• Journal of Korea Multimedia Society
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• v.20 no.4
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• pp.593-605
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• 2017

In applications which are covered wide range, it is possible that one or more number of Unmanned Aerial Vehicle(UAV) squadrons are used to perform a mission. In this case, it is most important to communicate seamlessly between the UAV squadrons. In this paper, we applied the modified OLSR(OSLR-Pds) which can prediction for state of the link for the communication in UAV squadron, and applied the modified AOMDV which can build multi-path for the communication between UAV Squadrons. The mobility of nodes are modeled using Gauss-Markov algorithm, and relative speed between nodes were calculated by derive equation of movement, and thereby we can predict link state for in a squadron and between squadrons. An experiment for comparing AODV, AOMDV and the proposed routing protocol was conducted by three factors such as packet delivery ratio, end to end delay, and routing overhead. In experiment result, we make sure that the proposed protocol performance are superior in these three factors. However, if the density of the nodes constituting FANET are too low, and if the moving speed of node is very slow, there is no difference to others protocols.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.623-629
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• 2010

A geographical routing protocol is typically utilized for a route selection of VANET. Even if it is conceptually well adapted into VANET, message delivery tends to be unreliable with frequent network partitions, which mainly come from the inherent characteristics such as high mobility and irregular traffic density. In this paper, we deal with a method to enable reliable message delivery with reflecting the traffic density on routing decision. By concatenating the message delivery cost of each of inbetween junction section, $1^{st}$ and $2^{nd}$ shortest paths are initially determined. When it is not possible to deliver the message on a junction on the 1st path, we utilize two novel ideas, that is, letting the message stay on the junction to find out a new relay node, and putting a replicated copy to reach via a detour path. By using the NS-2 network simulator, our method has been examined in terms of message delivery rate and delay. It shows that our method is much efficient than the other method in the low density environment, while it brings similar results in the high density environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.66-69
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• 2008

As a mobility support for IP have studied, Internet Engineering Task Force(ITEF) standardized the mobile IPv6 protocol. When a mobile node moves between networks, MIPv6 maintains connectivity to network and supports seamless communication, and these processes are called a Handover. IEEE 802.21 standardized MIH(Media Independent Handover) for seamless Handover. MIH used three services for Handover between low layer and upper layer. In this paper, we designed two modes on existing MIH for seamless Handover. We implemented a dual-interface mobile host(MH) model in network simulation2 (ns2) to evaluate how it performs in comparison with single-interface MH.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.293-300
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• 2004

Ad hoc networks are groups of mobile hosts without any fixed infrastructure. Frequent changes in network topology owing to node mobility make these networks very difficult to manage. Therefore, enhancing the reliability of routing paths in ad hoc networks gets more important. In this paper, we propose a ZRP(Zone Routing Protocol)-based route discovery scheme that can not only reduce the total hops of routing path, but Improve security through authentications between two nodes. And to solve the problem in maintenance of routing paths owing to frequent changes of the network topology, we adopt a query control mechanism. The effectiveness of our scheme is shown by simulation methods.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.309-318
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• 2004

AAAv6-based Diameter method is using in the user authentication to satisfy the users' increasing user authentication demand and to supply a safe communication between mobile node and server in the Mobile IP. therefore, In this paper, We design a model of server capacity based on EAP-TLS that in one of AAAv6 models with mobility among domains to get the optimized capacity index of the server for user authentication accomplishment. We elicitat the authentication capacity index for each server of which is accomplishing in user authentication using DSA/RSA algorithm and purpose the optimized condition for the AAAv6 capacity by the index.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3377-3395
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• 2015

Recently, several approaches to share road conditions and/or digital contents through VANETs have been proposed, and such approaches have generally considered the radial distance from the information source as well as the TTL to provision an ephemeral, geographically-limited information sharing service. However, they implement general MANETs and have not been tailored to the constrained movement of vehicles on roads that are mostly linear. In this paper, we propose a novel application-level mechanism that can be used to share road conditions, including accidents, detours and congestion, through a VANET. We assign probabilities to roads around each of the intersections in the neighborhood road network. We then use the graph representation of the road network to build a spanning tree of roads with the information source as the root node. Nodes below the root represent junctions, and the edges represent inter-connecting road segments. Messages propagate along the branches of the tree, and as the information propagates down the branches, the probability of replication decreases. The information is replicated until a threshold probability has been reached, and our method also ensures that messages are not delivered to irrelevant vehicles, independently of their proximity to the source. We evaluated the success rate and performance of this approach using NS-3 simulations, and we used IDM car following and MOBIL lane change models to provide realistic modeling of the vehicle mobility.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2245-2266
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• 2016

The hop count routing metric is widely used in routing protocols of Wireless Sensor Networks (WSNs) due to its simplicity and effectiveness. With a lower hop count route, fewer transmissions are required to send a packet from the source to the destination. This can improve the throughput of a network because fewer transmissions results in less channel contention and interference. Despite this, the hop count routing metric may not be ideal for mobile scenarios where the topology of a network changes constantly and rapidly. In this paper, we propose to increase route stability in mobile WSNs by discovering paths that are more stable during route discoveries using routing metrics. Two routing metrics were proposed, the true beauty of these routing metrics lies in the fact that they can even be used even without specialized hardware such as GPS and other sensors. We implemented the proposed routing metrics in the AODV routing protocol and found that they are highly effective and outperform other stability-based routing metrics and the hop count routing metric.

• Journal of the Korea Society for Simulation
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• v.15 no.4
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• pp.107-117
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• 2006

Wireless Sensor Network consists of sensor nodes and sink. A sink receives and processes signals created from sensor nodes. Many studies have been performed, since sensor network allows multiple nodes to run using a limited amount of energy, Most researches have focused on using fixed sink. However, in many cases, the sink has mobility effected by man, cars, and etc. This research proposes three methods for reducing the node's energy consumption which is applied the Grid method based on mobile sink. Most routing processes handled by the mobile sink and wireless sensor area is separated and operated respectively. So, this research allows decreasing the power costs. In addition, it also proposes methods using simulation to test the quality of the performance.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.4
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• pp.295-304
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• 2014

Communication infrastructure supports wide variety of mobile services such as photo and file sharing, location tracking, social network services and instant messaging. However, instances like power-loss and natural disasters disrupt these communication infrastructures unable to render support to these mobile services. Delay-tolerant networks (DTNs) offer a solution to these problems at hand. By utilizing mobility and opportunistic contacts among mobile devices, a plausible communication network can be establish and enable support to mobile applications. This paper presents an energy-efficient, reliable message delivery routing scheme with message prioritization rules for DTN. It uses the context information of nodes (mobile devices) such as the contact history (location and time of contact), speed/velocity, moving direction to determine the best forwarders among nodes in the network. The remaining energy of the nodes is also used to determine the message types a node can deliver successfully. The simulation results show that proposed approach outperforms Epidemic and Prophet routing schemes in terms of delivery ratio, overhead ratio, delivered messages per types and remaining energy.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1487-1492
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• 2012

Providing node mobility on IP-based wireless networks is required by the increasing Internet access of the mobile nodes and Mobile-IPv6 was suggested for IPv6. But Mobile-IPv6 degrades the overall performance of wireless networks by the packet loss while performing its handover function. Therefore, lots of efforts and researches to resolve this problem have been doing from now on. FMIPv6 is one of the improved methods that was designed to provide seemless handover. But it still has a problem that the handover is strictly depended on the triggered information of the unreliable link layer. In this paper, a scheme called mptFMIPv6 that minimizes delay of critical section of CoA registration process by reducing the link layer dependency was proposed.