• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.220-235
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• 2005

Internet Service Quality has been constantly the center of attention to Internet Service Providers. The KII project plan (Korea Information Infrastructure) aims to build broadband backbone networks mainly through optical fiber cables and ATM switches and to Provide the government ministries, local authorities and non-profit organizations with high-speed, highly capable broadband access to these networks at reasonable rates. The KB service model, however, is different from other Internet Service models much in the same way SP (Service Provider) and NP (Network Provider) differ from each other. In this paper, we evaluate KII service according to various customer satisfaction indicators under the methodologies and categories as put forth in both the ACSI (American Customer Satisfaction Index) and SEM (Structural Equation Model). We use a structural equation model (SEM) to demarcate the Korea Information Infrastructure Customer Satisfaction Index (KIICSI) in relation to network service quality. The results of our study suggest some strategies for the KII Project need to be modified and effectively implemented in order to increase the satisfaction level of the KII customers.

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.89-99
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• 2005

HPI system provides 1-3 Mbps data transmission speed to terminals moving up to 60 km/sec. Since HPI supports rtPS, nrtPS, and BE services requiring different QoS, it needs an efficient scheduling method based on those different QoSs. This paper suggests an uplink scheduling method which gives priority to services in the order of rtPS, nrtPS and BE services but which reserves some bandwidth for the low priority services before it allocates the bandwidth to higher priority services. Simulation results show that it can improve the uplink performance by reserving mean transmission rate to each nrtPS terminal and by reserving bandwidth, which amounts to about 1.5 times the mean transmission rate of the whole BE terminals, to the whole BE terminals.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.241-249
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• 2012

In the many countries, research about ultra wideband wireless transmission technique is widely studied for efficient utilization of frequency resource due to a sudden increase of demand of frequency resource all over the world. The ultra wideband communication system has the some specific advantages. First, it can transmit data with high speed, second short transmission range can increase the frequency reuse rate, and finally it has high security property. However, there is a interference between ultra wideband system and other communication system but study to solve this problem is insufficient. To efficient utilization of limited frequency resource, a novel frequency avoidance technique and setup the standardization of frequency interference must need. So, the purpose of this paper is that increases communication efficiency of microwave communication systems to analyze the technical trends for transmission of the low power device, and to research the implementation and technical research of wireless access network technique of wideband communication systems.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.304-316
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• 2004

When new services are introduced, one of the drivers for market performance of them is the interactions among existing and new services. They are characterized by the substitution or complementary effects among existing and new service or the cannibalization of existing services by new services. This paper analyzes these issues in the telecommunications service industry context. To analyze them, a simple graphical tool or State Transition Diagram(STD) is developed and used. The diagram helps to clearly represent and explain the substitution, complement and cannibalization impact. Then, using the face-to-face survey of 1,200 people, a new wireless internet access service or WiBro is analyzed to identify the substitution/complement and cannibalization impacts in relation with the other competing services. Additionally, the important factors explaining customer subscription and substitution behavior are identified. The analysis results indicate that males, students or on-line game users are more likely to subscribe WiBro. Also, among the potential WiBro subscribers, customers who are less satisfied with the existing fixed line broadband internet access services are more likely to stop subscribing the fixed line service, which implies substitution by a new service. Additionally, this raises the issue of cannibalization if the existing and new services are provided by the same company. In fact we find the cannibalization effect is more serious for the cost sensitive group. We believe that our tool, approach, analysis results and their implications would be very helpful to devise a winning strategy for the new services in the highly uncertain telecommunications business environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.14-26
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• 2008

IP over Ethernet technology widely used as Internet access uses the ARP(Address Resolution Protocol) that translates an ip address to the corresponding MAC address. recently, there are ARP security attacks that intentionally modify the IP address and its corresponding MAC address, utilizing various tools like "snoopspy". Since ARP attacks can redirect packets to different MAC address other than destination, attackers can eavesdrop packets, change their contents, or hijack the connection. Because the ARP attack is performed at data link layer, it can not be protected by security mechanisms such as Secure Shell(SSH) or Secure Sockets Layer(SSL). Thus, in this paper, we classify the ARP attack into downstream ARP spoofing attack and upstream ARP redirection attack, and propose a new security mechanism using DHCP information for acquisition of IP address. We propose a "DHCP snoop mechanism" or "DHCP sniffing/inspection mechanism" for ARP spoofing attack, and a "static binding mechanism" for ARP redirection attack. The proposed security mechanisms for ARP attacks can be widely used to reinforce the security of the next generation internet access networks including BcN.

• Broadcasting and Media Magazine
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• v.11 no.4
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• pp.104-117
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• 2006

In this Paper, we analyze the application of Interactive Data Broadcasting in DMB(Digital Multimedia Broadcasting) in the accordance with convergence of service and technology. With the acceleration of digital convergence in the Ubiquitous period substantial development of digital media technology and convergence of broadcasting and telecommunication industry are being witnessed. Consequently these results gave rise to newly combined-products such as DMB(Digital Multimedia Broadcasting), WCDMA(Wide-band code division multiple access), Wibro(Wireless Broadband Internet), IP-TV (Internet protocol TV) and HSDPA(High speed downlink packet access). The preparatory stage for the implementation of Interactive Data Broadcasting Service will be reached by the end of December, 2006. DMB is the first result of a successful convergence service between Broadcasting and Telecommunication in new media era. Multimedia technology and services are the core elements of DMB. The Data Broadcasting will not only offer various services of interactive information such News, Weather, Broadcasting Program etc, but also be linked with characteristic function of mobile phone such as calling and SMS(Short Message Service) via Return Channel.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.12
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• pp.45-51
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• 2010

The main issue in mobile cloud computing is how to support a seamless service to a mobile mode. Mobile IPv6 (MIPv6) is a mobility supporting protocol which is standardized by the Internet Engineering Task Force (IETF). Mobile IPv6 fast handovers (FMIPv6) is the extension of MIPv6 which is proposed to overcome shortcomings of MIPv6. Recently, fast handovers for Mobile IPv6 over IEEE 802.16e which is one of broadband wireless access systems has been proposed by the IETF. It was designed for supporting cross-layer fast handover. In this paper, we propose an enhanced cross-layering mobile IPv6 fast handover over IEEE 802.16e networks. In our scheme, a new access router generates a new address for the mobile node by using a layer 2 trigger. We utilize a layer 2 message which is sent from a new base station to the new access router in order to inform the new access router of information of the mobile node. A previous access router sends a binding update message to the mobile node's home agent when it acquires the new address of the mobile node. We evaluate the performance of the proposed scheme compared with the existing schemes in terms of the signaling cost and the handover latency. From the results, we observe that the proposed scheme can support fast handover effectively over IEEE 802.16e networks than existing schemes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.229-240
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• 2012

The development of multimedia applications followed by development of high-speed networks has improved the performance of mobile devices with high transfer speed broadband. Mobile internet access has made possible seamless indoor and outdoor mobile multicast services. Multicasting services are used to support efficient group communications. However, mobile multicasting services have two constraints: tunnel convergence and handover latency. Many protocols and handover methods have been proposed to address these problems. The inter-LMA optimized handover model for multicasting services has previously been proposed for PMIPv6-based networks. The proposed model removes the tunnel convergence issue and reduces router processing costs. It also makes possible the performance of fast handover operations with adaptive transmission mechanisms. In addition, the proposed scheme exhibits low packet delivery costs and handover latency in comparison with existing schemes, and ensures fast handover when moving the inter-LMA domain

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.1
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• pp.17-23
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• 2007

The home network has been revitalized due to the emergence of the high-speed broadband network and explosive increases of the home network services. Especially multicast based high-definition (HD) IPTV service is on high demand from both Internet service provider (ISP) and users. In order to provide high quality HD IPTV service without packet loss and delay, the ISP utilizes various network QoS mechanisms. Due to the misleading fact, that the home gateway is considered as an end terminal in terms of the ISP's viewpoint, the ISPs can not guarantee the end-to-end QoS within the scope of the current home network architecture. Therefore, an independent QoS guaranteed mechanism should be considered within the home network domain. As the home gateway manages both private home and public access network within the home network, we propose and implement a novel QoS mechanism for the multicast based HD IPTV service over the home gateway. In order to provide QoS guaranteed HD IPTV service, the proposed mechanism classifies the packets, manages home network bandwidth resources, and executes call admission control using the channel join message. Also, we utilize layer 2 multicast packet forwarding scheme to improve the overall performance of the home network services. Through the experiments of implementing the multicast based HD IPTV services, we will verify the efficiency of the proposed mechanism.

• Information and Communications Magazine
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• v.32 no.11
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• pp.41-49
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• 2015

현대 사회는 스마트폰 사용량의 급증으로 인한 모바일 트래픽의 폭발적인 증가와 IoT(Internet of Things)를 비롯한 융복합 유무선 서비스의 확대 등으로 국가적으로 한정적 자원인 주파수의 효율적 사용을 인한 대책 마련이 시급한 실정이다. 이에 미국 및 유럽을 중심으로 다양한 용도의 무선기기들이 한정적 주파수 대역을 효율적으로 이용하기 위한 방안으로 주파수 공동사용에 대한 정책도입 및 연구개발이 지속적으로 추진되고 있다. 본 고에서는 수요 대비 공급 부족 현상이 점차 심각해 지고 있는 한정적 주파수 자원의 효율적 이용을 위한 대안으로 급부상하고 있는 주파수 공동사용 기술에 대한 국내외 관련 정책 및 기술추진 현황에 대해 소개하고자 한다. 특히 본 고에서는 2010년 국가광대역계획(NBP, National Broadband Plan) 발표를 시작으로 전 세계적으로 주파수 공동사용 추진에 있어 가장 적극적인 행보를 보여주고 있는 미국에서의 3.5GHz 대역 주파수 공동사용을 위한 전파규칙인 CFR(Code of Federal Regulation) Part 96의 주요 내용을 자세히 소개하고자 한다. 본 고의 II장에서는 국내외에서 진행되고 있는 대표적인 주파수 공동사용 정책추진 현황에 대해 소개하였으며, III장에서는 올해 4월 최종 전파규칙이 발표된 미국의 SAS(Spectrum Access System) 기반 주파수 공동사용 전파규칙에 대해 소개하였다. 또한 IV장에서는 SAS 기반의 주파수 공동사용 기법 및 기존에 개발되고 있는 다양한 동적 스펙트럼 접속 기법들을 미국 내 주요 도심지역에 적용하기 위한 대규모 테스트베드 프로그램인'Model City'프로그램 소개 및 결론을 통하여 주파수 공동사용 도입의 당위성을 설명하고자 한다.