• 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.36 no.6C
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• pp.368-375
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• 2011

In the distributed video coding system, the parity bits, which are generated in encoders, are used to reconstruct Wyner-Ziv frames. Since the original Wyner-Ziv frames are not known in decoders, the efficient correlation noise modeling for turbo or LDPC code is necessary. In this paper, an efficient correlation noise modeling method is proposed and the performance is analyzed. The method to estimate the quantization parameters for key frames, which are encoded using H.264 intraframe coding technique, is also proposed. The performance of the proposed system is evaluated by extensive computer simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.537-545
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• 2011

This paper analyzed performance of three dimensional turbo code and turbo ${\Phi}$ codes proposed in the next generation DVB-RCS systems. In the view of turbo ${\Phi}$ codes, we proposed the optimal permutation and puncturing patterns for triple binary input data. We also proposed optimal post-encoder types and interleaving algorithm for three dimensional turbo codes. Based on optimal parameters, we simulated both turbo codes, and we confirmed that the performance of turbo ${\Phi}$ codes are better than that of three dimensional turbo codes. However, the complexity of turbo ${\Phi}$ is more complex than that of three dimensional turbo codes by 18%.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.6-14
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• 2007

In this paper, we propose and observe the Adaptive Modulation system with optimal Turbo Coded V-BLAST (Vertical-Bell-lab Layered Space-Time) technique that is applied the extrinsic information from MAP (Maximum A Posteriori) Decoder in decoding Algorithm of V-BLAST: ordering and slicing. The extrinsic information is used by a priori probability and the system decoding process is composed of the Main Iteration and the Sub Iteration. And comparing the proposed system with the Adaptive Modulation system using conventional Turbo Coded V-BLAST technique that is simply combined V-BLAST with Turbo Coding scheme, we observe how much throughput performance has been improved. In addition, we observe the proposed system using STD (Selection Transmit Diversity) scheme. As a result of simulation, Comparing with the conventional Turbo Coded V-BLAST technique with the Adaptive Modulation systems, the optimal Turbo Coded V-BLAST technique with the Adaptive Modulation systems has better throughput gain that is about 350 Kbps in 11 dB SNR range. Especially, comparing with the conventional Turbo Coded V-BLAST technique using 2 transmit and 2 receive antennas, the proposed system with STD (Selection Transmit Diversity) scheme show that the improvement of maximum throughput is about 1.77 Mbps in the same SNR range.

• 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 the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.193-199
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• 2009

Powerline communications (PLC) technology has been discussed and analyzed as a highly potential candidate of wireline access network solutions. In this paper, performance of double binary turbo coded orthogonal frequency division multiplexing (OFDM) system is analyzed and simulated in power line communications channel. In order to make power line channel environments, Bernoulli-Gaussian noise is considered. The performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the double binary turbo coding scheme offers considerable coding gain with reasonable encoding complexity. It is also shown that the system performance can be substantially improved by increasing the number of iterations.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1316-1319
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• 2002

In this paper, an online SNR estimator is derived for turbo coded multicode DS/SS systems in Nakagami fading channels. The multicode DS/SS approach is one of promising solutions to obtain higher-rate data transmission in DS/SS technologies. Turbo coding has paid much attention because of the significant improvements on error rate performances in various communication systems including multicode DS/SS systems. However, in the turbo decoding, channel state information, especially signal-to-noise ratio (SNR) at the correlator outputs, is desired in order to obtain such improvements. We evaluate the accuracy of the derived SNR estimation. It is shown that the bit error rate performance using our SNR estimation is close to the performance with perfect knowledge of channel state information.

• Journal of Broadcast Engineering
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• v.12 no.4
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• pp.373-376
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• 2007

Recently, research on the enhancement of the conventional VSB scheme for DTV signal transmission have been done. Not to affect on the performance of the widely spread conventional receivers and at the same time be able to receive the enhanced stream. there have been efforts to enhance the coding scheme which is backward compatible with the conventional method. The conventional schemes proposed so far is based on the idea of combining a new trellis encoder with the standard 8-VSB trellis encoder. In this paper, we Propose serial concatenated turbo TCM scheme which combines two trellis encoder with the interleaver between them. We compare the performance of the proposed scheme and the existing scheme through computer simulation.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.1-5
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• 2008

In this paper, we propose and analyze the AMC (Adaptive Modulation and Coding) system with efficient turbo coded V-BLAST (Vertical-Bell-lab Layered Space-Time) technique. The proposed algorithm adopts extrinsic information from a MAP (Maximum A Posteriori) decoder with iterative decoding as a priori probability in two decoding procedures of V-BLAST scheme; the ordering and the slicing. Also, we consider the AMC system using the conventional turbo coded V-BLAST technique that simply combines the V-BLAST scheme with the turbo coding scheme. And we compare the proposed decoding algorithm to a conventional V-BLAST decoding algorithm and a ML (Maximum Likelihood) decoding algorithm. In addition, we apply a STD (Selection Transmit Diversity) scheme to the systems for better performance improvement. Results indicate that the proposed systems achieve better throughput performance than the conventional systems over the entire SNR range. In terms of transmission rate performance, the suggested system is close in proximity to the conventional system using the ML decoding algorithm.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.857-864
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• 2002

Channel coding is one of the most important things to improve digital communications. In this paper, we analyze the performance of turbo code with block interleaver using hopping algorithm (i. e., non-linear interleaver) for high speed multi-media service. The input and output of conventional block interleaver is achieved by the order of column and row, but hoping algorithm is achieved by hopping the column and row that increase the minimum distance and average distance between the nearest data dually. To verify and compare the performance of an proposed method the computer simulation have been performed using turbo code in gaussian channel environment.