• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1688-1695
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• 2016

Underwater communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. The excessive multipath encountered in underwater communication channel creates inter symbol interference, which is a limiting factor to achieve a high data rate and bit error rate performance. Therefore, to increase throughput efficiency and improve performance, this paper consider FTN (Faster-than-Nyquist) signalling based on turbo equalization. FTN signalling is a technique of transmitting information at a rate higher than the allowed Nyquist limit. This paper presented efficient decoder structure of FTN transmission in the environment of multipath underwater channel and we compare the performance between FTN method and conventional punctured method in lake experimentation. As a results of lake experiment, we confirmed FTN method based on turbo equalization is applicable and efficiency in underwater communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1645-1652
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• 2016

FTN(Faster-Than-Nyquist) signaling is a method of transmitting symbols at rates faster than the Nyquist rate in the same bandwidth by overlapping transmission pulses. The transmission power of the FTN signal is greater than that of the Nyquist signal, because the number of symbols in the FTN signal is larger than that in the Nyquist signal for the same time interval. Hence, to evaluate the performance of an FTN-based transmission system properly, the performance evaluation criterion should be carefully set, and conversion formulas among the criteria which are used in Nyquist-based system should also be applied attentively. In this paper, the performance evaluation criteria of the FTN-based transmission system is analyzed and a valid way to set the criteria is proposed.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1291-1298
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• 2017

In this paper, we propose a decoding method that improves the transmission rate and reliability by integrating MIMO(Multiple Input Multiple Output) communication scheme using turbo code and FTN(Faster Than Nyquist) scheme among high rate and high reliability wireless communication schemes in wireless communication. The existing MIMO-FTN(Multiple Input Multiple Output-Faster Than Nyquist) scheme based on hierarchical space-time coded method induced data rate loss due to the application of the space-time trellis coding scheme to remove adjacent symbol interference due to FTN scheme. To solve these problems, this paper proposes a method using W-ZF(Weighted-Zero Forcing) which overcomes the disadvantages of ZF(Zero Forcing) scheme in MIMO-FTN scheme using ZF scheme. In this paper, we compared the performance and the transmission rate of the MIMO-FTN scheme based on the hierarchical space-time coding, the MIMO-FTN scheme using W-ZF and the SISO-FTN scheme. As a result, the MIMO-FTN scheme using the W-ZF scheme is two times better than the other two schemes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.409-411
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• 2013

In this paper, we used FTN(Faster than Nyquist) method that is transmission method faster than Nyquist theory. FTN signaling introduces intersymbol interference(ISI), but increases the bit rate while preserving the signaling bandwidth. Therefore, we need compensating ISI caused by FTN. In this paper, we propose decoding method for FTN signal that using BCJR Equalizer and Turbo Equalization. first ISI of inputted signal is restored by BCJR Equalizer, and then restored signal inputted in LDPC decoder, and repeat the process using the Turbo Equalization improves performance. finally, we shows performance comparison according to reduce percentage of FTN signal.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1323-1329
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• 2014

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. we proposed viterbi equalizer model to minimize ISI (Inter-Symbol Interference) when FTN signal is transmitted. the proposed model utilized interference as branch information. In this paper, to decode FTN singal, we used turbo equalization algorithms that iteratively exchange probabilistic information between soft Viterbi equalizer (BCJR method) and LDPC decoder. By changing the trellis diagram in order to maximize Euclidean distance, we confirmed that performance was improved compared to conventional methods as increasing throughput of FTN signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1147-1154
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• 2016

A faster-than-Nyquist (FTN) transmission scheme has been attracting great attention as a spectral efficient transmission scheme. In the FTN transmission scheme, modulated symbols are transmitted at a rate higher than Nyquist rate and thus, a performance loss due to the inter-symbol interference (ISI) is unavoidable. To minimize the performance loss in the FTN transmission scheme, parameters should be carefully optimized. Unfortunately, simulation-based parameter optimization requires significant amount of time and computing power, especially for 2-dimensional FTN systems. In this paper, we propose a 2-dimensional FTN transmission scheme using the optimized parameters based on numerical analysis and simulation results on the ISI. Compared with the conventional Nyquist system, the proposed 2-dimensional FTN transmission scheme not only offers virtually identical bit error performance but also offers higher spectral efficiency.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.240-241
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• 2016

본 논문은 FTN(faster-than-Nyquist) 신호가 적용된 DVB-T2 시스템의 동기 알고리듬에 미치는 영향에 대하여 분석하였다. 파일럿 기반의 동기 알고리듬은 FTN 신호의 간섭 영향으로 인하여 동기 성능의 열화가 발생한다. 기존의 DVB-T2 시스템을 기반으로 하여 FTN 변수에 따른 성능의 변화를 실험으로 분석하고 SUI 채널 환경에서의 성능을 분석하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.63-70
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• 2016

To increase throughput efficiency and improve performance, FTN(Faster Than Nyquist) method and LDPC(Low Density Parity Code) codes are employed in DVB-S3 system. In this paper, we proposed efficient turbo equalization model to minimize inter symbol interference induced by FTN transmission. This paper introduces two conventional scheme employing SIC(Successive Interference Cancellation) and BCJR equalizer. Then, we proposed new scheme to resolve problems in this two conventional scheme. To make performance improved in turbo equalization model, the outputs of LDPC and BCJR equalizer are iteratively exchange probabilistic information. In fed LDPC outputs as extrinsic informa tion of BCJR equalizer. we split LDPC output to separate bit probabilities. We compare performance of proposed scheme to that of conventional methods through using simulation in AWGN(Additive White Gaussian Noise) channel. We confirmed that performance was improved compared to conventional methods as increasing throughput parameters of FTN.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.157-162
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• 2016

The performance of turbo-like codes highly depends on their frame size and thus, the bit error rate performance of turbo-like codes can be improved by increasing the frame size. Unfortunately, increasing the frame size of channel codes induces some drawbacks such as the increase of not only encoding and decoding complexity but also transmission and decoding latencies. On the other hand, a faster than Nyquist (FTN) transmission causes intentional inter-symbol interference (ISI) and thus, induces some correlation among the transmission symbols. In this paper, we propose an FTN transmission with multiple channel codes. By exploiting the correlation among the modulated symbols, multiple code frames can be regarded as a code frame with a lager frame size. Due to the inherent parallel encoding scheme of proposed scheme, parallel decoding can be easily implemented.