• Journal of Internet Computing and Services
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• v.5 no.3
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• pp.25-33
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• 2004

Mobile IP Low Latency Handoffs(l) allow greater support for real-time services on a Mobile IP network by minimizing the period of time when a mobile node is unable to send or receive IP packets due to the delay in the Mobile IP Registration process. However, on Mobile IP network with AAA servers that are capable of performing Authentication, Authorization, and Accounting(AAA) services, every Registration has to be traversed to the home network to achieve new session keys, that are distributed by home AAA server, for a new Mobile IP session. This communication delay is the time taken to re-authentication the mobile node and to traverse between foreign and home network even if the mobile node has been previously authorized to old foreign agent. In order to reduce these extra time overheads, we present a method that performs Low Latency Handoffs without requiring further involvement by home AAA server. The method re-uses the previously assigned session keys. To provide confidentiality and integrity of session keys in the phase of key exchange between agents, it uses a key sharing method by gateway foreign agent that performs a trusted thirty party. The proposed method allows the mobile node to perform Low Latency Handoffs with fast as well as secure operation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.283-287
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• 2002

VoIP는 음성을 패킷 형태로 통합하여 real time으로 전송하는 기술이다. 최근 VoIP(Voice Internet Protocol)은 음성과 데이터를 통합하는 핵심 기술로 발전하고 있다. VoIP 구현을 위해 현재 가장 많이 사용되는 시그널링 프로토콜들은 H.323, SIP, MGCP, MEGACO 등이 있으며 현재 ITU-T의 H.323 프로토콜을 중심으로 서비스가 진행되고 있지만 많은 기능성과 확장성을 지닌 IETF의 SIP 프로토콜이 보편화될 것으로 예상된다. 본 논문에서는 이동 사용자를 고려하여 VoIP와 Mobile IP를 결합하여 성능 평가를 하였다. Mobile IP는 Mobie host가 인터넷상에서 임의의 위치에 접속하더라도 자신의 고유 주소로 전송되는 패킷을 수신 할 수 있도록 IP 프로토콜을 확장한 기술이다. 이러한 요구를 반영하기 위하여 본 논문에서는 이동 음성 서비스를 위한 H.323/SIP기반 Mobile IP 네트워크를 모델링 한 후 성능평가를 실시하였다.

• Journal of the Korea Convergence Society
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• v.3 no.3
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• pp.7-12
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• 2012

mVoIP (mobile Voice over Internet Protocol) service is a technology to transmit voice data through an IP network using mobile device. mVoIP provides various supplementary services with low communication cost. It can maximize the availability and efficiency by using IP-based network resources. In addition, the users can use voice call service at any time and in any place, as long as they can access the Internet on mobile device easily. However, SIP on mobile device is exposed to IP-based attacks and threats. Observed cyber threats to SIP services include wiretapping, denial of service, and service misuse, VoIP spam which are also applicable to existing IP-based networks. These attacks are also applicable to SIP and continuously cause problems. In this study, we analysis the threat and vulnerability on mVoIP service and propose several possible attack scenarios on existing mobile VoIP devices. Based on a proposed analysis and vulnerability test mechanism, we can construct more enhanced SIP security mechanism and stable mobile VoIP service framework after eliminating its vulnerability on mobile telephony system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.774-782
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• 2003

Generally, in the Mobile IP technologies, the use of RSVP(Resource ReSerVation Protocol) is recommended in order to provide a mobile node real-time service. However, the handoff of a mobile node increases the registration delay, RSVP reservation delay and signalling overhead in the Mobile IP and RSVP interworking. Specially, the resource reservation on the path between a mobile node and a correspondent node is the duplicated reservation and then causes unnecessary creation of the signalling overhead and waste of the resource, since the majority of the path before handoff and after handoff is same. If the radius of a cell providing a wireless interface to a mobile node is small, the number of handoff will increase and also signalling overhead and duplicated resource reservation will increase. In this paper, we proposed the integration model of Cellular IP and RSVP with RSVP proxy scheme. Here, Cellular IP protocol minimizes registration delay, transfer delay, and loss by handoff in micro cell network, the RS VP proxy that minimizes the duplication of resource reservation prevents the path for RSVP session from change using the address for reservation of a mobile node. Proposed scheme was evaluated in comparison with the existing Mobile IP and RSVP interworking scheme using the probability of resource reservation fail to the radius of a cell and the handoff rate.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.47-50
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• 1998

In recent years, it is required that computing support mobile user with computer. The advantage of mobile computing is that users may access all their applications from any location, whether they are in another building or a different state. So, Internet combines with mobile computing technology to make new communication environment for supporting mobility. The research for solving the problem of mobility is actively in progress. This paper describes the implementation of tunneling method for flexible bypass between specific region. Tunneling method provide mobile service to mobile hosts. IP datagram's address tranform method is IP-within-IP encapsulation by which an IP datagram may be encapsulated within an IP datagram. The developed IP-within-IP protocol can provide not only enhanced performance because it is implemented in kernel mode, but also convenience of usage to the application developers because it gives user interface as a dynamic link library. Verification of IP packet tunneling was text file transfer program.

• 한국IT서비스학회:학술대회논문집
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• 2008.11a
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• pp.139-142
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• 2008

VoIP(Voice over IP)는 패킷교환망을 통해 음성통신을 제공하는 기술이다. 초기의 VoIP에서는 사용상 제약조건과 불편함 때문에 사업모델이 성립하지 못하였다. 무선 광대역통신이 가능해지고, 멀티미디어 서비스에 적합하게 진화함에 따라 VoIP에서 무선접속기술을 이용한 Mobile VoIP서비스를 제공하고 있다. Mobile VoIP의 편리성으로 인하여 VoIP에서 새로운 사업모델이 창출되었고, 웹 2.0과 Mobile 인터넷전화의 결합에 의해 SNS(Social Network Service)으로 서비스가 확장되었다. 이로 인해 많은 서비스 제공자가 발생하였고, 이 서비스 제공 사업자는 크게 이동통신사업자, 소프트웨어 서비스 사업자, 가상이동통신사업자, 그리고 별정 사업자로 분류된다. 4가지의 서비스 제공 사업자는 각각 사업모델이 차별화 되어 있다. 본 논문에서는 Mobile 인터넷전화 기술동향을 살펴보고 서비스 동향을 분석한다. 그리고 Mobile 인터넷전화의 서비스 제공사업자의 차별화된 사업모델을 분석한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04b
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• pp.681-684
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• 2001

본 논문에서는 기존의 IP 망에서 호스트의 이동성을 지원하기 위한 Mobile IP 개념을 ATM 망에 적용할 경우, Mobile IP 망에서 HA(Home Agent)와 FA(Foreign Agent) 사이에 존재하는 Mobile-IP 터널링(tunneling) 구간을 기존의 LAN 기반의 IP 터널링 구간과 ATM 망에서의 단거리 터널링(short-cut tunneling) 구간으로 구분하여 관리하는 방안을 제안하였다. 특히 ATM 망에서의 short-cut 터널링을 구성하기 위하여 기존의 NHRP 프로토콜을 이용함으로써 대량의 데이터 전송 시 종단간 전송 지연을 줄일 수 있는 장점이 있다. 본 논문에서는 송신노드, 이동노드, HA 및 FA 가 이질적인 두 망에 존재하는 경우 적절한 Mobile-IP 터널링 구간을 이룰 수 있음을 보인다.

• The Journal of the Korea Contents Association
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• v.2 no.2
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• pp.85-90
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• 2002

This paper presents tuo implementation models for wireless service operators to offer Mobile-IP over IMT-2000 Data service under IMT-2000 network by taking advantage of the existing infrastructure for IMT-2000 services. For this purpose, a new Mobile-IP over IMT-2000-based protocol architectures are introduced and service operation schemes and handoff schemes according to various scenarios of packet data services in the IMT-2000 core network are presented. Also, this paper describes the handoff scheme in terms of channel states.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6B
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• pp.573-587
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• 2003

Due to the growth of mobile communication and the popularization of Internet, it is expected that wired and wireless communication network of the next generation will be integrated and flourished with IP-based. There have been a great deal of research efforts to provide mobile IP service onthe existing lower layer. The location update and the paging scheme is one of the most challenging technical issues for this topic. In this thesis, a paging method based on the distance-based location update scheme is proposed for IP network to support mobility in layer 3. The proposed scheme is implemented and verified with the OPNET.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.396-398
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• 2000

최근 무선 통신 기술의 발달과 휴대용 컴퓨터의 소형화, 수요증가에 따라 휴대용 컴퓨터에서의 통신은 차차 우리 생활에 없어서는 안될 요소가 되어가고 있으며 IP 기반에서의 Mobility 제공을 그 목적으로 하는 Mobile IP 기술은 차세대 인터넷망의 핵심기술이 될 전망이다. 이에 본 논문에서 Mobile IP Protocol을 Mobile Node를 중심으로 객체지향 개념을 도입하여 설계, 구현한다.