• Journal of the Korean Data and Information Science Society
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• 제20권6호
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• pp.1177-1190
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• 2009

In this paper, we propose a fuzzy proxy cache scheme for caching web documents in mobile base stations. In this scheme, a mobile cache model is used to facilitate data caching and data replication. Using the proposed cache scheme, the individual proxy in the base station makes cache decisions based solely on its local knowledge of the global cache state so that the entire wireless proxy cache system can be effectively managed without centralized control. To improve the performance of proxy caching, the proposed cache scheme predicts the direction of movement of mobile hosts, and uses various cache methods for neighboring proxy servers according to the fuzzy-logic-based control rules based on the membership degree of the mobile host. The performance of our cache scheme is evaluated analytically in terms of average response delay and average energy cost, and is compared with that of other mobile cache schemes.

• ETRI Journal
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• 제35권4호
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• pp.687-696
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• 2013

The development of proxy caching is essential in the area of video-on-demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted-Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot-Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2000년도 봄 학술발표논문집 Vol.27 No.1 (A)
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• pp.379-381
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• 2000

인터넷과 같은 WAN환경에서 멀티미디어 전송품질을 향상시키기 위해서 Proxy Cache가 많이 이용되고 있으며, 이에 기반하여 클라이언트에게 실시간으로 연속미디어를 서비스하기 위한 여러 가지 전송기법들이 요구되어지고 있다. 본 논문에서는 Proxy Cache안에 일정양의 메모리를 Relay Buffer로 할당하고 이를 이용한 흐름제어기법을 구현하며, RTSP서버의 전송스케쥴러의 idle time을 이용하는 재전송기법을 제안하고 구현한다. 실험 결과, 제안된 기법은 WAN상에서의 RTSP서버와 Proxy Cache사이 패킷손실량 현저하게 줄일 수 있음을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.155-158
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• 2003

This paper proposes a quality-of-service(QoS)-adaptive proxy-switching scheme for multimedia streaming over the Internet. characteristic of multimedia-object about that effect on weight and transport-time causes Streaming Application is restricted to high-quality-service. But using of Proxy or Cache can reduce restraint of media stream. However previous scheme propose only structure of proxy and skill of streaming-object. It couldn't propose proper scheme about limited cache and proxy error occasion. We propose adaptive-proxy-switching mechanism for solution about some problems that caused by single-proxy and limited cache in case of streaming service.

• 한국시뮬레이션학회논문지
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• 제12권2호
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• pp.25-34
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• 2003

Because of explosive growth in demand for web-based multimedia applications, proper proxy caching for large multimedia object (especially video) has become needed. For a video object which is much larger in size and has different access characteristics than the traditional web object such as image and text, caching the whole video file as a single web object is not efficient for the proxy cache. In this paper, we propose a proxy caching strategy with the constant-sized segment for video file and an improved proxy cache replacement policy. Through the event-driven simulation under various conditions, we show that our proposal is more efficient than the variable-sized segment strategy which has been proven to have higher hit ratio than other traditional proxy cache strategies.

• 한국시뮬레이션학회논문지
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• 제9권2호
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• pp.1-14
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• 2000

Recently, as construction of information infra including high-speed communication networks remarkably expands, more various information services have been provided. Thus the number of internet users rapidly increases, and it results in heavy load on Web server and higher traffics on networks. The phenomena cause longer response time that means worse quality of service. To solve such problems, much effort has been attempted to loosen bottleneck on Web server, reduce traffic on networks and shorten response times by caching informations being accessed more frequently at the proxy server that is located near to clients. And it is also possible to improve internet performance further by allowing clients to share informations stored in proxy caches. In this paper, we perform simulations of hierarchical proxy caches with the 3-level 4-ary tree structure by using real web traces, and analyze cache hit ratio for various cache replacement policies and cache sizes when the delayed-store scheme is applied. According to simulation results, the delayed-store scheme increases the remote cache hit ratio, that improves quality of service by shortening the service response time.

• Journal of Ubiquitous Convergence Technology
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• 제2권1호
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• pp.1-11
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• 2008

An effective solution to the problems caused by the explosive growth of World Wide Web is a web caching that employing an additional server, called proxy cache, between the clients and main server for caching the popular web objects near the clients. However, a single proxy cache can easily become the bottleneck. Deploying groups of cooperative caches provides scalability and robustness by eliminating the limitations caused by a single proxy cache. Two common architectures to implement the cooperative caching are hierarchical and distributed caching systems. Unfortunately, both architectures suffer from performance limitations. We propose an efficient hybrid caching architecture eliminating these limitations by using both the hierarchical and same level caches. Our performance evaluation with our investigated simulator shows that the proposed architecture offers the best of both existing architectures in terms of cache hit rate, the number of query messages from clients, and response time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
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• pp.99-102
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• 2004

Caching is one of essential functions in a wireless internet proxy server cluster. To serve best quality of service and choose suitable a proxy server for user, load balancer have to consider cache cooperation between proxy servers. Usually hashing is a simple way to support cache cooperation. In this paper, we compare and analysis static hashing and MD 5 that can be used for cache cooperation.

• 디지털융복합연구
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• 제10권4호
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• pp.207-215
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• 2012

본 논문에서는 무선 모바일 애드 혹 네트워크상에서 스트리밍 미디어 서비스 향상을 위한 프록시 기반 캐싱 최적화 기법을 제안한다. 제안된 기법은 WLAN상에서 미디어 서버와 노드들 간의 통신을 위해 프록시를 사용하며, 프록시는 무선 엑세스 포인터 근처에 설치한다. 그리고 캐싱 최적화가 수행되도록 NFCO(non-full cache optimization)과 CFO(cache full optimization)기법을 제안한다. NFCO와 CFO는 프록시에서 스트리밍이 수행될 때 캐시의 성능을 최적화하기 위해 사용된다. 제안된 기법의 성능을 알아보기 위하여 본 논문에서는 제안된 기법과 서버-중심 스트리밍 기법, 그리고 전송율 왜곡 스트리밍 기법과의 성능을 비교 분석하였다. 그 결과 제안된 기법이 서버-중심 스트리밍 기법과 전송율 왜곡 스트리밍 기법에 비해서 최적화 성능이 우수함을 알게 되었다.

• Journal of Communications and Networks
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• 제12권1호
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• pp.52-66
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• 2010

Since large objects consume substantial resources, web proxy caching incurs a fundamental trade-off between performance (i.e., hit-ratio and latency) and overhead (i.e., resource usage), in terms of caching and relaying large objects to users. This paper investigates how and to what extent the current dedicated-server based web proxy caching scheme is affected by large file transfers in a high bandwidth campus network environment. We use a series of trace-based performance analyses and profiling of various resource components in our experimental squid proxy cache server. Large file transfers often overwhelm our cache server. This causes a bottleneck in a web network, by saturating the network bandwidth of the cache server. Due to the requests for large objects, response times required for delivery of concurrently requested small objects increase, by a factor as high as a few million, in the worst cases. We argue that this cache bandwidth bottleneck problem is due to the fundamental limitations of the current centralized web proxy caching model that scales poorly when there are a limited amount of dedicated resources. This is a serious threat to the viability of the current web proxy caching model, particularly in a high bandwidth access network, since it leads to sporadic disconnections of the downstream access network from the global web network. We propose a peer-to-peer cooperative web caching scheme to address the cache bandwidth bottleneck problem. We show that it performs the task of caching and delivery of large objects in an efficient and cost-effective manner, without generating significant overheads for participating peers.