• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.577-580
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• 2012

Communication environment has rapidly evolved into All-IP based core network, which is centered on a variety of access network, and develops into ubiquitous environment for each user due to the development of multiple interface terminals and the spread of contents usage. Especially, mobile streaming technologies and integrated authentication technologies are needed for mobile users to provide seamless mobility. The technology for seamless mobility services is an important issue. In this paper, the IEEE 802.21 MIH information server is based on the network offering handover technology between heterogeneous network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.281-290
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• 2002

In this paper, we propose an efficient packet forwarding method for an IP-based wireless Internet access network. Packets are forwarded along with a flow, that is a kind of connection-oriented connection and established before delivering packets. For this purpose, we also propose a flow resolution method and a modified IPv6 header for delivering packet in the wireless Internet access network. In addition, the method to support the mobility of mobile stations is explained, and the implementation issues are discussed. In order to estimate the performance of the proposed method, we analyzed the delay time to deliver packets in the wireless Internet access network. The numerical results show that the proposed method is very efficient, in the view point of delay.

• Journal of KIISE:Information Networking
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• v.34 no.1
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• pp.1-15
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• 2007

Increase in the wireless mobile network users brings the issue of mobility management into the Virtual Private Network (VPN) services. We propose a provider edge (PE)-based provider provisioned mobile VPN mechanism, which enables efficient communication between a mobile VPN user and one or more correspondents located in different VPN sites. The proposed mechanism not only reduces the IPSec tunnel overhead at the mobile user node to the minimum, but also enables the traffic to be delivered through optimized paths among the (mobile) VPN users without incurring significant extra IPSec tunnel overhead regardless of the user's locations. The proposed architecture and protocols are based on the BGP/MPLS VPN technology that is defined in RFC24547. A service provider platform entity named PPVPN Network Server (PNS) is defined in order to extend the BGP/MPLS VPN service to the mobile users. Compared to the user- and CE-based mobile VPN mechanisms, the proposed mechanism requires less overhead with respect to the IPSec tunnel management. The simulation results also show that it outperforms the existing mobile VPN mechanisms with respect to the handoff latency and/or the end-to-end packet delay.

• Journal of Advanced Navigation Technology
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• v.17 no.4
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• pp.421-428
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• 2013

Voice over IP refers to technology that enables routing of voice conversations over the Internet or a TCP/IP network. VoIP communication costs cheaper than traditional analog phone. Phone calls can be made to anywhere / anyone: Both to VoIP numbers as well as people with normal phone numbers. VoIP protocol equipment available today follows the SIP standard. Older VoIP equipment though would follow H 323, MGCP, Megaco/H.248. A SIP server is the main component of an IP PBX, dealing with the setup of all SIP calls in the TCP/IP network. A SIP server is also referred to a Asterisk IP-PBX. A VoIP telephone, also known as a SIP phone or a softphone, allows the user to make phone calls to any softphone, mobile or PC by using App store. A VoIP telephone can be a simple software-based softphone. However, the SIP Server and the program is vulnerable to VoIP attacks. In this paper, eavesdropping attacks tested by using the Asterisk SIP server. Eavesdropping attacks and TLS security methods apply to VoIP system. TLS can be applied to determine whether the eavesdropping available for VoIP Environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.51-56
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• 2011

WiBro network technologies developed mainly by Korea are one of very promising 4G technologies. WiBro has been standardized as international standard called Mobile WiMAX, and has been deployed in many countries. Emergency Services in WiBro networks are infrastructure services and will be very essential to induce subscribers from other types of networks. This paper proposes a network architecture for supporting emergency services for WiBro mobile VoIP networks. The proposed architecture is based on WMF's architecture for international compatibilities, and reflects national considerations on interfacing PSAP for domestic compatibilities.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.49-54
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• 2011

In this paper, End-to-End VoIP(Voice over Internet Protocol) performance over large scale MANET(Mobile Ad-hoc Networks) is evaluated. VoIP implementation model, which can be used for large scale MANET, is suggested through this evaluation. VoIP simulator based on NS-2 network simulator is used for performance measurement. Call connection ratio as a connection performance, MOS and network delay as a transmission performance, packet loss rate as other performance is measured with this simulation. Finally, maximum $10{\sim}15km^2$ as a single MANET, 500 nodes and 100 call connections is suggested for VoIP implementation and operation conditions over large scale MANETs.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.678-682
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• 2005

IETF suggested AAA for safe and reliable user authentication on various network and protocol caused by development in internet and increase in users. Diameter standard authentication system does not provide mutual authentication and non-repudiation. AAA authentication system using public key was suggested to supplement such Diameter authentication but application in mobile service control nodes is difficult due to overhead of communication and arithmetic. ID based AAA authentication system was suggested to overcome such weak point but it still has the weak point against collusion attack or forgery attack. In this thesis, new ID based AAA authentication system is suggested which is safe against collusion attack and forgery attack and reduces arithmetic quantity of mobile nodes with insufficient arithmetic and power performance. In this thesis, cryptological safety and arithmetical efficiency is tested to test the suggested system through comparison and assessment of current systems. Suggested system uses two random numbers to provide stability at authentication of mobile nodes. Also, in terms of power, it provides the advantage of seamless service by reducing authentication executing time by the performance of server through improving efficiency with reduced arithmetic at nodes.

• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.393-404
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• 2004

Recently, mSCTP (Mobile SCTP) has been proposed as a transport layer approach for supporting mobility. mSCTP is based on the ‘multi-homing’ feature of Stream Control Transmission Protocol(SCTP), and utilize the functions to dynamically add or delete IP addresses of end points to or from the existing connectionin order to support mobility. In this paper, we propose a mechanism to determine when to add or delete an W address, utilizing the link layer radio signal strength information in order to enhance the performance of mSCTP We also propose a mechanism for a mobile node to initiate the change of data delivery path based on link layer radio signal strength information. In addition, if it takes long time to acquire new data path, we propose an approach for reducing handover latency. The simulation results show that the performance of proposed transport layer mobility support mechanism is competitive compared to the traditional network layer mobility supporting approach. Especially, when the moving speed of mobile node is fast, it shows better performance than the traditional network layer approaches.

• The Journal of the Korea Contents Association
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• v.1 no.1
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• pp.130-136
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• 2001

Real-time applications like VoIP in mobile networks need smooth handovers in order to minimize or eliminate packet loss as a mobile host(MH) transitions between network links. In this paper, we design a new variable buffering mechanism for IPv6 by which an MH can request that the router on its current subnet buffers pad(eta on its behalf while the MH completes registration procedures with the router of a new subnet. Performance results show that our proposed queueing scheme with a variable space allocation is quite appropriate for mobile internet environment in terms of the packet loss rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.240-249
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• 2004

For the effective IP-based service implementation in the wireless network environment, involvement of IP-related technologies in wireless networks is inevitable and globally unique IPv6 address allocation to the mobile node has become an important issue. In the 3GPP's address allocation mechanism, IPv6 address allocation procedure is performed by the GGSN, which is normally located far from the mobile nodes. This causes IPv6 address allocation time delay and traffics to be longer and increased in the core network, respectively. In this paper, we propose a new IPv6 address allocation mechanism that is performed by Node B located in RAN. The proposed IPv6 address allocation mechanism can provide IPv6 addresses to mobile nodes within a more reduced time than existing 3GPP's IPv6 address allocation mechanism, and co-operates with existing mechanism as an overlay model to improve reliability of wireless networks. And, for implementation of the proposed address allocation mechanism, it needs not to change the structure of current wireless networks except for the some functional addendum of Node B.