• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.51-59
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• 2017

In this paper, we propose a gray code order of antenna index permutations for differential spatial modulation (DSM). To facilitate the implementation, the well-known Trotter-Johnson ranking and unranking algorithms are adopted, which result in similar computational complexity to the existing DSM that uses the lexicographic order. The signal-to-noise ratio gain achieved by the proposed gray code order over the lexicographic order is also analyzed and verified via simulations. Based on the gray coding framework, we further propose a diversity-enhancing scheme named intersected gray (I-gray) code order, where the permutations of active antenna indices are selected directly from the odd (or even) positions of the full permutations in the gray code order. From analysis and simulations, it is shown that the I-gray code order can harvest an additional transmit diversity order with respect to the gray code order.

• KIISE Transactions on Computing Practices
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• v.21 no.2
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• pp.148-153
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• 2015

In our domestic software industries, it is focused on such a high quality development/ testing process, maturity measurement, and so on. But the real industrial fields are still working on a code-centric development. Most of the existing legacy systems did not keep the design and highly increased the code complexity with more patching of the original codes. To solve this problem, we adopt a code visualization technique which is important to reduce the code complexity among modules. To do this, we suggest a tool chaining method based on the existing open source software tools, which extends NIPA's Software Visualization techniques applied to procedural languages. In addition, it should be refactored to fix bad couplings of the quality measurement indicators within the code visualization. As a result, we can apply reverse engineering to the legacy code, that is, from programming via model to architecture, and then make high quality software with this approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1219-1225
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• 2007

In this paper, we propose a new quasi-orthogonal space-time block code(QO-STBC) achieving full rate and full diversity for general QAM and quasi-static Rayleigh fading channels with four transmit antennas. This code possesses the quasi orthogonal property like the conventional minimum decoding complexity QO-STBC(MDC-QO-STBC), which allows independently a maximum likelihood(ML) decoding to only require joint detection of two real symbols. By computer simulation results, we show that the proposed code exhibits the identical BER performance with the existing MDC-QO-STBC. However, the proposed code has an advantage in the transceiver implementation since the original coding scheme may be modified so that increases of peak-to-average power ratio occur at only two transmit antennas, but the MDC-QO-STBC does at all of transmit antennas.

• Journal of the Korea Society of Computer and Information
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• v.9 no.3
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• pp.27-34
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• 2004

As software developing paradigm has been changing to complicate Web environment, study of complexity becomes vigorous. Yet still it seems that general agreement has not to be reached to architecture or complexity measure of Web application. And so traditional complexity metrics - program size(LOC) and Cyclomatic Complexity can be derived from the source code after implementation. it is not helpful to the early phase of software development life cycle - analysis and design phase. In this study 6 Web projects has been used for deriving applications with possible errors suited by Complexity Indicator. Using 61 programs derived, linear correlation between complexity, number of classes and number of methods has been proposed. As Web application complexity could be estimated before implementation, effort and cost management will be processed more effectively.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.999-1000
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• 2006

The LDPC Code is focusing a powerful FEC(Forward Error Correction) codes for 4G Mobile Communication system. LDPC codes are used minimizing channel errors by modeling AWGN Channel as VDSL system. The performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. LDPC code are encoded by sparse parity check matrix. there are decoding algorithms for a LDPC code, Bit Flipping, Message passing, Sum-Product. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1551-1558
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• 2007

The standard of evaluating function of speech coder for mobile telecommunication can be shown in channel capacity, noise immunity, encryption, complexity and encoding delay largely. This study is an algorithm to reduce complexity applying to CDMA(Code Division Multiple Access) mobile telecommunication system, which has a benefit of keeping the existing advantage of telecommunication quality and low transmission rate. This paper has an objective to reduce the computing complexity by controlling the frequency band nonuniform during the changing process of LSP(Line Spectrum Pairs) parameters from LPC(Line Predictive Coding) coefficients used for EVRC(Enhanced Variable-Rate Coder, IS-127) speech coders. Its experimental result showed that when comparing the speech coder applied by the proposed algorithm with the existing EVRC speech coder, it's decreased by 45% at average. Also, the values of LSP parameters, Synthetic speech signal and Spectrogram test result were obtained same as the existing method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.303-309
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• 2006

By combining the space-time diversity technique and iterative turbo codes, space-time turbo codes(STTCS) are able to provide powerful error correction capability. However, the multi-path transmission and iterative decoding structure of STTCS make the decoder very complex. In this paper, we propose a low complexity decoder, which can be used to decode STTCS as well as general iterative codes such as turbo codes. The efficient implementation of the backward recursion and the log-likelihood ratio(LLR) update in the proposed algorithm improves the computational efficiency. In addition, if we approximate the calculation of the joint LLR by using the approximate ratio(AR) algorithm, the computational complexity can be reduced even further. A complexity analysis and computer simulations over the Rayleigh fading channel show that the proposed algorithm necessitates less than 40% of the additions required by the conventional Max-Log-MAP algorithm, while providing the same overall performance.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.10
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• pp.431-436
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• 2023

Recently the incorporation of artificial intelligence approaches in the field of software engineering has been one of the big topics. In the world, there are actively studying in two directions: 1) software engineering for artificial intelligence and 2) artificial intelligence for software engineering. We attempt to apply artificial intelligence to software engineering to identify and refactor bad code module areas. To learn the patterns of bad code elements well, we must have many datasets with bad code elements labeled correctly for artificial intelligence in this task. The current problems have insufficient datasets for learning and can not guarantee the accuracy of the datasets that we collected. To solve this problem, when collecting code data, bad code data is collected only for code module areas with high-complexity, not the entire code. We propose a method for exploring common weakness enumeration by learning the collected dataset based on transfer learning of the CodeBERT model. The CodeBERT model learns the corresponding dataset more about common weakness patterns in code. With this approach, we expect to identify common weakness patterns more accurately better than one in traditional software engineering.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.10
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• pp.213-220
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• 2020

The power consumption and performance of hardware-based mobile and IoT embedded systems that require high specifications are one of the important issues of these systems. In particular, the problem of excessive power consumption is because it causes a problem of increasing heat generation and shortening the life of the device. In addition, in the same environment, software also needs to perform stable operation in limited power and memory, thereby increasing power consumption of the device. In order to solve these issues, we propose a Low level power improvement via identifying performance dissipation. The proposed method identifies complex modules (especially Cyclomatic complexity, Coupling & Cohesion) through code visualization, and helps to simplify low power code patterning and performance code. Therefore, through this method, it is possible to optimize the quality of the code by reducing power consumption and improving performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.6 s.348
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• pp.1-8
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• 2006

In the asynchrous OFCDM(Orthogonal Frequency and Code Division Multiplexing) system, a three-step cell search algorithm is performed for the initial synchronization in the following three steps: OFCDM symbol timing, i.e., Fast Fourier Transform(FFT) window timing is estimated employing guard interval (GI) correlation in the first step, then the frame timing and CSSC (Cell Specific Scrambling Code) group is detected by taking the correlation of the CPICH(Common Pilot Channel) based on the property yeilded by shifting the CSSC phase in the frequency domain. Finally, the CSSC phase within the group is identified in the third step. This paper proposes a modification code(PCSSCG:Patial Cell Specific Scrambling Code Group) of the conventional CPICH based cell search algorithm in the second step which offers MS(Mobile Station) complexity reductions with the nearly same performance. The proposed method is to be compared and verified through the computer simulation.