• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.210-217
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• 2005

With rapid advance in wireless communication technologies, many researches are conducted for providing Internet data services while users are roaming around. Efficient management of mobility of mobile nodes is essential as the use of real-time application program grows. In this paper, we propose a multicast-based localized mobility support scheme in IPv6 networks. The proposed scheme utilizes a class of multicast routing protocol for the localized mobility support. Features of the proposed scheme are use of join to a multicast group and leave from that group to localize binding update information and provision of an extended multicast group management mechanism to reduce leave latency. The results of simulation show that the proposed scheme out-performs Mobile IPv6 and Hierarchical Mobile IPv6 in UDP and TCP traffic performance and in wasted bandwidth.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.3
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• pp.91-99
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• 2009

Development of high-speed Internet services and the increased supply of mobile devices have become the key factor for the acceleration of ubiquitous technology. WiBro system, formed with lP backbone network, is a MBWA technology which provides high-speed multimedia service in a possibly broader coverage than Wireless LAN can offer. Wireless telecommunication environment needs not only mobility support in Layer 2 but also mobility management protocol in Layer 3 and has to minimize handover latency to provide seamless mobile services. In this paper, we propose a fast cross-layer handover scheme based on signal strength prediction in WiBro environment. The signal strength is measured at regular intervals and future value of the strength is predicted by Exponential Smoothing Method. With the help of the prediction, layer-3 handover activities are able to occur prior to layer-2 handover, and therefore, total handover latency is reduced. Simulation results demonstrate that the proposed scheme predicts that future signal level accurately and reduces the total handover latency.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.269-274
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• 2010

Recently IPTV service is becoming an emerging service representing IP convergence that is enabled on the broadband networks. It is an essential and very important issue to manage the service quality of IPTV service effectively for its successful deployment because of the innate nature of current Internet that cannot support quality of service (QoS). In particular, it is required that subscriber can measure and judge the service quality of IPTV service directly, which is impossible with the current method usually depending on a measurement equipment. In this paper, therefore, we introduce an implementation of a software that is installed at a set-top on the subscriber side and measures the quality of IPTV service in real time. In order to verify the performance of the implemented software, we perform a number of tests and compare the result with the measurement equipments in common use. By the comparison, it is shown that the measurement by the implemented software is precise and reliable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1955-1961
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• 2009

As a core technology realizing ubiquitous world, recent researches are being concentrated to wireless sensor network. However, most research results were focused to the sensor network technology itself, even though interworking between the sensor network and Internet is also one of primitive requirements for ubiquitous world. In this paper, we design the tiny TCP/IPv6 profile which makes it possible to inter-connect the sensor network device to IPv6 based Internet. To confirm operation of the designed profile, we experimentally implemented and evaluated minimum TCP/IPv6 based on TinyOS. The evaluation result shows that throughput of our tiny TCP/IPv6 is almost same as that of TinyOS component.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.7-16
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• 2006

IPTV is referred to the service which provide integrated IPTV services for providing video, 10/100-Mbit/sec Internet, voice, video-on-demand (VOD), and other broadband applications including home security, video conferencing, and telemedicine. All services are integrated into an IP (Internet Protocol) architecture designed specifically for Gigabit Ethernet FTTH systems, HFC or xDLC. It is absolutely necessary that telecon operators provide IP video delivery platforms that enable service providers to transform their business. With their own products, they can better manage their existing services and generate new revenues from broadcast TV, movies on demand and multimedia. Triple-play is a combination of broadcast, telephony and broadband services offered through IPTV networks. With cable operators allowed to offer a triple-play bundle, the nation's telecom operators are beginning to get a little anxious. Cable operators assert that triple-play is a must-have and natural extension of the cable service bundle. The Korean Cable TV Association asserts that the triple-play model is of paramount importance to the cable industry's future growth. But the telecom sector considers itself unfairly disadvantaged, saying they cannot compete until regulatory issues are resolved. The start of web-based television in Korea may still be some time off with a confrontation between the nation's IT regulator and broadcasting sector over the service's legal boundaries shows no signs of being resolved my time soon. korea should be is the fastest-growing provider of IPTV solutions in the industry, with over worldwide customers.