• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.9
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• pp.3008-3028
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• 2022

In this paper, we investigate traffic scheduling for a delay-sensitive multi-hop relay network, and aim to minimize the priority-based end-to-end delay of different data packet via joint relay selection, subcarrier assignment, and power allocation. We first derive the priority-based end-to-end delay based on queueing theory, and then propose a two-step method to decompose the original optimization problem into two sub-problems. For the joint subcarrier assignment and power control problem, we utilize an efficient particle swarm optimization method to solve it. For the relay selection problem, we prove its convexity and use the standard Lagrange method to deal with it. The joint relay selection, subcarriers assignment and transmission power allocation problem for each hop can also be solved by an exhaustive search over a finite set defined by the relay sensor set and available subcarrier set. Simulation results show that both the proposed routing scheme and the resource allocation scheme can reduce the average end-to-end delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.876-882
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• 2009

In this paper, we propose a sub-cell coverage control algorithm for enhancement of the cell throughput in OFDMA based relay systems. Relay station (RS) is exploited for improved quality of the received signal in cellular communication systems, especially in shadow areas. However, since a RS requires additional radio resource consumption for the link between the base station (BS) and the RS, we have to carefully control the coverage areas if a mobile station (MS) is serviced via the BS or the RS considering the cell throughput. We consider radio resource reuse as well for the sub-cell coverage configuration by applying various reuse patterns between RSs. We also consider a time varying system by adaptively changing the threshold for coverage depending on the MSs' traffic in the cell. We initially determine the sub-cell coverage of the system depending on the ratio of received signal-interference-noise-ratio (SINR) of the MS from the BS and RSs, respectively. Then, the "sub-cell coverage threshold" varies based on the "effective transmitted bits per sub-channel" with time. Simulation result shows that the proposed "time varying coverage control algorithm" leads to throughput improvement compared to the fixed sub-cell coverage configuration.

• ETRI Journal
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• v.36 no.1
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• pp.22-30
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• 2014

Recently, efficient partial relay selection (e-PRS) was proposed as an enhanced version of PRS. In comparing e-PRS, PRS, and the best relay selection (BRS), there is a tradeoff between complexity and performance; that is, the complexity for PRS, e-PRS, and BRS is low to high, respectively, but vice versa for performance. In this paper, we study the outage probability for e-PRS in decode-and-forward (DF) relaying systems over non-identical Nakagami-m fading channels, where the fading parameter m is an integer. In particular, we provide closed-form expressions of the exact outage probability and asymptotic outage probability for e-PRS in DF relaying systems. Numerical results show that e-PRS achieves similar outage performance to that of BRS for a low or medium signal-to-noise ratio, a high fading parameter, a small number of relays, and a large difference between the average channel powers for the first and the second hops.

• Journal of Korea Multimedia Society
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• v.17 no.6
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• pp.687-696
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• 2014

An integrated ship area network has functionality of remote control and autonomous management of various sensors and instruments embedded or boarded in a ship. For such environment, an wireless bridge is essential to transmit control and/or managing information to sensors or instruments from a central integrated ship area network station. In this paper, one of reliable schemes of WiMedia based wireless bridge using relay cooperative transmission using WiMedia distributed MAC protocol is proposed to increase a communication reliability between cluster headers, irrespective of channel variation. Simulation results show that the proposed wireless bridge using relay cooperative transmission scheme increases communication reliability.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.191-193
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• 2000

In this paper, being different from traditional methods, we design digital protective relay which can be applied to power management and control systems of not only small and medium but also a large scale plants. The digital protective relay was designed with DSP CPU(TMS320C31) to protect and measure more quickly and precisely. We will present test result which it performed according to the standards of Korea Electrical Manufactures Cooperative to prove the faculties of digital protective relay. The test result on the basis of KEMC1120 and IEC60255, show that the operation time error of the digital motor protection relay is improved within ${\pm}5%$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.287-292
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• 2015

In this paper, we evaluated the performance of D2D advertisement dissemination algorithms with maximum-distance and transmission-efficiency based relay selections with respect to the total number of successfully received users and transmission efficiency. To assume more practical environment, we took into account pre-defined target-areas based on the information of user density and the limit for the maximum number of relay users. Through the simulations we compared the performance results of both D2D advertisement dissemination algorithms with maximum-distance and transmission-efficiency based relay selections according to increment of the number of sectors. And then, we analysed the superiority of algorithm with transmission-efficiency based relay selections more than maximum-distance based relay selections.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.442-444
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• 2001

최근 통신환경의 급속한 발전과 함께 점점 복잡 다양해지는 사회적 요구에 의해 유선망을 무선환경으로 옮겨 가기 위한 많은 연구들이 진행되고 있다. 본 논문에서는 Frame Relay 망과 WATM 백본 망라의 연동 환경을 제안하였고, 이 망에서 Frame Relay 망의 이동으로 인하여 발생하는 망의 이동성 지원 방안과 QoS를 보장하는 단말들의 멀티 핸드오버를 효율적으로 지원하기 위한 G-CAC알고리즘을 제안한다. 본 논문에서 제안한 G-CAC알고리즘은 망 단위의 이동환경에서 Frame Relay의 트래픽 특성, DE/CLP 맵핑 , 트래픽 파라미터 변환 방식을 이용하여 핸드오버 블락킹 율과 손실 율을 감소시킨다. 또한 여러 Frame Relay 망과 통신하고 있는 백본의 WATM에서는 다른 Frame Relay망들의 할당된 자원 중에 CLP비트가 세트된 셀들을 드롭하여 그 자원을 새로운 핸드오버를 요청하는 Frame Relay망에 접합된 WATM에 제공하는 QoS를 고려한 핸드오버 CAC(connection admission control)알고리즘을 제안한다.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.246-248
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• 2001

For protection of power system, it is a prerequisite to action characteristics of protective relay about a changing environment in power system and correcting the setting value. A substation operator always reside to correct of a relay, however there are problem of efficiency. Recently, power system operation become manless and supervision and control of incident is required anywhere, introduction of new concept as a intellectual manless protective relay is a recent trend. This paper is the web-based protective relay setting program that a manager make an analysis of operation and incident of power system through the web at a remote place corresponding recent manless of system and approach the protection relay and then can correct the error.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.24-26
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• 2005

This paper presents a framework for determining control strategies against unwanted tripping actions of relay operation that plays a very important role in cascading events leading to voltage collapse. The framework includes an algorithm for quick identification of possible zone 3 relay operation during voltage instability. The proposed approach comes up with control strategy of load shedding at the selected location with active power and relay margin criteria. In addition, Quasi Steady-State (QSS) simulation is employed to obtain time-related information which is valuable for both the timing and amount of control. The methodology is demonstrated through the modified New England 39-bus system.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.489-491
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• 2005

This paper presents the application study of substation automation protocol, IEC 61850 to digital relay (HiMAP). Especially, it implements the data modeling, ACSI definition, GOOSE, MSVCB and data service required in the existing digital relay. To verify the system performance, we develop the process emulator and HiMAP emulator, and describe the results.