• Title/Summary/Keyword: QPP

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A Low Power QPP Interleaver Address Generator Design Using The Periodicity of QPP (QPP 주기성을 이용한 저전력 QPP 인터리버 주소발생기 설계)

  • Lee, Won-Ho;Rim, Chong-Suck
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.45 no.12
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    • pp.83-88
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    • 2008
  • The QPP interleaver has been gaining attention since it provides contention-free interleaving functionality for high speed parallel turbo decoders. In this paper we first show that the quadratic term $f_2x^2%K$ of $f(x)=(f_1x+f_2x^2)%K$, the address generating function, is periodic. We then introduce a low-power address generator which utilizes this periodic characteristic. This generator follows the conventional method to generate the interleaving addresses and also to save the quadratic term values during the first half of the first period. The saved values are then reused for generating further interleaved addresses, resulting in reduced number of logical operations. Power consumption is reduced by 27.38% in the design with fixed-K and 5.54% in the design with unfixed-K on average for various values of K, when compared with the traditional designs.

Design of Contention Free Parallel MAP Decode Module (메모리 경합이 없는 병렬 MAP 복호 모듈 설계)

  • Chung, Jae-Hun;Rim, Chong-Suck
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.48 no.1
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    • pp.39-49
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    • 2011
  • Turbo code needs long decoding time because of iterative decoding. To communicate with high speed, we have to shorten decoding time and it is possible with parallel process. But memory contention can cause from parallel process, and it reduces performance of decoder. To avoid memory contention, QPP interleaver is proposed in 2006. In this paper, we propose MDF method which is fit to QPP interleaver, and has relatively short decoding time and reduced logic. And introduce the design of MAP decode module using MDF method. Designed decoder is targetted to FPGA of Xilinx, and its throughput is 80Mbps maximum.

A Design of Parallel Turbo Decoder based on Double Flow Method Using Even-Odd Cross Mapping (짝·홀 교차 사상을 이용한 Double Flow 기법 기반 병렬 터보 복호기 설계)

  • Jwa, Yu-Cheol;Rim, Chong-Suck
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.7
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    • pp.36-46
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    • 2017
  • The turbo code, an error correction code, needs a long decoding time since the same decoding process must be repeated several times in order to obtain a good BER performance. Thus, parallel processing may be used to reduce the decoding time, in which case there may be a memory contention that requires additional buffers. The QPP interleaving has been proposed to avoid such case, but there is still a possibility of memory contention when a decoder is constructed using the so-called double flow technique. In this paper, we propose an even-odd cross mapping technique to avoid memory conflicts even in decoding using the double-flow technique. This method uses the address generation characteristic of the QPP interleaving and can be used to implement the interleaving circuit between the decoding blocks and the LLR memory blocks. When the decoder implemented by applying the double flow and the proposed methods is compared with the decoder by the conventional MDF techniques, the decoding time is reduced by up to 32% with the total area increase by 8%.

Electrochemical Method for Measurement of Hydroxide Ion Conductivity and CO2 Poisoning Behavior of Anion Exchange Membrane (음이온 교환막의 정확한 OH-전도도 및 CO2 피독 효과 분석을 위한 전기화학적 측정법)

  • Kim, Suyeon;Kwon, Hugeun;Lee, Hyejin;Jung, Namgee;Bae, Byungchan;Shin, Dongwon
    • Journal of the Korean Electrochemical Society
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    • v.25 no.2
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    • pp.88-94
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    • 2022
  • The anion exchange membrane used in alkaline membrane fuel cells transports hydroxide ions, and ion conductivity affects fuel cell performance. Thus, the measurement of absolute hydroxide ion conductivity is essential. However, it is challenging to accurately measure hydroxide ion conductivity since hydroxide ions are easily poisoned in the form of bicarbonate by carbon dioxide in the atmosphere. In this study, we applied electrochemical ion exchange treatment to measure the absolute hydroxide ion conductivity of the anion exchange membrane. In addition, we investigated the effect of carbon dioxide poisoning of hydroxide ions on electrochemical performance by measuring bicarbonate conductivity. Commercial anion exchange membranes (FAA-3-50 and Orion TM1) and polyphenylene-based block copolymer (QPP-6F) were used.