• 교통기술과정책
• /
• 제7권4호
• /
• pp.75-79
• /
• 2010

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권3호
• /
• pp.872-885
• /
• 2015

The rapid increase of smart mobile devices and mobile applications has led to explosive growth of data traffic in cellular network. Offloading data traffic becomes one of the most urgent technical problems. Recent work has proposed to exploit opportunistic communications to offload cellular traffic for mobile data dissemination services, especially for accepting large delayed data. The basic idea is to deliver the data to only part of subscribers (called target-nodes) via the cellular network, and allow target-nodes to disseminate the data through opportunistic communications. Human mobility shows temporal and spatial characteristics and predictability, which can be used as effective guidance efficient opportunistic communication. Therefore, based on the regularity of human mobility we propose NodeRank algorithm which uses the encounter characteristics between nodes to choose target nodes. Different from the existing work which only using encounter frequency, NodeRank algorithm combined the contact time and inter-contact time meanwhile to ensure integrity and availability of message delivery. The simulation results based on real-world mobility traces show the performance advantages of NodeRank in offloading efficiency and network redundant copies.

• 산업공학
• /
• 제15권2호
• /
• pp.152-158
• /
• 2002

The explosive growth of the internet traffic in the last few years has imposed tremendous stress on today's routers, particularly in the core network. Recently, ATM LSRs(Label Switching Router) are potentially capable of providing the highest forwarding capacity in the backbone Internet network. VC merging is a mechanism in an ATM LSR that allows many IP routes to be mapped to the same VC label, and provides a scalable mapping method that can support thousands of destinations. VC merging requires reassembly buffers so that cells belonging to different packets intended for the same destination do not interleave with each other. In this study, we propose an architecture of the ATM LSR which supports VC merging. We propose traffic control scheme called APD(Active Packet Discard) algorithm so that predicts and controls the congestion of the Internet traffic effectively. We study the performance of this algorithm using simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권9호
• /
• pp.4108-4122
• /
• 2016

To address challenges of an unprecedented growth in mobile data traffic, the ultra-dense network deployment is a cost efficient solution to off-load the traffic over other small cells. However, the real traffic is often much lower than the peak-hour traffic and certain small cells are superfluous, which will not only introduce extra energy consumption, but also impose extra interference onto the radio environment. In this paper, an elastic energy efficient cell management scheme is proposed based on flow scheduling among multi-layer ultra-dense cells by a SDN controller. A significant power saving was achieved by a cell-level energy manager. The scheme is elastic for energy saving, adaptive to the dynamic traffic distribution in the office or campus environment. In the end, the performance is evaluated and demonstrated. The results show substantial improvements over the conventional method in terms of the number of active BSs, the handover times, and the switches of BSs.

• Journal of Communications and Networks
• /
• 제18권5호
• /
• pp.806-817
• /
• 2016

Opportunistic routing (OR) has been proposed as a viable approach to improve the performance of wireless multihop networks with lossy links. However, the exponential growth of the bandwidth-sensitive mobile traffic (e.g., mobile video streaming and online gaming) poses a great challenge to the performance of OR in term of bandwidth guarantee. To solve this problem, a novel mechanism is proposed to opportunistically forwarding data packets and provide bandwidth guarantee for the bandwidth-sensitive traffic. The proposal exploits the broadcast characteristic of wireless transmission and reduces the negative effect of wireless lossy links. First, the expected available bandwidth (EAB) and the expected transmission cost (ETC) under OR are estimated based on the local available bandwidth, link delivery probability, forwarding candidates, and prioritization policy. Then, the policies for determining and prioritizing the forwarding candidates is devised by considering the bandwidth and transmission cost. Finally, bandwidth-aware routing algorithm is proposed to opportunistically delivery data packets; meanwhile, admission control is applied to admit or reject traffic flows for bandwidth guarantee. Extensive simulation results show that our proposal consistently outperforms other existing opportunistic routing schemes in providing performance guarantee.

• 한국통신학회논문지
• /
• 제32권4B호
• /
• pp.217-226
• /
• 2007

디지털 멀티미디어 장치의 증가에 따라 네트워크를 통하여 실시간 트래픽을 전송을 지원하기 위한 연구들이 많이 진행되고 있다. 이 중에서도 이더넷이 가지는 장점으로 이더넷을 이용한 네트워크 기술을 활용하는 방안에 초점이 맞춰지고 있다. 이더넷에서 실시간 트래픽을 지원하기 위한 네트워크 기술의 표준화는 IEEE 802.1 AVB TG에서 진행 중이다. 본 논문은 이더넷에서 실시간 트래픽을 지원하기 위한 기술, 즉 동기식 이더넷에서의 장치간의 동기화 방법을 제안한다. 그리고 동기가 맞추어진 장치에서 시간에 실시간 트래픽을 전송하기 위해 필요한 대역폭을 예약하는 방법을 제안한다. 본 논문에서 동기식 이더넷 모델은 OPNET을 통해 구현하였고 제안한 동기화 방법과 대역폭 예약 방법의 효율성을 분석하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제15권1호
• /
• pp.114-130
• /
• 2021

With the drastic growth of Information and Communication Technology (ICT) industry, global energy consumption is exponentially increased by mobile communications. The huge energy consumption and increased environmental awareness have triggered great interests on the research of dynamic distribution of cell user and traffic, and then designing the energy efficient cellular network. In this paper, we explore the temporal and spatial characteristics of human mobility and traffic distribution using real data set. The analysis results of cell traffic illustrate the tidal effect in temporal and spatial dimensions and obvious periodic characteristics which can be used to design Base Station (BS) dynamic with sleeping or shut-down strategy. At the same time, we designed a new Cell Zooming and BS cooperation mode. Through simulation experiments, we found that running in this mode can save about 35% of energy consumption and guarantee the required quality of service.

• 한국경영과학회지
• /
• 제39권2호
• /
• pp.141-154
• /
• 2014

It is widely confirmed that online retailers can obtain crucial resources and greater growth potential by depending on the external web portal sites as it is explained in resource dependence theory. Nevertheless, recent studies show that the effect of dependence may not always be beneficial for firms and stress the importance of finding relevant contingent factors. In this study, we identify and suggest that firms' age and niche width strategy, whether generalist or specialist, are contributing factors on moderating the positive relationship between resource dependence and firm growth. To test our hypotheses based on the theory, we have collected monthly web traffic data of online retailers and portals from March 2000 and July 2008. The empirical results lend support to our theory of the firm age having a negative interaction effect on web traffic dependence. Moreover, results verified that positive effect of depending on the portals may become greater if the online retailer is a specialist in terms of niche width.

• International Journal of Internet, Broadcasting and Communication
• /
• 제14권2호
• /
• pp.89-97
• /
• 2022

The growth of online market is accelerating due to the development of technology and the era of pandemic. In order to deliver the ordered product to customers courier service should be used. In addition, the courier logistics market is growing with the growth of the online market. With the growth of the logistics market, traffic and environmental problems are emerging as social issues. Logistics technology of urban community logistics courier terminal system utilizing vacant space in the city has been developed as a new alternative to environment and traffic problems by increasing logistics efficiency in the city area. In this study, we propose a concept of a system that performs operational concept definition and scenario analysis by applying model-based perspective analysis to urban community logistics courier terminal system under development. Through this study, we defined the operating concept of the urban community logistics courier terminal, which is the target of development, and defined the scenario for system operation by grasping the structure and function of the system and applied it to system development.

• 한국ITS학회 논문지
• /
• 제22권4호
• /
• pp.132-144
• /
• 2023

유럽과 미국을 중심으로 내연기관 자동차에서 나오는 배기가스를 줄이기 위해 친환경 자동차를 적극적으로 보급하는 정책이 펼쳐지고 있다. 우리나라에서도 '제4차 친환경자동차 기본계획'을 통해 충전인프라 개선과 인센티브제도 확대로 2025년 113만대의 친환경 자동차 보급을 목표하고 있어 전기자동차의 급격한 성장이 예상된다. 따라서 대략적이지만 구체적인 성장규모와 그에 따른 전력수요량을 도출하는 것이 필요하다. 본 연구에서는 성장모형 중 향후 전기자동차의 보급대수를 잘 설명할 수 있는 모형을 활용하여 전기자동차의 대수를 예측하였다. 그리고 선행연구에서 제시한 전기에너지 산출모형을 활용하여 「제10차 전력수급기본계획」의 목표연도인 2036년까지 전기자동차의 보급대수와 전력수요량을 제시하였다. 본 연구 결과를 토대로 향후 전기자동차 인프라 계획·구축을 위한 기초 연구자료로 활용될 것을 기대된다.