• Journal of Communications and Networks
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• v.16 no.5
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• pp.534-547
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• 2014

Large-scale failures resulting from natural disasters or intentional attacks are now causing serious concerns for communication network infrastructure, as the impact of large-scale network connection disruptions may cause significant costs for service providers and subscribers. In this paper, we propose a new framework for the analysis and prevention of network service disruptions in large-scale failure scenarios. We build dynamic deterministic and probabilistic models to capture the impact of regional failures as they evolve with time. A probabilistic failure model is proposed based on wave energy behaviour. Then, we develop a novel approach for preventive protection of the network in such probabilistic large-scale failure scenarios. We show that our method significantly improves uninterrupted delivery of data in the network and reduces service disruption times in large-scale regional failure scenarios.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.133-140
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• 2008

The cable TV network has delivered downward broadcasting signals from distribution centers to subscribers. Since the traditional coaxial cable has been upgraded by the Hybrid Fiber Coaxial(HFC) cable, the upward channels has expanded broadband services such as Internet. This upward channel is vulnerable to ingress noises. When the noises from the children nodes accumulated in an amplifier exceeds a certain level, that node has to be cut off to prevent the noise propagation. The node selection problem(NSP) is defined to select nodes so that the noise in each node does not exceed the given threshold value and the sum of Profits of selected nodes can be maximized. The NSP has shown to be NP-hard. In this paper, we have proposed heuristics to find the near-optimal solution for NSP. The experimental results show that interval partitioning is better than greedy approach. Our heuristics can be used by the HFC network management system to provide privileged services to the premium subscribers on HFC networks.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.7
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• pp.1-8
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• 1999

In this paper, we have proposed and evaluated the performance of the routiong protocols servicing the mobile and fixed subscribers in a large e scale circuit switched telecommunication network, connected by gateways. The large scale network consists of several subnetworks, and a subnetwork is composed of $M{\times}N$ nodes in grid topology. When a call for mobile subscriber occurs, the current routing protocols search the whole large scale network to find a mobile subscriber. Therefore, it causes many redundant packets and long call setup delay. So, we have proposed a new routing protocol, in which the destination subscriber is first searched at the subnetwork where the call is proposed protocol is better than that of the current protocol.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.11a
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• pp.305-308
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• 2003

It is widely used that a network termination rate is calculated by using a Long Run Incremental Costing model. Interconnection Order issued Ministry of Information and Communication in Korea on December 2002 has declared that termination charges of local, national, payphone, and mobile calls are going to be determined by LRIC costing models after 2004. There are lots of preceding researches on a fixed network costing model for applying to LRIC method but on a mobile network not pretty much of them. Besides, Most important basis of current calculation models for termination charges are access costs to connect subscribers to network such as a local loop. In this paper, we look into being of access costs in mobile network and show the applicable standards for cost allocation of access costs in implementing LRIC costing model.

• ETRI Journal
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• v.35 no.2
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• pp.234-244
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• 2013

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.

• 한국IT서비스학회:학술대회논문집
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• 2006.11a
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• pp.366-371
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• 2006

To compensate the loss of leased-line subscribers and the excessive increase of residential xDSL (Digital Subscriber Line) ones of KT (Korea Telecom), the paper proposes the service model by which it can reinstate the subscription ratio status through employing next generation OSS (Operations Support System) and highquality MPLS (Multiprotocol Label Switching) VPN (Virtual Private Network). It also describes diverse modules comprising NeOSS (New OSS) of KT, followed by detailed accounts regarding the service delivery process of KT VPN. Shortly visited are the primary constituents as well as configuration parameters of MPLS VPN. Finally the network topology along with a feasible service model case is presented.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.2
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• pp.1-14
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• 2011

In this paper, we deal with an access network design problem of fiber-to-the-home passive optical network (FTTH-PON). The FTTH-PON network design problem seeks to minimize the total cost of optical splitters and cables that provide optical connectivity between central office and subscribers. We develop a flow-based mixed integer programming (MIP) model with nonlinear link cost. By developing valid inequalities and preprocessing rules, we enhance the strength of the proposed MIP model in generating tight lower bounds for the problem. We develop an effective Tabu Search (TS) heuristic algorithm that provides good quality feasible solutions to the problem. Computational results demonstrate that the valid inequalities and preprocessing rules are effective for improving the LP-relaxation lower bound and TS algorithm finds good quality solutions within reasonable time bounds.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.247-253
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• 2007

In this paper, downlink capacity of time duplex division (TDD) based cellular wireless networks utilizing fixed hopping stations is investigated. In the network, a number of fixed subscriber stations act as hopping transmission stations between base stations and far away subscribers, forming a cellular and ad hoc mobile network model. At the radio layer, TDD code division multiple access (CDMA) is selected as the radio interface due to high efficiency of frequency usage. In order to improve the system performance in terms of downlink capacity, we propose different time slot allocation schemes with the usage of fixed hopping stations, which can be selected by either random or distanced dependent schemes. Performance results obtained by computer simulation demonstrate the effectiveness of the proposed network to improve downlink system capacity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1359-1370
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• 2009

In wireless sensor networks, data dissemination is based on data-centric routing that well matches the publish/subscribe communication paradigm. The publish/subscribe paradigm requires decoupling properties: space, time, and synchronization decoupling. For large-scale applications, the three decoupling properties provide scalability and robust communication. However, existing data dissemination schemes for wireless sensor networks do not achieve full decoupling. Therefore, we propose a novel data dissemination scheme that fully accomplishes the three decoupling, called ARBIETER. ARBITER constructs an independent network structure as a logical software bus. Information interworking between publishers and subscribers is indirectly and asynchronously performed via the network structure. ARBITER also manages storage and mapping of queries and data on the structure because of supporting different time connection of publishers and subscribers. Our simulation proves ARBITER show better performance in terms of scalability, network robustness, data responsibility, mobility support, and energy efficiency.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.181-188
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• 2008

Nowadays, WiMAX which provides internet service with a middle and low speed serves more function and is wider than Wi-Fi. While they solve the security risks as subscribers do handover by subscriber's re-certification procedure as the Network range is getting wider, there are more security problems making the problems of electric-power consumption and delay. This paper suggests a handover mechanism which simplify the subscriber's re-certification procedure and prevents a security problem as doing handover for solving the problem of delay and the rate of processing. The mechanism can cooperate with PKI structure to increase flexibility and security and minimize network re-entry procedure or re-certification procedure by providing continual service. As a result. the mechanism's throughput as the number of subscribers is lower than IEEE 802.16e and the mechanism proves that it is secure from the attack of man-in-the-middle and reply as doing handover.