• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.91-99
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• 2011

Several repeater systems are used to enhance the cell coverage to location such as shadow and rural areas in mobile systems. But the general RF repeater solutions are not suitable for high power outdoor environment because it has the weakness such as self oscillation problem With adoption of a adaptive digital filter technology, feedback interference cancellation repeater prevents oscillation by detecting and canceling the unwanted feedback signal between transmission and receiver antenna. In this paper, dual NLMS based interference cancellation method is proposed and the step size adaptation can be implemented by the estimation of the feedback channel Doppler frequency characteristics. The performance of the proposed algorithm is quantified via analysis and simulation for the static and multipath fading feedback channels.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.5
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• pp.459-464
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• 2016

The mobile communication service is widely used and the repeaters is rapidly increasing because of the extending service areas. we propose a new Signed CMA(: Constant Modulus Algorithm) algorithm for ICS(: Interference Cancellation System) as a larger service area of mobile communication service. The proposed Signed CMA algorithm improved performances by adjusting step size values. We showed that the proposed algorithm could improve the Mean Square Error(: MSE) performance of Signed CMA. MATLAB(: Matrix Laboratory) is employed to analyze the proposed algorithm and to compare it with the experimental results. At the convergence of 1000 iteration state, the MSE(: Mean Square Error) performance of the proposed Signed CMA algorithm with step size of 0.0065 is about 5 dB better than the conventional CMA algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.660-667
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• 2000

This paper aims at analyzing the traffic of CDMA base station. RTD(Round Trip Delay) method, used for the study, is one of the developed tool for calculating the call setup time between the BTS(Base Station TransceiverSubsystem) and mobile station.We compare the calculated call setup time in air with the field experiments.And we suggest the RTD method for dividing the traffic of the connected repeater from that of the BTS, andwe can testify it by the experiment which analyze the difference of the received time between the base stationand the repeater including the forced delay elements.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.274-279
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• 2011

To increase the performance of mobile communication systems, base statations having beamforming function are released recently. For the proper beamforming function, it is required that each RF paths be calibrated periodically. However, the current calibration method has a problem when the base station is connected to a repeater. In this paper, we report the problem and propose a new calibration method to solve the problem.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.867-873
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• 2016

Even if ICS(Interference Cancellation System) repeater is used in wireless communication system, it has the disadvantage that it must have enough distance between Donor and Service antenna to be isolated. In this paper, new ICS repeater integrated antenna with high insolation characteristics is designed. The proposed antenna is fabricated for 800MHz and measured. Bandwidth and gain are optimized by changing the stub lengths near main patch and power divider, and also by changing the size of parasitic patch. The fabricated antenna has a return loss less than -13 dB, a gain over 3 dBi, and an isolation between the donor and the server antennas less than -56 dB from 824~894 MHz for CDMA mobile communication. Therefore, the proposed antenna structure can be applied to eliminate the shadow area and to expand the coverage area for any other wireless communication bands.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.51-55
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• 2015

In this paper, we proposed scheme that obtain diversity gain in the cooperative communication to mitigate, applied to the effects of fading in the vehicle communication. Relay used bus that can available in the city environment. In addition, we applied the double rayleigh fading environment so that can applied in real-environments. Therefore, proposed scheme through this paper applied to vehicle communication, user can acquire a high quality service and the operation efficiency of the network is improved. Finally, performance of the proposed protocol is analyzed in terms of bit error rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1125-1132
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• 2011

The purpose of this study is to suggest installation methods of a mobile-communication repeater into a lift system with consideration of EMC. Two approaches, one(Solution 1) is realized with a repeater installed in a lift hoistway and another(Solution 2) installed inside a lift, were proposed. It is confirmed that the Solution 1 is more effective than the Solution 2. And it is suggested that the EIRP of a repeater must be limited to be ${\leq}$-5 dBm by considering electromagnetic immunity level for a lift and safety margin of 20 dB. This limit can provide suitable electromagnetic environment inside a lift with precise power-control mechanism of mobile communication systems. This study could be a good example of Green ICT by improving electromagnetic environment in spite of radio use.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.5
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• pp.1-9
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• 2009

Relay-assisted multiple input technique has become a promising candidate for next generation broadband wireless communications. In this paper, we propose channel selective relay-based multiple input transmission system. In the proposed system, single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA) are adopted for uplink and downlink transmissions, respectively. The performance of relay-based system can be improved by using the subcarriers selectively based on the channel condition between relay station (RS) and mobile station, or between RS and base station. Simulation results show that the proposed relay-based system considerably outperforms the conventional relay-based system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1672-1678
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• 2022

In this paper, the relay antenna was designed in consideration of the performance of the 28GHz band 5G mobile communication relay horn antenna, such as radiation pattern and return loss. A horn array for 5G mobile communication repeater was designed by arranging the antenna elements in phase, and the performance was analyzed. Unlike conventional WCDMA (3G) and LTE (4G), in millimeter wave band communication, high path loss occurs between transmission and reception. In the design of a 5G millimeter wave horn antenna, antenna performance such as isolation and gain between antenna elements as well as gain and bandwidth of the antenna must be additionally considered. The antenna gain of the single horn antenna (1×1) and the array horn antenna (2×4) in the 28GHz band is about 10.44d Bi and 19.58dBi, respectively, and the return loss is designed to be less than -18dB. It has proven its validity and has been shown to be suitable for application to 5G mobile communication relay system.

• The Journal of the Korea Contents Association
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• v.3 no.2
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• pp.78-86
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• 2003

The Minisoy of Information and Communication(MIC) requires telecompanys to share base stations in order to prevent the duplicated investment and environmental destruction which would be caused by the indiscreet construction of basestations for enlarging their own service area among telecompanys. This paper discusses' the problems of mobile communication services that have been generated in common-repeater at the Metropolitan subway. These problem include factors of power obstacles, communication equipment and establishment obstacles. The content of this paper is helpful in organizing the basestation sharing of IMT-2000 and the 4th generation mobile system, and provides the basics of a higher quality service for common-service communication.