• Title/Summary/Keyword: Multiple Channels

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A burst-error-correcting decoding scheme of multiple trellis-coded $\pi$/4 shift QPSK for mobile communication channels (이동 통신 채널에서 다중 트렐리스 부호화된 $\pi$/4 shift QPSK의 연집 에러 정정 복호 방식)

  • 이정규;송왕철;홍대식;강창언
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.4
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    • pp.24-31
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    • 1995
  • In this paper, the dual-mode burst-error-correcting decoding algorithm is adapted to the multiple trellis-coded .pi./4 shift QPSK in order to achieve the improvement of bit error rate (BER) performance over fading channels. The dual-mode adaptive decoder which combines maximum likelihood decoding with a burst detection scheme usually operates as a Viterbi decoder and switches to time diversity error recovery whenever an uncorrectable error pattern is identified. Rayleigh fading channels and Rician fading channels having the Rician parameter K=5dB are used in computer simulation, and the simulation results are compared with those of interleaving techniques. It is shown that under the constraint of the fixed overall memory quantity, the dual-mode adaptive decoding scheme gains an advantage in the BER performance with respect to interleaving strategies.

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Performance of DS/SSMA Communications over Nonselective Fading Channels with Gaussian and Impulsive Noise Channels (가우스 잡음과 임펄스 잡음이 혼합된 비선택적 페이딩 채널에서의 DS/SSMA 통신의 성능 분석)

  • 진익수;김은묵;박용석;황금찬
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.16 no.9
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    • pp.838-849
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    • 1991
  • An accurate approximation based on the integration of the characteristic function of the multiple access interference which consists of specular and scatter components is obtained for the average probability of error for asynchronous binary PSK direct sequence spread spectrum multiple access(DS/SSMA) communications system operating over nonselective fading channels with additive white Gaussian and impulsive noise channels.

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Power Monitoring System with Multiple Input Channels Using the Definition of IEEE Standard 1459-2010 (IEEE 1459-2010 규격의 정의를 이용한 다중 입력 채널을 갖는 전력 감시 시스템)

  • Jeon, Jeong-Chay;Oh, Hun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.5
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    • pp.3100-3106
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    • 2014
  • This paper develops power measurement system with multiple sensor input channels (voltage-8 channels and current-10 channels) that simultaneously can monitor power components for both supply and load side of power system. The hardware implementation of the proposed system is based on TMS320C42 DSP and signal processing program algorithm to calculate power components use the definition of IEEE Standard 1459-2010 related power quality. The performance of the developed system is tested by using standard ac power source device, and the test results showed that accuracy of the developed system is less than 0.2 %. Also, field test of the proposed system in the three-phase and four-wire power system was implemented. Simultaneous multiple channel measurement and analysis of power components in commercial and industrial electrical power system using the proposed system will be necessary to reduce power quality problems.

A New Routing Protocol in Wireless Ad-hoc Networks with Multiple Radios and Channels

  • Ko, Sung-Won;Cho, Jeong-Hwan;Hong, Kwon-Eui
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.7
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    • pp.26-40
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    • 2010
  • We propose a new routing protocol, MCQosR, that is based on bandwidth estimation, admission control, and a routing metric, MCCR - suitable for wireless ad-hoc networks with multiple radios and channels. To use the full capacity of a wireless link, we assume a node with multiple radios for full duplex operation, and a radio using multiple channels to exclude route-intra interference. This makes it possible to use the capacity of a wireless link. Then, to provide bandwidth and delay guarantee, we have a radio with a fixed channel for layer-3 data reception at each node, used to estimate the available bandwidth and expected delay of a wireless link. Based on the estimate of available bandwidth and delay, we apply the call admission control to a new call requiring bandwidth and delay guarantee. New calls with traffic that will overflow link or network capacity are rejected so the accepted calls can use the required bandwidth and delay. Finally, we propose a routing metric, MCCR, which considers the channel contentions and collisions of a wireless link operating in CSMA/CA. MCCR is useful for finding a route with less traffic and distributing traffic over the network to prevent network congestion as much as possible. The simulation of the MCQosR protocol and the MCCR metric shows traffic is distributed and guaranteed service is provided for accepted calls.

Multi-Antenna Noncoherent ML Synchronization for UWB-IR Faded Channels

  • Baccarelli Enzo;Biagi Mauro;Pelizzoni Cristian;Cordeschi Nicola
    • Journal of Communications and Networks
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    • v.8 no.2
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    • pp.194-204
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    • 2006
  • This contribution focuses on the maximum likelihood (ML) noncoherent synchronization of multi-antenna transceivers working in faded environments and employing ultra-wideband impulse radio (UWB-IR) transmit technology. In particular, the Cramer-Rao bound (CRB) is derived for the general case of multiple input multiple output (MIMO) UWB-IR systems and used to compare the ultimate performance of three basic transmit schemes, thereinafter referred to as single input multiple output (SIMO), MIMO equal signaling (MIMO-ES), and MIMO orthogonal signaling (MIMO-OS) ones. Thus, the noncoherent ML synchronizer is developed for the better performing transmit scheme (i.e., the SIMO one) and its performance is evaluated under both signal acquisition and tracking operating conditions. The performance gain in the synchronization of UWB- IR signals arising by the utilization of the multi-antenna technology is also evaluated.

Space-Polarization Division Multiple Access System with Limited Feedback

  • Joung, Heejin;Jo, Han-Shin;Mun, Cheol;Yook, Jong-Gwan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.4
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    • pp.1292-1306
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    • 2014
  • This paper proposes a space-polarization division multiple access (SPDMA) system that has limited feedback channels. The system simultaneously serves data streams to multiple mobile users through dual-polarized antenna arrays, by using pre-determined sets of precoding vectors that are orthogonal in both space and polarization domains. To this end, a codebook whose elements are sets of the precoding vectors is systematically designed based on the discrete Fourier transform (DFT) matrix and considering the power imbalance of polarized channels. Throughput of the SPDMA system is evaluated and compared to that of space division multiple access (SDMA) system, according to the various parameters including cross polarization discrimination (XPD). The results show that the throughput of SPDMA system outperforms that of SDMA in the environments of high XPD with many mobile users.

Gated Multi-channel Network Embedding for Large-scale Mobile App Clustering

  • Yeo-Chan Yoon;Soo Kyun Kim
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.17 no.6
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    • pp.1620-1634
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    • 2023
  • This paper studies the task of embedding nodes with multiple graphs representing multiple information channels, which is useful in a large volume of network clustering tasks. By learning a node using multiple graphs, various characteristics of the node can be represented and embedded stably. Existing studies using multi-channel networks have been conducted by integrating heterogeneous graphs or limiting common nodes appearing in multiple graphs to have similar embeddings. Although these methods effectively represent nodes, it also has limitations by assuming that all networks provide the same amount of information. This paper proposes a method to overcome these limitations; The proposed method gives different weights according to the source graph when embedding nodes; the characteristics of the graph with more important information can be reflected more in the node. To this end, a novel method incorporating a multi-channel gate layer is proposed to weigh more important channels and ignore unnecessary data to embed a node with multiple graphs. Empirical experiments demonstrate the effectiveness of the proposed multi-channel-based embedding methods.

Performance Analysis of the Trellis-Coded 8DPSK with Multiple Symbol Differential Detection (다중 심볼 차동 검파를 이용한 트렐리스 부호화된 8DPSK의 성능 분석)

  • 문태현;김한종;홍대식;강창언
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.4 no.3
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    • pp.54-62
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    • 1993
  • In this paper, performance comparisions of MTCM systems with 8DPSK over mobile communication channels are obtained by computer simulation. The multiple symbol differential detection scheme is introduced in order to improve the bit error rate performance in the detection of the trellis-coded 8DPSK system. Rician fading channels are used as test channels. The simula- tion results show that the trellis-coded 8DPSK system with multiple symbol detection gives better performance than that of the uncoded DQPSK system. And symbol by symbol interleaving method gives better performance than the symbol pair interleaving method.

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Secrecy Performance Evaluation of OSTBC using One-Bit Feedback in Correlated MIMO Channels (상관관계를 갖는 MIMO 채널에서 하나의 피드백 비트를 이용한 OSTBC의 물리계층 보안 성능 평가)

  • Lee, Sangjun;Lee, In-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.10a
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    • pp.886-889
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    • 2014
  • In this paper, we evaluate a physical layer security performance of orthogonal space-time block code(OSTBC) using one-bit feedback in the presence of an eavesdropper in wiretap channels, where we assume spatially correlated MIMO(multiple-input multiple-output) channels. In this paper, we present the one-bit feedback based OSTBC(F-OSTBC) scheme and compare security outage performances of F-OSTBC, conventional OSTBC, and transmission antenna selection schemes for various spatial correlation conditions at each node.

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Massive MIMO TWO-Hop Relay Systems Over Rician Fading Channels

  • Cao, Jian;Yu, Shujuan;Yang, Jie;Zhang, Yun;Zhao, Shengmei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.11
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    • pp.5410-5426
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    • 2019
  • With the advent of the fifth-generation (5G) era, Massive multiple-input multiple-output (MIMO) relay systems have experienced the rapid development. Recently, the performance analysis models of Massive MIMO relay systems have been proposed, which are mostly based on Rayleigh fading channels. In order to create a more suitable model for 5G Internet of Things scenarios, our study is based on the Rician fading channels, where line-of-sight (LOS) path exists in the channels. In this paper, we assume the channel state information (CSI) is perfect. In this case, we use statistical information to derive the analytical exact closed-form expression for the achievable sum rate of the uplink for the Massive MIMO two-hop relay system over Rician fading channels. Moreover, considering the different communication scenarios, we derive the analytical exact closed-form expression for the achievable sum rates of the uplink for other three scenarios. Finally, based on these expressions, we make simulations and analyze the performance under different transmit powers and Rician-factors, which provides a theoretical basis and reference for further research.