• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.83-90
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• 2010

DTNs (Delay Tolerant Networks) refer to the networks that can support data transmission in the extreme networking situations such as continuous delay and no connectivity between ends. DTMNs (Delay Tolerant Networks) are a specific range of DTNs, and its chief considerations in the process of message delivery in the routing protocol are the transmission delay, improvement of reliability, and reduction of network loading. This article proposes a new LCN (Largest Common Neighbor) routing algorism to improve Spray and Wait routing protocol that prevents the generation of unnecessary packets in a network by letting mobile nodes limit the number of copies of their messages to all nodes to L. Since higher L is distributed to nodes with directivity to the destination node and the maximum number of common neighbor nodes among the mobile nodes based on the directivity information of each node and the maximum number of common neighbor nodes, more efficient node transmission can be realized. In order to verify this proposed algorism, DTN simulator was designed by using ONE simulator. According to the result of this simulation, the suggested algorism can reduce average delay and unnecessary message generation.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.281-290
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• 2010

In geographic forwarding algorithms, traditional route maintenance requires mobile nodes periodically exchange beacon messages with their neighbors. In beacon message based forwarding scheme, a longer interval reduces the number of beacons needed, but may result in significant location errors. Conversely, a shorter interval guarantees more accurate location information, but induces control overheads.Therefore, the fixed or dynamic interval scheme based forwarding schemes cannot adapt well to different mobility environments. Also, existing schemes result in the uncertainty of neighbor node's position in the forwarding table of mobile node. Therefore, this paper presents a self-adaptive location checking mechanism based proactive geo-routing algorithm for beacon-based geographic routing. Simulation results show that the proposed routing algorithm not only significantly increases the relay transmission rate but also guarantees the high end-to-end packet delivery in low and high mobility environments.

• Journal of Internet Computing and Services
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• v.9 no.2
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• pp.35-42
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• 2008

Mobile IP is a solution to support mobile nodes, however, it does not handle NEtwork MObility (NEMO). The NEMO Basic Support (NBS) protocol ensures session continuity for all the nodes in the mobile network. Since the protocol is based on Mobile IP, it inherits the same fundamental problem such as tunnel convergence, when supporting the multicast for NEMO. In this paper, we propose the multicast route optimization scheme for NEMO environment. We assume that the Mobile Router (MR) has a multicast function and the Nested Mobile Router Information (NeMRI) table. The NeMRI is used to record o list of the CoAs of all the MRs located below it. And it covers whether MRs desire multicast services. Any Route Optimization (RO) scheme can be employed here for pinball routing. Therefore, we achieve optimal routes for multicasting based on the given architecture. We also propose cost analytic models to evaluate the performance of our scheme. We observe significantly better multicast cost in NEMO compared with other techniques such as Bi-directional Tunneling, Remote Subscription, and Mobile Multicast based on the NBS protocol.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.127-136
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• 2009

Modeling and Simulation, especially in mobile ad hoc network(MANET), are the most effective way to analyze performance or optimize system parameters without establishing real network environment. Focusing mainly on overall network behaviors in MANET concerns dynamics of network transport operations, which can efficiently be characterized with event based system states rather than execution details of protocols. We thus consider the network as a discrete event system to analyze dynamics of network transport performance. Zeigler's set-theoretic DEVS(Discrete Event Systems Specification) formalism can support specification of a discrete event system in hierarchical, modular manner. The DEVSim++ simulation environment can not only provide a rigorous modeling methodology based on the DEVS formalism but also support modelers to develop discrete event models using the hierarchical composition methodology in object-orientation. This environment however hardly supports to specify connection paths of network nodes, which are continuously altered due to mobility of nodes. This paper proposes a DEVS-based modeling and simulation methodology of enabling node mobility, and develops DEVS models for the mobile ad hoc network. We also simulate developed models with the DEVSim++ engine to verify the proposal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.697-709
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• 2011

For improvement of wireless Internet service quality at vehicle's moving speed, it is advised to reduce the service disruption time by reducing the handover frequency on vehicle's moving path. Particularly, it is advantageous to avoid the handover to cell whose dwell time is short or can be ignored in terms of service continuity and average throughput. This paper proposes the handover scheme that is suitable for vehicle in order to improve the wireless Internet service quality. In the proposed scheme, the handover process continues to be learned before being modeled to Discrete-Time Markov Chain (DTMC). This modeling reduces the handover frequency by preventing the handover to cell that could provide service sufficiently to passenger even when vehicle passed through the cell but there was no need to perform handover. In order to verify the proposed scheme, we observed the average number of handovers, the average RSSI and the average throughput on various moving paths that vehicle moved in the given urban environment. The experiment results confirmed that the proposed scheme was able to provide the improved wireless Internet service to vehicle that moved to some degree of consistency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.37-41
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• 2018

As individuals generate and share various content anytime and anywhere, new networking architectures, such as content-centric networking (CCN) using the content name as a packet identifier, have been in the spotlight recently. However, the current CCN hardly takes into account node mobility problems, especially the mobility of content sources. The movement of content sources causes long delivery latency and long service disruptions. To solve that, the tunneling-based redirection scheme was proposed. However, the tunneling-based scheme requires a location-update procedure whenever the network changes, which creates many control messages and causes long latency. So, this paper presents hierarchical mobility management of mobile CCN to reduce the number of control messages and handoff latency. Performance evaluation shows that the proposed scheme can provide low control overhead, which results in network scalability.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.75-84
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• 2014

In order to solve the problems such as overload, single point of failure, non-optimized data path, and network scalability in conventional central mobility management protocols, distributed mobility management schemes have been continually studied in and around the IETF. In this paper, a network-based partially-distributed mobility management mechanism, pDMMv6, is suggested and the performance comparison with traditional protocols such as PMIPv6 and MIPv6 is made through simulation under the various user traffic environment. The simulation results include UDP packet delivery ratio, end-to-end packet delay, binding delay for registration signaling, CPU utilization in each node, and response delays in several server-client TCP applications such as web browsing, e-mail, telnet remote login, FTP file up/down-load, and database access.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.1-8
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• 2006

Currently, there are many efforts underway to provide Internet service on integrated wireless and wired networks. Supporting IP mobility is one of the major issues to construct IP based wireless network. Mobile IP has been proposed to solve the IP Mobility problem. But, in processing frequent handoffs in cellular based wireless access network, Micro mobility protocols have been proposed to solve these problems. Micro mobility protocols proposed the Cellular IP, HAWII, and Hierarchical Mobile IP. Cellular IP attracts special attention for it's seamless mobility support in limited geographical areas. New BS must be known to occur begging of handoff in Cellular IP indirect handoff. Therefore during perceiving of hanoff, packet loss or packet duplication still can occur in Cellular IP indirect handoff, which results in the degradation of UDP and TCP performance. In this paper, we propose a enhanced indirect handoff scheme for Cellular IP. Proposed handoff scheme is using a crossover node to minimize the signalling procedure and using a buffering to minimize the packet loss or packet duplication.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1015-1024
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• 2011

Mobile P2P protocols in ad-hoc networks have gained large attention recently. Although there has been much research on P2P algorithms for wired networks, existing P2P protocols are not suitable for mobile ad-hoc networks because they do not consider mobility of peers. This study proposes a new cluster-based P2P protocol for ad hoc networks which utilizes peer mobility. In typical cluster-based P2P algorithms, each cluster has a super peer and other peers of the cluster register their file list to the super peer. High mobility peers would cause a lot of file list registration traffic because they hand-off between clusters frequently. In the proposed scheme, while peers with low mobility behave in the same way as the peers of the typical cluster-based P2P schemes, peers with high mobility behave differently. They inform their entrance to the cluster region to the super peer but they do not register their file list to the super peer. When a peer wishes to find a file, it first searches the registered file list of the super peer and if fails, query message is broadcasted. We perform mathematical modeling, analysis and optimization of the proposed scheme regarding P2P traffic and associated routing traffic. Numerical results show that the proposed scheme performs much better than or similar to the typical cluster-based P2P scheme and flooding based Gnutella.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.348-351
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• 2016

Recently on IoT environment, there is necessary of protected network, which is only specific user can access it. Applying OAuth protocol on IoT, it can be easier to construct network authentication system, but it is hard to construct protected network authentication system. And there is weakness of OAuth protocol, which is easily attacked by sniffing Token by attacker. So, it is necessary to secondary authentication for OAuth. In ultimate IoT, the fog computing is essential. Fog computing is extension of cloud that enables networking not only in core system but also in edge system and communication node to node. Strength of fog computing is location awareness, support for mobility, and so on. If authentication in fog computing uses this strength, it can be more specialized in Fog Computing. So, in secondary Authentication, using Cyber-Physical-Social System will increase convenience of user than using existing authentication system, such as authentication certificate, id/password and group key, which is inconvenient for user. This study is about authentication based Cyber-Physical-Social System.