• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.535-541
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• 2016

In this paper, we analyzed efficient decoding scheme with FTN(Faster than Nyquist) method that is transmission method faster than Nyquist theory and increase the throughput. Applying the FTN method to satellite and underwater communication, we proposed an efficient transceiver model. To minimize ISI(Inter-Symbol Interference) induced by FTN signal, turbo equalization algorithms that iteratively exchange probabilistic information between Viterbi equalizer based on BCJR algorithm and LDPC decoder are used in satellite communication. In others, for underwater communication, DFE equalizer and LDPC decoder are concatenated to improve performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.599-606
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• 2008

In this paper, the channel estimation performance of proposed TSC (TSC-S) is investigated in terms of the BER and BLER performances when HSR is considered for GERAN evolution system. The performance is evaluated by the link level simulation and is compared with the other TSC proposal (TSC-E). Numerical results show that the performance employing the TSC-S is almost same to that using the TSC-E. In the case of cochannel interferences, the similar tendency is shown, when joint least square is adopted for channel estimation.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.66-71
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• 2011

This paper evaluates the performance and effectiveness of a layered coding scheme for an integrated mobile satellite systems, where the main target services are multimedia broadcasting and multicasting services (MBMS). In this integrated system, the satellite and complementary ground components (CGC) cooperate to provide high quality services. A layered coding scheme is a receiver driven adaptive schemes which adapts to the channel condition at the receiver. In this paper, we introduce a layered turbo coding scheme, and evaluates the performance in various scenarios, and discuss its effectiveness. The demonstrated results in the paper can be utilized in order to design an efficient integrated mobile satellite system, in the future.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.773-781
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• 2000

The average bit error rate of wideband CDMA in forward link is evaluated for frequency and timing errors in multipath Rayleigh fading channel. The channel BER is evaluated analytically and information BER is investigated with simulation. The performance degradation due to the code/frequency synchronization errors was obtained through simulation for particular two coding schemes - convolutional codes and turbo codes. The results show 1dB degradation due to Tc/4 timing error and 0.5dB degradation due to 50Hz frequency error, for both coding schemes.

• 전자공학회논문지 IE
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• v.43 no.2
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• pp.80-86
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• 2006

The wireless communication based on LDPC and adaptive spatial-subcarrier coded modulation using MQAM for orthogonal frequency division multiplexing (OFDM) wireless transmission by using instantaneous channel state information and employing multiple antennas at both the transmitter and the receiver. Adaptive coded modulation is a promising idea for bandwidth-efficient transmission on time-varying, narrowband wireless channels. On power limited Additive White Gaussian Noise (AWGN) channels, low density parity check (LDPC) codes are a class of error control codes which have demonstrated impressive error correcting qualities, under some conditions performing even better than turbo codes. The paper demonstrates OFDM with LDPC and adaptive modulation applied to Multiple-Input Multiple-Output (MIMO) system. An optimization algorithm to obtain a bit and power allocation for each subcarrier assuming instantaneous channel knowledge is used. The experimental results are shown the potential of our proposed system.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.353-360
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• 2004

In this Paper, We propose an efficient iteration decoding control method with variable iteration decoding of iteration codes decoding using Cyclic Redundancy Check. As the number of iterations increases, the bit error rate and frame error rate of the decoder decrease and the incremental improvement gradually diminishes. However, when the iteration decoding number is increased, it require much delay and amount of processing time for decoding. Also, It can be observed the error nor that the performance cannot be improved even though increasing of the number of iterations and SNR. So, Suitable number of iterations for stopping criterion is required. we propose variable iteration control method to adapt variation of channel using Frame Error-Check indicator. Therefore, the amount of computation and the number of iterations required for iteration decoding with CRC method can be reduced without sacrificing performance.

• Electronics and Telecommunications Trends
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• v.15 no.4 s.64
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• pp.12-22
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• 2000

1993년 Shannon 한계에 근접하는 우수한 성능을 가진 터보 부호가 발표된 이후 그에 대한 많은 연구들이 이루어져 왔지만, 한편으로는 반복 복호의 복잡도와 이로 인한 복호 지연을 고려할 때 실제 시스템에 적용이 가능할 것인가에 대한 의문 역시 함께 제기되어 왔다. 그러나 터보 부호를 구현하고자 하는 노력은 계속되었으며, 현재는 터보 부.복호기를 구현한 제품들이 시장에 등장한 상태이다. 특히 위성통신시스템에서의 적용을 위한 노력이 증가하고 있으며 곧 그 구현을 앞두고 있는 IMT-2000 시스템에서도 터보 부호는 일부 서비스에서 활용될 예정 등으로 앞으로 그 활용도는 급격히 늘어날 전망이다. 터보 부.복호기를 한 칩에 구현한 제품들도 이미 출시되어 있는 상태이다. 터보 부.복호기를 하드웨어로 구현한 제품들은 크게 길쌈 터보 부호를 사용한 것과 블록 터보 부호를 사용한 것으로 양분된다. 본 논문에서는 실제 상용 하드웨어로 구현되어 있는 터보 부호의 특징과 성능을 분석한 내용을 기술하고자 한다.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.333-340
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• 2017

In this paper, we describe HW/SW co-optimizations for reconfigurable application specific instruction-set processors (ASIPs). Based on our previous very long instruction word (VLIW) ASIP, the proposed framework realizes various forward error-correction (FEC) algorithms for wireless communication systems. In order to enhance the energy efficiency, we newly introduce several design methodologies including high-radix algorithms, task-level out-of-order executions, and intensive resource allocations with loop-level rescheduling. The case study on the radix-4 turbo decoding shows that the proposed techniques improve the energy efficiency by 3.7 times compared to the previous architecture.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.3
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• pp.60-67
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• 1989

An automated classification and coding system for structure of injection mold is developed based on the statistical analysis and the critical evaluation of the results for the sample survey of 200 assembly drawings of injection mold. The proposed system is a mixed code system consisting of 15 digits and each digit consists of 10 numerical codes. An interactive computer program is developed by using TURBO PASCAL on IBM PC/AT compatible system. A case study is discussed to show the procedure and the function of the system. The results for applications of the system to real problems show that the system works well and is useful for design, manufacturing and management of injection mold.