• Title/Summary/Keyword: ${\pi}$/4-DQPSK

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Bit Error Probability of $\pi$/4-DQPSK with Stepped Phase over a Frequency Selective Fading Channel (주파수선택성 페이딩전송로에서 스텝형 위상을 갖는 $\pi$/4-DQPSK의 비트오율)

  • 이철성;이재홍
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.9
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    • pp.1177-1183
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    • 1995
  • This paper proposes a new modulation scheme of $\pi$/4-DQPSK with stepped phase for a frequency selective fading channel. In the proposed modulation scheme, the phase of transmitted signal is shifted in the mid of a symbol duration in order to reduce the effect of multipath delay spread. It reduces the irreducible error of $\pi$/4-DQPSK over a frequency selective fading channel. It is shown that $\pi$/4-DQPSK with stepped phase achieves smaller average bit error probability than regular $\pi$/4- DQPSK by simulation. The former achieves much smaller average bit error probability than the latter for small TEX>${\tau}/T_{s}$.

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Simulation Study of VHF band π/4-DQPSK Maritime Digital Communication Modem According to ITU-R M.1842-1 Annex1 (ITU-R M.1842-1 Annex1 π/4-DQPSK VHF 대역 해상 디지털 통신모뎀의 시뮬레이션 연구)

  • Kwak, Jae-Min
    • Journal of Advanced Navigation Technology
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    • v.17 no.6
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    • pp.693-699
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    • 2013
  • In this paper, ${\pi}/4$-DQPSK modem according to ITU-R M.1842-1 recommendation Annex1 is investigated and simulated. At first, standardization and technical trend of VHF maritime mobile communication are introduced. The ${\pi}/4$-DQPSK modem defined in the Annex1 should support 28.8Kbps bit transmission rate within 25KHz frequency bandwidth. We describe the system model and simulation process of ${\pi}/4$-DQPSK modem transmitter and receiver design with RRC(Root Raised Cosine) transmitter and receiver filter. Then we suggest various graphical simulation results(time domain signals, constellation, power spectral density according to roll-off factor, eye diagram), and show simulated BER performance of the modem. From the simulation results, it is shown that roll-off factor of RRC filter affects to BER performance according to SNR and the designed simulation model meets the spectrum mask requirement suggested in ITU-R M.1842-1 recommendation.

A Study on ${\pi}$/4-DQPSK with Nonredundant Multiple Error Correction

  • Song, Seog-Il;Han, Young-Yearl
    • ETRI Journal
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    • v.21 no.2
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    • pp.9-21
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    • 1999
  • In this paper, to enhance the performance of ${\pi}$/4-DQPSK (${\pi}$/4-differential quadrature phase shift keying), the scheme using nonredundant multiple error correction is proposed and investigated. This scheme for the differential detection of ${\pi}$/4-DQPSK uses the signal output which is delayed for more than two time slots as the parity check bit and applies it to nonredundant multiple error correction. The proposed system was used for studying the performance of ${\pi}$/4-DQPSK with Nonredundant Error Correction (NEC) in additive white Gaussian noise (AWGN) and Nakagami fade modeled mobile communication channel, and it was observed that the performance increased as the error correction capability increased.

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${\frac{\pi}{4}}$-DQPSK with Nonredundant error correction in Nakagami fading channel (나카가미 페이딩채널에서 비용장 오류정정을 갖는 ${\frac{\pi}{4}}$-DQPSK의 성능분석)

  • 송석일;한영열
    • 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.

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Implementation of π/4-DQPSK Modem for Maritime Digital Communication in VHF Band (VHF 대역 해상 디지털 통신용 π/4-DQPSK 모뎀 구현)

  • Kwak, Jaemin
    • Journal of Advanced Navigation Technology
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    • v.18 no.6
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    • pp.541-545
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    • 2014
  • Rec. ITU-R M.1842-1 is international recommendation for VHF band communication guideline in maritime mobile service RR Appendix 18 channels. In this paper, we simulate 28.8 kbps VHF ${\pi}$/4-DQPSK digital baseband modem compatible with the recommendation, then it is designed and implemented with FPGA. Cazac sequence is used as a preamble since packet format is not defined untill now in the recommendation. Baseband modem is designed by VHDL language and implemented on NEXYS4 development platform having Atrix7 FPGA chip from Xilinx. For wireless communication test of total prototype system, ADC/DAC board is implemented and EV9730 RF module is utilized. From the experimental results, implemented FPGA modem shows spectral bandwidth of 25 kHz and successful data exchanges between tx and rx communication platform.

Improving the Base-Layer BER performance at AT-DMB using a Channel Estimation (AT-DMB 시스템에서 채널추정을 이용한 기본계층 수신 성능 향상기법)

  • Bang, Keuk-Joon
    • 전자공학회논문지 IE
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    • v.49 no.2
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    • pp.46-51
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    • 2012
  • Transmit signal of Enhancement Layer in AT-DMB system is received by Coherent Detection, but in Base Layer of AT-DMB, a differential modulation and demodulation is adopted, same as the T-DMB. Especially for the coherent dectection of enhancement layer in AT-DMB system, a channel estimation must be employed. In this paper, I will show that the BER performance of Base-Layer in AT-DMB system will be improved by using the channel estimation information. The suggested method is focusing the constallations after Equalizaing to the nearlest ${\pi}$/4-shift DQPSK constallation points. Simulation results show that for the non-coding environment, the BER performance of AWGN channel, about 2-dB gain can be achieved at $10^{-4}BER$.

Baseband Receiver Design for Maritime VHF Digital Communications (해양 VHF 디지털 통신을 위한 기저대역 수신기 설계)

  • Kim, Seung-Geun;Yun, Chang-Ho;Kim, Sea-Moon;Lim, Yong-Kon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.8B
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    • pp.1012-1020
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    • 2011
  • In this paper a design of $\pi$/4-DQPSK baseband receiver for the exchange of digital data and e-mail between shore and ship stations and/or among ship stations in the maritime mobile service VHF channels is described. Due to the permitted relatively big frequency instability of local oscillators at the transmitter and the receiver of maritime communication system, the designed baseband receiver should have the capabilities of correct estimation and compensation of the synchronization parameters, such as symbol timing and frequency offset, from the received signal which might include relatively big frequency error. Simulated BER results show that the designed baseband receiver works less than 0.5dB loss under AWGN channel when the normalized frequency offset of the received signal is more then 20%.

Error Rate Performance Variation by the Reception Phase Error in a Frequency-Selective Rayleigh Fading Channel Environment (주파수 선택성 레일리 페이딩 채널환경에서 수신 오차위상에 의한 오율 특성 변화)

  • 김용로;금홍식;류흥균
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.9
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    • pp.6-13
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    • 1993
  • In is well-known that system performance in the high speed digital radio communication system is usually deteriorted due to the frequency selective fading distortion. In this paper, bit error rate(BER) performance by the reception phase error in cellular mobile communication systems is derived and analyzed. The system is modeled as a frequency selective fast Rayleigh fading channel corrupted by additive white gaussian noise(AWGN) and co-channel interference(CCI). Our numerical results show that for the 24KBaud(48Kb/s) $\pi$/4-DQPSK operated at carrier frequency 800 MHz and C/I<20 dB, the BER will be dominated by CCI if the vehicular speed is below 100 Km/h. The results show that performance, when reception phase error is below $\pi$/12, is deterioreted less than 3 dB, and that performance, when reception phase error is above $\pi$/12, is degraded over 3 dB.

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A Study of Novel Stop-&-Go Equalization Using Bank Structure (Bank 구조를 이용한 Novel STOP-&-GO)

  • 조경철;강영창김선형
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.1195-1198
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    • 1998
  • A Novel Stop-&-Go Algorithm which incorporate a Bank structure for blind equalization is investigated in this paper. 16-QAM and $\pi/4-DQPSK$ modulation used in this paper. A Proposed novel algorithm of characteristic is high speed transfer by implementation of the equalization algorithm with less computations capacity. The computer simulations result reveal that the proposed Novel Stop-&-Go shows the comparable performance to the conventional Stop-&-Go, while requiring much less computations.

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A BER Performance of Analysis and Comparison for Ultra-Narrowband Digital Radio System

  • Chong, Young-Jun;Kang, Min-Soo;You, Sung-Jin;Lim, Dong-Min;Oh, Seung-Hyeub
    • Journal of electromagnetic engineering and science
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    • v.4 no.2
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    • pp.72-78
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    • 2004
  • In this paper, we evaluate the performance of the digital modulation schemes described in the APCO Project 25 FDMA specifications which can be used for applying the ultra-narrowband technology to the current domestic simple two-way radio systems, and discuss difficulties in the DSP implementation of the systems. We analyze the effect on the systems' BER performance of receiver non-matched filter and frequency-offset between the transmitter and receiver oscillators. And we present a frequency offset compensation method for improving the system performance. The results of performance analysis showed that the CQPSK of APCO Project 25 using non-matched filter degraded the BER by 0.5~1.0 ㏈ comparing with PI/4 DQPSK using matched filter. In the event of 2 % frequency offset, about 1 ㏈ performance loss was produced at the BER of $$10^{-3}TEX>. With the frequency-offset compensation method implemented in the systems using phase recovery scheme of PSK synchronization detection, the performance degradation of about 1.0 ㏈ was occurred at the BER of $$10^{-3}TEX> for 10 % of frequency offset. The proposed method can be used for the improvement of system performance.