• Title/Summary/Keyword: block codes

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Performance Analysis of MAP Algorithm and Concatenated Codes Using Trellis of Block Codes (블록부호의 트렐리스를 이용한 MAP 알고리즘 및 연접부호의 성능분석)

  • 백동철;양경철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6A
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    • pp.905-912
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    • 1999
  • In this paper we explain a trellis representation of block codes and derive their MAP decoding algorithm based on it. We also analyze the performance of block codes and concatenated codes with block codes as components by computer simulations, which were performed by changing the structures and constituent codes of concatenated codes. Computer simulations show that soft decision decoding of block codes get an extra coding gain than their hard decision decoding and that concatenated codes using block codes have good performance in the case of high code rate.

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LLR Based Generalization of Soft Decision Iterative Decoding Algorithms for Block Turbo Codes (LLR 기반 블록 터보 부호의 연판정 복호 알고리즘 일반화)

  • Im, Hyun-Ho;Kwon, Kyung-Hoon;Heo, Jun
    • Journal of Broadcast Engineering
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    • v.16 no.6
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    • pp.1026-1035
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    • 2011
  • This paper presents generalization and application for the conventional SISO decoding algorithm of Block Turbo Codes. R. M. Pyndiah suggested an iterative SISO decoding algorithm for Product Codes, two-dimensionally combined linear block codes, on AWGN channel. It wascalled Block Turbo Codes. Based on decision of Chase algorithm which is SIHO decoding method, SISO decoder for BTC computes soft decision information and transfers the information to next decoder for iterative decoding. Block Turbo Codes show Shannon limit approaching performance with a little iteration at high code rate on AWGN channel. In this paper we generalize the conventional decoding algorithm of Block Turbo Codes, under BPSK modulation and AWGN channel transmission assumption, to the LLR value based algorithm and suggest an application example such as concatenated structure of LDPC codes and Block Turbo Codes.

On the Design of Block Lengths for Irregular LDPC Codes Based on the Maximum Variable Degree

  • Chung, Kyu-Hyuk
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.11C
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    • pp.907-910
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    • 2010
  • This paper presents the design of block lengths for irregular low-density parity-check (LDPC) codes based on the maximum variable degree $d_{{\upsilon},max}$. To design a block length, the performance degradation of belief-propagation (BP) decoding performance from upper bounds on the maximum likelihood (ML) decoding performance is used as an important factor. Since for large block lengths, the performance of irregular LDPC codes is very close to the Shannon limit, we focus on moderate block lengths ($5{\times}10^2\;{\leq}\;N\;{\leq}\;4{\times}10^3$). Given degree distributions, the purpose of our paper is to find proper block lengths based on the maximum variable degree $d_{{\upsilon},max}$. We also present some simulation results which show how a block length can be optimized.

LDPC Codes' Upper Bounds over the Waterfall Signal-to-Noise Ratio (SNR) Region

  • Chung, Kyu-Hyuk
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.11C
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    • pp.880-882
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    • 2008
  • This paper presents LDPC codes' upper bounds over the waterfall SNR region. The previous researches have focused on the average bound or ensemble bound over the whole SNR region and showed the performance differences for the fixed block size. In this paper, the particular LDPC codes' upper bounds for various block sizes are calculated over the waterfall SNR region and are compared with BP decoding performance. For different block sizes the performance degradation of BP decoding is shown.

Piecewise Phase Recovery Algorithm Using Block Turbo Codes for Next Generation Mobile Communications

  • Ryoo, Sun-Heui;Kim, Soo-Young;Ahn, Do-Seob
    • ETRI Journal
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    • v.28 no.4
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    • pp.435-443
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    • 2006
  • This paper presents an efficient carrier recovery algorithm combined with a turbo-coding technique in a mobile communication system. By using a block turbo code made up of independently decodable block codes, we can efficiently recover the fast time-varying carrier phase as well as correct channel errors. Our simulation results reveal that the proposed scheme can accommodate mobiles with high speed, and at the same time can reduce the number of iterations to lock the phase.

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Exact Bit Error Probability of Orthogonal Space-Time Block Codes with Quadrature Amplitude Modulation

  • Kim, Sang-Hyo;Yang, Jae-Dong;No, Jong-Seon
    • Journal of Communications and Networks
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    • v.10 no.3
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    • pp.253-257
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    • 2008
  • In this paper, the performance of generic orthogonal space-time block codes (OSTBCs) introduced by Alamouti [2], Tarokh [3], and Su and Xia [11] is analyzed. We first define one-dimensional component symbol error function (ODSEF) from the exact expression of the pairwise error probability of an OSTBC. Utilizing the ODSEF and the bit error probability (BEP) expression for quadrature amplitude modulation (QAM) introduced by Cho and Yoon [9], the exact closed-form expressions for the BEP of linear OSTBCs with QAM in quasi-static Rayleigh fading channel are derived. We also derive the exact closed-form of the BEP for some OSTBCs which have at least one message symbol transmitted with unequal power via all transmit antennas.

Two-Dimensional Symmetric Balance Incomplete Block Design Codes for Small Input Power (작은 입력신호를 위한 Two-Dimensional Symmetric Balance Incomplete Block Design Code)

  • Jhee, Yoon Kyoo
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.5
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    • pp.121-127
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    • 2013
  • When input power is small, nonideal symmetric balance incomplete block design(BIBD) code design is effective in the spectral-amplitude-code(SAC) optical code-division multiple-access (OCDMA) system. But the number of simultaneous users is not sufficient. To overcome this property, we propose 2-D BIBD codes, where nonideal BIBD codes are used as spectral code and ideal BIBD codes are used as spatial codes. Analytical results show that the number of simultaneous users increases significantly.

Construction of Block-LDPC Codes based on Quadratic Permutation Polynomials

  • Guan, Wu;Liang, Liping
    • Journal of Communications and Networks
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    • v.17 no.2
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    • pp.157-161
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    • 2015
  • A new block low-density parity-check (Block-LDPC) code based on quadratic permutation polynomials (QPPs) is proposed. The parity-check matrix of the Block-LDPC code is composed of a group of permutation submatrices that correspond to QPPs. The scheme provides a large range of implementable LDPC codes. Indeed, the most popular quasi-cyclic LDPC (QC-LDPC) codes are just a subset of this scheme. Simulation results indicate that the proposed scheme can offer similar error performance and implementation complexity as the popular QC-LDPC codes.

The Construction and Viterbi Decoding of New (2k, k, l) Convolutional Codes

  • Peng, Wanquan;Zhang, Chengchang
    • Journal of Information Processing Systems
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    • v.10 no.1
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    • pp.69-80
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    • 2014
  • The free distance of (n, k, l) convolutional codes has some connection with the memory length, which depends on not only l but also on k. To efficiently obtain a large memory length, we have constructed a new class of (2k, k, l) convolutional codes by (2k, k) block codes and (2, 1, l) convolutional codes, and its encoder and generation function are also given in this paper. With the help of some matrix modules, we designed a single structure Viterbi decoder with a parallel capability, obtained a unified and efficient decoding model for (2k, k, l) convolutional codes, and then give a description of the decoding process in detail. By observing the survivor path memory in a matrix viewer, and testing the role of the max module, we implemented a simulation with (2k, k, l) convolutional codes. The results show that many of them are better than conventional (2, 1, l) convolutional codes.

Performance improvement and Realtime implementation in CELP Coder (CELP 보코더의 성능 개선 및 실시간 구현)

  • 정창경
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1994.06c
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    • pp.199-204
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    • 1994
  • In this paper, we researched abut CELP speech coding algorithm using efficlent pseudo-stochastic block codes, adaptive-codebook and improved fixed-gain codebook. The pseudo-stochastic block codes refer to stochastically populated block codes in which the adjacent codewords in an innovation codebook are non-independent. The adaptive-codebook was made with previous prediction speech data by storage-shift register. This CELP coding algorithm enables the coding of toll quality speech at bit rates from 4.8kbits/s to 9.6 kbits/s. This algorithm was realized TMS320C30 microprocessor in realtime.

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