• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1349-1355
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• 2016

It should guarantee high reliability and ultra low latency communication. Additionally, it should support connection between massive devices. As one of estimated scenarios for 5G mobile communication, mobile devices and sensors using low data rate wireless communication will increase. For communication of these devices, single-carrier system can be considered. In order to satisfy these requirements, in this paper, we propose CDMA (Code Division Multiple Access) system using complex spreading and Multi-level BPSK(Binary Phase Shift Keying). The proposed system spread transmit symbol by using chip code consisted of real and imaginary number. As simulation results, we can confirm that although the proposed system has 3dB lower BER (Bit Error Rate) performance than conventional CDMA system, the proposed system can support 2 times more users in comparison with conventional CDMA system.

• Electronics and Telecommunications Trends
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• v.34 no.6
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• pp.61-70
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• 2019

Recently, research and development for next-generation mobile communication and short-range wireless communication has begun worldwide along with the provision of commercial services of 5G mobile communication technology. In response to this trend, the THz band has attracted considerable attention as a frequency band for transmitting 100 Gbps of large-capacity wireless data. For communication in the THz band, research and development of approaches based on photonics and electronics is being actively performed; the configurations, characteristics, and performances of these two methods for THz transmission have been seriously examined. Among them, we reviewed the technical issues in implementing THz wireless transmission technology using photonics technology. We also introduced the Electronic and Telecommunications Research Institute's (ETRI) development of photonics-based THz short-range transmission technology starting from 2019 and including some initial results. In the near future, 100 Gbps high-capacity wireless data transmission technology utilizing photonics technology is expected to be commercially available and applied to various applications, such as 3D hologram transmission, uncompressed large capacity medical data transmission, and multiple augmented reality/virtual reality (AR/VR).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.1993-1998
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• 2010

This paper presents an integrated control module for controlling transportation machine and automatic navigation using a combined technology of mobile telematics and transportation machine telematics, i.e. Mobile In Vehicle (MIV). This development includes hardware implementation and its verification of control mechanism applied to vehicle. In particular, the module is designed to be versatile in such a way that it can collect various information and facilitate various options for convenience by supporting existing networks, such as TCP/IP, Wi-Fi and 3G mobile radio networks. The study offers its versatility, intelligence and cost-effectiveness by enabling the module to support network-independent service, whereas conventional modules operate only in a certain network. Based on this module, a multiple of subsequent convenient functions for transportation machine can further be developed for safe and intelligent transportation machines.

• International Journal of Contents
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• v.9 no.3
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• pp.15-18
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• 2013

In the preceding studies, an analysis of Saga Prefectural sightseeing information by a Self-Organizing Map (SOM) has been tried. And recent development on Information and Communication Technology (ICT) will help us to access any results via the mobile devices easily. This is why the mobile devices, e.g., smartphones and tablet computers, have an operating system installed, and we can improve their functions by downloading any applications on the Web. Then, in order to realize this basic idea, development of an application for the mobile devices is investigated through some computer simulations on the standard desktop PC in this paper. As a result, it is found that i) a developed feature map is useful to identify some candidate topics, ii) a touchscreen is suitable to show the feature map, and iii) arrangement of the feature map can be modified based on our interests. Then, it is concluded that the proposed idea seems to be applicable, even though further consideration is required to brush it up.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.631-637
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• 2018

In 5G mobile communication, it is necessary to provide different mobility to user equipments(UE) that do not require mobility management or need limited mobility management. In this paper, we propose a two-layer mobility management system that classifies multiple MTC devices with similar mobility levels into c-MTC and m-MTC groups. In order to improve the energy efficiency and service life by reducing the number of control signals generated when TAU is performed, the group header typically performs a Tracking Area Update(TAU) request and adjusts the periodic TAU update period according to the mobility level. The TAU update period of the m-MTC is set to 54 minutes proposed by the 3GPP standard and the c-MTC is set to 12 minutes. Compared to when the UEs perform TAU individually, it is found that the number of control signals decreases by 33% when the MME is not changed and by 49% when the MME is not changed in the m-MTC or c-MTC group.

• Journal of the Korea Society of Computer and Information
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• v.12 no.2 s.46
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• pp.209-220
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• 2007

Mobile devices become a pak of our daily life due to their versatility, such as the wireless phone calls, the wireless accessibility to Internet, the display of multimedia content, and the communication with nearby mobile devices. Third generation telecommunication service provides an easy access to the Internet for nubile devices. Mobile users pay a fee charged by the telecommunication provider based on the amount of data transferred. This paper introduces a special ad hoc network in which mobile devices cooperate each other to download an interesting content from the Internet in order to reduce the telecommunication cost. The mobile devices, called the peers, in the ad hoc network are assigned a portion of the target file, and are responsible for downloading the portion using their 3G connection. Then, the peers exchange their downloaded portion with other participating peers using their cost-free ad hoc connection in order to reconstruct the whole content. According to the simulation results, large number of participating peers saves the telecommunication cost up to 90% with as few as 10 peers, although it slightly increase the overall content reconstruction time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.186-188
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• 2014

In recent years, domestic as well as LTE wireless network of Wi-Fi and most used. In addition, mobile-intensive services that used mainly in our society makes it easier, SNS, application (APP), and file downloads. As such, the amount of data requested, while living at the time of mobile users will want to be safe from the earliest. And the wireless network communications mortality (3G, 4G (LTE), LTE-A) and Wi-Fi (802.11 n-2.4 G H z z H a c-5, 802.11 G), and users are mainly used in the death 4G (LTE), communication Wi-Fi, 802.11 n-2.4 GHz are used most frequently. As above, use the wireless network in order to safely and quickly developed the technology of the Li-Fi. Li-Fi light (visible light) technology to communicate with, and Wi-Fi (802.11 n-2.4 G z H) 100 times faster, LTE-A 66 times faster. However, the current Li-Fi to commercialise the big issue exists. In this paper, there are a lot of existing problems in the commercialization of Li-Fi being used in Wi-Fi, and a comparative analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.242-250
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• 2004

In this thesis, a new broadband PIFA(Planar Inverted-F Antenna) for PCS and IMP-2000 applications is designed. The dual-L antenna structure is adopted in order to improve the characteristics of PIFA which usually has a narrow band. The height of the antenna is fixed 6 mm considering terminal's thickness and the structure is deformed into the folded radiation patches to minimize the size of the antenna. The bandwidth of a realized antenna is 1.66∼2.35 ㎓(34.5 %) fur return loss below -10 ㏈ which contain the required bandwidth of PCS and IMT-2000. And Monopole antenna with λ/4 length is designed and compared with dual-L with folded patch in SAR. 1 g and 10 g averaged peak SAR of PIFA are about 25.7 %, 30.3 % lower than those of monopole antenna respectively.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.157-170
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• 2005

The combination of multiple antennas and multi-carrier code division multiple-access (MC-CDMA) is a strong candidate for the downlink of the next generation mobile communications. The study of such systems in scenarios that model real-life trans-missions is an additional step towards an optimized achievement. We consider a realistic MIMO channel with two or four transmit antennas and up to two receive antennas, and channel state information (CSI) mismatches. Depending on the mobile terminal (MT) class, its number of antennas or complexity allowed, different data-rates are proposed with turbo-coding and asymptotic spectral efficiencies from 1 to 4.5 bit/s/Hz, using three algorithms developed within the European IST-MATRICE project. These algorithms can be classified according to the degree of CSI at base-station (BS): i) Transmit space-frequency prefiltering based on constrained zero-forcing algorithm with complete CSI at BS; ii) transmit beamforming based on spatial correlation matrix estimation from partial CSI at BS; iii) orthogonal space-time block coding based on Alamouti scheme without CSI at BS. All presented schemes require a reasonable complexity at MT, and are compatible with a single-antenna receiver. A choice between these algorithms is proposed in order to significantly improve the performance of MC-CDMA and to cover the different environments considered for the next generation cellular systems. For beyond-3G, we propose prefiltering for indoor and pedestrian microcell environments, beamforming for suburban macrocells including high-speed train, and space-time coding for urban conditions with moderate to high speeds.

• Electronics and Telecommunications Trends
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• v.31 no.5
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• pp.80-89
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• 2016

현재 이동통신 분야에서는 5세대(5th Generation: 5G) 이동통신 표준화 작업이 한창 진행 중이며, 그 표준화 현황을 살펴보기 위하여 대표적인 국제 표준화 단체인 ITU-R에서의 활동 및 3GPP에서의 활동을 살펴보고자 한다. 최근 ITU-R WP 5D에서는 IMT-2020으로 명명되는 5세대 이동통신 비전 문서를 토대로 기술 요구사항 및 평가 기준 마련을 위한 작업이 수행되고 있으며, 3GPP의 TSG SA, RAN 및 하위 WG에서는 관련 상위 레벨 요구사항 정립 및 무선 구간에서의 기술적인 SI 논의가 수행되고 있다. 본고에서는 위 두 표준화 활동을 위주로 5G 이동통신에 대한 현황을 기술한다.