• Title, Summary, Keyword: serial concatenated code

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LDPC Decoding by Failed Check Nodes for Serial Concatenated Code

  • Yu, Seog Kun;Joo, Eon Kyeong
    • ETRI Journal
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    • v.37 no.1
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    • pp.54-60
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    • 2015
  • The use of serial concatenated codes is an effective technique for alleviating the error floor phenomenon of low-density parity-check (LDPC) codes. An enhanced sum-product algorithm (SPA) for LDPC codes, which is suitable for serial concatenated codes, is proposed in this paper. The proposed algorithm minimizes the number of errors by using the failed check nodes (FCNs) in LDPC decoding. Hence, the error-correcting capability of the serial concatenated code can be improved. The number of FCNs is simply obtained by the syndrome test, which is performed during the SPA. Hence, the decoding procedure of the proposed algorithm is similar to that of the conventional algorithm. The error performance of the proposed algorithm is analyzed and compared with that of the conventional algorithm. As a result, a gain of 1.4 dB can be obtained by the proposed algorithm at a bit error rate of $10^{-8}$. In addition, the error performance of the proposed algorithm with just 30 iterations is shown to be superior to that of the conventional algorithm with 100 iterations.

Analysis of Rate-Compatible Punctured Serial Concatenated Convolutional Codes Based on SNR Evolution

  • Shin Seung-Kyu;Shin Dong-Joon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.4C
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    • pp.324-330
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    • 2006
  • The next generation mobile communication systems require error correcting schemes that can be adaptable to various code rates and lengths with negligible performance degradation. Serial concatenated convolutional codes can be a good candidate satisfying these requirements. In this paper, we propose new rate-compatible punctured serial concatenated convolutional code (RCPSCCC) which performs better than the RCPSCCC proposed by Chandran and Valenti in the sense of the rate compatibility. These codes are evaluated and analyzed by using computer simulation and SNR evolution technique. As their application, Type-II hybrid automatic repeat request (HARQ) schemes using both RCPSCCCs are constructed and new RCPSCCC is shown to have better throughput.

Improved Reliability-Based Iterative Decoding of LDPC Codes Based on Dynamic Threshold

  • Ma, Zhuo;Du, Shuanyi
    • ETRI Journal
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    • v.37 no.4
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    • pp.736-742
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    • 2015
  • A serial concatenated decoding algorithm with dynamic threshold is proposed for low-density parity-check codes with short and medium code lengths. The proposed approach uses a dynamic threshold to select a decoding result from belief propagation decoding and order statistic decoding, which improves the performance of the decoder at a negligible cost. Simulation results show that, under a high SNR region, the proposed concatenated decoder performs better than a serial concatenated decoder without threshold with an Eb/N0 gain of above 0.1 dB.

Error Performance of Serially Concatenated Space-Time Coding

  • Altunbas, Ibrahim;Yongacoglu, Abbas
    • Journal of Communications and Networks
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    • v.5 no.2
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    • pp.135-140
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    • 2003
  • In this paper, we investigate the error performance of a serially concatenated system using a nonrecursive convolutional code as the outer code and a recursive QPSK space-time trellis code as the inner code on quasi-static and rapid Rayleigh fading channels. At the receiver, we consider iterative decoding based on the maximum a posteriori (MAP) algorithm. The performance is evaluated by means of computer simulations and it is shown that better error performance can be obtained by using low complexity outer and/or inner codes and the Euclidean distance criterion based recursive space-time inner codes. We also obtain new systems with large number of trasmit and/or receive antennas providing good error performance.

A New Concatenation Scheme of Serial Concatenated Convolutional Codes (직렬연접 길쌈부호의 새로운 연접방법)

  • Bae, Sang-Jae;Ju, Eon-Gyeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.39 no.3
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    • pp.125-131
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    • 2002
  • In this paper, a new concatenation scheme of serial concatenated convolutional codes is proposed and the performance analyzed. In the proposed scheme, each of information and parity bits of outer code is entered into inner code through interleaver and deinterleaver. Therefore, the interleaver size is same as the length of input frame. Since the interleaver size of proposed type is reduced to half of the conventional Benedetto type, the interleaver delay time required for iterative decoding is reduced. In addition the multiplexer and demultiplexer are not used in the decoder of the proposed type, the complexity of decoder can be also reduced. As results of simulation, the performance of proposed type shows the better error performance as compared to that of the conventional Benedetto type in case of the same interleaver size. And it can be observed that the difference of BER performance is increased with the increase of Eb/No. In case of the same length of input frame, the proposed type shows almost same performance with Benedetto type despite that the interleaver size is reduced by half.

On the SOVA for Extremely High Code Rates over Partial Response Channels

  • Ghrayeb, Ali
    • Journal of Communications and Networks
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    • v.5 no.1
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    • pp.1-6
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    • 2003
  • In this paper, we extend the derivation of the iterative soft-output Viterbi algorithm (SOVA) for partial response (PR) channels, and modify its decoding process such that it works consistently for arbitrary high code rates, e.g., rate 64/65. We show that the modified SOVA always outperforms the conventional SOVA that appears in the literature with a significant difference for high code rates. It also offers a significant cut down in the trace-back computations. We further examine its performance for parallel and serial concatenated codes on a precoded Class IC partial response (PR4) channel. Code rates of the form $\frac{k_0}{k_0+1}$($k_0$ = 4, 8, and 64) are considered. Our simulations indicate that the loss suffered by the modified SOVA, relative to the APP algorithm, is consistent for all code rates and is at most 1.2 dB for parallel concatenations and at most 1.6 dB for serial concatenations at $P_b$ = $10^{-5}$.

Multilevel Coded Modulation with Serial Concatenated Convolutional Code (직렬연접 길쌈부호를 사용한 다중레벨 부호변조방식)

  • 이상훈;여운동;주언경
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.9
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    • pp.366-372
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    • 2003
  • Multilevel coded modulation (MCM) with serial concatenated convolutional code (SCCC) is proposed and the performance is analyzed in this paper. Both high coding gain and bandwidth efficiency can be obtained if SCCC is adopted as a component code at the first level of MCM. Simulation results show that the performance of MCM with Ambroze's SCCC is saturated like that of MCM with PCCC. But MCM with Benedetto's SCCC shows no performance saturation and better performance than MCM with PCCC or Ambroze's SCCC. Thus MCM with Benedetto's SCCC may be a good choice for high quality system with limited bandwidth.

An adaptive hybrid ARQ scheme with RCPSCCC(Rate Compatible Punctured Serial Concatenated Convolutional Codes) for wireless ATM system (무선 ATM 시스템에서 RCPSCCC(Rate Compatible Punctured Serial Concatenated Convolutional Codes)를 이용한 적응 하이브리드 ARQ 기법)

  • 이범용;윤원식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.3A
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    • pp.406-411
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    • 2000
  • In wireless ATM system, powerful FEC code is required for highly reliable data transmission. In this paper, we propose an adaptive hybrid ARQ scheme using RCPSCCC for WATM system. The code rate of RCPSCC is adjusted to match channel conditions and data types. By using only the effective free distances of outer and inner encoders, we derive upper bounds of the bit and word error probabilities over Rayleigh and Rician fading channels. By applying RCPSCC to the adaptive hybrid ARQ protocol, highly reliable data transmission can be achieved.

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An adaptive hybrid ARQ scheme with RCPSCCC (Rate Compatible Punctured Serial Concatenated Convolutional Codes) for wireless ATM system (무선 ATM 시스템에서 RCPSCCC (Rate Compatible Punctured Serial Concatenated Convolutional Codes)를 이용한 적응 하이브리드 ARQ 기법)

  • 이범용;윤원식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.12A
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    • pp.1862-1867
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    • 1999
  • In wireless ATM system, powerful FEC code is required for highly reliable data transmission. In this paper, we propose an adaptive hybrid ARQ scheme using RCPSCCC for WATM system. The code rate of RCPSCCC is adjusted to match channel conditions and data types. By using only the effective free distances of outer and inner encoders, we derive upper bounds of the bit and word error probabilities over Rayleigh and Rician fading channels. By applying RCPSCCC to the adaptive hybrid ARQ protocol, highly reliable data transmission can be achieved.

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Efficient Cooperative Transmission Scheme for High Speed WPAN System in 60GHz (60GHz WPAN 시스템의 전송 효율 향상을 위한 협력 통신 기법)

  • Lee, Won-Jin;Lee, Jae-Young;Suh, Young-Kil;Heo, Jun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.3C
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    • pp.255-263
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    • 2010
  • In this paper, we present an efficient cooperative transmission scheme for high speed 60GHz WPAN system. In 60GHz, the cooperative transmission with relay is effective scheme because signals are exceedingly attenuated according to the distance and the transmission is impossible when there is no LOS between transmitter and receiver. Moreover, the reliability of signal in destination can be improved by receiving data from a relay as well as a transmitter. However, the overall data rate is reduced because transmission time is more required for relay. To solve this problem, we propose a cooperative transmission scheme with RS-CC serial concatenated codes. In the proposed cooperative transmission scheme, the relay can reduce the transmission data size because the only parity bits of systematic RS code are transmitted after encoding by CC. But the computational complexity is increased at the relay and the destination.