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Impact of Four Wave Mixing on Manchester Coded ASK Multichannel Optical Communication System (Manchester Coded ASK 다중채널 광통신 시스템의 Four Wave Mixing 에 대한 영향)

  • Lee, Ho-Joon;Leonid G. Kazovsky
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.11
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    • pp.1607-1617
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    • 1993
  • The performance of Manchester-coded ASK optical wavelength division multiplexing(WDM) systems is evaluated laking into account the shot noise and the four wave mixing(FWM) caused by fiber nonlinearities. The result is compared to conventional non-return-to-zero(NRZ) systems for ASK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power(limited by the FWM), to the minimum input power(limited by receiver sensitivity), is evaluated. For 1.55 rm 16 channel WDM systems, the dynamic range of ASK Manchester coded systems shows a 2.0 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.

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Error Performance Analysis of Trellis Coded QPSK Signal with Reed-Solomon Coding and MRC Diversity Reception in Micro-Cellular System (마이크로 셀룰러 시스템에서 MRC 다이버시티와 Reed-Solomon 부호를 적용한 Trellis Coded QPSK 신호의 오율 해석)

  • 노재성;김영철;박기식;조성언;조성준
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.4
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    • pp.427-438
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    • 1998
  • The bit error rate(BER) performance of Trellis Coded QPSK signal in the presence of cochannel interference (CCI) and Rician fading is investigated. The trellis coded QPSK system adopts Maximum Ratio Combining (MRC) diversity reception and Reed-Solomon code to enhance system performance. Using the derived error probability equation, the error performance of trellis coded QPSK system has been evaluated and shown in figures to discuss as a function of signal power to noise power ratio (SNR), signal power to interference power ratio(SIR), direct to indirect signal power ratio ($K_R$), the number of diversity branch (M), the frame length of Reed-Solomon code (n), the number of error correction symbol (t), and the number of state of trellis encoder. From the results, we know that proposed system is affected by cochannel interference and fading in microcell environment. Also, BER performance of Trellis Coded QPSK system can be improved as increasing either the power of desired signal or the value of SIR. And the BER floor in microcellular system is caused by the cochannel interference and it occurs at high BER when SIR is low. And Reed-Solomon code (n=15, t=2) is more effective to restrain the affection of CCI and fading than MRC diversity reception (M=2).

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Error Performance Analysis of DS/CDMA-Trellis Coded QPSK Signal with MRC Diversity Reception in Wireless Data Communication (무선 데이터 통신에서 MRC 다이버시티 수신시의 DS/CDMA-Trellis Coded QPSK 신호의 오율 해석)

  • 노재성;김영철;박기식;강희조;조성준
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.3
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    • pp.317-329
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    • 1998
  • In this paper, we have analyzed the packet error probability of DS/CDMA-Trellis Coded QPSK modulation signal with MRC(Maximum Ratio Combining) diversity reception in Rician fading, multi-user interferences and multipath channel. And then we have evaluated the performance and capacity of DS/CDMA-Trellis Coded QPSK system using the MRC diversity reception as a function of direct power to indirect power ratio ($K_R$), the number of diversity branch(M), the number of multi-user(U), PN chip rate(PN), the number of multipath channel($L_P$), and packet length(PL). From the results, we know that the coding gain of DS/CDMA-Trellis Coded QPSK system with 2 branch MRC diversity is about 6 dB against uncoded DS/CDMA BPSK system with 2 branch MRC diversity in Rician fading ($K_R=6dB), 5 multi-user interferences, and 3 multipath channel. And, we know that coded QPSK signal designed for the AWGN channel also perform well on a Rician fading channel with MRC diversity reception. Consequently, we expected that proposed system structure is reliable to the wireless data communication system in Rician fading, multi-user interferences, and multipath channel.

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Underwater Channel Analysis and Transmission Method Research via Coded OFDM (수중채널 분석과 Coded OFDM을 통한 전송방법 연구)

  • Jeon, Hyeong-Won;Lee, Su-Je;Lee, Heung-No
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.5B
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    • pp.573-581
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    • 2011
  • The underwater channel is known to offer poor communications channel. The channel medium is highly absorptive and the transmission bandwidth is limited. In addition, the channel is highly frequency selective; the degree of selectiveness depends on a detailed geometry of the channel. Furthermore, the response changes over time as the channel conditions affecting the response such as water temperature, sea surface wind and salinity are time-varying. The transceiver design to deal with the frequency and time selective channel, therefore, becomes very challenging. It has been known that deep fading at certain specific sub-carriers are detrimental to OFDM systems. To mitigate this negative effect, the proposed coded OFDM system employs an LDPC code based modulation. In this paper, we aim 1) to provide a detailed underwater channel model; 2) to design a robust LDPC coded OFDM system; 3) to test the proposed system under a variety of channel conditions enabled by the channel model.

Performance Analysis of the Optimal Turbo Coded V-BLAST technique in Adaptive Modulation System (적응 변조 시스템에서 최적의 터보 부호화된 V-BLAST 기법의 성능 분석)

  • Lee, Kyung-Hwan;Choi, Kwang-Wook;Ryoo, Sang-Jin;Kang, Min-Goo;Hong, Dae-Ki;You, Cheol-Woo;Hwang, In-Tae;Kim, Cheol-Sung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.2
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    • pp.385-391
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    • 2007
  • In this paper, we propose and observe the Adaptive Modulation system with optimal Turbo Coded V-BLAST (Vertical-Bell-lab Layered Space-Time) technique that is applied the extrinsic information from MAP (Maximum A Posteriori) Decoder with Iterative Decoding to use as a priori probability in two decoding procedures of V-BLAST: ordering and slicing. Also, comparing with the Adaptive Modulation system using conventional Turbo Coded V-BLAST technique that is simply combined V-BLAST with Turbo Coding scheme, we observe how much throughput performance has been improved. As a result of simulation, in the Adaptive Modulation systems with several Turbo Coded V-BLAST techniques, the optimal Turbo Coded V-BLAST technique has higher throughput gain than the conventional Turbo Coded V-BLAST technique. Especially, the results show that the proposed scheme achieves the gain of 1.5 dB SNR compared to the conventional system at 2.5 Mbps throughput.

Capacity Increasement of Trellis Coded 16 QAM Multi-Carrier CDMA System due to SC/MRC Diversity in Multiuser Interference and Rician Fading Channel.

  • 노재성;강희조;김춘길;김언곤;조성준
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.3A
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    • pp.362-374
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    • 2000
  • In this paper, trellis coded 16 QAM Multi-Carrior CDMA system is proposed, Using the equivalent signal-to-noise plus interference Power ratio (SNIR) of Multi-Carrier CDMA system in the reverse link, capacity and BER performance of trellis coded 16 QAM Multi-Carrier CDMA system are analyzed taking into account the number of multi-carrier, the number of multiple access user, the number of SC/MRC diversity branch, and Rician fading parameter in multiuser interference and Rician fading channel. And the capacity and the BER performance of trellis coded 16 QAM Multi-Carrier CDMA system using selection combining (SC) and maximal ratio cabining (MRC) diversity are numerically compared. Obtained results show that the capacity of proposed system depends on the number of multi-carrier. ti is found that the trellis coded 16 QAM Multi-Carrier CDMA system with SC/MRC antenna diversity scheme is efficient to combat multipath fading and to increase the maximum number of users in high speed data communication. With the results of analysis. MRC diversity technique provides the performance fro high speed data communications. Finally, we present a numerical approach to derive the capacity and the BER performance and to find the maximum number of multiple access user for Multi-Carrier system in multiuser interference and Rician fading channel.

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Serially Concatenated Space-Time Code using Iterative Decoding of High Data Rate Wireless Communication (고속 무선 통신을 위한 반복 복호 직렬 연쇄 시.공간 부호)

  • 김웅곤;구본진;양하영;강창언;홍대식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.4A
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    • pp.519-527
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    • 2000
  • This paper suggests and analyzes the Serially Concatenated Space-Time Code(SCSTC) with the possibility of a efficient high-speed transmission in a band limited channel. The suggested code has a structure that uses the interleaver to connect the space-time code as an inner code and the convolutional code as a outer code serially. This code keeps the advantage of high-speed transmission and also has the high BER performance. The performance of the suggested system is compared with the conventional bandwidth efficient trellis coded modulation, such as a Serially Concatenated Trellis Coded Modulation (SCTCM) and a Turbo-Trellis Coded Modulation(Turbo-TCM). The results show that the suggested system has a 2.8dB and 3dB better BER performance than SCTCM and Turbo-TCM respectively in case of the transmission rate 2b/s/Hz in fading channel.

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Simultaneous and Coded Driving System of Ultrasonic Sensor Array for Object Recognition in Autonomous Mobile Robots

  • Kim, Ch-S.;Choi, B.J.;Park, S.H.;Lee, Y.J.;Lee, S.R.
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.2519-2523
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    • 2003
  • Ultrasonic sensors are widely used in mobile robot applications to recognize external environments, because they are cheap, easy to use, and robust under varying lighting conditions. In most cases, a single ultrasonic sensor is used to measure the distance to an object based on time-of-flight (TOF) information, whereas multiple sensors are used to recognize the shape of an object, such as a corner, plane, or edge. However, the conventional sequential driving technique involves a long measurement time. This problem can be resolved by pulse coding ultrasonic signals, which allows multi-sensors to be fired simultaneously and adjacent objects to be distinguished. Accordingly, the current presents a new simultaneous coded driving system for an ultrasonic sensor array for object recognition in autonomous mobile robots. The proposed system is designed and implemented using a DSP and FPGA. A micro-controller board is made using a DSP, Polaroid 6500 ranging modules are modified for firing the coded signals, and a 5-channel coded signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances for each sensor were obtained from the received overlapping signals using correlations and conversion to a bipolar PCM-NRZ signal.

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An Analysis of Trellis-Coded Orthogonal Frequency Division Multiplex over Frequency-Selective Fading Channel (주파수선택성 페이딩을 갖는 통신로에 격자부호 직교주파수분할 다중통신방식의 성능 분석)

  • Suh, Heejong;Zhang, Ke
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.11
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    • pp.33-38
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    • 2004
  • In this paper, we review a trellis-coded orthogonal frequency division multiplex (TC-OFDM) system, which combines OFDM with trellis-coded modulation, for overcoming the frequency selective and multipath fading of time dispersive channels. We simulate and analyse the BER performance of rate 2/3 trellis coded 8DPSK-OFDM over time dispersive channels. Design of the trellis codes at different carrier numbers of OFDM is discussed. Results show that TC-OFDM system can provide 6 dB coding gain at a BER of 10$^{-3}$ compared with OFDM system without coding.

Impact of FWM on manchester coded DPSK WDM communication systems (Manchester coded DPSK WIDM 통신 시스템에서 FWM의 영향)

  • 이호준
    • Korean Journal of Optics and Photonics
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    • v.5 no.2
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    • pp.319-325
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    • 1994
  • The performance of Manchester-coded DPSK optical wavelength division multiplexing (WDM) systems using a stochastic approach is evaluated taking into account the shot noise and the four-wave mixing (FWM) caused by fiber nonlinearities. The result of Manchester-coded system is compared to conventional non-return-to-zero (NRZ) systems for DPSK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power (limited by the FWM), to the minimum input power (limited by receiver sensitivity), is evaluated. For $1.55.{\mu}m$16 channel WDM systems, the dynamic range of DPSK Manchester coded systems shows a 2.1 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber; it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.t rate.

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