• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.67-72
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• 2001

Convolutional code and turbo code are used in the forward and backward link of IMT-2000. In this research, we will be in consideration of Viterbi algorithm In this paper, we design Viterbi decoder with 3-bits soft decision and SMT for the convolutional code in the forward link and backward link of IMT-2000 system. The major parameters of 3-bits Viterbi decoder is determined by simulation to have identical performance with the 4-bit soft decision Viterbi decoder.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.307-312
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• 2005

In this work, we study the performance of a serial concatenated scheme comprising a convolutional code (CC) and an orthogonal space-time block code (STBC) separated by an inter-leaver. Specifically, we derive performance bounds for this concatenated scheme, clearly quantify the impact of using a CC in conjunction with a STBC, and compare that to using a STBC code only. Furthermore, we examine the impact of performing antenna selection at the receiver on the diversity order and coding gain of the system. In performing antenna selection, we adopt a selection criterion that is based on maximizing the instantaneous signal-to­noise ratio (SNR) at the receiver. That is, we select a subset of the available receive antennas that maximizes the received SNR. Two channel models are considered in this study: Fast fading and quasi-static fading. For both cases, our analyses show that substantial coding gains can be achieved, which is confirmed through Monte-Carlo simulations. We demonstrate that the spatial diversity is maintained for all cases, whereas the coding gain deteriorates by no more than $10\;log_{10}$ (M / L) dB, all relative to the full complexity multiple-input multiple-output (MIMO) system.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.243-247
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• 2005

We propose an efficient block least-mean-square (BLMS) adaptive algorithm, in conjunction with error control coding, for direct-sequence code division multiple access (DS-CDMA) systems. The proposed adaptive receiver incorporates decision feedback detection and channel encoding in order to improve the performance of the standard LMS algorithm in convolutionally coded systems. The BLMS algorithm involves two modes of operation: (i) The training mode where an uncoded training sequence is used for initial filter tap-weights adaptation, and (ii) the decision-directed where the filter weights are adapted, using the BLMS algorithm, after decoding/encoding operation. It is shown that the proposed adaptive receiver structure is able to compensate for the signal-to­noise ratio (SNR) loss incurred due to the switching from uncoded training mode to coded decision-directed mode. Our results show that by using the proposed adaptive receiver (with decision feed­back block adaptation) one can achieve a much better performance than both the coded LMS with no decision feedback employed. The convergence behavior of the proposed BLMS receiver is simulated and compared to the standard LMS with and without channel coding. We also examine the steady-state bit-error rate (BER) performance of the proposed adaptive BLMS and standard LMS, both with convolutional coding, where we show that the former is more superior than the latter especially at large SNRs ($SNR\;\geq\;9\;dB$).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.9
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• pp.366-372
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• 2003

Multilevel coded modulation (MCM) with serial concatenated convolutional code (SCCC) is proposed and the performance is analyzed in this paper. Both high coding gain and bandwidth efficiency can be obtained if SCCC is adopted as a component code at the first level of MCM. Simulation results show that the performance of MCM with Ambroze's SCCC is saturated like that of MCM with PCCC. But MCM with Benedetto's SCCC shows no performance saturation and better performance than MCM with PCCC or Ambroze's SCCC. Thus MCM with Benedetto's SCCC may be a good choice for high quality system with limited bandwidth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.542-545
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• 2006

In recent years, RFID is widely used in Industrial applications including factory, material flow, logistics and defense areas. In this paper, we developed a RFID baseband system with ASK modulation and convolutional channel code. A commercial ASK RF module is used and its frequency range in $350\sim351MHz$ and power is 10mW and the convolution code is constraint length k=3 and rate R=1/2. The performance is measured by frame error rate and the convolutional code is very useful in performance improvement and, also we implemented the binary search algorithm as anti-collision method and we show the wave shapes whit collision occurrence. This RFID system is designed by FPGA therefore it produces result of speed-up and improvement of reliability.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.3
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• pp.125-131
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• 2002

In this paper, a new concatenation scheme of serial concatenated convolutional codes is proposed and the performance analyzed. In the proposed scheme, each of information and parity bits of outer code is entered into inner code through interleaver and deinterleaver. Therefore, the interleaver size is same as the length of input frame. Since the interleaver size of proposed type is reduced to half of the conventional Benedetto type, the interleaver delay time required for iterative decoding is reduced. In addition the multiplexer and demultiplexer are not used in the decoder of the proposed type, the complexity of decoder can be also reduced. As results of simulation, the performance of proposed type shows the better error performance as compared to that of the conventional Benedetto type in case of the same interleaver size. And it can be observed that the difference of BER performance is increased with the increase of Eb/No. In case of the same length of input frame, the proposed type shows almost same performance with Benedetto type despite that the interleaver size is reduced by half.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.951-958
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• 2017

In an attack context, the adversary wants to retrieve the message from the intercepted noisy bit stream without any prior knowledge of the channel codes used. The process of finding out the code parameters such as code length, dimension, and generator, for this purpose, is called the blind recognition of channel codes or the reconstruction of channel codes. In this paper, we suggest an improved algorithm of the blind recovery of rate k/n convolutional encoders in a noisy environment. The suggested algorithm improves the existing algorithm by Marazin, et. al. by evaluating the threshold value through the estimation of the channel error probability of the BSC. By applying the soft decision method by Shaojing, et. al., we considerably enhance the success rate of the channel reconstruction.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.3
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• pp.21-30
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• 2020

With the widespread of smartphones, the Quick response (QR) code became one of the most popular codes. In this paper, a new type of QR code is proposed to increase the storage capacities and also to contain private information by changing the colors and the shape of patterns in the codes. Then, for a variety of applications of the printed QR codes, this paper proposes an efficient authentic certification system, which is built on an conventional CNN (Convolutional neural network) architecture - VGGNet and classifies authentic or counterfeit with smartphones, easily. For authentic codes, the proposed system extracts the embedded private information. Through practical experiments with a printed QR code, it is shown that the proposed system can classify authentic or counterfeit code, perfectly, and also, are useful for extracting private information.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.269-275
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• 2014

The DAB system was designed to provide CD quality audio and data services for fixed, portable and mobile applications with the required BER below $10^{-4}$. However for the T-DMB system with the video service of MPEG-4 stream, BER should go down $10^{-8}$ by adding FEC blocks which consist of the Reed-Solomon (RS) encoder/decoder and convolutional interleaver/deinterleaver. In this paper we propose two types of turbo coded T-DMB system without altering the puncturing procedure and puncturing vectors defined in the standard T-DMB system for compatibility. One(Type 1) can replace the existing RS code, convolutional interleaver and RCPC code by a turbo code and the other one (Type 2) can substitute the existing RCPC code by a turbo code. Simulation results show that two new turbo coded systems are able to yield considerable performance gain after just 2 iterations. Type 2 system is better than type 1 but the amount of performance improvement is small.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3C
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• pp.255-263
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• 2010

In this paper, we present an efficient cooperative transmission scheme for high speed 60GHz WPAN system. In 60GHz, the cooperative transmission with relay is effective scheme because signals are exceedingly attenuated according to the distance and the transmission is impossible when there is no LOS between transmitter and receiver. Moreover, the reliability of signal in destination can be improved by receiving data from a relay as well as a transmitter. However, the overall data rate is reduced because transmission time is more required for relay. To solve this problem, we propose a cooperative transmission scheme with RS-CC serial concatenated codes. In the proposed cooperative transmission scheme, the relay can reduce the transmission data size because the only parity bits of systematic RS code are transmitted after encoding by CC. But the computational complexity is increased at the relay and the destination.