• Information and Communications Magazine
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• v.26 no.2
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• pp.23-30
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• 2009

3GPP(3rd Generation Partnership Project)는 3세대 이동통신인 UMTS(Universal Mobile Telecommunication System)의 초기 표준화 이후 HSPA(High Speed Packet Access), MBMS(Multimedia Broadcast/Multicast Service) 등의 기술 개발로 UMTS 시스템을 지속적으로 발전시켜 왔다. 그리고, 최근 새로운 무선 접속 기술에 기반한 LTE(Long Term Evolution)시스템에 대한 표준화를 거의 완료하고 ITU-R(International Telecommunications Union-Radio)의 IMT-Advanced 요구사항을 만족하는 LTE-Advanced 시스템에 대한 연구를 진행하고 있다. 한편 최근 다양한 무선 접속 기술간 핸드오버 기술이 중요한 이슈로 부각됨에 따라 LTE-Advanced에서도 이를 수용하기 위한 기술이 요구된다. 본 고에서는 3GPP에서 추진하고 있는 LTE-Advanced기술의 표준화 동향과 향후 이에 적용 가능한 다양한 무선 접속 기술간의 핸드오버 지원 기술을 살펴봄으로써 LTE-Advanced에서의 끊김없는 이동성(seamless mobility) 제공을 위한 근간을 제시하고자 한다.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.1
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• pp.66-71
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• 2009

In view of mutual complementary feature of wide coverage and high data rate, the interworking between 3G cellular network and WLAN is a global trend of wireless communications. This paper introduces the analytic result of an authentication mechanism for 3GPP-WLAN seamless mobility under the USIM-based authentication test-bed. In a handover process between heterogeneous networks, authentication is the main factor of handover delay. So authentication processing time should be firstly reduced. This paper describes an USTM-based EAP-AKA test-bed implemented for handover in UMTS and WLAN interworking systems. Experimental result has shown that the fast re-authentication mechanism during handover has reduced the handover delay by about 48.6%.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.76-83
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• 2011

The IEEE WAVE-based communication systems do not provide handover services since most of the application layer messages of a small amount containing text data that are related to safe driving. Multimedia data service such as web pages and CCTV video clips, however, require a seamless handover for continuation of a session via multiple RSUs. In this paper, we propose a new proactive handover protocol based on IEEE WAVE. According to the proposed handover protocol, the OBU notifies the old RSU of its departure from the coverage such that the old RSU forwards to the new RSU the data heading towards the OBU to be cached for the further delivery upon its entry into the new RSU's coverage. The simulation results are presented which shows the performance of the proposed protocol in terms of throughput, delivery ratio and handover delay.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.168-180
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• 2018

Due to the spread of mobile devices and the introduction of high-quality services, mobile traffic is expected to increase sharply and overload of cellular networks is expected. D2D communication is a way to reduce the load and evolve to 5th generation. Since D2D communication directly communicates between the terminals, it can reduce the overload of the cellular network and improve energy efficiency, data rate and network performance. This paper proposes a D2D handover scheme for D2D communication in cellular networks. The cellular network is a 3GPP EPS, and the proposed D2D handover method improves the existing EPS handover process considering compatibility between existing EPS and D2D communication. We also demonstrate the superiority of the proposed handover scheme using the network simulator ns-3. Simulation results show that the proposed handover scheme is superior to existing handover methods in terms of CUE variation, packet transmission delay time, and throughput.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.277-284
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• 2009

With significant development in wireless communication technologies, the needs to handover from one network to another have grown dramatically. Recently IETF developed MIPv6 and FMIPv6 which are used to handover between different access networks. These handover mechanisms have some known weaknesses. MIPv6 can not serve time-critical application because it causes long handover latency and packet loss. By these reasons, MIPv6 does not guarantee session continuity. FMIPv6 uses handover preparation phase to reduce DAD latency. However FMIPv66 still suffers from long handover latency, because it must perform binding update at the end of handover procedure. In this paper we propose new handover mechanism FMIPv6-PBU which eliminates binding update latency. The proposed mechanism has compatability with lagacy FMIPv6. In this paper propose FMIPv6-PBU handover procedure and explain its procedures and evaluate it with MIPv6 and FMIPv6.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1129-1140
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• 2010

Wireless mesh networks have been widely studied as the next generation technology to solve the problems of conventional wireless networks. Particularly, Mobile WiMAX based wireless mesh networks are noticed due to many advantages. Mobile WiMAX standard provides two kinds of layer-3 handover schemes: Mobile IP and Proxy Mobile IP based handover schemes. MIP based handover scheme has a problem in that it incurs the long handover latency because mobile nodes generate a lot of handover messages. On the other hand, PMIP based handover scheme decreases the handover latency by reducing the number of handover messages, because mobile nodes do not participate in handover procedure. Therefore, layer-3 handover for Mobile WiMAX should be designed based on PMIP. However, conventional PMIP based handover still has latency overhead, because of many message exchanges between PBU and PBA after completing the layer-2 handover. Hence, in this paper, we propose a fast layer-3 handover scheme that achieves the lower handover latency for Mobile WiMAX based wireless mesh networks. Proposed scheme has advantages in terms of handover latency. Simulation results show that proposed scheme achieves low handover latency during the layer-3 handover.

• The Journal of the Korea Contents Association
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• v.10 no.10
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• pp.45-53
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• 2010

In this paper, we propose RFID network agent based user mobility support mechanism for secure information transmissions. When a user with RFID tag who enjoys service moves to different attachment points, the user mobility is supported to provide continuously service and the information can be securely transmitted. Although there is an existing study for providing user mobility, it has a problem which the handover latency time is long. To settle this problem, we present a scheme for minimizing handover latency time and compare handover latency time of existing and proposed scheme. We confirm that proposed mechanism has low latency time than existing mechanism by mathematical analysis using the queuing theory and show that proposed mechanism is more superior to the existing mechanism.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.261-268
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• 2005

Recently, Many People have studied in Mobile Ipv6 to provide seamless service. FMIPv6 is designed to reduce the procedure of handover and will be used SIP, VoIP and Mobile Internet moving picture service. But, If mobile node moves fast, it will happen to packet loss and interruption problem in handover procedure. So, In this paper, designed and evaluated traffic control mechanism using WFQ scheduling to reduce the packet loss that occurred to handover procedure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2847-2856
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• 2014

It is necessary for maritime multi-band networks, which provide ships with diverse and seamless multimedia services, to perform vertical handover. As IEEE 802.21 WG has standardized vertical handover technologies for terrestrial wireless networks that do not consider VHF, HF, satellite networks, they cannot be directly applied to maritime multi-band networks. In this paper, the vertical handover framework for use in maritime mutlti-band networks is proposed, which includes the logical architecture, the communication reference model, re-defined handover primitives, and the handover process. The proposed vertical handover for maritime multi-band network can be applied in the ocean alone, as well as to the heterogeneous wireless networks which embrace both terrestrial and maritime networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7B
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• pp.1018-1033
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• 2010

Recently, as the use of mobile terminal is generalized, the needs of high-speed Internet mobile service is increased. Also users want to receive the multimedia contents what they want through the various terminals in anywhere, anytime via wired and wireless integrated environment. Therefore, various mechanisms that support the mobility are proposed. However, these mechanisms are difficult to support seamless mobility and QoS awareness on the mobile multicast environment. In this paper, we propose a QoS aware handover mechanism that is able to provide the high-quality and real-time services such as mobile IPTV in an integrated environment for these requests of users. Proposed mechanism manages the multicast admission control and multicast handover using the 2-layer multicast information management at the wired and wireless integrated network that extended the service guaranteed methods through the probing based admission control of the wired network to the wireless network based on PMIPv6. We present a performance evaluation results and features analyzed by the simulations using the ㎱-2.