• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3550-3565
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• 2019

This paper proposes a new measurement method for the effective measurement of the 99% occupied bandwidth (OBW) at monitoring stations. Although the OBW measurement of radio signal is recommended by the International Telecommunication Union Radio (ITU-R) with several methods, there still does not exist a clear measurement recommendation or standard for terrestrial DTV signal on-air environment. Modified adjacent channel power ratio (MACPR), which can be applied to 8-VSB (Vestigial Side Band) DTV (Digital Television) signal, is herein defined to verify the results of measurements obtained using the proposed measurement method. MACPR is a proper measuring parameter for determining the measuring area of a monitoring station. From measurement results obtained in real field environment, it has been found that the OBW of 8-VSB DTV signal can be effectively measured in areas where the MACPR value is over 35 dB and when the measurements are repeated more than 600 times in the same reception site. It also has been verified that measured results are within an error range of +/-0.1% compared to results directly obtained at a transmission station. It is expected that the proposed method is able to be employed in order to determine the proper location of monitoring station and provide a reliable OBW measurement procedure for 8-VSB DTV signal on-air environment.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.64.2-64.2
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• 2013

Korea Astnonomy and Space Science Institute (KASI) operates two solar radio observing facilities, the Korean station of the e-CALLISTO and the Korean Solar Radio Burst Locator (KSRBL). The e-CALLISTO station had suffered from tracking problem for past several years. Since 2011, KASI has developed a new tracking system, and recently the antenna has regained the its sun-tracking capability and full day-time coverage. The KSRBL also suffered from the control computer breakdown last year. After one year of operational gap, the KSRBL restored its normal daily observation. We also expanded the data server storage capacity, to store the full original data of 25 ms integration time and 0.25 MHz frequency resolution, amounting to about 80 GB per day.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.222-225
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• 2001

This paper describes design and performance test of dual-mode horn antenna for HAPS (High Altitude Platform Station) in 47.2 - 47.5 GHz and 47.9 - 48.2 GHz bands. To obtain the optimal geometry parameters of it. the conical section is represented by a stepped transition composed of a set of cylindrical waveguide sections. For each step. the corresponding generalized scattering matrix is calculated. The elements of the matrices at the open end of the horn, are calculated by the rigorous formulas of the factorization method. To verify the theoretical results, a horn breadboard was manufactured for the medium frequency of 47.7 GHz and its radiation beam patterns were measured. The calculated and theoretical results are in good agreement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.1075-1082
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• 1997

In this paper, we propose a channel assignment scheme for reducing call blocking rate in a base station(BS) of DS-CDMA cellular systems. The proposed scheme can e applied to the case where the capacity of reverse radio link is enough, but not are the available traffic channels performing the digital modulation and demodulation functions between a mobile station and the base station. The proposed scheme takes advantage of the feature of soft handoff in which a mobile station keeps its communication link even if one of the two communication links is released. The scheme estimates the mean and variance of the received power level measured at the base station before assigning a traffic channel for a new call request. The BS makes decision based on the estimated balues whether the new call request will be accepted or not. If it is decided that the capacity of reverse radio link is enough, but all traffic channels are not available, then the BS increases the soft handoff parameter T_DROP to release the traffic channels of mobile stations loactedin soft handoff area. The BS assigns the released traffic channel to anew call or a handoff call. The performance of the proposed channel assignment scheme is evaluated by computer simulation. The results show that the call blocking rate for new calls and handoff calls is reduced.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.1
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• pp.11-24
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• 2022

Open Radio Access Network (O-RAN) standard has been proposed to separate the baseband signal processing unit from the Radio Frequency (RF) unit at base station system mainly for reducing the cost of base station systems through open-source interfaces between the two units. To satisfy the performance metrics in various scenarios, several fronthaul functional split options were presented by O-RAN. Amongst these options, the split option 7-2x is widely adopted in practical applications due to its excellent trade-off between the required bandwidth and RU overhead. In this paper, we present a hardware implementation of a base station system that is compliant with the Category B of O-RAN split option 7-2x. It consists of O-DU and O-RU implemented with a commercial off-the-shelf Digital Signal Processor and RF transceiver, respectively. The performance of the proposed base station system is evaluated in terms of Bit Error Rate and received signal power as well as the required fronthaul bandwidth. Through various experimental tests, we have observed that the proposed system reduces the fronthaul bandwidth nearly by 89.7% compared to the conventional system that dose not employ the O-RAN standard.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.404-411
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• 2016

In this paper, we investigate the radio wave radiation pattern to measure the actual field strength for the transmission antenna dipole antenna and the CP-ring antenna being used in our country as FM station, and the comparison was for field application. Compare results, If the transmitting station and the relay station which is located in the middle of a service area has been a useful CP-dipole antenna (four directions). CP-ring antenna having a directivity because the reflection effect of the tower was able to adjust the orientation to prevent the spread of menstrual another service area in the main direction was able to radiate high propagation 5~9dB. Especially, If the transmitting station and the relay station is located on one side of the service area for radiating radio waves in three directions by using the CP-ring antennas focus the orientation of the antenna in populated areas and road area can improve the broadcast reception environment.

• Journal of electromagnetic engineering and science
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• v.18 no.4
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• pp.242-247
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• 2018

This paper studies a convenient electromagnetic field (EMF) compliance assessment for base station installations at a millimeter wave (mmW) frequency. We utilize ray-tracing analysis as a numerical method for examining the wave propagation characteristic. Various installation cases are considered and the important parameters with a significant effect on the maximum power density levels are produced. We finally suggest the several scenarios for the convenient assessment of mmW base stations, which allow us to conduct cost effective computational tests compared with the current assessment procedure in the guideline.

• ETRI Journal
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• v.19 no.3
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• pp.202-227
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• 1997

This paper describes the development of the CDMA mobile station to support non-speech, mobile office services such as data, fax, and short message service in addition to voice. We developed some important functions of layer 2 and layer 3. To provide non-speech services, we developed a terminal adapter and user interface software. The description of development process, software architecture and external interfaces required to provide such services is given. The description of a TTA-62 message analysis tool, a mobile station monitoring software, and an automatic test system developed for integration tests and performance measurements is also given.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.135-149
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• 2016

Cloud radio access network (C-RAN) refers to the virtualization of base station functionalities by means of cloud computing. This results in a novel cellular architecture in which low-cost wireless access points, known as radio units or remote radio heads, are centrally managed by a reconfigurable centralized "cloud", or central, unit. C-RAN allows operators to reduce the capital and operating expenses needed to deploy and maintain dense heterogeneous networks. This critical advantage, along with spectral efficiency, statistical multiplexing and load balancing gains, make C-RAN well positioned to be one of the key technologies in the development of 5G systems. In this paper, a succinct overview is presented regarding the state of the art on the research on C-RAN with emphasis on fronthaul compression, baseband processing, medium access control, resource allocation, system-level considerations and standardization efforts.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.379-379
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• 2006