keying modulation scheme. Analytical expressions for the probability density function (PDF) and moment-generating function (MGF) are derived. The average bit error probability can be calculated by averaging the conditional bit error probability over the PDF or using the MGF-based approach. Numerical results are graphically presented to show the effects of macrodiversity, correlation, number of diversity branches, and severity of both fading and shadowing.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.256-261
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• 2011

We demonstrate 3-Gb/s wireless link using a 60-GHz receiver front-end fabricated in $0.25-{\mu}m$ SiGe:C bipolar complementary metal oxide semiconductor (BiCMOS) and a mixed-mode quadrature phase-shift keying (QPSK) demodulator fabricated in 60-nm CMOS. The 60-GHz receiver consists of a low-noise amplifier and a down-conversion mixer. It has the peak conversion gain of 16 dB at 62 GHz and the 3-dB intermediate-frequency bandwidth of 6 GHz. The demodulator using 1-bit sampling scheme can demodulate up to 4.8-Gb/s QPSK signals. We achieve successful transmission of 3-Gb/s data in 60 GHz through 2-m wireless link.