• Title/Summary/Keyword: asymmetric channel

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Joint Relay Selection and Power Allocation for Two-way Relay Channels with Asymmetric Traffic Requirements

  • Lou, Sijia;Yang, Longxiang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.8
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    • pp.1955-1971
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    • 2013
  • This paper studies relay selection and power allocation for amplify-and-forward (AF) based two-way relay networks (TWRN) with asymmetric traffic requirements (ATR). A joint relay selection and power allocation algorithm is proposed to decrease the outage probability of TWRN with ATR. In this algorithm, two sources exchange information with the help of the relay during two time slots. We first calculate the optimal power allocation parameters based on instantaneous channel state information (CSI), and then derive a tight lower bound of outage probability. Furthermore, we propose a simplified relay selection criterion, which can be easily calculated as harmonic mean of instantaneous channel gains, according to the outage probability expressions. Simulation results verified the theoretical analyses we presented. It is shown that the outage probability of our algorithm improves 3-4dB comparing with that of other existing algorithms, and the lower bound is tight comparing with actual value for the entire signal-to-noise ratio (SNR) region.

A study of electrical stress on short channel poly-Si thin film transistors (짧은 채널 길이의 다결정 실리콘 박막 트랜지스터의 전기적 스트레스에 대한 연구)

  • 최권영;김용상;한민구
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.8
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    • pp.126-132
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    • 1995
  • The electrical stress of short channel polycrystalline silicon (poly-Si) thin film transistor (TFT) has been investigated. The device characteristics of short channel poly-Si TFT with 5$\mu$m channel length has been observed to be significantly degraded such as a large shift in threshold voltage and asymmetric phenomena after the electrical stress. The dominant degradation mechanism in long channel poly-Si TFT's with 10$\mu$m and 20$\mu$m channel length respectively is charage trappling in gate oxide while that in short channel device with 5.mu.m channel length is defect creation in active poly-Si layer. We propose that the increased defect density within depletion region near drain junction due to high electric field which could be evidenced by kink effect, constitutes the important reason for this significant degradation in short channel poly-Si TFT. The proposed model is verified by comparing the amounts of the defect creation and the charge trapping from the strechout voltage.

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Effects of Channel Structure on the Quality Competition of Exclusively Distributed Products

  • Kang, Yeong Seon
    • Asia Marketing Journal
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    • v.19 no.4
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    • pp.37-59
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    • 2018
  • This study investigates the effects of the distribution channel structure on quality decisions under duopoly competition. I considers a set-up in which two retailers compete on product quality and retail price. In the set-up, the integrated retailer has the power to determine the quality of its exclusive product, while the decentralized retailer does not. For the decentralized retailer, the supplier determines product quality. I find that asymmetric pairs of a decentralized channel by one retailer and an integrated channel by the other retailer can be a Nash equilibrium in a simultaneous-channel-choice model. The two retailers select different levels of quality, and this quality competition benefits retailers by softening price competition. In a sequential-channel-choice model, I find that the leader can obtain a first-mover advantage. From the perspective of the supplier, which can decide the distribution channel structure and level of quality, both suppliers choose the decentralized channel in equilibrium.

Electrical Characteristics of NMOSFET's with Asymmetric Source/Drain Region (비대칭 소오스/드레인을 갖는 NMOSFET의 전기적 특성)

  • 공동욱;이재성이용현
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.533-536
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    • 1998
  • The electrical characteristics of NMOSFETs with asymmetrical source/drain regions have been expermentally investigated using test devices fabricated by $0.35\mu\textrm{m}$ CMOS technology. The performance degradation for asymmetric transistor and its causes are analyzed. The parasitic resistances, such as series resistance of active regions and silicide junction contact resistance, are distributed in parallel along the channel. Depending on source/drain geometry, the array of those resistances is changed, that results the various electrical properties.

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Symmetric and Asymmetric Double Gate MOSFET Modeling

  • Abebe, H.;Cumberbatch, E.;Morris, H.;Tyree, V.;Numata, T.; Uno, S.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.9 no.4
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    • pp.225-232
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    • 2009
  • An analytical compact model for the asymmetric lightly doped Double Gate (DG) MOSFET is presented. The model is developed using the Lambert Function and a 2-dimensional (2-D) parabolic electrostatic potential approximation. Compact models of the net charge and channel current of the DG-MOSFET are derived in section 2. Results for the channel potential and current are compared with 2-D numerical data for a lightly doped DG MOSFET in section 3, showing very good agreement.

PRML Detection Method Using PRSNR (부분응답 신호대잡음비를 이용한 PRML 검출 방법)

  • Park Ae-Kyung;Lee Jae-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.9C
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    • pp.840-845
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    • 2006
  • This paper presents a partial response maximum likelihood (PRML) detection method using partial response signal-to-noise ratio (PRSNR) that evaluates the signal quality of asymmetric optical recording channel. It is confirmed that the equalizer maximizing the PRSNR value can be most properly adapted to the asymmetric optical recording channel. The proposed PRML detection using this result has 1.8dB SNR gain at $8.5{\times}10-5$ bit error rate compared to PRML detection using typical adaptive equalizer.

Asymmetric channel model for a perpendicular magnetic recording system with a ring-head (Ring-헤드를 갖는 수직 자기기록 시스템을 위한 비대칭 채널 모델)

  • Lee, Joo-Hyun;Lee, Jae-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.1C
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    • pp.45-49
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    • 2004
  • An image enhancement method using modified anisotropic diffusion filter is proposed in this paper. It employs sensor noise estimation and scale space methods based on the minimum reliable scale. Then the anisotropic diffusion filter is modified by the calculated critical value function and local gradient. Through simulation, it is verified that the proposed algorithm has the capability of little or no noise amplification in homogenous region as well as superior edge enhancement.

Numerical analysis of viscoelastic flows in a channel obstructed by an asymmetric array of obstacles

  • Kwon, Young-Don
    • Korea-Australia Rheology Journal
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    • v.18 no.3
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    • pp.161-167
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    • 2006
  • This study presents results on the numerical simulation of Newtonian and non-Newtonian flow in a channel obstructed by an asymmetric array of obstacles for clarifying the descriptive ability of current non-Newtonian constitutive equations. Jones and Walters (1989) have performed the corresponding experiment that clearly demonstrates the characteristic difference among the flow patterns of the various liquids. In order to appropriately account for flow properties, the Navier-Stokes, the Carreau viscous and the Leonov equations are employed for Newtonian, shear thinning and extension hardening liquids, respectively. Making use of the tensor-logarithmic formulation of the Leonov model in the computational scheme, we have obtained stable solutions up to relatively high Deborah numbers. The peculiar characteristics of the non-Newtonian liquids such as shear thinning and extension hardening seem to be properly illustrated by the flow modeling. In our opinion, the results show the possibility of current constitutive modeling to appropriately describe non-Newtonian flow phenomena at least qualitatively, even though the model parameters specified for the current computation do not precisely represent material characteristics.

Analysis of Laminar Flow and Heat Transfer in Asymmetric, Sudden Expansion Channel (비대칭급확대채널의 층류유동 및 열전달 해석)

  • Won, Seung-Ho;Maeng, Joo-Sung;Son, Byung-Jin
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.13 no.1
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    • pp.5-13
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    • 1984
  • This analysis of numerical procedure is prediction of laminar flow and heat transfer at two dimension and steady flow in asymmetric sudden expansion channel. At former study, to analyse the flows with separation, the full Navier-Stokes equation is used, but there are many difficulties to analyse, and although significant progress has been made in the development of efficient computational methods for the Navier-Stokes equations, very large computation times are still required. In case of reward-facing flow, boundary-layer equation is used instead of full Navier-Stokes equation to analyse velocity fields, and result of this numerical analysis is good agreement with the given experimental study. In this case, since the computer time required for the boundary-layer calculation is an order of magnitude less than required for the solution of the full Navier-Stokes equation, this boundary-layer model provides a good approximate solution.

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EM Algorithm for Designing Soft-Decision Binary Error Correction Codes of MLC NAND Flash Memory (멀티 레벨 낸드 플래시 메모리용 연판정 복호를 수행하는 이진 ECC 설계를 위한 EM 알고리즘)

  • Kim, Sung-Rae;Shin, Dong-Joon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.3
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    • pp.127-139
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    • 2014
  • In this paper, we present two signal processing techniques for designing binary error correction codes for Multi-Level Cell(MLC) NAND flash memory. MLC NAND flash memory saves the non-binary symbol at each cell and shows asymmetric channel LLR l-density which makes it difficult to design soft-decision binary error correction codes such as LDPC codes and Polar codes. Therefore, we apply density mirroring and EM algorithm for approximating the MLC NAND flash memory channel to the binary-input memoryless channel. The density mirroring processes channel LLRs to satisfy roughly all-zero codeword assumption, and then EM algorithm is applied to l-density after density mirroring for approximating it to mixture of symmetric Gaussian densities. These two signal processing techniques make it possible to use conventional code design algorithms, such as density evolution and EXIT chart, for MLC NAND flash memory channel.