• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.384-392
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• 2004

Mobile contents service providers have some difficulties to timely and proper service deployment due to rapid development cycle of diverse portable devices with different capabilities. A way to resolve the problem is to introduce a mobile contents service paltform that can adapt original mobile contents to diverse devices dynamically and automatically. In this paper, we propose a mobile contents service platform based on active network mechanisms, called Mobile Content Adaptation Network(MobiCAN). The MobiCAN node provides effective service deployment, execution, and maintenance features and accommodates service layering and service customization capabilities for easy deployment. The basic functional units of the MobiCAN node are micro services with well-defined service interfaces and service layering features. For reliable services among the MobiCAN nodes, we design new distributed and robust Overlay Management Protocols(OMPs). As an example of practical MobiCAN applications, we finally describe Dynamic Contents Customization Proxy(DCCP) service.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.9-16
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• 2005

In this paper, we focus on supporting the convergence of broadcasting and communication in home network systems with E-PON based home gateway. We propose a new architecture to provide broadcasting and data services in integrated home network using overlay transport mechanism in access network and If multicast techniques of IGMP and IGMP snooping in home network. We also detail a set of mechanisms and procedures for home broadcasting service through the home gateway system. Our new scheme is composed of three parts: a) an overlay transmission model of video broadcasting signals (satellite and/or cable TV) and Internet data, b) to select a specific video broadcasting channel and to make of the selected video broadcasting stream into IP multicast packets in tuner/conversion module using multiple tuner system and c) to transfer the converted If multicast packets to L2 switch of home gateway's core module and to send them out to target port(s) by L2 multicast using IGMP snooping.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.791-800
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• 2009

Multicasting is fundamental to many ad hoc network applications requiring collaboration of multiple nodes in a group. A general approach is to construct an overlay tree and to deliver a multicast packet to multiple receivers over the tree. This paper proposes adaptive overlay trees (AOTs) on wireless ad hoc networks of static nodes for delay- and energy-efficient multicast. A tradeoff function is derived, and an algorithm for AOT construction is developed. Note here that the requirements of delay and energy consumption may vary with different classes of applications. By adjusting parameters in the tradeoff function, different AOTs can be adaptively chosen for different classes of applications. An AOT is constructed in O(ke) time where e is the number of wireless links in a network and k is the number of member nodes in a multicast group. The simulation study shows that AOT adaptively provides tradeoffs between the fastest multicast (which is the choice if delay is the most important factor) and the most energy efficient multicast (which is used when energy consumption is the primary concern). In other words, one of AOTs can be appropriately chosen in accordance with the operation requirement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.440-450
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• 2003

The reverse link of a spectrally overlaid macrocell/microcell cellular CDMA system supporting multimedia traffic is characterized in terms of the required signal power, interference, and capacity. Several narrowband subsystems are overlaid with a wideband subsystem in macrocells, while a single wideband subsystem is operated in a microcell with the same spectrum as the macrocell wideband subsystem. Using a typical propagation model the reverse link signal power and interference are characterized as the relative user signal power and the cross-tier interference factors between the macrocell and the microcell. The reverse link capacity of the overlay system is then analyzed. Analytical results show that the dominant parameters affecting the system performance are the spectral overlay ratio and the distance between the microcell and macrocell base stations. In particular, when the distance equals a half of macrocell radius, optimum performance can be achieved by minimizing the cross-tier interference factors. These results can be applied to CDMA multimedia network planning in heavily populated traffic areas.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3312-3334
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• 2015

In this paper, a mechanism for spectrum allocation in overlay cognitive radio networks is proposed. In overlay cognitive radio networks, the secondary users (SUs) must first sense the activity of primary users (PUs) to identify unoccupied spectrum bands. Based on their different contributions for the spectrum sensing, the SUs get payoffs that are computed by the fusion center (FC). The unoccupied bands will be auctioned and SUs are asked to bid using payoffs they earned or saved. Coalitions are allowed to form among SUs because each SU may only need a portion of the bands. We formulate the coalition forming process as a coalition forming game and analyze it by game theory. In the coalition formation game, debtor-creditor relationship may occur among the SUs because of their limited payoff storage. A debtor asks a creditor for payoff help, and in return provides the creditor with a portion of transmission time to relay data for the creditor. The negotiations between debtors and creditors can be modeled as a Bayesian game because they lack complete information of each other, and the equilibria of the game is investigated. Theoretical analysis and numerical results show that the proposed auction yields data rate improvement and certain fairness among all SUs.

• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.396-400
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• 2011

P2P(peer to Peer) network is a distributed network architecture composed of participants that make a portion of their resources directly available to other network participants, without the need for a central server. Currently, convergence network industry using wired and mobile are grows rapidly. So P2P protocols will be used between mobile and wired network. But current P2P protocols are focused on the wired networks only and there are no simulators for performance analysis of mobile P2P. In this paper, we design a P2P simulation system for performance analysis of P2P protocols in mobile, wired and convergence networks. It is constructed by a well-known mobile network simulator and wired based P2P protocol simulator. Finally we have implemented a smart TV test-bed using our P2P test-bed for convergence networks.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.232-239
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• 2009

Emerging social networking services provide a new paradigm for human-to-human communication. However, these services are centralized and managed by single service provider. In this paper, we propose MicroPost, a decentralized event notification service architecture for social applications based on publish/subscribe model. In our design space, event brokers are structured as an overlay network which provides the substrate of distributed peer-to-peer lookup service for storing and retrieving subscriptions with hashed keys. Event clients interact with event brokers to publish or subscribe social messages over the wide-area network. Using XML standards, we present an efficient algorithm to forward events for rendezvous-based matching in this paper. In our design space, the cost of routing is O(${\omega}log_kN$), where N is the number of event brokers, ${\omega}$ is the number of meta-data obtained from event messages, and k is a constant, which is selected by our design, to divide the identifier space and to conquer the lookup of given key. Consequently, what we achieved is an asynchronous social messaging service architecture which is decentralized, efficient, scalable, and flexible.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.415-417
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• 2006

분산형 P2P 그리드 시스템을 구축하는데 있어 연산 수행을 위한 노드 구성 기법과 구성된 토플로지에 적합한 연산 수행 보델 및 스케줄링 기법은 필수 요소이다. 하지만 기존 연구에서는 자원 제공자와 휘발성을 고려하지 않은 연산 수행 모델을 사용하였기 때문에 연산의 안정적인 수행이 보장되지 못하고, 시스템의 성능이 떨어지는 문제점이 발생한다. 이에 본 논문에서는 가용성 기반의 자가 조직적 계산 오버레이 네트워크(SelfCON:Self-organizing Computation Overlay Network) 구성 기법과 구성된 토폴로지에 적합한 연산 수행 모델 및 스케줄링 기법을 제안한다. 제안 기법은 자원 제공자 노드의 휘발성을 고려하여 안정성을 높임으로써 전체 연산 성능을 향상시킨다.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.1 s.24
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• pp.39-44
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• 2003

Recently, GIS has been increasing its applicability in water resource field. The GIS based modeling process can generally be used for extracting channel network and watershed delineation. Through the overlay analysis, the extracted channel network can be overlayed with topographic and landuse maps to generate the input files for running a hydrologic model. This lead to consider GIS as a tool which can include subjective factors of the model designers in hydrologic analysis. Therefore, this study has compared GIS based HEC-GEOHMS with the classical approach. In general, both approaches have similar results, however, HEC-GROHMS has showed some errors. Based on the results, a GIS based approach could be more effective method with better credibility to obtain input parameters from topographic information as subsequent efforts were made to lessen the errors.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.589-591
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• 2005

최근에 P2P(Peer-to-Peer) 시스템에서 효율적인 자원 탐색 방범에 대해 많이 연구되고 있다. P2P overlay network 중 하나인 Chord는 자원을 효율적으로 탐색할 수 있는 간단한 P2P 프로토콜이다. 대부분의 P2P 시스템은 overlay network를 형성하므로 노드와 노드 사이의 물리적인 거리를 고려하지 않으므로 서로 이웃한 노드라도 실제 물리적인 latency가 클 수 있다는 문제점을 가지고 있다. 이 논문은 물리적으로 가까운 노드들을 하나의 subnet으로 만들어서 물리적인 latency를 감소시키고 각 subnet안에 복사본(replica)을 둠으로써 탐색(lookup)의 효율성을 향상시킨다.