• 한국군사과학기술학회지
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• 제17권5호
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• pp.637-642
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• 2014

Military communications have limited resources such as poor bandwidth and insufficient link capacity. Numerous hosts in conventional IP networks, including the Tactical Information Communication Network (TICN), the tactical communication system of the Army, focus heavy traffic on a single server via end-to-end connections and in which data delivery latency is caused by exchanging routing information. Content-Centric Networking (CCN), one framework of Information-Centric Networking (ICN), is a novel Internet paradigm in which data can be accessed by the name of the content instead of the location information. This paper provides content caching strategies for applying CCN to military tactical IP networks based on TICN environment.

• Journal of Communications and Networks
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• 제17권6호
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• pp.549-557
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• 2015

Mobile cellular networks are becoming increasingly complex to manage while classical deployment/optimization techniques and current solutions (i.e., cell densification, acquiring more spectrum, etc.) are cost-ineffective and thus seen as stopgaps. This calls for development of novel approaches that leverage recent advances in storage/memory, context-awareness, edge/cloud computing, and falls into framework of big data. However, the big data by itself is yet another complex phenomena to handle and comes with its notorious 4V: Velocity, voracity, volume, and variety. In this work, we address these issues in optimization of 5G wireless networks via the notion of proactive caching at the base stations. In particular, we investigate the gains of proactive caching in terms of backhaul offloadings and request satisfactions, while tackling the large-amount of available data for content popularity estimation. In order to estimate the content popularity, we first collect users' mobile traffic data from a Turkish telecom operator from several base stations in hours of time interval. Then, an analysis is carried out locally on a big data platformand the gains of proactive caching at the base stations are investigated via numerical simulations. It turns out that several gains are possible depending on the level of available information and storage size. For instance, with 10% of content ratings and 15.4Gbyte of storage size (87%of total catalog size), proactive caching achieves 100% of request satisfaction and offloads 98% of the backhaul when considering 16 base stations.

• 디지털융복합연구
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• 제15권2호
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• pp.327-334
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• 2017

네트워크 성능 향상을 위하여 CDN/P2P와 같은 기술들은 이전에 사용자들 또는 프락시 시스템에 저장되어 있는 복사본을 사용하도록 설계 되었다. CCN 역시 이와 같은 기능을 구현한다. 그러나 CDN/P2P와 달리, CCN은 이와 같은 캐시 기능을 네트워크 노드에 구현하고, 네트워크 노드들이 콘텐츠 요청 메시지에 직접 응답할 수 있도록 설계 되었다. 그러므로 CCN의 성능에 가장 중요한 요소는 캐시 되는 콘텐츠와 노드를 결정하는 기술이다. 기본적으로, CCN은 콘텐츠가 전송될 때 경유하는 모든 네트워크 노드들에 해당 콘텐츠가 캐시 되도록 설계되었지만, 이와 같은 접근 방법은 중복 캐시 발생으로 인하여 매우 비효율적이라 할 수 있다. 이러한 문제를 해결하기 위하여 다양한 캐시 운영 방법이 제안되었다. 본 논문에서는 지금까지 제안된 캐시 운영 방안들을 살펴보고, 실제 운영을 위해 필요한 효과적인 캐시 운영을 위한 핵심 요구사항들을 제안한다.

• 한국전자거래학회지
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• 제13권4호
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• pp.161-171
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• 2008

웹 사용자의 폭발적인 증가는 웹 시스템의 부하 및 네트워크 트래픽을 증가시키는 가장 큰 원인이 되고 있으며, 이는 웹 사용자의 서비스 만족도를 떨어뜨리고 있다. 이러한 현상을 극복하기 위해서 웹 콘텐트 가속화에 대한 연구가 활발히 진행되고 있다. 웹 캐싱은 클라이언트 요청을 신속하게 처리하고, 네트워크에 대한 트래픽을 줄여 전체 웹 시스템의 부하를 줄이게 하는 가속화 기법 중의 하나이다. 본 논문은 웹 처리의 단위인 객체의 특성을 기반으로 한 연관 웹 객체(Related Web Object：RwO)를 기반으로 하는 새로운 웹 캐싱 기법을 제안하였다. 또한 실험을 통해 기존의 기법과 제안기법의 성능을 비교함으로서 본 연구의 유용성을 입증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2680-2696
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• 2018

The collaborative content caching system is an effective solution developed in recent years to reduce transmission delay and network traffic. In order to decrease the service end-to-end transmission delay for future 5G ultra-dense networks (UDN), this paper proposes a novel service migration method that can guarantee the continuity of service and simultaneously reduce the traffic flow in the network. In this paper, we propose a service migration optimization model that minimizes the cumulative transmission delay within the constraints of quality of service (QoS) guarantee and network condition. Subsequently, we propose an improved firefly algorithm to solve this optimization problem. Simulation results show that compared to traditional collaborative content caching schemes, the proposed algorithm can significantly decrease transmission delay and network traffic flow.

• 융합정보논문지
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• 제10권1호
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• pp.22-27
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• 2020

5G 인프라 보급과 더불어 기하급수적으로 증가하는 1인 미디어 방송, 유튜브와 같은 모바일 콘텐츠 서비스를 안정적으로 제공하기 위해서는 사용자 부근에 캐시 서버를 분산 배치하는 콘텐츠 전송 네트워크(CDN:Content Delivery Network) 도입이 필수적이다. 지역 캐시 없이 사용자가 콘텐츠 사업자(Content Provider)로부터 직접 서비스를 받는 트래픽이 늘어날수록 모바일 백홀(Backhaul)과 프론트홀(Fronthaul)에서 감당해야 할 부담은 상당히 증가하게 된다. 본 연구는 광기반 5G 프론트홀 구조와 캐싱 방법을 제안하여 모바일 백홀의 대역폭 및 서비스 품질을 개선하는 데 목적이 있다. 이를 위해 우선 전용 광케이블을 프론트홀로 사용하는 콘텐츠 전송 네트워크와 수동광가입자망(PON:Passive Optical Network)을 사용하는 구조를 제안한다. 그 위에 PON 캐싱에 특화된 집화된 콘텐츠 요청 방법을 제안하고 모델링과 시뮬레이션을 통해 그 성능을 기존의 방식과 비교한다. 제안된 PON 캐싱은 기존 캐싱이 없는 구조에 비해 최대 0.5초의 평균접근시간 감소, 1/n개의 수신된 요청 패킷 감소, 약 60% 백홀 대역폭 절감 효과를 나타냈다. 이 연구는 모바일 백홀 비용과 서비스 품질 사이에서 고민하는 통신사업자들에게 하나의 참고 자료가 될 수 있으며, 추후 캐시 적중률을 더욱 끌어올리는 방안으로 확장될 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.4912-4933
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• 2015

Information Centric Networking (ICN) has recently attracted great attention. It names the content decoupling from the location and introduces network caching, making the content to be cached anywhere within the network. The benefits of such design are obvious, however, many challenges still need to be solved. Among them, the local caching policy is widely discussed and it can be further divided into two parts, namely the cache permission policy and the cache replacement policy. The former is used to decide whether an incoming content should be cached while the latter is used to evict a cached content if required. The Internet is a user-oriented network and popular contents always have much more requests than unpopular ones. Caching such popular contents closer to the user's location can improve the network performance, and consequently, the local caching policy is required to identify popular contents. However, considering the line speed requirement of ICN routers, the local caching policy whose complexity is larger than O(1) cannot be applied. In terms of the replacement policy, Least Recently Used (LRU) is selected as the default one for ICN because of its low complexity, although its ability to identify the popular content is poor. Hence, the identification of popular contents should be completed by the cache permission policy. In this paper, a cache permission policy called Cache-Filter, whose complexity is O(1), is proposed, aiming to store popular contents closer to users. Cache-Filter takes the content popularity into account and achieves the goal through the collaboration of on-path nodes. Extensive simulations are conducted to evaluate the performance of Cache-Filter. Leave Copy Down (LCD), Move Copy Down (MCD), Betw, ProbCache, ProbCache⁺, Prob(p) and Probabilistic Caching with Secondary List (PCSL) are also implemented for comparison. The results show that Cache-Filter performs well. For example, in terms of the distance to access to contents, compared with Leave Copy Everywhere (LCE) used by Named Data Networking (NDN) as the permission policy, Cache-Filter saves over 17% number of hops.

• 산업기술연구
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• 제27권B호
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• pp.185-192
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• 2007

Transcoding video proxy is necessary to support various bandwidth requirements for mobile multimedia and to provide adapting video streams to mobile clients. Caching algorithms for proxy are to reduce the network traffic between the content servers and the proxy. This paper proposes a Meta-tailed caching for transcoding proxy that is efficient to lower network load and CPU load. Caching of two different data types - transcoded video, and metadata - provides a foundation to achieve superior balance between network resource and computation resource at transcoding proxies. Experimental results show that the Meta-tailed caching lowers at least 10% of CPU-load and at least 9% of network-load at a transcoding proxy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.514-535
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• 2019

Information-centric networks operate under the assumption that all network components have built-in caching capabilities. Integrating the caching strategies of information centric networking (ICN) with wireless virtualization improves the gain of virtual infrastructure content caching. In this paper, we propose a framework for software-defined information centric virtualized wireless device-to-device (D2D) networks. Enabling D2D communications in virtualized ICN increases the spectral efficiency due to reuse and proximity gains while the software-defined network (SDN) as a platform also simplifies the computational overhead. In this framework, we propose a joint virtual resource and cache allocation solution for latency-sensitive applications in the next-generation cellular networks. As the formulated problem is NP-hard, we design low-complexity heuristic algorithms which are intuitive and efficient. In our proposed framework, different services can share a pool of infrastructure items. We evaluate our proposed framework and algorithm through extensive simulations. The results demonstrate significant improvements in terms of visiting latency, end user QoE, InP resource utilization and MVNO utility gain.

• Journal of Information Processing Systems
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• 제12권4호
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• pp.577-590
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• 2016

We studied the current state-of-the-art of Smart TV, the challenges and the drawbacks. Mainly we discussed the lack of end-to-end solution. We then illustrated the differences between Smart TV and IPTV from network service provider point of view. Unlike IPTV, viewer of Smart TV's over-the-top (OTT) services could be global, such as foreign nationals in a country or viewers having special viewing preferences. Those viewers are sparsely distributed. The existing TV service deployment models over Internet are not suitable for such viewers as they are based on content popularity, hence we propose a community based service deployment methodology with proactive content caching on rendezvous points (RPs). In our proposal, RPs are intermediate nodes responsible for caching routing and decision making. The viewer's community formation is based on geographical locations and similarity of their interests. The idea of using context information to do proactive caching is itself not new, but we combined this with "in network caching" mechanism of content centric network (CCN) architecture. We gauge the performance improvement achieved by a community model. The result shows that when the total numbers of requests are same; our model can have significantly better performance, especially for sparsely distributed communities.