• Journal of Broadcast Engineering
• /
• v.16 no.6
• /
• pp.1026-1035
• /
• 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.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.2
• /
• pp.35-39
• /
• 2011

Error correcting codes with easy variability in code rate and codeword length in addition to powerful error correcting capability are required for present and future mobile multimedia communication systems. And low complexity is also needed for the compact mobile terminals. In general, the irregular random LDPC(low-density parity-check) code is known to have the superior performance among various LDPC codes. But it has inefficiency since the various parity check matrices for various services should be stored for encoding and decoding. The structured LDPC codes which can easily provide various rates and lengths are studied recently. Therefore, the flexibility, memory size, and error performance of various structured LDPC codes are compared and analyzed in this paper. And the most appropriate structured LDPC code is also suggested.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.11
• /
• pp.3-8
• /
• 2012

Two-dimensional product code has been studied for correcting burst errors on the storage systems. An RS-LDPC product code consists of an RS code in horizontal direction and an LDPC code in vertical direction. First, we detect the position of burst errors by using RS code, then LDPC code corrects the errors by using the burst error positions. In storage system, long burst errors are occurred by various reason. So, we need a strong code for correcting the long burst errors. RS-LDPC product code is good for long burst errors. However, as the storage density grows the length of the burst errors will be longer. Thus, we propose an LDPC-LDPC product code, it is strong for correcting the very long burst errors. Also, the proposed LDPC-LDPC product code performs better than RS-LDPC product code when the random errors are occurred, because a row direction LDPC code performs better than row direction RS code.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.12C
• /
• pp.1006-1013
• /
• 2008

CZZ (Concatenated Zigzag) Code is a class of fast encodable LDPC codes. In the case that LDPC codes including CZZ codes have short length, short cycles seriously affect the code performance. In this paper, we construct CZZ codes using various degree-2 polynomial interleavers which eliminate cycles of length 4 and through simulation, compare the performance of these CZZ codes and turbo codes in many different fading channels. Especially, quasi-static fading channel, block fading channel, uncorrelated fading channel, and correlated fading channel are considered. Since CZZ codes show similar performance as turbo codes, they can be used in the next generation wireless communication systems.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.3
• /
• pp.703-714
• /
• 1998

Translation of a Korean text into a braille text causes no problem under the existing Korean braille-code System that maintains I: I correspondence between Korean characters and braille codes. However, reverse translation of a braille text into a Korean text would cause unavoidable mis-translation due to I : N correspondences between braille codes and Korean characters. The analysis shows that in Korean braille-code System, the major reasons for mis-translation are the conflicts between Korean Chosung (initial consonant) letters and numbers, between Korean Jongsung (final consonant) letters and punctuations, between Korean Jongsung (final consonant) letters and English mode delimiter codes, and overlapping use of the same braille code such as opening and closing parentheses. In this paper, we firstly established a reverse translation rule, that is to use an ordinary braille code unless the braille code causes any conflict in braille code sequences. If any ordinary braille code may cause some conflict during the reverse translation, an extended braille code that we propose in this paper must be used. In the experimentation, we cannot get any translation errors with the newly designed braille-code System compared with 25% of errors with the existing braille-code System.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.1
• /
• pp.189-195
• /
• 2008

The OFDMA Physical layer in the WiMAX standard of IEEE 802.16e adopts 114 LDPC codes with various code rates and block sizes as a channel coding scheme to meet varying channel environments and different requirements for transmission performance. In this paper, the performances of the LDPC codes are evaluated according to various code rates and block-lengths throueh simulation studies using min-sum decoding algorithm in AWGN chamois. As the block-length increases and the code rate decreases, the BER performance improves. In the cases with code rates of 2/3 and 3/4, where two different codes ate specified for each code rate, the codes with code rates of 2/3A and 3/4B outperform those of 2/3B and 3/4A, respectively. Through the statistical analyses of the number of decoding iterations the decoding complexity and the word error rates of LDPC codes are estimated. The results can be used to trade-off between the performance and the complexity in designs of LDPC decoders.

• Convergence Security Journal
• /
• v.21 no.1
• /
• pp.149-158
• /
• 2021

In this paper, we propose military symbols for cyber operations to understand the situation in cyberspace intuitively. Currently, standardized military symbols are mainly for kinetic operations, and they do not consider cyber operations. Although, MIL-STD-2525D includes some symbols for cyber operations, only icons that are composed of three letters are standardized. So there is a limit to effectively expressing cyber operations. That is why we propose military symbols for cyber operations compatible with existing military symbol building rules. In addition to merely presenting the symbols, we present examples of expressing various cyber situations using the proposed symbols. It proves the usefulness of the proposed symbol. The small number of symbols proposed in this paper will not be able to represent all cyber situations. However, based on the proposed symbols, it is expected that more symbols will be standardized in the future to more clearly express the cyber situation.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.10
• /
• pp.16-20
• /
• 2015

We propose three multi-level modulation codes of the code rate 1/2 for holographic data storage considered as a promising candidate for next generation storage systems. Since a pixel with multi-levels can represent more than 1 bit, it is possible to increase the storage capacity and have many codewords. Thus, we can choose a code that the minimum distance is as far as possible. When we compare the codes with the code rate 1/2, the performance of the code with small number of levels is better than that of large number of levels.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.7
• /
• pp.831-836
• /
• 2015

This paper studied scrambling occurrence in the line coder for UTF-8 hangul syllable code based on unicode. The paper suggested that scrambling is occurred when consecutive four "0" bit is entered into the line coder from the source codes. Currently, ITU-T is applying HDB-3 scrambling method in AMI line coder, According to the study result, scrambling is occurred about 39% in UTF-8 code on Unicoe Hangul syllable.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.14 no.6
• /
• pp.590-603
• /
• 1989

In tnis paper, the CRC-CCITT code and primitive polynomial CRC code are selected for analysing error detecting performance. However, general formulas for obtaining the weight distribution of these two CRC codes are not so far dericed. So, a new method for calculating the weight distribution of the shortened cyclic Hamming code is presented and an undetected error probability of these two codes is obtained when used in cell of ATM for broadband ISDN user-network interface. Consequently, we show that CRC code too much does affect its error detection performance. All the computer simulation is performed by IBM PC/AT.