• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.4015-4033
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• 2015

The future mobile networks consist of hyper-dense heterogeneous and small cell networks of same or different radio access technologies (RAT). Integrating mobile networks of different RATs to provide seamless and smooth mobility service will be the target of future mobile converged network. Generally, handover from high-speed networks to low-speed networks faces many challenges from application perspective, such as abrupt bandwidth variation, packet loss, round trip time variation, connection disruption, and transmission blackout. Existing inter-RAT handover solutions cannot solve all the problems at the same time. Based on the high-layer convergence sublayer design, a new receiver-aided soft inter-RAT handover is proposed. This soft handover scheme takes advantage of multihoming ability of multi-mode mobile station (MS) to smooth handover procedure. In addition, handover procedure is seamless and applicable to frequent handover scenarios. The simulation results conducted in UMTS-WiMAX converged network scenario show that: in case of TCP traffics for handover from WiMAX to UMTS, not only handover latency and packet loss are eliminated completely, but also abrupt bandwidth/wireless RTT variation is smoothed. These delightful features make this soft handover scheme be a reasonable candidate of mobility management for future mobile converged networks.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.205-215
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• 2008

convergence networks (BcN). The problem seeks to minimize the total cost of switch and cable while satisfying the requirement of demand and quality of service (QoS). We develop mixed integer programming models to obtain the optimal switch location of the access network. We develop a Tabu Search (TS) heuristic algorithm for finding a good feasible solution within a reasonable time limit. We propose real networks with up to 25 nodes and 180 demands. In order to demonstrate the effectiveness of the proposed algorithm, we generate lower bounds from nonlinear QoS relaxation problem. Computational results show that the proposed heuristic algorithm provides upper bounds within 5% optimality gap in 10 seconds.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.740-746
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• 2013

Machine to machine (M2M) communication is a converged ICT(Information and Communications Technology) platform which can utilize communications services among people and things anytime, any place in realtime. The M2M platform consists of three components; M2M area networks sensing and generating data of things by various sensors and devices; public networks transporting those data; and M2M applications utilizing the aggregated data. There exist however two practical obstacles to realize the M2M communications in terms of interoperability between the WCDMA-based public network and the local networks based on W-Fi or ZigBee; one is the cost problem required to access the public network, and the other is the lack of a cost-effective modem or gateway to connect two different networks. In this paper, we proposed and implemented a novel M2M platform based on PWW (Person Area Network) which can resolve those two issues by using a proposed gateway connecting the local network and smartphones as application devices without access the WCDMA-based public network. We have shown that the proposed platform is very practical to adopt to the real environment by actual testing with the own developed smartphone applications.