• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.36-41
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• 2006

In this paper, we present the performance of iterative decoding with a Turbo decoder and a M-ary QAM(Quadrature Amplitude Modulation) demapper. The demappers are designed with Max-Log-MAP algorithm and it's approximated one. In addition, we provide implementing block for the approximated algorithm. From the results of computer simulations, the approximated algorithm of the Max-Log-MAP has little bit worse than the Max-Log-MAP but suggests low complexity for practical implementation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.533-536
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• 2005

MAP algorithm is known for optimal decoding algorithm of Turbo codes, but it has very large computational complexity and delay. Generally log-MAP algorithm is used in order to overcome the defect. In this paper we propose modified scheme of the state metric calculation block which can improve the computation speed in log-MAP decoder and simple linear offset unit without using LUT. The simulation results show that the operation speed of the proposed scheme is improved as compared with that of the past scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.81-88
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• 2004

Turbo code has been adopted in the 3GPP standard, since its performance is very close to the Shannon limit. However, the turbo decoder requires a lot of computations and the amount of the memory increases as the block size of turbo codes becomes larger. In order to reduce the complexity of the turbo decoder, the Log-MAP, the Max-Log-MAP and the sliding window algorithm have been proposed. In this paper, the performance of turbo codes adopted in the 3GPP standard is analyzed by using the floating point and the fixed point implementation. The efficient decoding method is also proposed. It is shown that the BER performance of the proposed method is close to that of the Log-MAP algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2C
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• pp.117-122
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• 2006

In this paper, we present a simple and general soft bit decision expression for a Gray coded PAM signal over additive white Gaussian noise(AWGN) channel with the log likelihood ratio(LLR). In order to reduce the complexity of the LLR calculation, we make the bitwise LLR expression simple by replacing the mathematical max functions of the conventional Max-Log-MAP expression with simple arithmetic functions associated with some deterministic parameters, such as a received value and distance between symbols on a signal space. Taking the implementation issues, like the area of silicon, the power consumption, the timing latency, and so on, into consideration, we submit that the proposed method is a promising alternative way to conventional methods for reconfigurable systems.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.4
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• pp.45-50
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• 2008

The Fourier-Mellin transform is the theoretical basis for the translation, rotation, and scale invariance of an image. However, its implementation requires a log-polar map of the original image, which requires logarithmic sampling of a radial variable in that image. This means that the mapping process is accompanied by considerable loss of data. To solve this problem, we propose a dual log-polar map that uses both a forward image map and a reverse image map simultaneously. Data loss due to the forward map sub-sampling can be offset by the reverse map. This is the first step in creating an invertible log-polar map. Experimental results have demonstrated the effectiveness of the proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6C
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• pp.438-443
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• 2008

The efficient method to implement the Max-Log-MAP algorithm is proposed by modifying the conventional algorithm. It is called a parallel soft output Viterbi algorithm (SOVA) and the rigorous proof is given for the equivalence between the Max-Log-MAP algorithm and the parallel SOVA. The parallel SOVA is compared with the conventional algorithms and we show that it is an efficient algorithm implementing the modified SOVA in parallel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3702-3707
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• 2009

In this paper, a new approximated MAP algorithm for soft bit decision from QAM symbols is proposed for Gray Coded QAM signals, based on the Max-Log-MAP and a Gray coded QAM signal can be separated into independent two Gray coded PAM signal, M-PAM on I axis with M symbols and N-PAM on Q axis with N symbols. The Max-Log-MAP used distance comparisons between symbols to get the soft bit decision instead of mathematical exponential or logarithm functions. But in accordance with the increase of the number of symbols, the number of comparisons also increase with high complexity. The proposed algorithm is used with the Euclidean distance and constituted with plain arithmetic functions, thus we can know intuitively that the algorithm has low implementing complexity comparing to conventional ones.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.9
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• pp.589-594
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• 2013

As the concept of web characteristics represented by openness and mind sharing grows more and more popular, device log data generated by both users and developers have become increasingly complicated. For such reasons, a log data processing mechanism that automatically produces meaningful data set from large amount of log records have become necessary for mobile device UX(User eXperience) analysis. In this paper, we define the attributes of to-be-analyzed log data that reflect the characteristics of a mobile device and collect real log data from mobile device users. Along with the MapReduce programming paradigm in Hadoop platform, we have performed a mobile device User eXperience analysis in a distributed processing environment using the collected real log data. We have then demonstrated the effectiveness of the proposed analysis mechanism by applying the various combinations of Map and Reduce steps to produce a simple data schema from the large amount of complex log records.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.438-441
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• 2000

In this paper, Turbo rode is describing a performance near the Shannon's channel capacity limit. So, basic theory of turbo code and MAP,Log-MAP decoding algorithm was arranged. The foundation of this using VHDL, Log-MAP turbodecoder was implemented by Altera´s FLEX10K CPLD.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.62-68
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• 2016

The fingerprint, which is one of the methods of indoor localization using WiFi, has been frequently studied because of its ability to be implemented via wireless access points. This method has low positioning resolution and high computational complexity compared to other methods, caused by its dependence of reference points in the radio map. In order to compensate for these problems, this paper presents a radio map designed algorithm based on the log-distance path loss model fusing a WiFi and BLE fingerprint. The proposed algorithm designs a radio map with variable values using the log-distance path loss model and reduces distance errors using a median filter. The experimental results of the proposed algorithm, compared with existing fingerprinting methods, show that the accuracy of positioning improved by from 2.747 m to 2.112 m, and the computational complexity reduced by a minimum of 33% according to the access points.