• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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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.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.631-640
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• 2003

Because of multi-hop wireless communication, P2P applications in ad hoc networks suffer poor performance. We Propose neighbor caching strategy to overcome this shortcoming and show it is more efficient than self caching that nodes store data in theirs own cache individually. A node can extend its caching storage instantaneously with neighbor caching by borrowing the storage from idle neighbors, so overcome multi-hop wireless communications with data source long distance away from itself. We also present the ranking based prediction that selects the most appropriate neighbor which data can be stored in. The node that uses the ranking based prediction can select the neighbor that has high possibility to keep data for a long time and avoid caching the low ranked data. Therefore the ranking based prediction improves the throughput of neighbor caching. In the simulation results, we observe that neighbor caching has better performance, as large as network size, as long as idle time, and as small as cache size. We also show the ranking based prediction is an adaptive algorithm that adjusts times of data movement into the neighbor, so makes neighbor caching flexible according to the idleness of nodes

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.103-106
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• 2004

A wireless Internet proxy server cluster has to Distillation and Caching functions in order that a user on wireless internet can use existing wired internet service. Distillation function works to distill HTML documents and included images according to the defined preference by a user. When a user requests repeatedly, Caching function decreases response time by reusing original and distilled images or HTML documents. In this paper, we proposed enhanced distillation and caching functions. We performed experiments using 16 PCs and experimental results show the effectiveness of the proposed system compared to the existing system.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.3
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• pp.91-98
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• 2013

Node which plays the role of cache server does not exist in the wireless ad-hoc network consisting of only mobile nodes. Even if it exists, it is difficult to provide cache services due to the movement of nodes. Therefore, the cooperative cache technique is necessary in order to improve the efficiency of information access by reducing data access time and use of bandwidth in the wireless ad-hoc network. In this paper, the whole network is divided into zones which don't overlap and master node of each zone is elected. General node of each zone has ZICT and manages cache data to cooperative cache and gateway node use NZCT to manage cache information of neighbor zone. We proposed security structure which can accomplish send and receive in the only node issued id key in the elected master node in order to prepare for cache consistent attack which is vulnerability of distributed caching techniques. The performance of the proposed method in this paper could confirm the excellent performance through comparative experiments of GCC and GC techniques.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1498-1507
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• 2017

According to recent report, global mobile data traffic is expected to increase by 11 times from 2016 to 2020. Moreover, this growth is expected to be driven mainly by mobile video traffic which is expected to account for about 70% of the total mobile data traffic. To cope with enormous mobile traffic, we need to understand video traffic's characteristic. Recently, the repetitive requests of some popular content such as popular YouTube videos cause a enormous network traffic overheads. If we constitute a network with the nodes capable of content caching based on the content popularity, we can reduce the network overheads by using the cached content for every request. Through device-to-device, multicast, and helpers, the video throughput can improve about 1.5~2 times and prefix caching reduces the playback delay by about 0.2~0.5 times than the conventional method. In this paper, we introduce some recent work on content popularity-based caching techniques in wireless networks.

• Journal of Information Technology Services
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• v.8 no.1
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• pp.179-192
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• 2009

In wireless environments, it is very effective to introduce a data broadcast system for providing a number of clients with mobile data services. In particular, an efficient broadcast scheduling and a caching strategy are very important for performance of data broadcast systems in wireless environments which have such inherent restrictions as low bandwidth, frequent disconnections, and short battery life. In this paper, we present a data broadcast scheduling strategy using bit vectors to cope with dynamic request patterns of clients. In addition, we also propose an efficient caching strategy, 2FWT, that takes characteristics of the broadcast scheduling strategy into account. Finally, we evaluate performance of the data broadcast system. According to the results, the proposed system generally shows better performance than others.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.449-449
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• 2004

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.535-542
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• 2005

A data broadcast is an efficient technique to deliver data to a number of clients in wireless computing environments. In data broadcast systems, which generally have a narrow bandwidth, a caching is introduced to reduce contention for the bandwidth so that the response time can be decreased. In this paper, unlike previous works that use information maintained by clients, we propose several caching strategies using information on data requests of clients maintained by a server. Then, we evaluate the performance of proposed strategies by using simulation approach. According to the results, the strategy that considers both popularity and waiting time maintained by a server generally shows better performance than other strategies.

• Convergence Security Journal
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• v.12 no.4
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• pp.91-96
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• 2012

MANET is developed technique fairly among many field of wireless network. Nodes which consist of MANET transmit data using multi-hop wireless connection. Caching scheme is technique which can improve data access capacity and availability of nodes. Previous studies were achieved about dynamic routing protocol to improve multi-hop connection of moving nodes. But management and maintenance of effective cache information because of movement of nodes is not easy. In this study, we proposed cluster-based caching scheme to manage connection by decreasing overhead and moving of nodes as moving node discovers cache of wish information. And HLP was used to maintain effective cache table in each cluster head. Efficiency of proposed technique in this study was confirmed by experiment.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.101-111
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• 2004

As different from wired internet, wireless internet has limitations due to the following characteristics; low bandwidth, frequent disconnection, low computing power, small screen in user terminal, and user mobility. Also, wireless internet server should be scalable to handle a large scale traffic due to rapidly growing users. Wireless proxy servers are used for the wireless internet because their caching and transcoding functions are helpful to overcome the above limitation. TranSend was proposed as a clustering based wireless proxy server but its scalability is difficult to achieve because there is no systematic way to do it. In this Paper. we proposed a clustering based wireless internet proxy server which can be scalable in a systematic way. We performed experiments using 16 PCs and experimental results show 32.17% performance improvement of the proposed system compared to TranSend system.