• Journal of Korea Multimedia Society
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• v.9 no.12
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• pp.1689-1699
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• 2006

A nonlinear channel blind equalizer by using a hybrid genetic algorithm, which merges a genetic algorithm with simulated annealing, and a RBF network is presented. In this study, a hybrid genetic algorithm is used to estimate the output states of a nonlinear channel, based on the Bayesian likelihood fitness function, instead of the channel parameters. From these estimated output states, the desired channel states of the nonlinear channel are derived and placed at the center of a RBF equalizer to reconstruct transmitted symbols. In the simulations, binary signals are generated at random with Gaussian noise. The performance of the proposed method is compared with those of a conventional genetic algorithm(GA) and a simplex GA, and the relatively high accuracy and fast convergence of the method are achieved.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.29-35
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• 2009

An efficient stochastic channel selection algorithm for cognitive radio networks is proposed and analyzed in this paper. With the new algorithm utilizing quality of channels, the stationary level of the channels in idle state and history performance, we can find the best channel for secondary users to transmit data. Moreover, this method not only restricts channel switching of secondary users but also adapts to random resource environment of cognitive radio network. The advantages of the proposed algorithm are demonstrated clearly through computer simulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.23-29
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• 1995

In this study, Active noise controlis implemented with single channel and multi-channel adaptive algorithm in 3 dimensional reverberant enclosure sound. field, which occurrs in complicated acoustic mode. First, for the one case excited with the resonant frequency of an enclosure, a target of control and the other cases excited with band-pass filtered random noise(100~400Hz), it is implemented to control reducing interior noise of enclosure with single channel and realtime multi-channel adaptive algorithm for global noise reduction in enclosure.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2493-2495
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• 2001

Burst Error Channel의 에러 정정 기술로써 Reed-Solomon Product Code(RSPC)가 광범위하게 사용되고 있다. 그러나 Random Error Channel과는 달리 Burst Error Channel 상에서 RSPC의 에러 정정 평가 방법에는 많은 어려움이 있다. 우리는 이번 논문에서 Burst Error Channel 상에서 RSPC의 Error Correction Capability의 확률적인 계산 방법을 기술하려 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.3
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• pp.19-25
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• 2009

In this thesis, design effective elimination interference algorithm of ICS repeat system for repeater that improve frequency efficiency. Error convergence speed and accuracy of LMS Algorithm are influenced by reference signal. For improve LMS Algorithm, suggest Adaptive channel estimate algorithm. For using channel characteristic, adaptive channel estimate algorithm make reference signal similar interference signal by convolution operation and complement LMS algorithm demerit. For make channel similar piratical channel, apply Jake's Rayleigh multi-path model that random five path with 130Hz Doppler frequency. LMS algorithm and suggested adaptive channel estimate algorithm that have 16 taps apply to ICS repeat system under Rayleigh multi-path channel, so simulate with MATLAB. According to simulate, ICS repeat system with LMS algorithm show -40dB square error convergent after 150 datas iteration and ICS repeat system with adaptive channel estimate algorithm show -80dB square error convergent after 200 datas iteration. Analyze simulation result, suggested adaptive channel estimate algorithm show more three times iteration performance than LMS algorithm, and 40dB accuracy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.3
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• pp.607-625
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• 2011

Two-party key exchange protocol is a mechanism in which two parties communicate with each other over an insecure channel and output the same session key. A key exchange protocol that is secure against an active adversary who can control and modify the exchanged messages is called authenticated key exchange (AKE) protocol. LaMacchia, Lauter and Mityagin presented a strong security definition for public key infrastructure (PKI) based two-pass protocol, which we call the extended Canetti-Krawczyk (eCK) security model, and some researchers have provided eCK-secure AKE protocols in recent years. However, almost all protocols are provably secure in the random oracle model or rely on a special implementation technique so-called the NAXOS trick. In this paper, we present a PKI-based two-pass AKE protocol that is secure in the eCK security model. The security of the proposed protocol is proven without random oracles (under three assumptions), and does not rely on implementation techniques such as the NAXOS trick.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.43-52
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• 2012

This paper presents and analyzes laboratory test results of Interference Cancellation Digital On Channel Regenerative Repeater(IC-DOCR) to broadcast digital television signals in the Advanced Television Systems Committee(ATSC) transmission systems using single frequency networks(SFN). IC-DOCR laboratory test is classified to receiver test, transmitter test, and feedback interference cancellation test. The receiver part includes random noise, single echo, multi-path ensembles, and adjacent channel interference test. The transmitter part includes out-of channel emission, equality of transmitting signal, and phase noise test. By the laboratory test, the receiver part of the IC-DOCR eliminates 28dB of feedback signal higher than the received signal and has 17.8dB at TOV(Threshold Of Visibility) under random noise environment. Also, the transmitter part satisfies the specification of US FCC(Federal Communications Commission) as well as maintains good output signal quality for guaranteeing more than SNR 30dB.

• Journal of Korea Multimedia Society
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• v.2 no.1
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• pp.47-58
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• 1999

In this paper, we design the radio interface protocols of wideband Wireless Local Loop(WLL) that uses wideband Code Division Multiple Access(CDMA), and propose the random access procedures on access channel and analyze the performance of the channel. The structure of radio interface protocols are designed by three modular parts to meet the requirements of IMT-2000 : radio resource controlling part that depends on the radio resources, connection controlling part that is independent of the radio resources, and application part that supports the interface between different parts and user terminals. In addition, we propose the random access procedures on access channel and analyze the performance of the channel. We assume that both near-far effect and shadow fading can be compensated by open loop power control. We observe that the number of access probes(delay) depend on the initial mobile transmission power and power increment, and the poor estimation of initial mobile transmission power might increase the average number of access probes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10A
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• pp.987-996
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• 2008

In this paper, the conventional anti-collision algorithms, such as Channel Monitoring algorithm and Pulse Protocol algorithm are analyzed. To decrease tag identification time, and increase system throughput and efficiency, we propose a new reader anti-collision algorithm, Pulse Protocol-based Hybrid Reader Anti-collision Algorithm, using Slot-occupied Probability under dense reader environment. The proposed algorithm uses Slot-occupied Probability to improve the performance of Pulse Protocol Algorithm. That is, A reader checks Slot-occupied Probability after generating random backoff time. If Slot-occupied Probability is greater than 0, it uses another new random backoff time to avoid reader collision. We also compare the performance of the proposed algorithm with those of Channel Monitoring and Pulse Protocol algorithms in respect of identification time system throughput, and system efficiency. Simulation results show that the proposed algorithm has an increment of 5% of identification time and system throughput as increasing the number of readers.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.542-547
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• 2019

Autonomous train is investigated to increase the capacity of railroad, and the reliability of wireless communication plays a critical role in terms of decreasing the inter-train distance. In this paper, we propose a transmission scheme for autonomous train communication in highly congested environment. The proposed scheme, namely distributed uplink orthogonal frequency division multiple access (OFDMA) random access (UORA), applies the triggered uplink access (TUA) and the UORA, introduced in the sixth generation WLAN standard, IEEE 802.11ax, for communication devices on vehicle and platform in a distributed manner. The simulation results show that the proposed scheme efficiently improves the packet transmission success rate in highly congested channel conditions compared to the conventional enhanced distributed channel access (EDCA) transmission scheme.