• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11B
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• pp.997-1004
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• 2006

There is a growing demand to access the broadband internet while on the very fast move. In order to meet these users needs, much research has been made for providing the broadband internet and HDTV services via satellite broadband internet systems even at top train speeds above 200km/h. In this paper, economic analyses on the satellite broadband internet services for KTX are to be reviewed. Broadband internet to trains in Europe are investigated, and Boeing cases for planes are also examined. In the first step, system configuration which is composed of a hub, terminals, satellite, and gap fillers for the tunnel areas has been proposed. A terminal includes a ultra-fast high gain antenna installed on the roof of the train, and APs inside the coaches. Secondly, cost estimation on the capital expenditures as well as operating expenditures has been performed in the proposed configuration. From the european and Boeing cases, demand and tariff are postulated, consequently, service revenues are derived on the scenario basis. Thirdly, estimated costs and derived revenues make up net present value and internal rate of return in each scenario. Finally, conclusions and contribution of this study are presented.

• 한국벤처창업학회:학술대회논문집
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• 2017.11a
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• pp.155-161
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• 2017

In the field of information technology, broadband, internet and information flow have been found to be the primary elements to indicate access to information in this current information age. We examine whether the country difference in Broadband use, Internet use and information flow existing in 1991 has been reduced and if so how fast. Convergence framework had been utilised to answer these questions for 43 African countries. The results indicated that all the three chosen information technology indicators for 43 African countries are converging toward a reduction of dispersion and a catch-up process during the period 1991-2015. However, there are marked differences exhibited in the convergence processes for the Total groups and for the subgroups of countries by income level.

• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.173-178
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• 2006

In this paper, a channel estimation based on the time-domain windowing and its imperfectness in OFDM-based multiple-antenna transmission systems are analyzed with an emphasis on a preamble design for multi-channel separation, From the computer simulation results, the OFDM-CDMA system applying a space-time-frequency diversity with a full-rate full diversity code can give the diversity of D = 4 and D = 8 for both multi-user cases of maximum user and half user capacities, respectively

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5601-5613
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• 2011

The purpose of this paper is to better understand the socio-economic differentials of Internet access and use. Data from '2008 Korean Internet usage behavior' were used to conduct logistic regression analysis. The findings show that there are significant socio-economic(age, gender, educational attainment, employment situation, and Internet access type) disparity in Internet access(Internet access at home, broadband Internet access). Also socio-economic variables enter in as statistically significant in most specifications for Internet use intensity (Intensive internet use, frequent internet use, less frequent internet use). The gender, household income and education attainment explanations for large differential in Internet use intensity are generally very similar. It is shown that age, education attainment and household income level cause a large digital divide on Internet service use(information use, communication and community use, e-commerce use, Internet banking use).

• Journal of the Korean Geographical Society
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• v.43 no.2
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• pp.202-219
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• 2008

As demand for high speed Internet service has explosively increased in the United States for the past decade, the construction or upgrades of telecommunication infrastructure has also been rapidly followed. Though currently many people in urbanized areas can be provided advanced broadband services, there are still challengeable areas to be served, such as remote or low populated areas because those areas are potentially non-profitable to commercial broadband service providers. This paper addresses the spatial disparity or in a broader term, the 'digital divide' of the broadband access by the county level in the United States. We propose the quantified measure of the county level broadband accessibility for identifying such digital divide. The developed measure is a hybrid form of the classical gravity based potential model and network topological accessibility, encouraged from the lack of prior efforts eying to explicitly incorporate the understanding of the whole process of the Internet access. The computational tasks are performed in a GIS platform, which includes several programmed functions.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.33-37
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• 2008

Recently, there have been intensive researches on the wireless Internet access through WiFi WLAN using WiRro network as backhaul link in the Internet service providing business area. However, in the wireless Internet access method, we need to solve the compatibility problem for different user authentications between licensed WiBro network and unlicensed WiFi network for billing and user management. In this paper, we propose an authentication method for WiFi users by BWAN operators through WiNNERs which is RS connecting the two networks, and discuss the effectiveness of the method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1101-1112
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• 2006

With the recent growth in demand for high-data rate multimedia services in the wireless environments, the Mobile Broadband Wireless Access (MBWA) technologies, such as WiBro (Wireless Broadband internet) system, are gradually coming into the spotlight. Unlike the conventional mobile communication networks based on cellular system, the WiBro system basically consists of IP based backbone networks that will be ultimately deployed by Ipv6 (IP version six) based backbone networks according to the All-IP trend for the network evolution. In such wireless mobile environments, it is needed to support the mobility management protocol on network layer as well as physical layer and Medium Access Control (MAC) layer in WiBro system. Accordingly, in this paper, we propose a fast handover scheme for improving the handover performance in IPv6 based WiBro system and show that the proposed scheme achieves loss-free and low handover latency during inter-subnet movement of the mobile stations through the simulation.

• ETRI Journal
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• v.26 no.1
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• pp.48-52
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• 2004

In this letter, we consider a new packet scheduling algorithm for an orthogonal frequency division multiplexing access/frequency division duplex (OFDMA/FDD)-based system, e.g., mobile broadband wireless access or high-speed portable internet systems, in which the radio resources of both time and frequency slots are dynamically shared by all users under a proper scheduling policy. Our design objective is to increase the number of non-realtime service (e.g., WWW) users that can be supported in the system, especially when the minimum bit rate requirement is imposed on them. The simulation results show that our proposed algorithm can provide a significant improvement in the average outage probability performance for the NRT service, i.e., significantly increasing the number of NRT users without much compromising of the cell throughput.

• Journal of Digital Contents Society
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• v.7 no.3
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• pp.161-168
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• 2006

Wibro(Wibro - Wireless Broadband Internet ) is a system that can accept effectively the IP-based Wireless data traffic with upward / downward asymmetric transfer characteristic by using a Wirelss broadband transfer technology in OFDMA/TDD (Orthogonal frequency Division Multiple Access/Time Division Duplex). Wibro service should support handover to maintain connection continuously in movement because the service is based on If system which is different from cellular system. Current Micro Mobility system and general Mobile If system has got a problem of delayed speed and lost packets during handover. IETF protocol has been proposed for minimizing this problem and its standardization is under process, mainly focused on Mip4, Mip6 and Mipshop WG. This article studies and analyzes an effective method of minimizing handover delay to improve the problem of WiBro system and its revitalization & outlook.

• ETRI Journal
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• v.35 no.2
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• pp.234-244
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• 2013

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.