• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.3
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• pp.452-458
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• 2002

Although the reuse of the cached data for scrolling the map reduces the amount of passed data between client and server, it needs the conversions of data coordinates, selertive deletion of objects and cache compaction at client. The conversion is time intensive operation due to limited resources of mobile phones such as low computing power, small memory. Therefore, for the efficient map control in the vector map service based mobile phone, it is necessary to study the method for reducing wireless network bandwidth and for overwhelming the limited resources of mobile phone as well. This paper proposes the methods for racking pre-received spatial objects in client-server systems for mobile CIS. We also analyze the strengths and drawbacks between the reuse of cached data and transmission of raw data respectively.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.651-658
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• 2006

Mobile computing environment is known to be quite difficult to provide user with a stable QoS(Qualify of Service) due to its mobility nature. In order to protect the inherent characteristics of wireless network such as low bandwidth and high transmission delay along with the user's mobility, many works are conducted to apply caching and prefetching methods. This paper presents a novel prefetching technique which is based on user's preference, that is, interest and Uuかity. It tries to improves the effectiveness of prefetching by separating and appling the interest with personal tendency of a given information, and the popularity with general tendency of the information. The proposed scheme shown relatively superior performance in terms of the utilization ratio of prefetched information and the failure ratio of information retrieval than the existing methods.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.364-371
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• 2011

In P2P distribution mobile networks, QoS of streaming media services are under heavy influence from overheads such as congestion, latency, and interference. The problem is further complicated by the fact that the popularity of media objects changes over time. This paper proposes a new FSMS+ (Fuzzy Similarity-based Multi-level Streaming Scheme) which minimizes performance degradation of streaming services due to overhead. We then utilize fuzzy similarity-based relevance that can dynamically stream the streaming media object with minimum overhead. The simulation result showed that the proposed scheme has better performance in retransmission rate, congestion control rate and latency rate than the other existing methods of distance method, DC (disk caching) method, and prefix method.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.630-632
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• 1998

The basic user location strategies proposed in current PCS(Personal Communication Services) Network are two-level Database strategies. These Databases which exist in the Signalling network always maintain user's current location information, and it is used in call setup process to a mobile user. As the number of PCS users are increasing, this strategies yield some problem such as concentrating signalling traffic on the Database, increasing Call setup Delay, and so on. In this paper, we proposed RCP(Reverse Connection setup Protocol) model, which apply RVC(Reverse Virtual Call setup) algorithm to PCS reference model, and CRCP(Cache algorithm in RCP) model, which adopt Caching strategies in the RCP model. When Cache-miss occur, we found that CRCP model require less miss-penalty than PCS model. Also we show that proposed models are always likely to yield better performance in terms of reduced Location Tracking Delay time.

• ETRI Journal
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• v.42 no.5
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• pp.643-657
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• 2020

Sixth generation will exploit satellite, aerial, and terrestrial platforms jointly to improve radio access capability and unlock the support of on-demand edge cloud services in three-dimensional (3D) space, by incorporating mobile edge computing (MEC) functionalities on aerial platforms and low-orbit satellites. This will extend the MEC support to devices and network elements in the sky and forge a space-borne MEC, enabling intelligent, personalized, and distributed on-demand services. End users will experience the impression of being surrounded by a distributed computer, fulfilling their requests with apparently zero latency. In this paper, we consider an architecture that provides communication, computation, and caching (C3) services on demand, anytime, and everywhere in 3D space, integrating conventional ground (terrestrial) base stations and flying (non-terrestrial) nodes. Given the complexity of the overall network, the C3 resources and management of aerial devices need to be jointly orchestrated via artificial intelligence-based algorithms, exploiting virtualized network functions dynamically deployed in a distributed manner across terrestrial and non-terrestrial nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.947-954
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• 2009

In mobile ad hoc networks, service discovery to search for an available service is an important issue. In this paper, we propose an efficient service discovery protocol that is combined a dht-based service discovery scheme and a P2P caching-based information spreading scheme. Proposed scheme store key information in hashed zone and search services using it's information. To search quickly a service, it use its physical neighbors information which collected by 1-hop hello message between a node and its physical neighbors. We do not use a central look up server and do not rely on flooding. Hence, it uniquely balanced all node's load in mobile ad hoc networks and reduced the number of messages exchanged, network load and response time. The simulation results show that our protocol outperforms DHT-based and flooding protocols.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.497-500
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• 2018

As the fourth industrial revolution began to take off in earnest, the quality and quantity of data shared among devices began to increase exponentially over the network. In addition, the category of devices where people are exposed to such data has become diversified into desktops, mobile phones, smart phones, smart pads, and smart watches. As a result, the medium that contacts the data has begun to change, and the place where modern society has the most data is smart device. However, smart devices still leave much to be desired in terms of network speed and hardware specifications to handle large amounts of data at one time. Therefore, in this paper, we analyze the use of Service Worker, IndexedDB, and LocalStroage, which can retrieve a large amount of web contents more efficiently from mobile devices, and suggest ways to improve it.

• Journal of KIISE:Databases
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• v.27 no.1
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• pp.53-63
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• 2000

The mobile computing service market is increasing rapidly due to the development of low-cost wireless network technology and the high-performance mobile computing devices. In recent years, several methods have been proposed to effectively deal with restrictions of the mobile computing environment such as limited bandwidth, frequent disconnection and short-lived batteries. Amongst those methods, much study is being done on the caching method - among the data transmitted from a mobile support station, it selects those that are likely to be accessed in the near future and stores them in the local cache of a mobile host. Existing cache replacement methods have some limitations in efficiency because they do not take into consideration the characteristics of user mobility and spatial attributes of geographical data. In this paper, we show that the value and the semantic of the data, which are stored in the cache of a mobile host, changes according to the movement of the mobile host. We argue it is because data that are geographically near are better suited to provide an answer to a users query in the mobile environment. Also, we define spatial location of geographical data has effect on, using the spatial attributes of data. Finally, we propose two new cache replacement methods that efficiently support user mobility and spatial attributes of data. One is based on the location of data and the other on the meaningful region of data. From the comparative analysis of the previous methods and that they improve the cache hit ratio. Also we show that performance varies according to data density using this, we argue different cache replacement methods are required for regions with varying density of data.

• Convergence Security Journal
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• v.8 no.4
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• pp.105-113
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• 2008

Mobile computing environment is known to be quite difficult to provide user with a stable Quality of Service (QoS) due to vehicle mobility nature. In order to protect the inherent characteristics of wireless network such as low bandwidth and high transmission delay along with the vehicle's mobility, many works are conducted to apply caching and prefetching methods. This paper presents a novel prefetching technique which is based on owner's profile. It is the scheme with the vehicle velocity, the visit frequency and resident time of specific region for vehicle owner's past given period, and the user profile which has owner's personal inclination about a certain place. The proposed scheme shown relatively superior performance in terms of the utilization ratio of prefetched information and the failure ratio of information retrieval than the previous methods.

• Journal of KIISE:Databases
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• v.34 no.5
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• pp.448-464
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• 2007

Location-Based Services (LBSs) provide results to queries according to the location of the client issuing the query. In LBS, techniques such as caching and prefetching are effective approaches to reducing the data transmission from a server and query response time. However, they can lead to cache inefficiency and network overload due to the client's mobility and query pattern. To solve these drawbacks, we propose a semantic prefetching (SP) scheme using prefetching segment concept and improved cache replacement policies. When a mobile client enters a new service area, called semantic prefetching area, proposed scheme fetches the necessary semantic information from the server in advance. The mobile client maintains the information in its own cache for query processing of location-dependent data (LDD) in mobile computing environment. The performance of the proposed scheme is investigated in relation to various environmental variables, such as the mobility and query pattern of user, the distributions of LDDs and applied cache replacement strategies. Simulation results show that the proposed scheme is more efficient than the well-known existing scheme for range query and nearest neighbor query. In addition, applying the two queries dynamically to query processing improves the performance of the proposed scheme.