• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1935-1941
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• 2013

We can use NAT(Network Address Translation) technology to solve the lack of IP address. The problem of NAT traversal is happened when the filtering characteristics of NAT remove the packet that has no binding in the address translation table of NAT. There were many kinds of way to solve these problems by using additional device. Lately, network market is changed into integrating wired and wireless network by the IMS(IP Multimedia Subsystem). The IMS integrates to control network of wired and wireless network, has emerged to control convergence network effectively. Lately, the additional devices like IBCF(Interconnection Border Control Function) and IBGF(Interconnection Border Gateway Function) are used to solve the NAT traversal problem in the IMS. In this paper, we propose the solution of NAT traversal using P-CSCF without any additional equipment in the IMS.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.173-173
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• 2004

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.7
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• pp.1329-1345
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• 2011

After the 9.11 terror attack, lawful Interception (LI) has emerged as an important tool for anti-terrorist activity. Law enforcement agents and administrative government bodies effectively monitor suspicious target users of permanent IP-based network devices by LI in Packet Data Networks (PDNs). However, it is difficult to perform LI in monitoring migrating users from a location to another, who change their IPs due to the proliferation of portable Internet devices enabling 3G IP Multimedia Subsystems (IMS). The existing, manual handover technique in 3G IMS makes it even more difficult to continue the LI activities due to time-lag reissuance of LI authority warrants when the target users move to a new LI jurisdiction via a roaming service. Our proposed model is a seamless LI handover mechanism in 3G IMS to support mobility detection of the target users. The LI warrants are transferred to the new LI agent automatically with the target users when they move to a new LI jurisdiction. Thus, time-lag human intervention of reissuance of the LI warrants is removed and enables the LI authorities to continue monitoring. In the simulation of our proposed mechanism, the quality of lawful interception achieves a mean score of over 97.5% out of the possible 100% maximum score, whereas the quality of the existing mechanism has a mean score of 22.725%.

• Annual Conference of KIPS
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• 2008.11a
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• pp.1262-1264
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• 2008

기존의 유/무선 전화, 인터넷, TV 등을 통합하여 다양한 멀티미디어 서비스를 지원하기 위한 차세대 통신망으로 3GPP (3rd Generation Partnership Project)에서 최초 3세대 이동 통신망으로 제안되었던 IMS(IP Multimedia Subsystem) 가 표준으로 자리 잡아가고 있으며, 전 세계 통신 회사들이 IMS를 기반으로 차세대 통신망을 구축하고 있다. 이러한 IMS 망을 이해, 분석하기 위해서는 IMS 망에서 이용되는 SIP(Session Initiation Protocol)에 대한 이해와 SIP 패킷을 분석할 수 있는 패킷 분석기가 필요하다. SIP는 VoIP환경에서 호 설정을 위해 개발된 텍스트 기반의 프로토콜로써 포맷의 간결성과 확장성으로 인하여 차세대 통신망인 IMS의 주요 프로토콜로 채택되었으며, IMS 망 환경에 맞게 확장 되었다. 본 논문에서는 SIP 패킷 분석기를 IMS 기반으로 패킷 분석 결과를 비주얼한 화면으로 보여줄 수 있도록 설계, 구현하여 사용자가 SIP 패킷 분석을 통하여 IMS 망을 이해, 분석하는데 도움을 주고자 한다.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.91-96
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• 2009

In Public Switched Telephone Networks(PSTN) number portability is implemented by utilizing Intelligent Network(IN) functions for number mapping. And voice over IP(VoIP) and IP Multimedia Subsystem(IMS) networks can deploy number portability by using E.164 Number Mapping(ENUM). This paper discuss the possibility of using E.164 Number Mapping(ENUM) for number portability in voice over IP/IP Multimedia Subsystem and Public Switched Telephone Networks, eliminating the need for Number Portability Database(NPDB) for number portability routing data in Public Switched Telephone Networks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.694-699
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• 2017

In accordance with the development of information and communications technology, a network user has to be able to use quality of service (QoS)-based multimedia services easily. Thus, information and communications operators began to focus on a technique for providing multimedia services. The IP Multimedia Subsystem (IMS) is a platform based on Internet Protocol (IP) as a technology for providing multimedia services and application services. The emerging 5G networks are described as having massive capacity and connectivity, adaptability, seamless heterogeneity, and great flexibility. The explosive growth in network services and devices for 5G will cause excessive traffic loads. In this paper, software-defined networking (SDN) is applied as a kind of virtualization technology for the network in order to minimize the traffic load, and Simple Network Management Protocol (SNMP) is used to provide more efficient network management. To accomplish these purposes, we suggest the design of a dynamic routing algorithm to be utilized in the IMS network using SDN and an SNMP private management information base (MIB). The proposal in this paper gives information and communications operators the ability to supply more efficient network resources.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.19-24
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• 2018

The IP Multimedia Subsystem(IMS) is an architectural framework for delivering IP multimedia services to mobile users. In order to guarantee the reliability and Quality of Service(QoS) of a variety of multimedia services, we need a new evolutionary approach that maintains the IMS based signaling platform which can perform the processing of flow through distributed controllers. Software Defined Network(SDN) is an architecture purporting to be distributed, dynamic, cost-effectives as well as adapting and seeking to be suitable for the high-bandwidth, dynamic nature of today's applications. It requires some methods for the control plane to communication with the data plane. One of such mechanisms is OpenFlow which is a prominent standard protocol and interface that is responsible for managing the network resources by using the remote SDN controller. In this paper, we propose a straightforward approach for integrating SDN technology together with the IMS architecture. Therefore we propose and construct a combined architecture model that performs flow processing using OpenFlow via the IMS based signaling platform, which maintains the existing telecom call service. Additionally, we describe some relevant experimentation results from the proposed architecture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.250-258
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• 2011

In this paper we propose a load balancing scheme for heterogeneous multiple AS's (Application Server) in IMS (IP Multimedia Subsystem) based network. In IMS network, to perform load balancing among multiple ASs with different registration pattern, different weight value should be set for each AS. In previous systems, there exists an inconvenience that the weight value should be set manually by the operator after monitoring the result. In this paper we propose a method to calculate optimal weight in automatic manner and to perform load balancing simultaneously. We also propose a simplified algorithm to reduce calculation in specific situation and present a way to apply our proposed scheme in adaptive manner according to the situation. Through simulation result, we verify that our proposing scheme outperforms previous schemes in load balancing and adjusts well to the change of the system in automatic manner with fast convergence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.797-804
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• 2009

Recently, SIP(Session Initiation Protocol) is used to set up and manage sessions for multimedia applications such as VoIP(Voice over IP) and IMS(IP Multimedia Subsystem). However, because SIP operates over the Internet, it is exposed to pre-existed internet security threats such as service degradation or service disruptions. Multimedia applications which are delay sensitive even suffers more from the threats mentioned above. The proposed methods so far to detect SIP INVITE flooding are CUSUM(Cumulative Sum), Hellinger distance and adaptive threshold, but among methods only take normal state into consideration. So, it is not capable of adapting the condition of the network congestion which are dynamically changing. In this paper, SIP INVITE flooding detection algorithm considering network congestion which enables efficient detections of such attacks is proposed. The proposed algorithm is expected to detect other types of attacks such as BYE and CANCEL more precisely compared to other methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2136-2152
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• 2012

The growth of Internet technologies and the widespread use of mobile devices have been paving the way for the increasing use of conferencing services. Two types of systems have been designed to provide conferencing services: 1) a conferencing system using session control over a peer-to-peer (P2P) network and 2) an IP Multimedia Subsystem (IMS) conferencing system. The IMS conferencing system was developed to adapt to a server-based centralized system, whereas the benefits of the P2P operational model in providing such conference services are widely acknowledged. However, each system provides conferencing services only to its own users. Therefore, in this paper, we propose an interworking model to support multimedia conferencing service between the P2P environment and IMS networks. We also introduce protocol architecture and some service scenarios. To verify this system model and the design architecture, we perform an actual implementation and show experienced test results.