• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2010.07a
• /
• pp.1-3
• /
• 2010

스피어 복호 알고리즘 (sphere decoding algorithm)은 다중 입출력 (MIMO) 통신 시스템에서 사용되는 복호기중 최대 우도 복호기 (Maximum Likelihood Detector)와 비슷한 BER(bit error rate)성능을 가지고 복잡도를 줄일수 있어서 최근 많이 연구되어 왔다. 이때 공간 다중화와 채널 부호의 연접시스템에서 연판정 정보(Soft output information) 를 스피어 복호 알고리즘을 통해 생성하기 위한 방법으로 리스트 스피어 복호 알고리즘 (List Sphere Decoding)이 알려져있다. 기존 리스트 스피어 디코딩 알고리즘은 리스트를 반지름을 업데이트 하지 않으므로 탐색시 복잡도가 매우 높다는것이 문제가 되므로, 차원별로 최적해의 가능성이 높은 격자 주변으로 검색을 제한하여 복잡도를 줄이는 알고리즘을 제안하고 성능과 복잡도를 실험한다.

• Journal of the Korea Society of Computer and Information
• /
• v.27 no.3
• /
• pp.63-69
• /
• 2022

In this paper, we propose a new GPU-based framework for quickly calculating adaptive and continuous SDF(Signed distance fields), and examine cases related to rendering/collision processing using them. The quadtree constructed from the triangle mesh is transferred to the GPU memory, and the Euclidean distance to the triangle is processed in parallel for each thread by using it to find the shortest continuous distance without discontinuity in the adaptive grid space. In this process, it is shown through experiments that the cut-off view of the adaptive distance field, the distance value inquiry at a specific location, real-time raytracing, and collision handling can be performed quickly and efficiently. Using the proposed method, the adaptive sign distance field can be calculated quickly in about 1 second even on a high polygon mesh, so it is a method that can be fully utilized not only for rigid bodies but also for deformable bodies. It shows the stability of the algorithm through various experimental results whether it can accurately sample and represent distance values in various models.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.10
• /
• pp.721-727
• /
• 2001

In this paper, we propose a two-dimensional interleaving structure of holographic digital data storage. In this storage, many of the digital binary data are recorded, retrieved and processed in a two-dimensional data image (1000$\times$1000 bits). Therefore, burst errors in this digital device also have two-dimensional characteristics and it is required to use effective two-dimensional interleaving to overcome them. Bits of every code word should be distributed in an equilateral triangular lattice structure when they are scattered considering the random shape and occurrence of burst errors. We deal with factors and algorithm to construct this interleaving structure of equilateral triangular lattice.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.1
• /
• pp.15-20
• /
• 2016

Compared to the MIMO system using the spatial multiplexing methods and the MIMO system using the diversity scheme achieved a high rate, but the lower the diversity gain to improve the data transmission reliability should separate the spatial stream at the MIMO receiver. In this paper, we compared Channel capacity detection methods with the Lattice code, the 3-user interference channel and linear channel interference detection methods ZF (Zero Forcing) and MMSE (Minimum Mean Square Error) detection methods. The channel is a Diagonal channel. In other words, Diagonal channel is confirmed by the inverse matrix satisfies the properties of Jacket are element-wise inverse to $[H]_N[H]_N^{-1}=[I]_N$.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.3
• /
• pp.47-53
• /
• 1998

Multi-dimensional DC-free trellis codes based on two-dimensional constellation which can be omplemented more easily than conventional codes are proposed and their performances are analyzed in this paper. 2N-dimensional constellation of the proposed codes is constructed by concatenating N 2-dimensional constellation. Thus, for the proposed codes, information bits can be assigned easily to each signal point of the 2-dimensional consteellation and DC-free characteristic can be simply obtained by the symmetric structure of the constellation. In addition, since Viterbi decoder can calculate multi-dimensional Euchlidean distance between signals by simple sum of each 2-dimensional Euclidean distanc, decoding complexity can be reduced. The performance analysis shows that the proposed codes have almost same spectral characteristic and error performance as compared with conventional codes. However, the complexity is shown to be reduced further due to the construction method of contellation and the simple decoding algorithm of the proposed codes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.4
• /
• pp.950-956
• /
• 1998

In this paper, we investigate the effects of impulsive noise on the DS/SSMA system using TCM. We obtain the bound on the probability of bit error of the system, considering bothing impulsive noise and Rician fading, which are unavoidable in mobile communication environments. it turns out that we can achieve some coding gain by using TCM under impulsive noise environment. It is observed that the bit error probability is dominated by the background noise variance when the SNR is low and by the tail noise variance when the SNR is high.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.17 no.3
• /
• pp.158-165
• /
• 2005

In order to analyze incompressible two-phase flow, Level Set method was applied on pseudo-compressibility formulation. Level Set function is defined as a signed distance function from the phase interface, and gives the information of the each phase location and the geometric data to the flow. In this study, Level Set function transport equation was coupled with flow conservation equations, and owing to pseudo-compressibility technique we could solve the resultant vector equation iteratively. Two-phase flow analysis code was developed on general curvilinear coordinate, and numerical tests of bubble dynamics and surging wave problems demonstrate its capability successfully.

• Journal of the Korea Computer Graphics Society
• /
• v.17 no.2
• /
• pp.45-53
• /
• 2011

This paper proposes a volume meshing method that fills the inside of an object with tetrahedra, of which dihedral angles are good. The suggested method is fast, stable and easy to implement It can also utilize an octree structure to space-efficiently fill an object with graded tetrahedra by reducing the total number of tetrahedra. To obtain a high-quality mesh with good dihedral angles, we restrict the octree such that any pair of neighboring cells only differs by one level. To efficiently construct a restricted-octree and generate a volume mesh from the octree, we utilize a signed distance field of an object on its bounded workspace. The suggested method can be employed in FEM-based simulation of large elasto-plastic deformation and tetrahedral-mesh-based simulation of fluid flow.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.7
• /
• pp.1579-1588
• /
• 2014

The LAN method is the most widely used in domestic high-speed internet access and rapidly moving to 1 Gbps Ethernet from 100 Mbps one to provide high-speed services such as UHD TV. The 1000BASE-T PHY with 4 pairs UTP transmits a PAM-5 signal at the 125 MHz clock per each pair to achieve 1 Gbps rate. In order to correct errors over the channel, the transmitter uses a TCM which is combined the convolutional encoder and PAM-5, and the receiver uses the Viterbi decoder. In this paper, we implement a Viterbi decoder which can correct two pair errors and operate at the least 125 MHz clock speed. Finally, we will verify the error correction function and the operating speed of the implemented decoder with a logic analyzer.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.3
• /
• pp.193-201
• /
• 2022

SOQPSK-TG is a modulated signal for aircraft telemetry with excellent frequency efficiency and power efficiency. In this paper, the phase waveform of the partial response SOQPSK-TG modulation is linearly approximated and modeled as a full response double duobinary SOQPSK (SOQPSK-DD) signal. And using the XTCQM method and the Laurent decomposition method, the SOQPSK-DD signal was approximated as OQPSK having linear pulse waveforms, and the results of the two methods were proved to be the same. In addition, it was confirmed that the Laurent decomposition waveform of the SOQPSK-DD signal approximates the Laurent decomposition waveform of the original SOQPSK-TG signal. And it was shown that the decision feedback IQ-detector, which applied the Laurent decomposition waveform of SOQPSK-DD to the detection filter, exhibits almost the same performance even with a simpler waveform than before.