• Title/Summary/Keyword: superposition modulation

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On Calculation of Total Power and Allocation for Achieving Near 1+1 Capacity Region of 2PAM NOMA in 5G Networks (5G 네트워크에서 비직교 다중 접속 2PAM의 근접 1+1 용량 영역 달성을 위한 총 전력과 할당의 계산)

  • Chung, Kyuhyuk
    • Journal of Convergence for Information Technology
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    • v.11 no.5
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    • pp.9-16
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    • 2021
  • In binary-modulation non-orthogonal multiple access (NOMA), there has been rare researches for the 1+1 capacity region to be achieved; how much total power is required and what power allocation is assigned for this total power. In this paper, the average total transmitted power to achieve 1+1 capacity region of binary pulse amplitude modulation (2PAM) NOMA is investigated, with a tolerable loss. Then, based on the sufficient average total transmitted power, we calculate the power allocation coefficient to achieve 1+1 capacity region. Furthermore, it is shown by numerical results that with the tolerable loss less than 0.008, near 1+1 capacity region is achieved. We also calculate numerically the power allocation coefficient for both users to achieve near 1+1 capacity region. As a result, for 2PAM NOMA to operate near 1+1 capacity region, proper total power with appropriate power allocation could be calculated in design of NOMA systems.

Bidirectional Zeta-Flyback Converter for Improved Efficiency (개선된 효율을 가지는 양방향 Zeta-Flyback 컨버터)

  • Jung, Mun-Kyu;Kwon, Young-Ahn
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.6
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    • pp.844-849
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    • 2012
  • In this paper, a bidirectional Zeta-Flyback converter is proposed. The topology of the proposed converter is analyzed, which is superposition of bidirectional Flyback converter mode and bidirectional Zeta converter mode in a cycle. The proposed converter allows power flow in either a forward direction or a backward direction. Bidirectional power flow is obtained by a transformer and components. The proposed converter's output is controlled by duty of constant frequency PWM of switch. Compared to conventional bidirectional isolated DC-DC converters, the proposed isolated bidirectional DC-DC converter has high power density and high transformer utilization. To confirm the proposed converter, the simulation and experimental results are presented.

Near-BER lossless Asymmetric 2PAM non-SIC NOMA with Low-Complexity and Low-Latency under User-Fairness

  • Chung, Kyuhyuk
    • International Journal of Internet, Broadcasting and Communication
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    • v.13 no.2
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    • pp.43-51
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    • 2021
  • As the number of mobile devices has been increasing tremendously, system capacity should be enlarged in future next generation communication, such as the fifth-generation (5G) and beyond 5G (B5G) mobile networks. For such future networks, non-orthogonal multiple access (NOMA) has been considered as promising multiple access technology. In this paper, to reduce both latency and complexity in existing NOMA, we propose non-successive interference cancellation (SIC) NOMA with asymmetric binary pulse amplitude modulation (2PAM), nearly without bit-error rate (BER) loss. First, we derive the closed form of BER expressions for non-SIC NOMA with asymmetric 2PAM, especially under Rayleigh fading channels. Then, it is shown that the BER performance of the stronger channel user who is supposed to perform SIC in conventional NOMA can be nearly achieved by the proposed non-SIC NOMA with asymmetric 2PAM, especially without SIC. Furthermore, we also show that the BER performance of the weaker channel user in conventional NOMA can be more closely achieved by the proposed non-SIC NOMA with asymmetric 2PAM. These BERs are shown to be achieved over the part of the power allocation range, which is consistent with the NOMA principle of user fairness. As a result, the non-SIC NOMA scheme with asymmetric 2PAM could be considered as a promising NOMA scheme toward next generation communication.

Non-interfering Non-orthogonal Multiple Access: With Application to Improving BER of Weakest Channel User in 3-User 2PAM (비간섭 비직교 다중접속: 삼중 2PAM의 최약 채널 사용자의 BER 향상 관점에서)

  • Chung, Kyu-Hyuk
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.4
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    • pp.585-590
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    • 2021
  • This paper proposes a 3-user non-interfering binary pulse amplitude modulation(2PAM) and non-orthogonal multiple access(NOMA) scheme, to improve the bit-error rate(BER) performance of the weakest channel user with the tolerable BER loss of the stronger channel users. First, we design the 3-user non-interfering 2PAM NOMA, and then derive the closed-form expressions for the BERs of the proposed scheme. Numerical results are also presented to demonstrate that the BER of the weakest channel user improves greatly, with the small BER losses of the stronger channel users. As a result, the non-interfering 2PAM could be considered in NOMA of 5G systems.

Effect of Microcurrent Wave Superposition on Cognitive Improvement in Alzheimer's Disease Mice Model (알츠하이머 질환 마우스에서 중첩주파수를 활용한 미세전류가 인지능력 개선에 미치는 효과)

  • Kim, Min Jeong;Lee, Ah Young;Cho, Dong Shik;Cho, Eun Ju
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.5
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    • pp.241-251
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    • 2019
  • In the present study, we investigated the effect of microcurrent against cognitive impairment in Alzheimer's disease (AD) mice model. The cognitive impairment was induced by intracerebroventricularly injection of amyloid beta ($A{\beta}$) to ICR mouse brain, and four kinds of micorocurrent wave were applied to AD mice. We observed the improved cognitive ability in microcurrent-applied AD mice through novel object recognition test and Morris water maze test, compared to $A{\beta}$-injected control group. The contents of malondialdehyde generated by $A{\beta}$ in the brain were also reduced by microcurrent application. These effects of microcurrent were related to the modulation of $A{\beta}$ producing and brain-derived neurotrophic factor (BDNF). Microcurrent down-regulated ${\beta}$-secretase, presenilin 1, and presenilin 2 which were related amyloidogenic pathway, and up-regulated human brain-derived neurotrophic factor in the mice brain, especially Wave4 group [STEP FORM wave form (0, 1.5, 3, 5V), wave superposition]. These results suggest that microcurrent application could provide help for improvement learning and memory ability, at least partly.

On Design and Performance Analysis of Asymmetric 2PAM: 5G Network NOMA Perspective (비대칭 2PAM의 설계와 성능 분석: 5G 네트워크의 비직교 다중 접속 관점에서)

  • Chung, Kyuhyuk
    • Journal of Convergence for Information Technology
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    • v.10 no.10
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    • pp.24-31
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    • 2020
  • In non-orthogonal multiple access (NOMA), the degraded performance of the weaker channel gain user is a problem. In this paper, we propose the asymmetric binary pulse amplitude modulation (2PAM), to improve the bit-error rate (BER) performance of the weaker channel user in NOMA with the tolerable BER loss of the stronger channel user. First, we design the asymmetric 2PAM, calculate the total allocated power, and derive the closed-form expression for the BER of the proposed scheme. Then it is shown that the BER of the weaker channel user improves, with the small BER loss of the stronger channel user. The superiority of the proposed scheme is also validated by demonstating that the signal-to-noise ratio (SNR) gain of the weaker channel user is about 10 dB, with the SNR loss of 3 dB of the stronger channel user. In result, the asymmetric 2PAM could be considered in NOMA of 5G systems. As a direction of the future research, it would be meaningful to analyze the achievable data rate for the propsed scheme.

MRI Artifact Correction due to Unknown Respiratory Motion (미지 호흡운동에 의한 MRI 아티팩트의 수정)

  • 김응규
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.41 no.5
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    • pp.53-62
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    • 2004
  • In this study, an improved post-processing technique for correcting MRI artifact due to the unknown respiratory motion in the imaging plane is presented. Respiratory motion is modeled by a two-Dimensional linear expending-shrinking movement. Assuming that the body tissues are incompressible fluid like materials, the proton density per unit volume of the imaging object is kept constant. According to the introduced model, respiratory motion imposes phase error, non-uniform sampling and amplitude modulation distortions on the acquired MRI data. When the motion parameters are known or can be estimatead a reconstruction algorithm based on biliner superposition method was used to correct the MRI artifact. In the case of motion parameters are unknown, first, the spectrum shift method is applied to find the respiratory fluctuation function, x directional expansion coefficient and x directional expansion center. Next, y directional expansion coefficient and y directional expansion center are estimated by using the minimum energy method. Finally, the validity of this proposed method is shown to be effective by using the simulated motion images.

Transport parameters in a-Se:As films for digital X-ray conversion material (디지털 X-선 변환물질 a-Se:As의 수송변수)

  • Park, Chang-Hee
    • Korean Journal of Digital Imaging in Medicine
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    • v.8 no.1
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    • pp.51-55
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    • 2006
  • The effects of Asaddition in amorphous selenium(a-Se) films for digital X-ray conversion material have been studied using the moving photocarrier grating(MPG) technique. This method utilizes the moving interference pattern generated by the superposition of the two frequency shifted laser beams for the illumination of the sample. This moving intensity grating induces a short circuit current, j$_{sc}$ in a-Se:As film. The transport parameters of the sample are extracted from the grating-velocity dependent short circuit current induced in the sample along the modulation direction. The electron and hole mobility, and recombination lifetime of a-Se films with arsenic(As) additions have been obtained. We have found an Increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density. The transport properties for As doped a-Se films obtained by using MPG technique have been compared with X-ray sensitivity for a-Se:As device. The fabricated a-Se(0.3% As) device film exhibited the highest X-ray sensitivity out of 5 samples.

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A study on the natural history virtual reality contents using depaysement (데페이즈망 기법을 활용한 자연사VR 콘텐츠 연구)

  • Park, Ki-Deok;Chung, Jean-Hun
    • Journal of Digital Convergence
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    • v.17 no.6
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    • pp.365-371
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    • 2019
  • In this study, VR contents were produced by using the rose which is the material of the tomb of the surrealistic work wrestler of Rene Magritte, an artistic genre, as a motive. In conclusion, the distortion (spatial modulation) of the image scale is connected to the dynamic-curve and texture-soft areas, and the superposition (combination of contradictory images) is called the big-size, irregular-depth area, Are connected to the positions of big-size and irregular-space regions. The theme of the work was Dream, and the plants and roses patterns were produced in each timeline, and overlap, scale, distortion, overlap, distortion, and scale were used.

Crystal Structure of Thiolase from Clostridium butyricum (Clostridium butyricum 유래 Thiolase의 입체구조규명 연구)

  • Kim, Eun-Jung;Kim, Kyung-Jin
    • Journal of Life Science
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    • v.26 no.3
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    • pp.353-358
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    • 2016
  • Thiolase is an enzyme that catalyzes condensation reactions between two acetyl-CoA molecules to produce acetoacetyl-CoA. As thiolase catalyzes is the first reaction in the production of n-butanol, knowledge of the molecular and regulatory mechanism of the enzyme is crucial for synthesizing high-value biofuel. Thiolase from Clostridium butyricum (CbTHL) was expressed, purified, and crystallized. X-ray diffraction data were collected from the crystals, and the 3-dimentional structure of the enzyme was determined at 2.0 Å. The overall structure of thiolase was similar to that of type II biosynthetic thiolases, such as thiolase from C. acetobutylicum (CaTHL). The superposition of this structure with that of CaTHL complexed with CoA revealed the residues that comprise the catalytic and substrate binding sites of CbTHL. The catalytic site of CbTHL contains three conserved residues, Cys88, His349, and Cys379, which may function as a covalent nucleophile, general base, and second nucleophile, respectively. For substrate binding, the way in which CbTHL stabilized the ADP moiety of CoA was unlike that of other thiolases, whereas the stabilization of β-mercaptoethyamine and pantothenic acid moieties of CoA was quite similar to that of other enzymes. The most interesting observation in the CbTHL structure was that the enzyme was regulated through redox-switch modulation, using a reversible disulfide bond.