• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.906-914
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• 2007

In the upstream link of EPON, numerous ONUs In the reverse link of the EPON network, numerous ONUs receive the privileges to use the optical medium from the scheduler of the LOT, but not through the competition with others. Therefore, it is very important to select a proper DBA algorithm to allocatethe frequency band to each ONU in an effectively and fair manner. In our preceding study, we proposed the RC-DBA algorithm that complements many problems in existing DBA algorithms. In this paper, we designed the MAC scheduler for the OLT, which the proposed algorithmwas applied to and implement it in the FPGA. In addition, in order to verify the operation of the scheduler, we developed the embedded Linux based testbed.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.228-231
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• 2006

Mobile ad hoc 환경에서의 TDMA(time division multiple access)는 contention 없이 node 간에 충돌(collision) 없는 전송을 제공하며 동일 주파수대를 시간으로 분할하여 신호가 겹치지 않도록 상호통신을 하는 시분할다중접속 방식이다. TDMA는 충돌 없이 전송할 수 있다는 이점 때문에 Mobile 환경에서 많이 응용하여 사용되어 지고 있다. 하지만 할당 되어진 time slot을 사용하지 않을 경우 대역폭의 낭비가 발생할 수 있다는 문제 점도 가지고 있다. 본 논문에서는 사용하지 않는 time slot의 재사용을 통해서 성능을 향상시키는 방법을 제안하고 그 것을 Mobile ad hoc 환경에 적용하는 방법에 대해 연구한다.

• Journal of Internet Computing and Services
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• v.4 no.5
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• pp.61-68
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• 2003

In this paper, we propose a wireless MAC protocol named APRMA, which is capable of supporting the ABR type data service and Maximizing channel utilization. Data terminals with random data packets are not provided slot reservation with PRMA protocol. 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, and contended their quality of service, Therefore, in wireless MAC, reservation technique has to be used for both voice and data services. So the terminal which wants to request for ABR type service, is allocated a minimum bandwidth from system for the first time, If the system have some 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 high.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.220-222
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• 2021

In this paper, we propose a resource allocation scheme based on entropy for tactical wireless networks. In a tactical situation, the sensing nodes that are located randomly provide transmitted data values depending on environmental conditions. Since they share wireless resources, nodes providing valuable data compared to others need to have more resources. The proposed scheme evaluates the value of received data by a sink node. Based on the results, the sink node reallocates resources to sensing nodes. Through various experiments, we verified the proposed scheme is superior to the fixed allocation scheme.

• Convergence Security Journal
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• v.11 no.1
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• pp.3-10
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• 2011

This paper proposes DPA(Dynamic Priority Assignment) MAC protocol to improve the traffic QoS on the HFC-CATV(Hybrid Fiber Coax CAble TeleVision) network. In results, DPA MAC protocol is the best performance compare with to IEEE 802.14a MAC in mean request delay, mean access delay. Also, the paper prove a reliability of proposed protocol through comparison between performance analysis and simulation result of DAP MAC protocol.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1477-1480
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• 2001

기존 통신사업자가 급변하는 통신시장에 대응하기 위한 구체적 접근방법에 초점을 맞추어 통신기술의 변화와 이에 따른 기존망을 어떻게 개선하여야만 수익성에 차질을 빚지 않을 수 있느냐가 전재 조건이 된다. 먼저 통신기술의 변화에 따른 망의 진화방향을 음성의 패킷화 실현, 망 구조의 단순화 및 통합화를 통한 운용비용의 절감, 향후 신규서비스의 수용에 용이한 방향이 있어야 한다. 본 논문에서는 ATM을 중심으로 한 차세대 교환망에서 음성과 데이터가 동일 패킷망을 사용하므로서 망 대역폭을 효율적으로 활용하는 방법과 유효 대역 사용률을 향상하는 유연한 대역관리 방법에 대해 개괄적으로 논하였으며, 이를 바탕으로 대역폭 할당 프로토콜을 분석한 수 있는 모델을 제안하고, 주어진 음성 및 데이터 트래픽의 요구와 제약을 조건으로 시스템 파라미터를 최적화하기 위해 update interval 시간과 음성과 데이터 트래픽에 예약된 슬롯의 수를 사용하였다. 분석적인 모델은 성능에 관한 트래픽 유형들의 영향뿐만 아니라 혼합 트래픽 시스템의 동적 할당 방법과 대역관리 방법을 제공한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1427-1433
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• 2003

This paper presents the routing and wavelength and timeslot assignment problems for a circuit-switched time division multiplexed (TDM) wavelength-routed networks. In this paper, we propose an efficient distributed control protocol for establishing lightpath dynamically. The protocol uses backward reservation to reduce the chance of blocking. We use aggressive reservation method with usable multiple channels and select only one in multiple channel. We show through simulation that the proposed protocol improves the success rate in TDM-based lightpath establishment and the proposed aggressive reservation method improve blocking probability with appropriate reservation channel count.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.4
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• pp.468-478
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• 2002

In this paper, we designed a B-WLL MAC(Media Access Control) protocol and validated its operation for implementation of high-speed subscriber networks. Our MAC protocol was designed by SDL using the DAVIC specifications based upon the variable contention/reserved time slot allocation algorithm. For validation of our MAC protocol, Syntax and semantic error check were performed by the Simulation Builder of ObjectGeode and the MAC(Message Sequence Chart) respectively. The validation results showed that our B-WLL MAC protocol is working correctly and may successfully support B-WLL services.

• Journal of Digital Contents Society
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• v.2 no.1
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• pp.93-102
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• 2001

In this paper we proposed a wireless MAC Protocol called DTDD/PS (Dynamic Time Division Duplex using Poll/Select scheme), and throughput performance is evaluated using computer simulation. Simulation results indicate that the proposed DTDD/PS protocol increases the limitation of allowable loads that guarantee duality of services by dynamic allocation of slot based on the system status. Also the proposed protocol is shown to maintain stable throughput even in the case of traffic variations.

• Journal of the Korea Society for Simulation
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• v.20 no.4
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• pp.81-89
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• 2011

Underwater wireless network can be useful in various fields such as underwater environment observation, catastrophe prevention, ocean resources exploration, ocean organism research, and vessel sinking exploration. We need to develop an efficient design for Medium Access Control (MAC) protocol to improve multiple data communication in underwater environment. Aloha protocol is one of the basic and simple protocols, but it has disadvantage such as collision occurs oftenly in communication. If there is collision occured in RF communication, problem can be solved by re-sending the data, but using low frequency in underwater, the re-transmission has difficulties due to slow bit-rate. So, Time Division Multiple Access (TDMA) based MAC protocol is going to be used to avoid collisions, but if there is no data to send in existing TDMA, time slot should not be used. Therefore, this paper proposes dynamic TDMA protocol mechanism with reducing the time slots by sending short "I Have No Data" (IHND) message, if there is no data to transmit. Also, this paper presents mathematic analysis model in relation to data throughput, channel efficiency and verifies performance superiority by comparing the existing TDMA protocols.