• Journal of Internet Computing and Services
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• v.7 no.5
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• pp.33-41
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• 2006

Wireless LAN is intrinsically weak in security of transmissions. WPKI (Wireless Public Key Infrastructure) is a well known Method to deal with the security issues in wireless LAN. The authentication required by the method becomes a source of unrellability of the hand-off performance. This paper suggests a solution to overcome the instability while using the WPKI technique, Prior to getting into the next region, a station is provided with the keys of the surrounding regions so that the possible delay problem can be avoided during the actual hand-off time. Thereby the hand-off instability can be solved in the WPKI framework.

• Journal of Intelligence and Information Systems
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• v.22 no.1
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• pp.107-118
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• 2016

The advent of 5G mobile communications, which is expected in 2020, will provide many services such as Internet of Things (IoT) and vehicle-to-infra/vehicle/nomadic (V2X) communication. There are many requirements to realizing these services: reduced latency, high data rate and reliability, and real-time service. In particular, a high level of reliability and delay sensitivity with an increased data rate are very important for M2M, IoT, and Factory 4.0. Around the world, 5G standardization organizations have considered these services and grouped them to finally derive the technical requirements and service scenarios. The first scenario is broadcast services that use a high data rate for multiple cases of sporting events or emergencies. The second scenario is as support for e-Health, car reliability, etc.; the third scenario is related to VR games with delay sensitivity and real-time techniques. Recently, these groups have been forming agreements on the requirements for such scenarios and the target level. Various techniques are being studied to satisfy such requirements and are being discussed in the context of software-defined networking (SDN) as the next-generation network architecture. SDN is being used to standardize ONF and basically refers to a structure that separates signals for the control plane from the packets for the data plane. One of the best examples for low latency and high reliability is an intelligent traffic system (ITS) using V2X. Because a car passes a small cell of the 5G network very rapidly, the messages to be delivered in the event of an emergency have to be transported in a very short time. This is a typical example requiring high delay sensitivity. 5G has to support a high reliability and delay sensitivity requirements for V2X in the field of traffic control. For these reasons, V2X is a major application of critical delay. V2X (vehicle-to-infra/vehicle/nomadic) represents all types of communication methods applicable to road and vehicles. It refers to a connected or networked vehicle. V2X can be divided into three kinds of communications. First is the communication between a vehicle and infrastructure (vehicle-to-infrastructure; V2I). Second is the communication between a vehicle and another vehicle (vehicle-to-vehicle; V2V). Third is the communication between a vehicle and mobile equipment (vehicle-to-nomadic devices; V2N). This will be added in the future in various fields. Because the SDN structure is under consideration as the next-generation network architecture, the SDN architecture is significant. However, the centralized architecture of SDN can be considered as an unfavorable structure for delay-sensitive services because a centralized architecture is needed to communicate with many nodes and provide processing power. Therefore, in the case of emergency V2X communications, delay-related control functions require a tree supporting structure. For such a scenario, the architecture of the network processing the vehicle information is a major variable affecting delay. Because it is difficult to meet the desired level of delay sensitivity with a typical fully centralized SDN structure, research on the optimal size of an SDN for processing information is needed. This study examined the SDN architecture considering the V2X emergency delay requirements of a 5G network in the worst-case scenario and performed a system-level simulation on the speed of the car, radius, and cell tier to derive a range of cells for information transfer in SDN network. In the simulation, because 5G provides a sufficiently high data rate, the information for neighboring vehicle support to the car was assumed to be without errors. Furthermore, the 5G small cell was assumed to have a cell radius of 50-100 m, and the maximum speed of the vehicle was considered to be 30-200 km/h in order to examine the network architecture to minimize the delay.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.8
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• pp.33-44
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• 2000

The lightning with high voltage and current can enter the basestations for mobile communication through their antenna. The device which can protect the basestation against the lightning, is surge arrestor. In this paper, the concept, kind, operating mechanism, design and fabrication of surge arrestor were studied. Based on the studied data, variable surge arrestors were designed for the current mobile communication service like a cellular, GSM and PCS and the next generation mobile communication like a IMT-2000. Computer simulation for the prediction of their characteristics and inner structure optimization for the improvement of their electrical characteristics were carried with high frequency 3D structure simulator. Quarter wave short stub surge arrestors for IMT-2000 were fabricated with their final design and then the measurement of electrical characteristics and the lightning test were executed. As a results of measurement, we obtained below 1.05 of VSWR, -0.035 dB of insertion loss, -150 dBc of intermodulation and 7∼ll V of residual voltage.

• Journal of KIISE:Information Networking
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• v.35 no.1
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• pp.11-20
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• 2008

An inevitable trend in the next generation wireless network environments is coexistence of different wireless access networks in a complementary, manner. In addition, mobile devices equipped with multiple air interfaces simultaneously executing diverse applications have been emerging, In such network environment, It is required that a solution for mobile users to seamlessly roam between different access networks as well as to satisfy QoS requirements of each application by efficiently utilizing coexisting various wireless access networks. In this paper, therefore, we propose a mobility management platform based on per-application end-to-end mobility management and cross-layer handover controls. Four core functional modules composing the proposed platform for end user devices are defined: Monitoring Agents, Profile Database, Decision Engine, and IP Agent. We show through simulations that the presented platform provides an improved QoS as it selectively utilizes the best available networks.

• Electronics and Telecommunications Trends
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• v.20 no.4 s.94
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• pp.139-154
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• 2005

인터넷 및 정보통신 기술의 발달로 우리 산업에서 콘텐츠 산업이 차지하는 비중이 날로 증가하고 있고, 질적으로도 중요한 위치를 차지하고 있다. 아울러 콘텐츠 관련 기술도 종래의 단순 요소 기술에서 차세대 IT 환경의 발달과 더불어 복잡하면서도 관련 기술이 통합되는 추세이다. 즉, 초고속, 대용량, 유무선 통합 환경에서는 콘텐츠가 사용자중심, 실감성, 이동성 및 저작권 보장이라는 특성을 갖게 되며 이러한 형태의 콘텐츠를생성/제작, 저장/관리, 보호/유통 및 서비스하는 새로운 기술의 개발이 필요하다. 특히, 매년 생성되는 모든 콘텐츠의 약 80%(1엑사 바이트(ExaByte=$10^18$, 100경 바이트), 1018바이트)를 차지하는 디지털 콘텐츠는, 그 특성상 내용의 손실이 없이 무한복제가 가능하기 때문에 인터넷상에서 유통될 때 디지털 콘텐츠의 저작권을 관리하는 기술이 절실하게 요구된다. 현재, 일반적으로 사용되고 있는 디지털 콘텐츠의 저작권 보호기술 중 대표적인 기술이 DRM 기술이다. 본 고에서는 이러한 DRM 기술에 대해, 최근 IT기술의 발전에 있어서의 DRM 기술의 의미와 역할, 그리고 표준화 및 평가 기술에 대한 국내외 동향과 디지털 비디오 콘텐츠에 대한 활용 예에 대해 설명한다.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.1-7
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• 2009

As the information age comes out, the aspect of future war brings about the many changes in terms of war-fighting environment. Accordingly, information superiority and intelligence-centric warfare have been important and new war-fighting concept such as NCW(network centric warfare) have been turned up. This paper proposed all-weather core-strategy communications systems guaranteeing not only the real-time transmission of the information collected in a battlefield and expansion, automation, and rapidity of a battlefield but also broadband, mobility, survivability, and flexibility. The proposed military satellite communications system is classified into wideband mass capacity link, survivability, and the system supporting OTM(on the move) communication for the real-time transmission of battlefield information. This paper analyzed the essential operation concepts and core schemes of the U.S. Army's next generation system, TSAT(Transformational Satellite Communication System). Base on the analysis results, this paper proposed that the architecture of next generation military satellite communications systems for NCW have to provide the data rate, anti-jamming capability, network control and management capability which are optimally adaptable for the wireless channel environments such as jamming and interference and to support the variety of platforms like high-speed mobile vehicles, micromini devices, super-high speed unmanned aerial vehicles. Finally, this paper also proposed that next generation military satellite communications systems need the technologies such as the adaptable multi-antenna, laser link, and next-generation anti-jamming waveform.

• Journal of Information Technology Services
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• v.9 no.4
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• pp.243-259
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• 2010

It is expected that the next generation mobile communication system will be a service-driven developed system capable to realize the human-centric mobile convergence services. and it is different from the technology-driven development approach of the second and the third generation mobile communication systems. As a preliminary research work on such service-driven system development approach for the next generation mobile communication system. we developed the scenario based service analysis process (2SAP) framework to derive core service technologies and functionalities. In this paper. we propose the next generation mobile convergence service business model creation methodology based on research results of the 2SAP framework. To achieve this goal, we first establish a service model contains several components such as infrastructures. operations. and provision of services that are indispensible for providing next generation mobile services. Then, the next generation mobile services and its corresponding business models can be created by adding service and value flows to the developed service model after defining necessary components of business model including actors, their relationships, and roles.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.3
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• pp.31-38
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• 2010

In this paper, we have analyzed and compared the BER and the throughput performance through the computer simulation, after applying several MIMO schemes on the MIMO-OFDM system. Then, the throughput performance of the proposed system, Adaptive-MCM, is analyzed. As a result, the MIMO-OFDM Adaptive-MCM system proposed has a higher average data rate than Non Adaptive-MCM system through the improvement of Trade-off problem between throughput and SNR.

• Review of KIISC
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• v.31 no.3
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• pp.7-12
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• 2021

사이버 공간은 제4차 산업혁명의 진전과 5세대 이동통신(5G) 시대의 도래로 초연결사회의 핵심요소로 등장하였다. 하지만 이러한 사이버공간 활용성의 증대와 함께 취약성도 증대하고 있어 사이버상의 산업기술 유출 역시 증가할 전망이다. 실제로 국내외에서 중소기업, 대기업을 막론하고 다양한 사이버공격을 통한 산업기술 유출 사례가 속속 보고되고 있다. 특히, 과거 No Tech상의 사이버공격에서 APT, 다크웹, 클라우드 서비스 등 High Tech를 이용하는 고도화된 사이버공격으로 진화하고 있다. 이는 기업의 영업비밀 유출 노하우 손실, 일자리와 경쟁우위 손실 등 경제력 손실과 평판 하락에 큰 영향을 미친다. 이에 본 논문에서는 국내외 사이버공격을 통한 산업기술 유출사고의 영향력을 산정하고 이에 대한 시사점을 서술 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.11
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• pp.979-985
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• 2012

The design of an efficient scheduler is a key design factor in IEEE 802.16m systems, in order to support services with various QoS smoothly. Although conventional studies of schedules have been suggested, those had problems that are not able to satisfy the delay condition and make the through-put declined, because they only focused on a specific action scenario rather than reflecting practical action scenarios which have real-time and non-real-time traffics variously. In this paper, an efficient uplink scheduling algorithm is proposed for IEEE 802.16m system by introducing the concepts of Virtual Time(VT) and Virtual Finish Time(VFT) based priority determination, and separate buffers for each QoS class in the mobile terminal. Simulation results showed that the proposed scheme had satisfied the delay requirement of real-time services even with improved throughput performance compared to conventional methods.