• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.67-74
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• 2007

Turbo code, a kind of channel coding technique, has ben used in the field of digital mobile communication system if the number of iterations is increased in the several channel environments, my further iteration results in very little improvement, and requires much delay and computation in proportion to the number of iterations. In this paper, it proposes an efficient stopping rules for the iteration process in turbo decoding. By using absolute mean values for the LLR difference values between the first and second decoder in the present decoding process, the proposed algorithm can largely reduce the average number of iterations without BER performance degradation in all SNR regions. As a result of simulation, the average number of iterations of proposed algorithm is reduced by about $18.25%{\sim}20.58%$ compared to SDR algerian in the lower SNR region, and is reduced by about $22.96%{\sim}28.74%$ compared to method using variance values of extrinsic information in the upper SNR region.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.143-149
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• 2006

Turbo code, a kind of error correction coding technique, has been used in the field of digital mobile communication system. As the number of iterations increases, it can achieves remarkable BER performance over AWGN channel environment. However, if the number of iterations is increased in the several channel environments, any further iteration results in very little improvement, and requires much delay and computation in proportion to the number of iterations. To solve this problems, it is necessary to device an efficient criterion to stop the iteration process and prevent unnecessary delay and computation. In this paper, it proposes an efficient and simple criterion for stopping the iteration process in turbo decoding. By using sign changed ratio of extrinsic information values in turbo decoder, the proposed algorithm can largely reduce the average number of iterations without BER performance degradation. As a result of simulations, the average number of iterations is reduced by about $12.48%{\sim}22.22%$ compared to CE algorithm and about $20.43%{\sim}54.02%$ compared to SDR algorithm.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.536-541
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• 2000

Turbo code has excellent decoding performance but had limitations for real time communications because of the system complexity and time delay in decoding procedure. To overcome this problem, a new SRI(Semi-Random Interleaver) algorithm which realize the reduction of the interleaver size is proposed for reducing the time delay during the decoding prodedure. SRI compose the interleaver 0.5 size from the input data sequence. In writing the interleaver, data is recorded by row such as block interleaver. But, in reading, data is read by randomly and the text data is located by the just address simultaneously. Therefore, the processing time of with the preexisting method such as block, helical random interleaver.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.845-849
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• 2012

The next-generation wireless communication requires fast transmission speeds with various services and high reliability. In order to satisfy these needs we study MIMO system used layered space time coded system (LST) combining space time trellis codes (STTC) with turbo codes. In LST, two codes that are inner and outer codes are concatenated in the serial fashion. The inner codes are turbo Pi codes suggested in DVB-RCS NG system, and outer codes are STTC codes proposed by Blum. The interleaver technique is used to efficiently combine two codes. And we proposed and simulated that a full iteration method between turbo decoder and BCJR decoder to improve the performance instead of only processing inner-iteration turbo decoder. The simulation results of proposed effective layered method show improving BER performance about 1.3~1.5dB than conventional one.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.905-908
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• 2008

In this paper, an Adaptive Modulation (AM) system with an efficient turbo-coded Vertical-Bell-lab Layered Space-Time (V-BLAST) technique is proposed. The proposed decoding algorithm adopts iteratively the extrinsic information from a Maximum a Posteriori (MAP) decoder as a priori probability in the two decoding procedures of the V-BLAST scheme of ordering and slicing. In this analysis, each MIMO channel is assumed to be a part of the system of performance improvement.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.77-80
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• 2005

In this paper, we introduce the efficient carrier phase estimating algorithm collaborate with the channel decoder of turbo coded QPSK modulation for mobile DVB-RCS systems. At low SNR, the phase estimation using soft information of turbo decoder is able to improve power efficiency because of achieving the good synchronization. We investigate performance of external single estimator and internal multiple estimator in the PSP (Per Survivor Processing) manner over AWGN channel. For phase estimation, the LMS (Least Mean Square) scheme is considered. Three different APP-based methods are also proposed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.426-432
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• 2007

The MAP algorithm is designed and implemented through the sliding window method for turbo decoding. First, the implementation issues, which are the length of the sliding window and the normalization method of state metrics are reviewed, and their optimal values are obtained by the simulation. All component schemes of the decoder including the branch metric evaluator are also presented. The proposed MAP architecture can be easily redesigned according to the size of sliding window, that is, sub-frame length because of its simplicity on buffer control.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.999-1000
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• 2006

The LDPC Code is focusing a powerful FEC(Forward Error Correction) codes for 4G Mobile Communication system. LDPC codes are used minimizing channel errors by modeling AWGN Channel as VDSL system. The performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. LDPC code are encoded by sparse parity check matrix. there are decoding algorithms for a LDPC code, Bit Flipping, Message passing, Sum-Product. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.872-877
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• 2011

In this paper, the new decoding algorithm of Block Turbo Codes using Channel State Information(CSI), which is estimated to compensate for the distorted signal caused by multi-path fading, is proposed in order to improve error correction capacity during decoding procedure in OFDM system. The performance of the new decoding algorithm is compared to that of the conventional decoding algorithm without using channel state information under the Rayleigh fading channel. Experimental results showed that in case of only one iteration coding gains of up to 5.0dB~9.0dB can be obtained by applying the channel state information to the conventional decoding algorithm according to the modulation methods. In addition to that, the new decoding algorithm using channel state information at only one iteration shows a performance improvement of 3.5dB to 5.0dB when compared to the conventional decoding algorithm after four iterations. This leads to reduce the considerable amount of computation.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.203-209
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• 2006

In this paper, proposed diversity algorithm that decrease fading. In the wireless channel, if fading occurs due to the multipaths the performance of the system is apparently reduced. This study applied tap-delay receiver. It applied QPSK and OQPSK modulation methods and applied the convolutional codes, where the code rate is 1/2 and 1/3 and the constraint length is 11 and the turbo code where the constraint length is 6. The diversity algorithm proposed in this paper could be compared and analyzed the average error probability of modulation method variable of fading factor to uplink and downlink channels.