• Title/Summary/Keyword: z-interference channel

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Degrees of Freedom for MIMO Z-Interference Channels with Reconfigurable Antennas in the Absence of CSIT (송신단 채널 정보가 없는 재구성 안테나를 사용한 다중입출력 Z-간섭 채널에서의 자유도)

  • Yang, Heecheol;Lee, Jungwoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.2
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    • pp.291-298
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    • 2017
  • In this paper, we derive the achievable degrees of freedom (DoF) for multiple-input multiple-output (MIMO) Z-interference channels (Z-IC) with reconfigurable antennas at the receivers, assuming that channel state information is not available at the transmitters. We propose a new linear scheme to align interfering signals and to decode desired signals through the designed preset mode switching pattern of reconfigurable antennas at the receivers. The key idea of our scheme is to use interfering signals as a side information at the interfered receiver by being silent at the corresponding transmitter during some time slots. Consequently, it is shown that the reconfigurable antennas at the receivers can bring a DoF gain if the number of preset modes is greater than the number of RF chains at the receivers.

Closed-Form Expressions for Selection Combining System Statistics over Correlated Generalized-K Fading Channels in the Presence of Interference

  • Nikolic, Bojana Z.;Stefanovic, Mihajlo C.;Panic, Stefan R.;Anastasov, Jelena A.;Milosevic, Borivoje
    • ETRI Journal
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    • v.33 no.3
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    • pp.320-325
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    • 2011
  • This paper considers the effects of simultaneous correlated multipath fading and shadowing on the performances of a signal-to-interference ratio (SIR)-based dual-branch selection combining (SC) diversity receiver. This analysis includes the presence of cochannel interference. A generalized fading/shadowing channel model in an interference-limited correlated fading environment is modeled by generalized-K distribution. Closed-form expressions are obtained for probability density function and cumulative distribution function of the SC output SIR, as well as for the outage probability. Based on this, the influence of various fading and shadowing parameter values and the correlation level on the outage probability is examined.

QoS Analysis of Wireless Sensor Network with ARQ Scheme (ARQ 방식을 적용한 무선 센서 네트워크의 QoS 해석)

  • Roh, Jae-Sung;Kim, Wan-Tae
    • Journal of Advanced Navigation Technology
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    • v.14 no.1
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    • pp.49-56
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    • 2010
  • Severe energy constraints and the low power consumption require the significance of the energy efficient error control mechanisms in wireless sensor network (WSN). In this paper, an automatic repeat request (ARQ) methodology for the analysis of error control schemes in WSN is presented such that the effects of packet length, the modulation scheme and the interference effect of the wireless channel are investigated. Moreover, an analyis of ARQ error control is provided by considering two major architectures for wireless sensor network, i.e., Mica2 and MicaZ sensor nodes. And the throughput performance of WSN with asynchronous FSK signal and DSSS-OQPSK signal with selective repeat ARQ scheme are analyzed in multiple interference environment, and the probability of receiving a correct bit and packet from target node to sink node is evaluated as a function of the channel parameter, the number of wireless sensor node, and the spreading factor.

The Study of Space-Time Code using Z·F Detection Technique for Underwater Communication Environment (수중 통신 환경에서 Z·F 검출기법을 이용한 시공간 부호화 방식 연구)

  • Park, Tae-doo;Park, Gun-yeol;Jung, Ji-won;Kim, Beom Mu;Jeon, Sung Min;Lee, Seong-Ro
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2013.10a
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    • pp.405-408
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    • 2013
  • The performance of underwater acoustic(UWA) communication system is sensitive to the Inter-Symbol Interference(ISI) due to delay spread develop of multipath signal propagation. And due to limited frequency using acoustic wave, UWA is a low transmission rate. Thus, it is necessary technique of Space-time code, equalizer and channel code to improve transmission speed and eliminate ISI. In this paper, UWA communication system were analyzed by simulation using these techniques. In the result of simulation, the proposed Space-time code, Turbo code, and Zero forcing techniques is shown that improved performance than conventional UWA communication.

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A channel parameter-based weighting method for performance improvement of underwater acoustic communication system using single vector sensor (단일 벡터센서의 수중음향 통신 시스템 성능 향상을 위한 채널 파라미터 기반 가중 방법)

  • Kang-Hoon, Choi;Jee Woong, Choi
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.6
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    • pp.610-620
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    • 2022
  • An acoustic vector sensor can simultaneously receive vector quantities, such as particle velocity and acceleration, as well as acoustic pressure at one location, and thus it can be used as a single input multiple output receiver in underwater acoustic communication systems. On the other hand, vector signals received by a single vector sensor have different channel characteristics due to the azimuth angle between the source and receiver and the difference in propagation angle of multipath in each component, producing different communication performances. In this paper, we propose a channel parameter-based weighting method to improve the performance of an acoustic communication system using a single vector sensor. To verify the proposed method, we used communication data collected from the experiment conducted during the KOREX-17 (Korea Reverberation Experiment). For communication demodulation, block-based time reversal technique which is robust against time-varying channels were utilized. Finally, the communication results showed that the effectiveness of the channel parameter-based weighting method for the underwater communication system using a single vector sensor was verified.

Down-Regulation of Survivin by Nemadipine-A Sensitizes Cancer Cells to TRAIL-Induced Apoptosis

  • Park, Seong Ho;Park, So Jung;Kim, Joo-Oh;Shin, Ji Hyun;Kim, Eun Sung;Jo, Yoon Kyung;Kim, Jae-Sung;Park, So Jung;Jin, Dong-Hoon;Hwang, Jung Jin;Lee, Seung Jin;Jeong, Seong-Yun;Lee, Chaeyoung;Kim, InKi;Cho, Dong-Hyung
    • Biomolecules & Therapeutics
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    • v.21 no.1
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    • pp.29-34
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    • 2013
  • The tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family of cytokines. TRAIL selectively induces apoptotic cell death in various tumors and cancer cells, but it has little or no toxicity in normal cells. Agonism of TRAIL receptors has been considered to be a valuable cancer-therapeutic strategy. However, more than 85% of primary tumors are resistant to TRAIL, emphasizing the importance of investigating how to overcome TRAIL resistance. In this report, we have found that nemadipine-A, a cell-permeable L-type calcium channel inhibitor, sensitizes TRAIL-resistant cancer cells to this ligand. Combination treatments using TRAIL with nemadipine-A synergistically induced both the caspase cascade and apoptotic cell death, which were blocked by a pan caspase inhibitor (zVAD) but not by autophagy or a necrosis inhibitor. We further found that nemadipine-A, either alone or in combination with TRAIL, notably reduced the expression of survivin, an inhibitor of the apoptosis protein (IAP) family of proteins. Depletion of survivin by small RNA interference (siRNA) resulted in increased cell death and caspase activation by TRAIL treatment. These results suggest that nemadipine-A potentiates TRAIL-induced apoptosis by down-regulation of survivin expression in TRAIL resistant cells. Thus, combination of TRAIL with nemadipine-A may serve a new therapeutic scheme for the treatment of TRAIL resistant cancer cells, suggesting that a detailed study of this combination would be useful.