• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.21-28
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• 2004

In this paper we apply block turbo coding at the transmitter and iterative decoding algorithm at the receiver for different operating modes, based on the 5 ㎓ IEEE 802.1 la WLAN system, instead of convolutional coding and soft decision viterbi algorithm to improve forward error correcting performance. Experimental results showed that each coding scheme outperforms coding gains of up to 3.5 ㏈ at the BER of 10$\^$-3/.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.861-868
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• 2001

In this paper, the performance of Reed Solomon(RS)/convolution리 concatenated codes and turbo code using semi random interleaver over the radio communication channel was analyzed. In the result, we proved that the performance of decoder was excellent as increase the interleaver size, constraint length, and iteration number. When turbo code using semi random interleaver and Hsiconvolutional concatenated codes was constant constraint length L=5, BER=10-4 , each value of $E_b/N_o$ was 4.5〔dB〕 and 2.95〔dB〕. Therefore, when the constraint length was constant, we proved that the performance of turbo code is superior to RS/Convolutional concatenated codes about 1.55〔dB〕 in the case of BER=10-4.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4A
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• pp.519-527
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• 2000

This paper suggests and analyzes the Serially Concatenated Space-Time Code(SCSTC) with the possibility of a efficient high-speed transmission in a band limited channel. The suggested code has a structure that uses the interleaver to connect the space-time code as an inner code and the convolutional code as a outer code serially. This code keeps the advantage of high-speed transmission and also has the high BER performance. The performance of the suggested system is compared with the conventional bandwidth efficient trellis coded modulation, such as a Serially Concatenated Trellis Coded Modulation (SCTCM) and a Turbo-Trellis Coded Modulation(Turbo-TCM). The results show that the suggested system has a 2.8dB and 3dB better BER performance than SCTCM and Turbo-TCM respectively in case of the transmission rate 2b/s/Hz in fading channel.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.7
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• pp.13-23
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• 2009

In this paper, the network performance of a turbo coded optical code division multiple access (CDMA) system with cross-layer, which is between physical and network layers, concept is analyzed and simulated. We consider physical and MAC layers in a cross-layer concept. An intensity-modulated/direct-detection (IM/DD) optical system employing pulse position modulation (PPM) is considered. In order to increase the system performance, turbo codes composed of parallel concatenated convolutional codes (PCCCs) is utilized. The network performance is evaluated in terms of bit error probability (BEP). From the simulation results, it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is confirmed that the performance of such an optical CDMA network can be substantially improved by increasing e interleaver length and e number of iterations in e decoding process. The results of this paper can be applied to implement the indoor optical wireless LANs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.15-20
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• 2009

For perpendicular magnetic recording (PMR) channels, noise-predictive maximum likelihood (NPML) detection method has been used. But, it is hard to expect improving the performance when the bit density is increased. Hence, we exploit the coding methods which has good performance. In this paper, we show the performance of the recursive systematic convolutional (RSC) codes with turbo-equalization method with different channel bit densities. The noise model is 80% jitter noise and 20% AWGN.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.205-208
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• 2001

According to the IMT-2000 specification of 3GPP(3rd Generation Partnership Project) and 3GPP2, Turbo codes is selected as a FEC(forward error correction) code for even higher reliable data communication. In 3GPP complied IMT-2000 system, channel coding under consideration is the selective use of convolutional coding and Turbo codes of 1/3 code rate with 4 constraint length. Suggesting a new path metric normalization method, we achieved a low complexity and high performance SOVA decoder for Turbo Codes, Further more, we analyze the decoding performance with respect to update depth and find out the optimal value of it by using computer simulation. Based on the simulation result, we designed a SOVA decoder using VHDL and implemented it into the Altera EPF10K100GC503FPGA.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.45-49
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• 2016

The performance of underwater acoustic communication systems is sensitive to inter-symbol interference caused by delay spread developed from multipath signal propagation. The multipath nature of underwater channels causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Of the various iterative coding schemes, turbo code and convolutional code based on the BCJR algorithm have recently dominated this application. In this study, the performance of iterative codes based on turbo equalizers with equivalent coding rates and similar code word lengths were analyzed. Underwater acoustic communication system experiments using these two coding techniques were conducted on Kyeong-chun Lake in Munkyeong City. The distance between the transmitter and receiver was 400 m, and the data transfer rate was 1 Kbps. The experimental results revealed that the performance of turbo codes is better for channeling than that of convolutional codes that use a BCJR decoding algorithm.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.187-196
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• 2003

We consider the use of error control coding in direct sequence-code-division multiple access (OS-COMA) systems that employ multiuser detection (MUO) and space diversity. The relative performance gain between Reed-Solomon (RS) code and convolutional code (CC) is well known in [1] for the single user, additive white Gaussian noise (AWGN) channel. In this case, RS codes outperform CC's at high signal-to-noise ratios. We find that this is not the case for the multiuser interference channel mentioned above. For useful error rates, we find that soft-decision CC's to be uniformly better than RS codes when used with DS-COMA modulation in multiuser space-time channels. In our development, we use the Gaussian approximation on the interference to determine performance error bounds for systems with low number of users. Then, we check their accuracy in error rate estimation via system's simulation. These performance bounds will in turn allow us to consider a large number of users where we can estimate the gain in user-capacity due to channel coding. Lastly, the use of turbo codes is considered where it is shown that they offer a coding gain of 2.5 dB relative to soft-decision CC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2C
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• pp.155-160
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• 2008

In this letter, we propose a new design of recursive systematic convolutional (RSC) codes based on the distance spectrum properties which can maximize the performance. Good constituent RSC codes of code rate 1/2 are searched by computer and presented in a table. Their performances are shown by computer simulation. New designed codes shows faster convergences according to iterative decoding and good performances.

• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.487-492
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• 2013

Underwater acoustic communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Among the iterative coding scheme, turbo codes, LDPC codes and convolutional code based on BCJR algorithm are dominant channel coding schemes in recent. Therefore this paper analyzed the performance of iterative codes based on turbo equalizer with the same coding rate and similar codeword length. The performances of three kinds of iterative codes were evaluated in the environment of underwater acoustic communication channel that are real data collected in Korean east sea. The distance of transmitter and receiver was 5Km and data rate was 1Kbps. As a result, convolutional code based on BCJR algorithm has better performance in underwater channel than turbo codes and LDPC codes.