• Title/Summary/Keyword: Forward error correction code

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Analysis of Hybrid ARQ System Using Cross Layer (Cross Layer를 이용한 Hybrid ARQ System 분석)

  • Park, Tae-Doo;Kim, Min-Hyuk;Kim, Chul-Seong;Jung, Ji-Won
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.11
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    • pp.1229-1234
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    • 2010
  • High quality and high speed multimedia services will be required in the next generation mobile communications. To satisfy these services, powerful error correction techniques are used. ARQ(Auto Repeat Request) techniques, aspects of the throughput, and FEC(Forward Error Correct) techniques have disadvantages in terms of reliability. H-ARQ(Hybrid Auto Repeat Request) systems have been studied extensively as a solution of these disadvantages. In this paper introduce double layer coding and H-ARQ type, proposed H-ARQ system using double layer coding methods. Simulate BER performance and throughput. And we suggest that according to channel condition suitable H-ARQ type.

Energy Efficiency in Wireless Sensor Networks using Linear-Congruence on LDPC codes (LDPC 코드의 Linear-Congruence를 이용한 WSN 에너지 효율)

  • Rhee, Kang-Hyeon
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.44 no.3
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    • pp.68-73
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    • 2007
  • Recently, WSN(wireless sensor networks) consists of several sensor nodes in sensor field. And each sensors have the enforced energy constraint. Therefore, it is important to manage energy efficiently. In WSN application system, FEC(Forward error correction) increases the energy efficiency and data reliability of the data transmission. LDPC(Low density parity check) code is one of the FEC code. It needs more encoding operation than other FEC code by growing codeword length. But this code can approach the Shannon capacity limit and it is also can be used to increase the data reliability and decrease the transmission energy. In this paper, the author adopt Linear-Congruence method at generating parity check matrix of LDPC(Low density parity check) codes to reduce the complexity of encoding process and to enhance the energy efficiency in the WSN. As a result, the proposed algorithm can increase the encoding energy efficiency and the data reliability.

Analysis a LDPC code in the VDSL system (VDSL 시스템에서의 LDPC 코드 연구)

  • Joh, Kyung-Hyun;Kang, Hee-Hoon;Yi, Sang-Hoi;Na, Kuk-Hwan
    • Proceedings of the IEEK Conference
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    • 2006.06a
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    • pp.999-1000
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    • 2006
  • The LDPC Code is focusing a powerful FEC(Forward Error Correction) codes for 4G Mobile Communication system. LDPC codes are used minimizing channel errors by modeling AWGN Channel as VDSL system. The performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. LDPC code are encoded by sparse parity check matrix. there are decoding algorithms for a LDPC code, Bit Flipping, Message passing, Sum-Product. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten.

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Further Results on Performance of LDPC coded IM-OFDM-QOS System

  • Kim, Hyeongseok;Kim, Jeongchang
    • Journal of Broadcast Engineering
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    • v.24 no.7
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    • pp.1221-1227
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    • 2019
  • This paper describes a low-density parity-check (LDPC) coded index modulated orthogonal frequency division multiplexing with quasi-orthogonal sequence (IM-OFDM-QOS) and provides performance evaluations of the proposed system. By using QOS as the spreading code, IM-OFDM-QOS scheme can improve the reception performance than IM-OFDM-SS scheme for a given data rate. On the other hand, LDPC code is widely used to the latest wireless communication systems as forward error correction (FEC) scheme and has Shannon-limit approaching performance. Therefore, by applying LDPC code to IM-OFDM-QOS system as FEC scheme, the reception performance can be further improved. Simulation results show that significant signal-to-noise ratio (SNR) gains can be obtained for LDPC coded IM-OFDM-QOS system compared to the LDPC coded IM-OFDM-SS system and the SNR gain increases with the higher code rate.

A Performance Analysis of the Speech Coders for Digital Mobile Radio (디지털 이동통신을 위한 음성 부호기의 성능 분석)

  • 정영모;이상욱
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.4
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    • pp.491-501
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    • 1990
  • Recently, four speech coding techniques, namely, SBC-APCM(sub-band coding adaptive PCM), RPE-LPC(regualr pulse excitation linear predictive codec), MPE-LTP(multi-pulse excited long-term prediction) and CELP (code-excited linear prediction) are proposed for digital mobile radio applications. However, a performance comparison of these coders in the Rayleigh fading environment has not been made yet. In this paper, the performances of the four spech coders in the random bit error and burst error environment are investigated. For the channel coding of SBC-APCM, RPE-LPC and MPE-LTP, the sensitivity of output bit stream is measured and a bit selective forward error correction is provided acording to the measured bit sensitivity. And for an attempt to improve the performance of CELP, an optimum quantizer is applied for transmitting scalar quantities in CELP. However, an improvement over the conventional approach is found to be negligible. For the channel coding of CELP, Reed-Solomon code, Golay code, convolutional code of rate 1/2 shows the best performance. Finally, from the simulation results, it is concluded that CELP is the best candidate for digital mobile radio and is followed by MPE-LTP, SBC-APCM and RPE-LPC.

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A Study on Forward Error Correction of Long-Distance Submarine Optical Communication Systems (장거리 해저 광통신시스템의 순방향에러정정 기술 연구)

  • Jung, Jae-Jin;Lee, Young-Sun;Shin, Hyun-Sik
    • The Journal of the Korea institute of electronic communication sciences
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    • v.3 no.3
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    • pp.170-176
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    • 2008
  • According to the development of Internet, DWDM system needs to improve the performance for long distance transmission international optical signals. For higher the transmission capacity, we have to raise the transmission speed and increase a number of channels. To make qualifications, there are a lot of technologies such as line coding, modulation, precious fiber, broadband amplification, dispersion and forward error correction. Especially, FEC has been considered as a progressive technology for long distance transmission to carry out high speed and large capacity traffic. This paper introduced the progress of each new generation of FEC and the way to employ by current system analyzed the coding gain.

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Traffic Optimized FEC Control Algorithm for Multimedia Streaming Applications.

  • Magzumov, Alexander;Jang, Wonkap
    • Proceedings of the IEEK Conference
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    • 2003.07a
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    • pp.477-480
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    • 2003
  • Packet losses in the Internet can dramatically degrade quality of multimedia streams. Forward Error Correction (FEC) is one of the best methods that can protect data from packet erasures by means of sending additional redundant information. Proposed control algorithm provides the possibility of receiving real-time multimedia streams of given quality wifth minimal traffic overhead. The traffic optimization is reached by adjusting packet size as well as block code parameters. Calculations and simulation results show that for non-bursty network conditions traffic optimization can lead to more than 50% bandwidth reduction.

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Performance Evaluation of Underwater Code Division Multiple Access Scheme on Forward-Link through Water-Tank and Lake Experiment (수조 및 저수지 실험을 통한 수중 코드 분할 다중 접속 기법 순방향 링크 성능 분석)

  • Seo, Bo-Min;Son, Kweon;Cho, Ho-Shin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39C no.2
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    • pp.199-208
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    • 2014
  • Code division multiple access (CDMA) is one of the promising medium access control (MAC) schemes for underwater acoustic sensor networks because of its robustness against frequency-selective fading and high frequency-reuse efficiency. As a way of performance evaluation, sea or lake experiment has been employed along with computer simulation.. In this study, we design the underwater CDMA forward-link transceiver and evaluate the feasibility aginst harsh underwater acoustic channel in water-tank first. Then, based on the water-tank experiment results, we improved the transceiver and showed the improvements in a lake experiment. A pseudo random noise code acquisition process is added for phase error correction before decoding the user data by means of a Walsh code in the receiver. Interleaving and convolutional channel coding scheme are also used for performance improvement. Experimental results show that the multiplexed data is recovered by means of demultiplexing at receivers with error-free in case of two users while with less than 15% bit error rate in case of three and four users.

Space-Time Carrier Interferometry Techniques with Low-density Parity Check Code for High-speed Multimedia Communications

  • Chung Yeon-Ho
    • Journal of Korea Multimedia Society
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    • v.9 no.6
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    • pp.728-734
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    • 2006
  • Carrier interferometry code is considered as a promising scheme that provides significant performance improvement via frequency diversity effect. Space-time coding is commonly employed to achieve a performance gain through space diversity. The combination of these techniques and forward error correction coding will lead to enhanced system capacity and performance. This paper presents a low-density parity check (LDPC) coded space-time orthogonal frequency division multiplexing (OFDM) transmission scheme with carrier interferometry code for high-capacity and high-performance mobile multimedia communications. Computer simulations demonstrate that the proposed mobile multimedia transmission system offers a considerable performance improvement of approximately 9dB in terms of Eb/No in the Rayleigh fading channel with relatively low delay spread, in comparison with space-time OFDM. Performance gains are further increased, comparing with traditional OFDM systems.

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Design and performance analysis of turbo codes employing the variable-sized interleaver (가변 크기 인터리버를 사용한 turbo 부호의 설계와 성능 해석)

  • Lee, Chang-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.2A
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    • pp.86-95
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    • 2003
  • With the advent of future mobile communication systems, the wireless transmission of the huge amount of multimedia data over the error-prone multipath fading channel has to overcome the inherent sensitivity to channel errors. To alleviate the effect of the channel errors, hosts of techniques based on the forward error correction(FEC) has been proposed at the cost of overhead rate. Among the FEC techniques, turbo code, whose performance has been shown to be very close to the Shannon limit, can be classified as a block-based error correction code. In this paper, considering the variable packet size of the multimedia data, we analyzed turbo codes employing the variable-sized interleaver. The effect of the various parameters on the BER performance is analyzed. We show that the turbo codes can be used as efficient error correction codes of multimedia data.