• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.5
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• pp.575-580
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• 2006

It is important matter that inflect well allocated frequency resource in cellular network and is still more serious element in environment that provide multimedia services. This paper describes model and algorithm that increase two elements that is frequency allocation and job scheduling that consider multimedia service traffic special quality by emphasis that do mapping present in CDMA cellular system. We proposed the model composed three parts (channel allocation algorithm, mapping algorithm and scheduling algorithm) and simulation results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12C
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• pp.1020-1028
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• 2010

Relay has attracted great attention due to its inherent capability to extend the service coverage and combat shadowing in next generation mobile communication systems. So far, most relay technologies have been developed under the half-duplex (HD) constraint that prevents relays from transmitting and receiving at the same time. Although half-duplex relay (HDR) is easy to implement, it requires partitioning of resource for transmission and reception, reducing the whole system capacity. In this paper, we propose a multinser precoding and power control scheme with sum rate matching for a full-duplex (FD) multiple-input multiple-output (MIMO) relay. Full-duplex relay (FDR) can overcome the drawback of HDR by transmitting and receiving on the same frequency at the same time, while it is crucial to reduce the effect of self-interference that is caused by its own transmitter to its own receiver. The proposed precoding scheme cancels the self-interference of the FDR as well as to support multiuser MIMO. Moreover, we suggest a power allocation scheme for FD MIMO relay with the constraint that the sum rate of the relay's received data streams is equal to that of the relay's transmit data streams.

• Information and Communications Magazine
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• v.24 no.9
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• pp.5-14
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• 2007

이동통신관련 산업이 발전함에 따라 전파 자원의 수요가 급증하여 스펙트럼의 경제적 가치는 계속적으로 높아지고 있다. 따라서 기존의 명령과 통제에 의한 정부의 일방적인 주파수 할당 방식에서 벗어나 시장원리를 도입함으로써 주파수의 활용을 극대할 필요성이 제기 되고 있다. 나라마다 조금씩의 차이는 있지만 주요 내용은 스펙트럼을 거래 가능한 재화로 취급하여 시장원리에 따라 스펙트럼을 관리하려는 것과 스펙트럼 접속 에티켓(etiquette)을 바탕으로 모두가 스펙트럼을 공유하는 관리 방식이 그것이다. 본 원고는 이러한 정책 흐름의 변화 과정 속에서 현재 국내외 주파수 정책의 최신 동향을 살펴보고 이를 분류하고 필요한 정책적, 기술적 과제를 살펴봄으로써 동적 스펙트럼 관리 기술 및 비즈니스 모델 개발의 가이드라인을 제공하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.391-400
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• 2009

Recently, cellular communication networks are migrating from 2G to 3G. Spectrum utilization tends to be inefficient during the transition. Cognitive radio (CR) technology can be a key solution to increase spectrum efficiency by allowing secondary networks to utilize frequency resource of primary networks. However, conventional CR approaches which do not utilize the frequency reuse factor of primary networks may incur degradation of whole network performance. In this paper, we propose a mechanism that a secondary network senses pilot signals of a primary network and select optimum frequency bands. In order to maximize whole network performance, we formulate an optimization problem subject to interference constraints for a primary network and present algorithms. Simulation results compare the proposed method with the conventional method. Our proposed method shows performance gain over the conventional method if channel variation of a primary network is dynamic and the frequency reuse factor of a primary network is high.

• Information and Communications Magazine
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• v.26 no.10
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• pp.18-24
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• 2009

본고에서는 북미 차세대 모바일 DTV(Digital Television) 규격인 ATSC-M/H(Mobile/Handheld) 기술의 주요 특징을 살펴본다. ATSC-M/H 기술은 6MHz 대역폭을 통해 총 19.39Mbps의 전송률을 지원할 수 있는 ATSC(Advanced Television Standard Committee) 시스템에서 HD 콘텐츠 전송 시 생성되는 여유 공간에 모바일 콘텐츠를 추가하여 전송하는 기술로 최대 120km/h의 이동속도를 지원한다. ATSC-M/H는 모바일 서비스를 위한 별도의 주파수 할당이 필요 없고, 기존 ATSC 시스템에 간섭을 주지 않으면서 동시방송이 가능하며, 저렴한 투자비용으로 모바일 방송 시스템을 구축할 수 있는 특징이 있다.

• Environmental and Resource Economics Review
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• v.9 no.1
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• pp.251-274
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• 1999

정부는 2000년에 차세대이동통신(IMT-2000) 사업자 선정을 완료하고 2002년부터 서비스를 시작한다는 계획을 발표했다. 차세대이동통신은 통신장비 및 기술규격의 국가별 차이가 줄어들고 기존의 국내, 국제, 유선, 무선전화, 위성통신, 인터넷, 고속 테이타 송수신 등 모든 현존 신규통신수단을 하나로 통합하는 혁명적 신기술로 사업권을 따내려는 업체들간의 경쟁 및 기존 통신업체들간의 경쟁이 치열해질 전망이다. 정부는 2000년 6월까지 차세대이동통신 면허발급 숫자와 사업자 선정방식을 발표할 계획을 가지고 있다. 정부는 아직 어떤 방식으로 차세대 이동통신 사업자를 선정하고 전파대역을 할당할지 확정하지 못하고 있으나 경매에 의한 주파수 할당제를 도입할 것을 검토중이다. 지금까지 정부의 전파자원 배분은 뚜렷한 원칙이 없고 그때그때 필요에 따라 정하였다. 최근에는 면허제를 채택하여 신청자들의 기술능력, 자금능력 등을 심사하여 전파자원을 할당하는 방식을 써왔다. 그러나 이와 같은 자원배분 방식은 중복투자와 과잉경쟁으로 이어져 무선통신 서비스의 비용상승과 품질저하를 초래하고 있다는 비난을 받고 있다. 전파자원의 효율적 이용을 위해서는 기존의 기술심사에 의한 면허제보다는 경제원리에 입각하여 가장 높은 자원사용료를 지불할 수 있는 사업자에게 주파수자원이 배정되도록 하는 것이 바람직하다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.17-24
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• 2013

In this paper, the measurement data is analyzed and channel characteristics are derived through MIMO Channel measurements at 781MHz considering antenna correlation. 781MHz frequency band currently operates the DTV system, however, it will be allocated new mobile communication frequency band. The channel characteristics at 781MHz seem to be similar existing mobile communication system at 900MHz but quite a different part of the existing research has demonstrated. In addition, the signal procedure of the channel characteristics, considering the correlation of the antenna, for a more accurate prediction research is needed. To avoid interference with Korean DTV broadcasting, we measured channel characteristics in urban areas of Jeju island by channel sounder and $4{\times}4$ antenna. Channel characteristics with antenna correlation were derived based on the measured data in the urban area.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.1
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• pp.46-52
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• 2016

LTE-Advanced system consisting of the number of cells in the cellular environment because it is built to allow efficient use of limited frequency resources of adjacent cell interference avoidance should be considered. Transition services in accordance with the development of the mobile communication technology, wireless multimedia content from voice-centric mobile communications services and causing a lot of mobile data traffic, such as smart phones and tablet terminals spread of a data-driven surge in mobile data traffic base stations in urban areas by increasing became a reality that can not be prevented. In this paper, we propose a new Hybrid resource allocation technique for improving the performance of the cell boundary and analyzed the performance of the proposed new techniques to perform the simulation using LTE-Advanced system level simulator based on 19cell of cellular system model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2B
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• pp.269-278
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• 2010

In the clustering protocol, lifetime of the cluster members radically decrease because frequency interference between clusters make every cluster member consume a lot of energy to maintain or increase its transmission rate. In this paper, we analyze the frequency interference among the clusters with the game theory which deals with resource bargaining problems between players, and present a rational power allocation strategy. Both the cases that each cluster tries to selfishly occupy and cooperatively share the resource are analyzed in terms of non-cooperative and cooperative games. In simulation, we compare the cooperative game with non-cooperative game in terms of the node lifetime.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.3-11
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• 2017

UAV system has the limitation to allocate enough spectrum bandwidth for the operation of multiple UAVs due to the market expansion. In addition, the communication environment of UAV network varies dynamically due to the UAV's mobility. Thus, to operate the stable UAV system and maximize the transmission data rate, it needs to allocate the resource effectively in the limited bandwidth considering the given network environment. In this paper, we propose the resource allocation algorithm which can maximize the network throughput as well as satisfy the minimum data requirement for the UAV system operation in the given network environment based on TDMA(Time Division Multiple Access). By performance analysis, we show that the proposed algorithm can allocate the resource to satisfy the high network throughput as well as the minimum data requirement in the given network environment.