• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.72-84
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• 2005

Optical burst switching networks usually employ one-way reservation by sending a burst control packet with a specific offset time, before transmitting each data burst Same. Due to such a Property, burst-contentions occur when multiple bursts contend for the same wavelength in the same output link simultaneously in a node, leading to burst losses, eventually degrading the quality of service. Therefore, in this paper, we propose a dynamic routing algorithm using minimum local state information in order to decrease burst-contentions. In this proposed scheme, if burst loss rate exceeds a threshold value at a certain node, a new alternative routing path is chosen according to burst priority and location of burst generation, which enables the contending bursts to detour around the congested link. Moreover, for reducing the effect of sending bursts on the primary path due to the alternative path, we also apply a minimum path-cost based routing on link-cost concept. Our simulation results show that proposed scheme improves the network performance in terms of burst loss probability and throughput by comparing with conventional one.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.496-498
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• 2001

무선 ATM에서 사용하는 고주파 대역에서 채널의 효율성을 유지하기 위해서는 셀의 반경이 작아지게 되고 이는 단말의 이동시 빈번한 핸드오버를 야기시킨다. 이는 QoS 저하를 야기하거나, 핸드오버를 위한 채널이 부족하면 호가 절단되는 현상을 야기하게 된다. 이를 방지하기 위하여 사용자의 이동 패턴을 고려하여 이동 단말의 이동 경로를 예측하고, 이 패턴에 따라 핸드오버에 필요한 채널을 예약하여 효율적인 채널 할당이 가능한 기법이 제안되었다. 본 논문에서는 컴퓨터 시뮬레이션을 사용하여 이러한 이동성 예측 알고리즘의 성능을 비교 및 분석하였다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2000.11a
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• pp.463-470
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• 2000

In this paper, we describe a wireless MAC protocol named APRMA(Abitrary Period Reservation Multiple Access), which is capable of supporting the ABR type data service and maximizing channel utilization. In original PRMA protocol, data terminals with random data packets cannot reserve slot. That is, slot reservation is applicable to the. time constraint voice packet exclusively. But the reservation scheme have to be performed for loss sensitive data packet, so data packets can get their quality of service. The aspects of service, if fixed bandwidth is allocated to data terminals, time constraint voice packets may have a low efficiency So in this study, the terminal which wants to request for ABR type service, acquires a minimum bandwidth from system for the first time. If the system have extra available bandwidth, ABR terminals would acquire additional bandwidth slot by slot. As a result, APRMA protocol can support the data service with loss sensitivity and maintain their channel utilization highly. Also high Priority services like voice can be satisfied with their QoS by APRMA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.126-130
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• 1999

In packet CDMA networks, it is important to design a MAC protocol that meets the QoS requirements , of the different traffic types and allocates the radio channels efficiently. In this paper, a RRS$^2$-CDMA MAC protocol is proposed for integrating voice and data services in the microcellular packet CDMA networks. In PRS$^2$-CDMA, a voice terminal can resolve a spreading code to transmit voice packets during a talkspurt while a data terminal has to contend for a code for each packet transmission. The numerical results show that the proposed protocol can improve the system capacity, while guaranteeing the QoS of voice and data services.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1995.10a
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• pp.118-121
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• 1995

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1995.06a
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• pp.480-484
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• 1995

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.220-222
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• 1998

유선 통신과 다르게 무선 통신은 자원의 한정성이란 매체의 특성을 가지고 있어 다중의 사용자가 다른 QoS를 요구하는 멀티미디어 서비스를 지원하기 위해서는 각각의 서비스에 따른 트래픽에 차별화를 두어 매체 접속을 제어하는 것이 효과적인 방법이 될 것이다. 현재, 음성과 데이터를 통합하여 매체 접속 제어를 하는 패킷 예약 다중 접속 방식은 많은 연구가 이루어진 상태이고, 특히, 멀티미디어 지원을 위해 적응형 패킷 예약 다중 접속(APRMA: Adaptive Packet Peservation Multiple Access)방식의 연구가 진행되었다. 본 논문에서는 멀티미디어 지원을 위한 다른 한가지 방법으로 패킷이 경쟁에 참여할 수 있는 파라미터를 서비스의 종류와 활성중인 슬롯의 수에 따라 조정하여 채널의 효율을 보다 향상시키고 패킷 충돌이 일어날 확률도 감소 시킬 수 있는 우선 순위 기반 적응형 패킷 예약 매체 접속 방법 (APRMA_P : APRMA with Prioroty)을 제시한다. 제안된 APRMA_P의 성능을 분석하기 위해 시뮬레이션을 통해서 체널 효율을 기존의 APRMA와 비교 분석한다.

• Journal of Digital Contents Society
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• v.8 no.3
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• pp.347-353
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• 2007

As the number of channels and programs are increasing dramatically, a viewer seriously needs to book a program at the very time of watching its promotion program by "only one time" pressing remote controller's button. The program reserving system requiring to search a program via EPG is usually hard to operate and some researches that allow a viewer to book a program via its promotion program require additional heavy facilities such as image processing or ultra-frequency recognizing systems. In this paper, a new program reservation system is introduced. the system allows a viewer to book a program via its promotion program. The system is conformable to MHP (which is the data service standard most widely adopted in the world) so that the broadcasting stations need no additional equipments to implement it as long as they follow the MHP standard.

• 전자공학회논문지 IE
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• v.43 no.1
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• pp.39-45
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• 2006

The increment of user at mobile communication system requires the need of increased system capacity. To increase the system capacity can be realized by decreasing the size of cell. But, this method causes various problems. Therefore, it be used the hierarchical cellular system with macrocell and microcell for a efficient working. The users feel more inconvenience about the drop of connected call than the block of new call. Therefore, it is to be desired that the dropping rate of handoff call is lowered. At this paper, we use non reversible hierarchical scheme and fixed channel assignment scheme at the hierarchical cellular system with macrocell and microcell for the call process strategy. We analyze the system performance in accordance with the number of guard channel for handoff.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1141-1148
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• 1999

In this paper, an RRA_CDMA protocol is proposed for the integrated voice and data services in the cellular packet CDMA systems. The proposed protocol employs the RRA scheme. In the cellular CDMA systems, the backward logical channels are composed of time slots with multiple spreading codes per slot based on WB-TD-CDMA concept. When a voice terminal begins a talkspurt, it reserves one of the available spreading codes in the next slot and uses the reserved channel exclusively untill it ends the talkspurt. On th other hand, whenever a data terminal generates a packet, it selects an avaliable spreading code and transmits its packet. Throughout the results, it is shown that the system capacity increases in proportion to the number of spreading codes.