• Title/Summary/Keyword: Coherent modulation

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The Error Rate Evaluation for Differential Demodulation of 2-h Continuous Phase Modulation (차동 복조 2-h 연속 위성 변조의 오류 확률)

  • 윤동원;한영열
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.7
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    • pp.29-35
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    • 1994
  • The performance of continuous phase modulation signals is well known for the coherent demodulation. But the carrier recovery circuits of the coherent receiver have long acquisition time and the receiver experiences high error floors for fading channels. In this paper, we propose the differential demodulation of 2-h continuous phase modulation signals. The sets of modulation indices of 2-h phase codes adequate to the differential demodulation for differentially encoded input are obtained and the average bit error probability in Additive White Gaussian Noise environments is derived and analyzed.

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ODSB and OSSB Error Performance Analysis of MMoF Systems in Rician Fading Channel

  • Yun, Chang-Ho;Cho, Tae-Sik;Kim, Kiseon
    • Proceedings of the IEEK Conference
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    • 2003.07a
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    • pp.182-185
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    • 2003
  • Error performance of two modulation schemes of millimeter-wave over fiber (MMoF) system i.e., optical double side band (ODSB) and optical single side band (OSSB) modulations is analyzed under Rician fading. Bit error rates (BER) of two detection techniques i.e., coherent and noncoherent detection are also compared in Rician fading. In aspect of error performance, ODSB modulation scheme has better BER than OSSB modulation scheme has under Rician fading. On the other hand, OSSB modulation scheme is advantageous in case of considering high bandwidth efficiency and small power degradation. Coherent detection technique is proper in Rician fading, because coherent detection provides more SNR gain whether fading is serious or not. Noncoherent detection can be applied when we need a simple receiver structure.

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Transmission Performance Comparison of Direction Detection-Based 100-Gb/s Modulation Formats for Metro Area Optical Networks

  • Chung, Hwan Seok;Chang, Sun Hyok;Lee, Jonghyun;Kim, Kwangjoon
    • ETRI Journal
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    • v.34 no.6
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    • pp.800-806
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    • 2012
  • Transmission performances of direct detection-based 100-Gb/s modulation formats are investigated and compared for metro area optical networks. The effects of optical signal-to-noise ratio sensitivity, chromatic dispersion, cross-channel nonlinearity, and transmission distance on the performance of differential 8-ary phase-shift keying (D8PSK), differential phase-shift keying plus three-level amplitude-shift keying (DPSK+3ASK), and dual-carrier differential quaternary phase-shift keying (DC-DQPSK) are evaluated. The performance of coherent dual-polarization quadrature phase-shift keying (DP-QPSK) with block phase estimation and coherent DP-QPSK with digital differential detection are also presented for reference. According to our analysis, all three direct detection modulation formats could transmit a 100-Gb/s signal over several hundred kilometers of a single-mode fiber link. The results also show that DC-DQPSK outperforms D8PSK and DPSK+3ASK, and the performance of DC-DQPSK is comparable to that of coherent DP-QPSK with digital differential detection. The maximum transmission distance of DC-DQPSK is over 1,000 km, which is enough distance for metro applications.

Coherent optical transmission experiment using FSK modulation and heterodyne detection scheme (FSK/Heterodyne 변복조 방식에 의한 코히런트 광송수신 실험)

  • 박희갑
    • Proceedings of the Optical Society of Korea Conference
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    • 1991.06a
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    • pp.121-125
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    • 1991
  • A basic coherent optical transmission was demonstrated using FSK modulation and heterodyne detection scheme. Optical frequency of DFB LD light source at the transmitter side was stabilized with Fabry Perot etalon and bias feedback circuit. A tunable external cavity LD was used as a local oscillator at the receiver. Heterodyned output signal at IF frequency of 2GHz was measured and discussed.

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Circuit Models for Low Frequency Modulation Characteristics of Semiconductor Lasers (반도체 레이저의 저주파 변조특성의 회로 모델)

  • 소준호
    • Proceedings of the Optical Society of Korea Conference
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    • 1989.02a
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    • pp.214-217
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    • 1989
  • The most attractive feature of semiconductor lasers as sources for coherent optical communication system is the ability to produce frequency modulation by modulation of the bias current. The frequency deviation of semiconductor lasers under direct modulation depends on the laser structure and modulation frequency. This paper describes a circuit modeling techniques for the directly frequency modulated CSP (Channeled Substrated Planner) semiconductor laser. Predictions from this model are compared with the other published results of sinusoidal frequency modulation below than 1 GHz.

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Performance of Relay Networks with Partially Differential Modulation Scheme Depending on Energy Allocation in Railway Environments (철도환경에서 에너지 할당에 따른 부분차등변조 방식을 이용한 중계 네트워크의 성능)

  • Cho, Woong;Cho, Han-Byeog
    • The Journal of the Korea institute of electronic communication sciences
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    • v.11 no.1
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    • pp.17-22
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    • 2016
  • In relay networks, relay nodes amplify or demodulate/remodulate the received signal from the transmitter, and transmit that signal to the receiver. The received signals from several relays are combined and used for demodulation at the receiver, which enhances the performance of the overall system. Partially differential modulation scheme which uses coherent modulation at the relay and non-coherent modulation scheme at the receiver is adopted for modulation scheme. We analyze the performance of systems depending on various energy allocations of source and relays given the total energy in relay networks.

All-optical Signal Processing of Fiber Impairments in Dual-Polarization 112 Gbit/s m-ary QAM Coherent Transmission

  • Asif, Rameez;Islam, Muhammad Khawar;Zafrullah, Muhammad
    • Journal of the Optical Society of Korea
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    • v.17 no.1
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    • pp.57-62
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    • 2013
  • We have numerically implemented a receiver side all-optical signal processing method, i.e. optical backward propagation (OBP), by dispersion compensating fiber (DCF) and non-linear compensator (NLC) devised by effective negative Kerr non-linear coefficient using two highly non-linear fibers (HNLFs). The method is implemented for the post-processing of fiber transmission impairments, i.e. chromatic dispersion (CD) and non-linearities (NL). The OBP module is evaluated for dual-polarization (DP) m-ary (m=4,16,32,64,256) quadrature amplitude modulation (QAM) in 112 Gbit/s coherent transmission over 1200 km standard single mode fiber (SMF). We have also investigated an intensity limited optical backward propagation module (IL-OBP) by using a self-phase modulation-based optical limiter with an appropriate pre-chirping to compensate for the intensity fluctuations in the transmission link. Our results show that in highly non-linear sensitive 256QAM transmission, we have observed a 66% increase in the transmission distance by implementing IL-OBP as compared to conventional OBP.

Adaptive Modulation Method using Flexible PPM Method in WPAN LR-UWB System (WPAN LR-UWB 시스템에서 유동적인 PPM 방식을 이용한 적응적인 변복조 방법)

  • Choi, Nak-Hyun;Hwang, Jae-Ho;Kim, Joo-Kyung;Kim, Jae-Moung
    • Proceedings of the IEEK Conference
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    • 2007.07a
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    • pp.91-92
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    • 2007
  • LR-UWB utilizes BPSK and PPM for the transmission, which embeds the information in the transmitted pulse position. Meanwhile, by using coherent method, there is approximately 3dB enhancement on the BER performance over that using non-coherent method. However, due to the variable channel conditions, conventional system which uses fixed modulation is not efficient. To maximize the efficient and performance, in this paper, we propose an adaptive method including 4PPM+BPSK mode and 2PPM mode, in which the modulation method is dynamically changed depending on the channel condition which is determined according to the preamble correlation output.

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Performance analysis of UWB receiver using PPM and BPSK modulation scheme in the LR-WPAN System (LR-WPAN 시스템에서 PPM+BPSK 변조 방식을 사용하는 UWB 송수신기의 성능 분석)

  • Lee, Kyoung-Tak;Lim, Dong-Guk;Sohn, Sung-Hwan;Kim, Jae-Moung
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.5 no.2 s.10
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    • pp.19-28
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    • 2006
  • In the IEEE 802.15.4a system, they require simple, economical and low power consumption transmitter and receiver to transmit low rate data and to identify distance and location. To meet these requirements, LR-WPAN system use transmitter and receiver with simple modulation and demodulation scheme. In this paper, use PPM+BPSK modulation and windowing scheme to overcome multipath fading effect. Then we apply this channel estimation scheme to LR-WPAN system and compare performance depends on transmitter scheme. Proposed method using preamble to find channel characteristic out and we compensate distorted data with that information. Therefore we can detect signal easily at the demodulation part. Simulation result shows that performance evaluation is greater at the NLOS channel than LOS channel no matter what the receiver scheme.

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