• Title/Summary/Keyword: puncturing

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Design of UEP Irregular LDPC Code Using Puncturing Scheme (Puncturing 기법을 이용한 UEP Irregular LDPC Code 설계)

  • Kim, Sung-Won;Choi, Sung-Hoon;Heo, Jun
    • Proceedings of the IEEK Conference
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    • 2006.06a
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    • pp.1051-1052
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    • 2006
  • In this paper, we propose a puncturing scheme to design low-density parity-matrix (LDPC) codes for unequal error protection (UEP). Two different puncturing schemes are compared. Simulation results show that proposed puncturing scheme outperforms regular puncturing scheme for more important bits. Future work is to find an optimized puncturing patten for UEP irregular LDPC codes.

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A Good Puncturing Scheme for Rate Compatible Low-Density Parity-Check Codes

  • Choi, Sung-Hoon;Yoon, Sung-Roh;Sung, Won-Jin;Kwon, Hong-Kyu;Heo, Jun
    • Journal of Communications and Networks
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    • v.11 no.5
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    • pp.455-463
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    • 2009
  • We consider the challenges of finding good puncturing patterns for rate-compatible low-density parity-check code (LDPC) codes over additive white Gaussian noise (AWGN) channels. Puncturing is a scheme to obtain a series of higher rate codes from a lower rate mother code. It is widely used in channel coding but it causes performance is lost compared to non-punctured LDPC codes at the same rate. Previous work, considered the role of survived check nodes in puncturing patterns. Limitations, such as single survived check node assumption and simulation-based verification, were examined. This paper analyzes the performance according to the role of multiple survived check nodes and multiple dead check nodes. Based on these analyses, we propose new algorithm to find a good puncturing pattern for LDPC codes over AWGN channels.

Sufficient Conditions for the Existence of an (n, 1) Mother Code and Its Puncturing Pattern to Generating a Given Convolutional Code (임의의 생성다항식 행렬을 갖는 길쌈부호도 (n, 1) 마더부호의 천공으로 생성 가능한가?)

  • Chung, Habong;Seong, Jinwoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.4
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    • pp.379-386
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    • 2016
  • Puncturing is the most common way of increasing the rate of convolutional codes. The puncturing process is done to the original code called the mother code by a specific puncturing pattern. In this article, we investigate into the question whether any convolutional code is obtainable by puncturing some (n, 1) mother codes. We present two sufficient conditions for the mother code and the puncturing pattern to satisfy in order that the punctured code is equivalent to the given (N, K) convolutional code.

Performance Comparison of Turbo Codes at Various Puncturing Rates (다양한 부호율로 펑처링된 터보 부호의 성능 비교)

  • 권이경;송홍엽
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.7A
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    • pp.1074-1079
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    • 1999
  • In this paper, the concept of puncturing is introduced to turbo code in order to implement various code as code rate varies.rates. First, several different puncturing matrices are applied into rate 1/3 encoder in order to produce various rate 1/2 turbo codes. By analyzing and comparing these results, we can show which puncturing pattern should be selected in order to maintain good performance. Second, we select some appropriate puncturing patterns which provide the best performance of turbo codes of various rates from 1/3 to 2/3 among all the possible candidates. Finally, we provide the change of required Eb/No at $P_b=10^{-4}$ as code rate varies.

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Channel Estimation and LDPC Code Puncturing Schemes Based on Incremental Pilots for OFDM

  • Jung, Sung-Yoon;Kim, Sung-Hwan
    • ETRI Journal
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    • v.32 no.4
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    • pp.603-606
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    • 2010
  • In this letter, we propose a channel estimation algorithm based on incremental pilots. These are pilots additionally inserted after puncturing the modulated orthogonal frequency division multiplexing (OFDM) symbols to enhance channel estimation performance without lowering bandwidth efficiency. A low-density parity-check code puncturing scheme is also proposed to prevent the performance degradation due to the codeword bit loss caused by punctured OFDM symbols.

On the Existence of the (2,1) Mother Code of (n,n-1) Convolutional Code ((n,n-1) 길쌈부호에 대한 (2,1) 마더부호의 존재)

  • Jang, Hwan-Seok;Chung, Ha-Bong;Seong, Jin-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.4
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    • pp.165-171
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    • 2014
  • The rate of the channel code can be controlled by various methods. Puncturing is one of the methods of increasing the code rate, and the original code before puncturing is called the mother code. Any (n,k) convolutional code is obtainable by puncturing some mother codes, and the process of finding the mother code is necessary for designing the optimum channel decoder. In this paper, we proved that any (n,n-1) convolutional code has (2,1) mother codes regardless of the puncturing pattern and showed that they must be equivalent.

Treatment Outcomes of Percutaneous Radiofrequency Ablation for Hepatocellular Carcinomas: Effects of the Electrode Type and Placement Method

  • Jiyeon Park;Min Woo Lee;Soo Hyun Ahn;Seungchul Han;Ji Hye Min;Dong Ik Cha;Kyoung Doo Song;Tae Wook Kang;Hyunchul Rhim
    • Korean Journal of Radiology
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    • v.24 no.8
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    • pp.761-771
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    • 2023
  • Objective: To investigate the association among the electrode placement method, electrode type, and local tumor progression (LTP) following percutaneous radiofrequency ablation (RFA) for small hepatocellular carcinomas (HCCs) and to assess the risk factors for LTP. Materials and Methods: In this retrospective study, we enrolled 211 patients, including 150 males and 61 females, who had undergone ultrasound-guided RFA for a single HCC < 3 cm. Patients were divided into four combination groups of the electrode type and placement method: 1) tumor-puncturing with an internally cooled tip (ICT), 2) tumor-puncturing with an internally cooled wet tip (ICWT), 3) no-touch with ICT, and 4) no-touch with ICWT. Univariable and multivariable Cox proportional-hazards regression analyses were performed to evaluate the risk factors for LTP. The major RFA-related complications were assessed. Results: Overall, 83, 34, 80, and 14 patients were included in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. The cumulative LTP rates differed significantly among the four groups. Compared to tumor puncturing with ICT, tumor puncturing with ICWT was associated with a lower LTP risk (adjusted hazard ratio [aHR] = 0.11, 95% confidence interval [CI] = 0-0.88, P = 0.034). However, the cumulative LTP rate did not differ significantly between tumor-puncturing with ICT and no-touch RFA with ICT (aHR = 0.34, 95% CI = 0.03-1.62, P = 0.188) or ICWT (aHR = 0.28, 95% CI = 0-2.28, P = 0.294). An insufficient ablative margin was a risk factor for LTP (aHR = 6.13, 95% CI = 1.41-22.49, P = 0.019). The major complication rates were 1.2%, 0%, 2.5%, and 21.4% in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. Conclusion: ICWT was associated with a lower LTP rate compared to ICT when performing tumor-puncturing RFA. An insufficient ablation margin was a risk factor for LTP.

A Study on the Performance Improvement in T-DMB System

  • Erke, Li;Kim, Hanjong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2009.10a
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    • pp.766-769
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    • 2009
  • In this paper we propose a new turbo coded T-DMB system that replaces the existing RS code, convolutional interleaver and RCPC code by a turbo code without altering the puncturing procedure and puncturing vectors defined in the standard T-DMB system for compatibility. Simulation results show that the new turbo coded system yields considerable performance gain after just 2 iterations.

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Full Data-rate Viterbi Decoder for DAB Receiver (최대 데이터율을 지원하는 DAB 수신기용 Viterbi 디코더의 설계)

  • 김효원;구오석;류주현;윤대희
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.6C
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    • pp.601-609
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    • 2002
  • The efficient Viterbi decoder that supports full data-rate output of DAB system was proposed. Viterbi decoder consumes lots of computational load and should be designed to be fast specific hardware. In this paper, SST scheme was adopted for Viterbi decoder with puncturing to reduced the power consumption. Puncturing vector tables are modified and re-arranged to be designed by a hardwired logic to save the system area. New re-scaling scheme which uses the fact that the difference of the maximum and minimum of the path metric values is bounded is proposed. The proposed re-scaling scheme optimizes the wordlength of path metric memory and greatly reduces the computational load for re-scaling by controlling MSB of path metric memory. Another saving of computation is done by proposed algorithm for branch metric calculation, which makes use of pre-calculated metric values. The designed Viterbi decoder was synthesized using SAMSUNG 0.35$\mu$ standard cell library and occupied small area and showed lower power consumption.