• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.5
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• pp.516-521
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• 2010

In the high-speed packet service, next generation mobile communication system has emerged as a major feature. If the fire of these high-speed D kit services and non-continuous transmission of data due to the symmetrical nature of daeyiteo traffic for D-CDMA system has been actively studied. In this paper, we apply turbo codes for D-CDMA has been investigated. Considering the nature of the system configuration of the transmission frame type, such as physical channel structure and channel coding has been investigated. In addition to TD-CDMA system, one HARQ gibeopjung hase Combining the performance analysis techniques were applied.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.271-279
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• 2006

This study proposes a new diversity algorithm to improve the signal-to-noise ratio. In the wireless channel, if fading occurs due to the multipaths, the performance of the system is apparently reduced. One of the methods to reduce fadings like this is the diversity method, and this study aims to improve the performance of the system by proposing a new diversity algorithm. This study applied rake receiver It applied QPSK and OQPSK modulation methods and applied the convolutional codes, where the code rate is 1/3 and the constraint length is 9, and the turbo code where the constraint length is 4. Under these conditions, this study compared and analyzed the average error probability of Multicarrier CDMA system.

• 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.

• Journal of Broadcast Engineering
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• v.14 no.6
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• pp.721-732
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• 2009

AT-DMB system has been developed to increase data rate up to double of conventional T-DMB in same bandwidth while maintaining backward compatibility. The AT-DMB system adopted hierarchical modulation which adds BPSK signal or QPSK signal as enhanced layer to existing DQPSK signal. The enhanced layer signal should be small enough to maintain backward compatibility and to minimize the coverage loss of existing T-DMB service area. But this causes the enhanced layer signal of AT-DMB susceptible to fading effect in transmission channel. A turbo code which has powerful error correction capability is applied to the enhanced layer signal of the AT-DMB system for compensating channel distortion. We developed the prototype AT-DMB transmitter and receiver systems for performance evaluation. LAB test for analysing the effect of constellation ratio between existing base layer signal and enhancement layer signal, was conducted and the measurement results are shown with analysis comments.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.228-237
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• 2009

This paper examines the potential of Ultra-High Definition TV (UD-TV) broadcasting transmission systems beyond HD-TV over cable channel. Firstly, we analyze the trend of TOV(Threshold of Visibility) by extending the OpenCable (J.83 Annex B) system 256QAM which is the standard of Korean and American cable television transmission to 1024QAM, and realize that the OpenCable 1024QAM has nearly 30% higher data rate than 256QAM at the expense of impractically higher TOV (Threshold of Visibility). To achieve practical TOV, we control code rates of inner convolutional coder and replace turbo coder in forward error correction (FEC) part, thereby analyzing the best performance of the OpenCable systems having conventional FEC. In that result, it is necessary to modify conventional FEC of the OpenCable system to achieve under 31.5dB TOV. Moreover we study the potential of UD-TV transmission via two or more TV channels, so called channel bonding, through the Shannon capacity in 6MHz channel and the relationship with next generation A/V codec technologies.

• 전자공학회논문지 IE
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• v.43 no.4
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• pp.115-121
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• 2006

In this paper, we proposed about data error check and correction on channel transmission in the communication system. LDPC codes are used for minimizing channel errors by modeling AWGN Channel as a VDSL system. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten. Also the performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. This algorithm is better than conventional algorithms to correct errors, the proposed algorithm assigns weights for errors concerning parity bits. The proposed weighted Bit-flipping algorithm is better than the conventional Bit-flipping algorithm and we are recognized improve gain rate of 1 dB.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.45-52
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• 2015

Since the broadcast message in satellite signals the security of the data is extremely poor compared to other communication technologies such as the broadcast signal. Thus, encryption of the communication satellite has become a very important issue, an analysis of the communication performance of a general service is always required. In this paper, In order to analyze the encrypted communication the turbo code in an IP-based satellite communication applies the code rate compatible punctured and The wireless channel in consideration of the actual satellite communication was constructed by placing a weight on the Rayleigh fading and the Rician fading two channels. Retransmission-based error control scheme were constructed in the best performance of H-ARQ Type-II, III scheme of a number of ways that are recently considered. we analyzed the effects of normal service against a satellite communication network The security services were configured with encryption algorithms AES, ARIA (CTR, CBC mode).

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1051-1059
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• 2013

This paper proposes a complexity reduced list sphere decoding (LSD) scheme for joint iterative soft detection scheme for coded MIMO system. The conventional LSD scheme is based on searching the candidates with a fixed radius. However, once the candidate list is full, it is highly probable that the radius can be reduced. By reducing the radius, the complexity can be also reduced. We propose a simple and efficient radius update method for complexity reduction of list version sphere decoding and its application to iterative soft MIMO detection. We evaluate the performance of the proposed scheme with a joint soft-input-soft-ouput iterative MIMO detection in combination with turbo codes. Simulation results show that the proposed methods provide substantial complexity reduction while achieving similar bit error rate (BER) performance as the conventional LSD scheme.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.23-27
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• 2014

In this paper, we propose a soft demapping method for 64-ary APSK in the DVB-S3 system. The proposed method in this paper uses the hard decision threshold (HDT) line for each constituent bit in a symbol, and calculates the soft bit information with the distance between the HDT line and the detected symbol. If the HDT lines are defined in a simple manner, the complexity to estimate soft information can be largely reduced compared with the maximum likelihood detection (MLD) which has an exponential complexity. By considering this, we first derive HDT lines for each constituent bit for a 64-APSK symbol, and propose a method to calculate soft bit information. We simulate the BER performance of the proposed scheme by using a turbo codes which requires soft-input-soft-output information, and compare it that of the MLD. The result show that the proposed scheme produces approximating performance to MLD with largely reduced complexity.