• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.323-325
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• 2014

The consensus algorithm has a faster convergence speed as the number of cooperating neighbors increases, but the information sharing delay in the wireless network increases due to access collisions as the number of cooperating neighbors increases. Therefore, there exists a tradeoff between these two performances according to node's coverage. In this paper, we present a method of coverage control that minimizes consensus time according to network scale.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.6
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• pp.417-426
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• 2013

The Korea Internet AS-level topology was constructed using three data sources: Border Gateway Protocol (BGP) trace collector, Internet Routing Registry (IRR), and Internet Exchange Point (IXP). It has 685 nodes and 1,428 links. The Korea Internet AS-level topology is a small regional subgraph of the massive global one. We investigate how well the Korea Internet preserves the topological characteristics of the global one or how different they are. We carefully select several topology metrics that can analyze the characteristics of the Korea Internet AS-level topology. We also investigate how well Internet topology generators can represent the characteristics of the Korea Internet AS-level topology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.857-859
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• 2015

In this letter, we consider a directional routing protocol that reduces the duplicated packets for AODV-based flooding in the course of establishing the end-to-end route in the multi-hop maritime ad-hoc networks. We propose an adaptive means of reducing the routing overhead subject to the node density and the target probability of successful routing that is analyzed by the stochastic geometry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.860-862
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• 2015

In this paper, we propose a new type of IAM clustering architecture for the efficiency of user authentication and authorization in the Inter-Cloud environment. clustering architecture allows users to easily use un-registered services with their registered authentication and access permissions through pre-Access Agreement. through this paper, we explain our authentication protocol and IAM clustering architecture components.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.809-811
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• 2015

In this paper, for the purpose of providing high data rate services, the multi-hop frame structure is designed for the underwater acoustic (UWA) short-range system which is proposed as a part of ocean surveillance and tracking network (OSTN). Under the measured underwater channel environment, the link-level system performance are also evaluated. Simulation results show not only the packet error rate (PER) comparisons, but the optimal modulation and coding scheme (MCS) levels for the orthogonal frequency division multiplexing (OFDM) based short-range UWA communications network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.806-808
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• 2015

In this paper, we suggest the method of pilot tone design for a compressed channel sensing in order to decrease the peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1934-1936
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• 2015

This paper proposes an optimal relay selection and adaptive throughput enhancement scheme utilizing superposition modulation in cooperative communication. The optimal relay is selected and the channel state is estimated by utilizing superposition modulation. The source determines the number of superimposed signal in accordance with the estated channel state. As a result, throughput is increased in accordance with the channel state.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1931-1933
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• 2015

This paper proposes inter-cell cooperative transmission scheme in order to improve the reliability of the wireless communication system at the heterogeneous network environments. The heterogeneous network can increase data rate by using existing network technologies. However, degradation of communication performance in the cell edge has been a serious problem. Therefore, this letter proposes an adaptive transmission scheme according to the diverse situations in order to solve this problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1865-1870
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• 2015

In signal processing, the zero-error probability (ZEP) criterion and related algorithm (MZEP) outperforms MSE-based algorithms and yields superior and stable convergence in impulsive noise environment. In this paper, the analysis of the relationship with MSE criterion proves that ZEP criterion has equivalent optimum solution of MSE criterion. Also this work reveals that the magnitude controlled input of MZEP algorithm plays the role in keeping the optimum solution undisturbed from impulsive noise.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.2065-2067
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• 2015

In this paper, we analyze the performance of visible light communication system using rolling shutter CMOS sensor. For analysis, the effect of ISI (Inter-symbol Interference) on visible communication has been formulated. We validate our analysis through computer simulations.