• Information and Communications Magazine
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• v.12 no.5
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• pp.68-84
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• 1995

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.666-675
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• 2008

The IEEE 802.22 standard is being developed with the target of improving the efficiency of spectrum utilization and importing the new wireless communication service. The WRAN standard based on Cognitive Radio is being processed for sharing TV bands. In this paper, the efficient spectrum allocation scheme and the optimal power allocation scheme, Partial Constant Power Water Filling (PCPWF), are proposed to maximize the channel capacity and spectrum efficiency and minimize the interference between adjacent cells. And we maximize the system throughput and fairness by using proposed dynamic cell plan that efficiently allocates channel. The results of the simulations are presented to verify the utilization of our proposed scheme.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.457-467
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• 2018

This paper presents performance comparison of several high-resolution frequency estimation algorithms for pure real tone signal. Algorithms are DFT (Discrete Fourier Transform - for reference purpose), Jacobsen, Candan, reassignment and Cedron. Each algorithm is evaluated under various experimental conditions, e.g., different SNR (Signal to Noise Ratio), window function and window length and performance is compared in the perspective of bias, MSE (Mean Square-Error) and variance. Experimental results indicate that Cedron algorithms works well in the most cases. For actual usage in the engineering problem, each algorithm needs additional analysis and modification.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.1
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• pp.50-61
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• 2014

Operating small cell with existing macro cell is of interest in wireless communication technology to enhance network capacity. Closed-access small cell allows the access of users registered in it and causes severe interference to nearby users connected to macrocell. We propose a dynamic channel allocation for small cells in the same building that first aim to minimize call-drop of the nearby macrocell users, and then want to reduce interferences between the small cells. Since the interference effect of small cells on the nearby macrocell users mainly depends on the small cells' position, the proposed algorithm includes a self-configuration to flexibly allocate frequency channels according to the variation of downlink quality of the macrocell users. Furthermore the algorithm is very simple and practical, which is main contribution of this paper. We observe that the proposed algorithm provides 82-94% of maximum achievable throughput.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.51-60
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• 2009

In radio frequency identification(RFID) systems, when an RFID reader uses the same or adjacent frequency with neighbor readers, the interference between the readers may occur, which causes the reader collision and errors in tag recognition. In the previous study on RFID reader anti-collision, the techniques based on Frequency Division Mutiplex(FDM) or Time Division Multiplex(TDM) are proposed. However in these paper, the problem on the condition of RFID reader-to-reader interference considering the distance between interfering readers, frequency and operating time is not define exactly. In this paper, the interference effect is analyzed through RFID reader interference model considering the TDM and FDM, and the optimization problem is defined. To solve this, genetic-resource allocation technique is proposed. Therefore the optimal resource allocation applied RFID environment faithfully is accomplished.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.805-819
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• 2013

In this paper, we analyze the paradigm shift of radio policy with the development of radio technology. In particular, we propose the definition of spectrum sharing, which is now omitted in the Korean radio law, and analyze the category of spectrum sharing depending on the licensing regime. Also we propose to extend the spectrum usage right, which defines only exclusive usage rights by spectrum auction in the Korean radio law, to all the stations which use radio spectrum and to restructure the Korean radio law.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.54-61
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• 2009

In this paper, Switching to digital TV broadcasting and mobile operators license expiration period of the frequency, time and 700MHz, 800MHz and 900MHz frequency band plan for the redistribution is actively being discussed. Redistribution policy direction of these frequency 800MHz (bandwidth 10MHz) integrated command frequency for wireless networks(i.e TETRA) is expected to be considered a redistribution. These Integrated Wireless Network Infrastructure configurations at the time and data communication capabilities of the system unwilling TETRA Release 2 standard for the system is presented. This system is analyzed that Release 1 of the existing system takes up more than 6 times the increase of frequency bands. Therefore, integration of the frequency band assigned to the command of a wireless network with the introduction of advanced systems will not be able to do. In this paper to the digital TV transition, and the policy based on analysis of trends in the 700MHz band for the integration of wireless networks, provides policy direction for the allocation plan.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.3-15
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• 2008

주파수는 무선 통신 및 방송 등 무선 서비스 제공에 필수적인 매개체로서, 국가에 의해 관리되는 자원이다. 이동 통신을 중심으로 무선 서비스가 지속적으로 발전하고 경제에 미치는 효과가 커짐에 따라 주파수에 대한 수요가 급증하면서 경제적으로 희소성을 띄게 되었다. 이에 흔신 관리에 치중했던 기존의 전파 관리 체계에서 점점 경제적 가치를 고려한 시장 기반의 전파 관리 체계로의 전환에 대한 관심이 높아지고 있다. 시장 기반의 전파 관리 체계에서 주파수 이용자를 선정하는 할당 방식으로 많이 이용되고 있는 것이 주파수 경매제(auction)이다. 주파수 경매제는 주파수 수요자들의 입찰을 통해 주파수의 가격 및 이용자가 결정되는 방식으로 아직 우리나라에서는 시행되지 않고 있으나, 미국, 영국, 독일, 호주 등이 시행하고 었으며, 현재 우리나라도 도입을 검토하고 있는 단계이다. 이에 본 논문에서는 주파수 경매제의 개념 및 장단점, 이론적 배경 등에 대해 살 펴보고 주요국의 경매 정책 및 최근 경매 동향에 대 해 살펴본 후 국내 적용을 위한 시사점을 도출한다.

• Journal of Broadcast Engineering
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• v.13 no.6
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• pp.883-891
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• 2008

Multiple antenna orthogonal frequency division multiplexing (OFDM) is a promising technique for the high downlink-capacity in the next generation wireless systems, in which adaptive resource allocation is an important research issue that can significantly improve the performance with guaranteed QoS for users. However, most of the current resource allocation algorithms are limited to unicast system. In this paper, dynamic resource allocation is studied for multiple antenna OFDM based systems with multicast service. In the simulation, the performance of multicast system was compared with that of the unicast system. Numerical results also show that by using the proposed algorithms the system capacity is significantly improved compared with the conventional scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.90-97
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• 2009

The advantages of the orthogonal frequency division multiplexing (OFDM) are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. To further utilize vast channel capacity of the multiuser OFDM, one has to find the efficient adaptive subchannel and bit allocation among users. In this paper, we propose an 0-1 integer programming model formulating the optimal subchannel and bit allocation problem of the multiuser OFDM. We employ a dual-decomposition method that provides a tight linear programming (LP) relaxation bound. Simulation results are provided to show the effectiveness of the 0-1 integer programming model. MATLAB simulation on a system employing M-ary quardarature amplitude modulation (MQAM) assuming a frequency-selective channel consisting of three independent Rayleigh multi-paths are carried with the optimal subchannel and bit allocation solution generated by 0-1 integer programming model.