• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.610-614
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• 2003

The bands 27.5 - 28.35GHz and 31.0 - 31.3GHz were allocated to the High Altitude Platform Station in WRC-2000. However, since these bands were already allocated to the existing fired-satellite service, the analysis on the interference effects between the existing FSS/GSO system and FS/HAPS system should be needed. To do study on the interference effects between above two systems, we can consider two frequency operational renditions, one is the Reverse mode and the other Forward mode. In this paper, we considered the Forward mode as the frequency operational condition and analyzed the interference effect from a number of GSO satellites to HAPS ground station due to the I/N values, the latitude of HAPS and the satellite separation. In future, these results will be vital data to share between HAPS and GSO systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.523-528
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• 2004

The bands 27.5 ∼ 28.35GHz and 31.0 ∼ 31.3GHz were allocated to the High Altitude Platform Station in WRC-2000. However, since these bands were already allocated to the existing fixed-satellite service, the analysis on the interference effects between the existing FSS/GSO system and FS/HAPS system should be needed. To do study on the interference effects between above two systems, we can consider two frequency operational conditions, one is the Reverse mode and the other Forward mode. In this paper, we considered the Forward mode as the frequency operational condition and analyzed the interference effect from a number of GSO satellites to HAPS ground station due to the I/N values, the latitude of HAPS and the satellite separation. In future, these results will be vital data to share between HAPS and GSO systems.

• Electronics and Telecommunications Trends
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• v.22 no.3 s.105
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• pp.166-173
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• 2007

WRC-97에서 HAPS 개념이 도입된 후, HAPS 이용 주파수 대역으로 IMT-2000 대역과 Ka 및 V 대역이 지정되었다. IMT-2000 대역에 대한 공유 및 규정 연구는 WRC-03에서 종료되었으나, Ka 및 V 대역에서 타 무선업무와 HAPS를 이용한 고정업무 간의 기술적, 운용적 그리고 규정에 관한 연구를 지속하고 WRC-07에서 연구결과를 검토하기로 하였다. 본 고에서는 WRC-03 회의에서 결의한 IMT-2000 서비스를 제공하는 HAPS 시스템의 이용에 관한 규정 현황을 알아보고, 현재 ITU-R에서 논의중인 Ka및 V 대역에서 HAPS 시스템 활용을 위한 규정 연구 현황을 살펴보고자 한다.

• Electronics and Telecommunications Trends
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• v.21 no.5 s.101
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• pp.154-162
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• 2006

본 논문에서는 성층권 통신망(HAPS)과 기존 위성망 및 지상망과의 원활한 공유를 위해서 진행되고 있는 HAPS 시스템의 간섭경감기법에 관한 연구 동향을 분석한다. 이를위해서 2006년 6월 27일부터 7월 5일까지 개최된 ITU-R WP9B 회의를 통하여 논의된 주요 결과들을 중심으로 살펴보고자 한다. Ka 대역에서 고정업무(FS)용으로 활용가능한 HAPS 시스템의 간섭경감기법으로 5가지가 제안되었으며, 특히 본 회의에서는 디지털빔형성(DBF) 기법을 적용한 탑재안테나의 다중빔 패턴의 성능분석 결과들이 제시되었다. HAPS 시스템의 간섭경감기법으로 디지털빔 형성기법을 적용함에 있어서 그 필요성과 ITU-R WP9B에서 논의되고 있는 내용들을 중심으로 간섭경감기법 분석 결과를 기술하고 본 내용과 관련한 ITU-R에서의 향후 연구 전망 등을 살펴보고자 한다.

• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.20-27
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• 2009

In this paper, HAPS operation scenario is proposed to minimize the interference from HAPS user terminal(HUT) to geostationary earth orbit(GEO) satellite receiver. The conventional scenario has been assumed for fully operated situation of HUT. However, all the HUTs could not be fully operated in a real system operation. Therefore, in order to reduce the interference to other systems, multibeam operation scenarios such as time division and adaptive time division methods are proposed and the interference effect of HUT to satellite receiver is evaluated according to various operation rate of HUT.

• IE interfaces
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• v.17 no.spc
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• pp.62-68
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• 2004

HAPS (High Altitude Platform Station) which is defined as a station located on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the earth is a promising technology capable of providing broadband multimedia services. In this study, economical aspects of HAPS service are analyzed by estimating the revenue and costs incurred by the service. To evaluate the profitability of HAPS service, the number of subscribers is estimated and then the net present value (NPV), payback period, and the rate of return on investment (ROI) are calculated under various scenarios.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.759-762
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• 1999

In this paper, we introduce the concept of a HAPS(High Altitude Platform Station) system which is expected to be a next generation communication system and suggest several error correcting codes to provide high quality services. Since a HAPS system encounters serious signal attenuation due to rain and scattering in the air, concatenated codes which have a high coding gain is considered to be a proper error correcting method. In this paper, we provide performance analyses result of two candidate coding schemes for a HAPS. The first one is a conventional concatenated coding scheme, and the second one is a iterative decoding method known as Turbo Codes.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.8-15
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• 2006

Under Resolution 122 (Rev. WRC-03), ITU-R is invited to study, as a matter of urgency, power limitations applicable for HAPS ground stations to facilitate sharing with space station receivers in the bands 47.2-47.5 GHz and 47.9-48.2 GHz. However, there have been no studies on this issue. Recommendation ITU-R SF.1481-1 which was developed during past study period, provides methodology and system characteristics for analyzing the sharing feasibility between systems in the FS using HAPS and systems in the FSS. System characteristics for a typical HAPS in the bands above are also given in Recommendation ITU-R F.1500. This paper provides the results on power limitations applicable for HAPS ground stations in accordance with Resolution 122 (Rev. WRC-03). As already shown in ITU-R Recommendation the results show that a sufficient separation distance is required for sharing between HAPS ground stations and FSS satellite systems. We obtain some examples of the sharing conditions considering reducing the power level of HAPS ground stations and using the antenna beam pattern with the low sidelobe to decrease the interference level affecting FSS satellite receiver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.819-825
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• 2002

Resolution 221 requests the ITU-R to conduct studies, as a matter of urgency, on the feasibility of utilizing HAPS system as a base station to provide IMT-2000 services. And HAPS base stations should not cause harmful interference to the cellular IMT-2000 services. To study on the interference between HAPS system and cellular system is divided into two cases. One is the interference into HAPS system from the cellular system and the other is the interference into the cellular system from HAPS system. Since the former case has been already studied[1]. this paper describes the interference the interference to the noise power ration(I/N) with various parameters, such as the transmitting power, the number of users per cell, maximum antenna gain and the multibeam cell radius of HAPS. With the proposed estimation, we can determine the optimum values of various parameters in HAPS IMT-2000 system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7B
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• pp.719-726
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• 2002

In WRC-2000, Resolution 734 was adopted to study the use of high altitude platform station(HAPS) operating in the bands above 30GHz. Therefore, frequency sharing feasibility between a new HAPS systems and an existing terrestrial fixed-service(FS) system should be analyzed primarily. In this paper, interference effects from the HAPS system into the radio-relay station are analyzed in terms of two cases; one is the interference distribution from the power-flux density(PFD) of HAPS airships, and the other the interference power from the ground stations. In conclusion, the new PFD criteria different from the exiting satellite system should be required, and the coordinated distance between the HAPS nadir and the radio-relay station should be 60km ∼ 253km for P$\sub$HG/ = -50dBW/MHz of transmitting power spectral density to share the new HAPS system into the existing FS system.