• Title/Summary/Keyword: error code

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Performance Analysis Based On Log-Likelihood Ratio in Orthogonal Code Hopping Multiplexing Systems Using Multiple Antennas (다중 안테나를 사용한 직교 부호 도약 다중화 시스템에서 로그 우도비 기반 성능 분석)

  • Jung, Bang-Chul;Sung, Kil-Young;Shin, Won-Yong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.12
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    • pp.2534-2542
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    • 2011
  • In this paper, we show that performance can be improved by using multiple antennas in the conventional orthogonal code hopping multiplexing (OCHM) scheme, which was proposed for accommodating a larger number of users with low channel activities than the number of orthogonal codewords used in code division multiple access (CDMA)-based communication systems through downlink statistical multiplexing. First, we introduce two different types of OCHM systems together with orthogonal codeword allocation strategies, and then derive their mathematical expression for log-likelihood ratio (LLR) values according to the two different schemes. Next, when a turbo encoder based on the LLR computation is used, we evaluate performance on the frame error rate (FER) for the aformentioned OCHM system. For comparison, we also show performance for the existing symbol mapping method using multiple antennas, which was used in 3GPP standards. As a result, it is shown that our OCHM system with multiple antennas based on the proposed orthogonal codeword allocation strategy leads to performance gain over the conventional system---energy required to satisfy a target FER is significantly reduced.

Design of A Reed-Solomon Code Decoder for Compact Disc Player using Microprogramming Method (마이크로프로그래밍 방식을 이용한 CDP용 Reed-Solomon 부호의 복호기 설계)

  • 김태용;김재균
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.10
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    • pp.1495-1507
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    • 1993
  • In this paper, an implementation of RS (Reed-Solomon) code decoder for CDP (Compact Disc Player) using microprogramming method is presented. In this decoding strategy, the equations composed of Newton's identities are used for computing the coefficients of the error locator polynomial and for checking the number of erasures in C2(outer code). Also, in C2 decoding the values of erasures are computed from syndromes and the results of C1(inner code) decoding. We pulled up the error correctability by correcting 4 erasures or less. The decoder contains an arithmetic logic unit over GF(28) for error correcting and a decoding controller with programming ROM, and also microinstructions. Microinstructions are used for an implementation of a decoding algorithm for RS code. As a result, it can be easily modified for upgrade or other applications by changing the programming ROM only. The decoder is implemented by the Logic Level Modeling of Verilog HDL. In the decoder, each microinstruction has 14 bits( = 1 word), and the size of the programming ROM is 360 words. The number of the maximum clock-cycle for decoding both C1 and C2 is 424.

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A Study on EUROFIX Reed Solomon Code Design Using Finite Galois Field Fourier Transformation (유한체 푸리에 변환을 이용한 EUROFIX RS Code 설계에 관한 연구)

  • Kim, Min-Jee;Kim, Min-Jung;Chung, Se-Mo;Cho, Hyung-Rae
    • Journal of Navigation and Port Research
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    • v.28 no.1
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    • pp.23-29
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    • 2004
  • This paper deals with Reed-Solomon Coding for EUROFIX system EUROFIX is an integrated navigation and communication system, which combines Differential GNSS and Loran-C EUROFIX transmits DGNSS(Differential Global Navigation Satellite Systems) (data by pulse position modulation of Loran-C pulses. Loran-C system is regarded as a satellite backup system in recent. And now, it is important to detect and correct much errors in communication systems. Error corrections or correction algorithm is actively studied nowadays because of this. In this paper, we study and design encoder and decoder of Reed Solomon Code using Finite Galois Field Fourier Transformation for error corrections in EUROFIX data transmission. Through extensive simulation, the designed Reed Solomon code is shown to be effective for error correction in EUROFIX data transmission.

Augmented QSBC(Quantum Short-Block Code)-QURC(Quantum Unity-Rate Code)(II) with Pauli X,Y,Z error detection (파울리 X,Y,Z 오류검출 기능을 갖는 증강된 QSBC(Quantum Short-Block Code)-QURC(Quantum Unity-Rate Code)(II))

  • Dong-Young Park;Sang-Min Suh;Baek-Ki Kim
    • The Journal of the Korea institute of electronic communication sciences
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    • v.18 no.3
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    • pp.495-508
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    • 2023
  • This paper proposes a method to find out the type and location information of Pauli X, Y, Z errors generated in quantum channels using only the quantum information processing part of the multiple-rate quantum turbo short-block code without external help from the classical information processing part. In order to obtain the location information of the Pauli X,Y error, n-auxiliary qubits and n-CNOT gates were inserted into the C[n,k,2] QSBC-QURC encoder. As a result, the maximum coding rate is limited to about 1/2 as the trade-off characteristics. The location information of the Pauli Z error for C[n,k,2] QSBC-QURC was obtained through the Clifford-based stabilizer measurement. The proposed method inherits all other characteristics of C[n,k,2] QSBC-QURC except for the coding rate.

Error Resilient and Concealment Schemes for Still Image Transmission over DSRC System Channel (DSRC시스템 채널 환경에서 정지 영상 전송을 위한 에러 복구 및 은닉 기법)

  • 최은석;백중환
    • Proceedings of the IEEK Conference
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    • 2001.06d
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    • pp.13-16
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    • 2001
  • In the Dedicated Short Range Communication (DSRC) system channel, a large number of bit errors occur because of Additive White Gaussian Noise (AWGN) and fading. When an image data is transmitted under the condition, reconstructed image quality is significantly degraded. In this paper, as an alternative to the error correcting code and/or automatic repeat request scheme, we propose an error recovery scheme for image data transmission. We first analyze how transmission errors in the DSRC system channel degrade image quality. Then, in order to improve image quality, we propose error resilient and concealment schemes for still image transmission using DCT-based fixed length coding, hamming code, cyclic redundancy check, and interleaver. Finally, we show its performance by an experiment.

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Analysis on the transition characteristics of extrinsic information according to iterative decoding of turbo code (터보부호의 반복복호에 따른 부가정보 변화 특성 분석)

  • Kang Se Hoon;Kim Woo Tae;Kim Jeong Goo;Joo Eon Kyeong
    • Proceedings of the IEEK Conference
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    • 2004.06a
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    • pp.59-62
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    • 2004
  • The performance of turbo code is improved by updating extrinsic information. The bit patterns are categorized by the transition characteristics of extrinsic information in this paper. And the distribution of these patterns is surveyed according to signal-to-noise ratio. Based on the results, the dominant error pattern is determined at high signal-to-noise ratio range. Thus, it is expected to improve the error performance in the error floor region by correcting the dominant error pattern which is found in this paper.

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A Study on an Embedded DPCM with Convolutional Coding (길쌈부호를 사용한 Embedded DPCM 방식에 관한 연구)

  • 임종수;이상곤;문상재
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.28A no.1
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    • pp.1-7
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    • 1991
  • Degradation of communication quality is due to transmission error rather than quantization noise when DPCM signal is transmitted over a heavily noise channel. The communication quality can be improved by employing an error correcting code to the DPCM signal transmission over such a channel. We considered both quantization noise and transmission error simultaneously in evaluating the signal to noise ratio. To efficiently improve the signal to noise ratio, we analyze the unequal symbol error probability of convolutional code, and encoded to more protect significant symbols from channel errors than least ones, so that the signal to noise ratio is improved. We derived related formulas and also made computer simulations.

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Performance Analysis of DS-CDMA System of Phase Estimation Error for Mobile Satellite Wireless Communication Channel (이동위성 무선통신 채널에서 위상추정 에러가 있는 DS-CDMA 시스템의 성능 해석)

  • Kang, Heau-Jo
    • Journal of Advanced Navigation Technology
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    • v.11 no.2
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    • pp.170-176
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    • 2007
  • In this paper, we improve performance for system when the carrier recovery signal is not perfect in the multipath mobile wireless communication fast fading channel based on DS-CDMA system. In the case, we use the phase estimation, diversity and adaptive FEC code technique in order to overcome this carrier phase error and mobile wireless fading. As a results in DS-CDMA system, we know that the appropriate use of diversity and adaptive FEC code technique reduced considerably performance degradation due to phase error.

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Adaptive current-steering analog duty cycle corrector with digital duty error detection (디지털 감지기를 통해 전류 특성을 조절하는 아날로그 듀티 사이클 보정 회로)

  • Choi, Hyun-Su;Kim, Chan-Kyung;Kong, Bai-Sun;Jun, Young-Hyun
    • Proceedings of the IEEK Conference
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    • 2006.06a
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    • pp.465-466
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    • 2006
  • In this paper, novel analog duty cycle corrector (DCC) with a digital duty error detector is proposed. The digital duty error detector measures the duty error of the clock and converts it into a digital code. This digital code is then used to accurately correct the duty ratio by adaptively steering the charge-pump current. The proposed duty cycle corrector was implemented using an 80nm DRAM process with 1.8V supply voltage. The simulation result shows that the proposed duty cycle corrector improves the settling time up to $70{\sim}80%$ at 500MHz clock frequency for the same duty correction accuracy as the conventional analog DCC.

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An Evaluation of Error Performance Estimation Schemes for DS1 Transmission Systems Carrying Live Traffic

  • Eu, J.H.
    • Journal of Korean Institute of Industrial Engineers
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    • v.14 no.1
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    • pp.1-15
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    • 1988
  • DS1 transmission systems use framing bit errors, bipolar violations and code-detected errors to estimate the bit error rate when determining errored and severely errored seconds. Using the coefficient of variation under the memoryless binary symmetric channel assumption, a basic framework to evaluate these estimation schemes is proposed to provide a practical guideline in determining errored and severely errored seconds which are fundamental in monitoring the real-ime error performance of DS1 transmission systems carrying live traffic. To evaluate the performance of the cyclic redundancy check code (CRC), a computer simulation model is used. Several drawbacks of the superframe format in association with real time error performance monitoring are discussed. A few recommendations are suggested in measuring errored and severely errored seconds, and determining service limit alarms through the use of the superframe format. Furthermore, we propose a new robust scheme for determining service limit alarms which take into consideration the limitations of some estimation schemes for the time interval of one second.

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