• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.8
• /
• pp.3904-3917
• /
• 2017

IP multimedia subsystem (IMS) is an open standardized architecture for delivering multimedia service over IP network in a route-agnostic manner. With the increasing popularity of conversational class service, the delivery of a traffic flow with a certain bandwidth demand over a single network path is either not possible or not cost-effective. Multipath transmission is considered to be a promising solution to provide high-quality delivery service. This paper proposes a software defined service overlay network (SDSON) based multipath transmission framework for IMS, which is complementary to existing network architecture. The framework transforms original two-party session negotiation into three-party session negotiation that supports participants to negotiate multipath transmission capacity and path information by signaling message. Based on existing IETF standards, SIP and SDP are scalable to support these functions. Finally, the proposed framework is fully implemented on open source platform and examined by experiments. Experimental results show that multipath-enabled IMS is an effective way to improve the delivery performance of conversational class service.

• International journal of advanced smart convergence
• /
• v.13 no.1
• /
• pp.1-11
• /
• 2024

Cognitive small cell networks, consisting of macro-cells and small cells, are foreseen as a promising candidate solution to address 5G spectrum scarcity. Recently, many technological issues (such as spectrum sensing, spectrum sharing) related to cognitive small cell networks have been studied, but the common control channel (CCC) establishment problem has been ignored. CCC is an indispensable medium for control message exchange that could have a huge significant on transmitter-receiver handshake, channel access negotiation, topology change, and routing information updates, etc. Therefore, establishing CCC in cognitive small cell networks is a challenging problem. In this paper, we propose a potential game theory-based approach for CCC establishment in cognitive radio networks. We design a utility function and demonstrate that it is an exact potential game with a pure Nash equilibrium. To maintain the common control channel list (CCL), we develop a CCC update algorithm. The simulation results demonstrate that the proposed approach has good convergence. On the other hand, it exhibits good delay and overhead of all networks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.1
• /
• pp.95-102
• /
• 2009

In 2006, Haddad, Krishnan and Soliman proposed a Cryptographically Generated Address based protocol as a standard for protecting HMIPv6. Though this protocol can provide both the strong message authentication and binding update key negotiation based on the public-key cryptography, it is still vulnerable to several attacks such as denial of service attacks and redirection attacks. This paper improves the problems caused by the protocol. The improved protocol is analyzed in terms of security and performance, and then is shown to be better than the previous one considering the two factors together.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.11
• /
• pp.2091-2098
• /
• 2006

In this paper, it proposes a protocol of resource adaptive data dissemination for sensor nodes in a wireless sensor network. In general, each sensor node used in a wireless sensor network delivers the required information to the final destination by conducting cooperative works such as sensing, processing, and communicating each other using the battery power of a independent sensor node. So, a protocol used for transferring the acquired information to users through the wireless sensor network can minimize the power consumption of energy resource given to a sensor node. Especially, it is very important to minimize the total amount of power consumption with a method for handling the problems on implosion. data delivery overlapping, and excessive message transfer caused by message broadcasting. In this paper, for the maintaining of the shortest path between sensor nodes, maximizing of the life time of a sensor node and minimizing of communication cost, it presents a method for selecting the representative transfer node for an event arising area based on the negotiation scheme and maintaining optimal transfer path using hop and energy information. Finally, for the performance evaluation, we compare the proposed protocol to existing directed diffusion and SPIN protocol. And, with the simulation results, we show that the proposed protocol enhances the performance on the power consumption rate when the number of overall sensor nodes in a sensor network or neighbor sensor nodes in an event area are increased and on the number of messages disseminated from a sensor node.

• The KIPS Transactions:PartC
• /
• v.11C no.4
• /
• pp.519-526
• /
• 2004

This paper presents an efficient interoperation scheme of a VPN(Virtual Private Network) and Mobile IP using a hierarchical structure of a FA(Foreign Agent). In the proposed scheme, the GFA(Gateway Foreign Agent) plays a role of VPN gateway on behalf of the MN(Mobile Node). When the MN moves in the same GFA domain, because the GFA has already an IPsec security association with a VPN gateway in the home network of the MN, the MN does not need an IPsec re-negotiaion. In this way, our mechanism reduces a message overhead and a delay resulted from an IPsec negotiation. And a MN can send a data to a correspondent node without a packet leakage. We show a performance of our scheme by using a discrete analytical model. Analytical results demonstrated that the total processing cost calculated by a registration update cost and a packet delivery cost is significantly reduced through our proposed scheme.

• The Journal of Korean Association of Computer Education
• /
• v.8 no.1
• /
• pp.13-23
• /
• 2005

In this study, messages from on-line discussions of 28 preservice teachers were analyzed based on social constructivist learning theory. After preliminary discussion session for a week, small group discussions were conducted every single week with different topics during 4 weeks. One transcript with most frequent messages in each topic was selected, and a total of 72 messages were analyzed. Discussion topics were the issues related to the nature of science. The Interaction Analysis Model for Examing Social Construction of Knowledge in Computer Conferencing was used for the analysis. Analysis of the messages indicated that 'sharing information' was the most frequent, and that 'discovering/exploring dissonance' and 'negotiation of meaning/co-construction of knowledge' were the nex. However, messages of 'testing and modification of proposed synthesis' and 'testing and application of newly constructed meaning' were found to be rare. This result indicated that students' interaction through on-line discussion did not reach to the social construction of knowledge.

• Journal of Arbitration Studies
• /
• v.15 no.3
• /
• pp.233-266
• /
• 2005

The world trading system has been under many changes in recent years. One notably important development is that much attention away from the multilateralism-oriented World Trade Organization towards FTA(Free Trade Agreement). The Free Trade Agreement signed between korea and chile formally have been come effective for free trade in goods and services as from April 1, 2004. During Free Trade Agreement negotiations between both countries. This study aims at presenting the suggestion for the Korea to make the WTO rules and FTA by analyzing The interpretation of FTA under WTO System. It was founded by the investigation of WTO rules, most of the provisions are similar with other FTA, but a little provisions different from other FTA's. It is an appearance from the contracting party's peculiar circumstances such as state of industrial development or future prospect, conditions around international trade. The whole world has entered the new stage of bilateral and multilateral FTA. The essential or new generation or bilateral and multilateral FTA is creating more trade opportunities, promoting all factors, commodity, service, capital, technology and talent freely flow through canceling the trade barriers between FTA, in order to develop together within the regions. It shows that the cooperations transfer form the whole region into FTA. FTA makes not only the free trade smooth ,but also takes place the trade distortion effect. especially as the agriculture has a speciality each country, should it is ignored in negotiation, many reactions will be occurred in the process of fta Therefore Korea needs to deliver the message that Korea's hub is an essential ingredient for an efficient FTA and WTO system in a bilateral and multilateral win-win framework. Consequently Korea should have criterions about the rules of FTA and WTO system for peculiar circumstances of Korean economy and international trade.

• Journal of Korea Multimedia Society
• /
• v.15 no.8
• /
• pp.1048-1058
• /
• 2012

This paper proposes the DDMPF(Distributed Data Management Protocol using FAT) which prevents data loss and keeps the security of self-organized storages by comprising a client, a storage server, and a verification server in clouding environment. The DDMPF builds a self-organized storage server, solves data loss by decentralizing the partitioned data in it in contrast to the centralized problem and the data loss caused by the storage server problems of existing clouding storages, and improves the efficiency of distributed data management with FAT(File Allocation Table). And, the DDMPF improves the reliability of data by a verification server's verifying the data integrity of a storage server, and strengthens the security in double encryption with a client's private key and the system's master key using EC-DH algorithm. Additionally, the DDMPF limits the number of verification servers and detects the flooding attack by setting the TS(Time Stamp) for a verification request message and the replay attack by using the nonce value generated newly, whenever the verification is requested.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.4
• /
• pp.39-45
• /
• 2011

In this paper, we propose an efficient multichannel MAC protocol with idle nodes assistance to avoid the multi-channel hidden terminal problem in cognitive radio ad hoc network and further to improve the performance of the network. The proposed MAC protocol can be applied to the cognitive radio adhoc network where every node is equipped with the single transceiver and one common control channel exists for control message negotiation. In the proposed protocol, the idle nodes available in the neighbour of communication nodes are utilized because the idle nodes have the information about the channels being utilized in their transmission range. Whenever the nodes are negotiating for the channel, idle nodes can help the transmitting and receiving nodes to select the free data channel for data transfer. With the proposed scheme, we can minimize the hidden terminal problem and decrease the collision between the secondary users when selecting the channel for data transfer. As a result, the performance of the network is increased.

• Journal of Information Processing Systems
• /
• v.13 no.5
• /
• pp.1229-1242
• /
• 2017

In this paper, an interference aware distributed multi-channel MAC (IDMMAC) protocol is proposed for wireless sensor and actor networks (WSANs). The WSAN consists of a huge number of sensors and ample amount of actors. Hence, in the IDMMAC protocol a lightweight channel selection mechanism is proposed to enhance the sensor's lifetime. The IDMMAC protocol divides the beacon interval into two phases (i.e., the ad-hoc traffic indication message (ATIM) window phase and data transmission phase). When a sensor wants to transmit event information to the actor, it negotiates the maximum packet reception ratio (PRR) and the capacity channel in the ATIM window with its 1-hop sensors. The channel negotiation takes place via a control channel. To improve the packet delivery ratio of the IDMMAC protocol, each actor selects a backup cluster head (BCH) from its cluster members. The BCH is elected based on its residual energy and node degree. The BCH selection phase takes place whenever an actor wants to perform actions in the event area or it leaves the cluster to help a neighbor actor. Furthermore, an interference and throughput aware multi-channel MAC protocol is also proposed for actor-actor coordination. An actor selects a minimum interference and maximum throughput channel among the available channels to communicate with the destination actor. The performance of the proposed IDMMAC protocol is analyzed using standard network parameters, such as packet delivery ratio, end-to-end delay, and energy dissipation, in the network. The obtained simulation results indicate that the IDMMAC protocol performs well compared to the existing MAC protocols.