• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.12-16
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• 2013

This paper we introduce operated public test-bed satellite system configuration for satellite communications and usage for services via COMS(Communication, Ocean and Meteorological Satellite). According to trial public test-bed operation, the broadband multimedia services are expected to be available at the next generation VSAT services due to the increasing of Ka-band utilization. In addition, UHD broadcasting services via satellite is expected to improve the universal accessibility of broadcast services.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.4
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• pp.181-186
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• 2009

This paper presents an efficient synchronizer architecture using a common autocorrelator for Digital Video Broadcasting via Satellite, Second generation (DVB-S2). To achieve the required performance under the worst channel condition and to implement the efficient H/W resource utilization of functional synchronization blocks, we propose a new efficient common autocorrelator structure. The proposed architecture can decrease about 92% of multipliers and 81% of adders compared with the direct implementation. Moreover, the proposed architecture has been thoroughly verified in XilinxTM Virtex IV and R&STM SFU (Signaling and Formatting Unit) broad-cast test equipment.

• ETRI Journal
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• v.22 no.1
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• pp.12-19
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• 2000

Wireless communication systems using airship have been proposed in worldwide. The airship will be located at the stratosphere about $20{\sim}23\;km$ above the sea level. The position of airship will vary within the station keeping range with time due to the drag of the wind in the stratosphere. When the earth station antenna has a high gain without the tracking function, the antenna performance may be degraded by a small variation of the airship. This means that variation of airship location could result in serious degradation of the system performance. In this paper, degradation in earth station's Equivalent Isotropic Radiated Power (EIRP) and Gain to noise Temperature ratio (G/T) due to the stratospheric platform movements has been derived by calculating the deviation angle of the main beam directions between the earth station and the platform antenna. In this case, the antenna of the earth station has been assumed circular and/or patch array antennas.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.1-9
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• 2007

In this paper, we describe the performance degradation of satellite Wibro system and compensation method in the high-speed railroad channel environment. High-speed railroad channel environment is divided into LOS channel and tunnel. In the LOS channel, signal blocking caused by railroad power feeder structures can be a critical problem which is can be solved with antenna diversity. On the other hand, multi path interference phenomenon, representable by propagation model of Optic Fiber, occurred in the tunnel may be another obstacle. These satellite Wibro system performance degradations in railroad channel environment are addressed and adequate compensation methods are proposed and verified through computer simulation. In addition, the ICI caused by Doppler shift in OFDM system is analyzed with its compensation method.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.309-313
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• 2009

In this paper, the network performance of a turbo coded optical code division multiple access (CDMA) system with cross-layer, which is between physical and network layers, concept is analyzed and simulated. We consider physical and MAC layers in a cross-layer concept. An intensity-modulated/direct-detection (IM/DD) optical system employing pulse position modulation (PPM) for satellite broadcasting communications is considered. In order to increase the system performance, turbo codes composed of parallel concatenated convolutional codes (PCCCs) is utilized. The network performance is evaluated in terms of bit error probability (BEP). From the simulation results, it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is confirmed that the performance of such an optical CDMA network can be substantially improved by increasing the interleaver length and the number of iterations in the decoding process. The results of this paper can be applied to implement the satellite broadcasting communications.

• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.50-53
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• 2017

Satellite communications are vulnerable to malicious eavesdroppers and interceptors due to wide coverage and broadcasting applications. However, technologies for securing satellite networks have yet to be more articulated beyond high-layer packet encryption. As attempts for jamming and spoofing attacks spread out, it is extremely critical to invest on the development of physical layer security solutions. In this paper, we review current technologies for satellite communication network security both in high and physical layers. We also present recent research results on physical layer security in the fields of information theory and wireless networks. We suggest a future direction for satellite communication security, including a cross-layer approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10C
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• pp.1051-1058
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• 2007

Digital Broadcasting Services get abroad from satellite services to terrestrial services and cable services. As broadcasting services become digital from analog, diverse services such as multi-channel, high quality, time-shift function and so on can be possible. It also generates new digital businesses. The Conditional Access System(CAS) is a technology for providing prevention of illegal access to digital contents. It was applied to digital satellite services at Europe and America from the beginning of 90's. In 2002, a domestic digital satellite service provider adopt a CAS system to their broadcasting services. DRM technologies protect intellectual properties and digital rights of digital contents. This paper suggests a design method to construct a CAS system with DRM which can be applied to a CAS for a small digital broadcasting service.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.728-740
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• 2016

Korea developed several satellites through government-led satellite development projects, and now operates earth observation satellites of various sensors, science and technology satellites, and communication satellites. Satellites can be utilized in many fields, and Satellite Information, Global Navigation Satellite System, Satellite Communications and Broadcasting, Space Solar Power System are typical application fields. Now that we have developed and operated several satellites, we have to concentrate more efforts on satellite application. In this paper, we reviewed the current states of the technologies of four satellite application fields mentioned above and analyzed the future prospects of them.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6A
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• pp.488-498
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• 2005

The DAB(Digital Audio Broadcasting) service which is based on the Eureka-147 of Europe is developed to DMB(Digital Multimedia Broadcasting) service that is divided into Terrestrial DMB and Satellite DMB. The Satellite DMB is a new broadcasting service, which will service multi-channel multimedia broadcasting by the portable receiver or the vehicle receiver. In this paper, we consider that link level performance of satellite DMB system A which is based on the COFDM(Coded Orthogonal Division Multiplexing). It uses the OFDM method which is sensitive to nonlinearity, so we analyze the effect of the HPA(High Power Amplifier) nonlinearity. And then we define the appropriate back-off value by performing the link level simulation considering back-off effect. Also we consider the effect of frequency and time offset, and then confirm the overall link level performance by analyzing and verifying a suitable synchronization method for satellite DMB system A.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.9
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• pp.2514-2525
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• 1996

This paper presents the possibility of the satellite broadcasting reception as a means of microstrip antenna of the planar structure. The paper discusses the design of the optimal KOREASAT DBS(Direct Broadcasting Satellite) reception microstrip antenna. Experimental results for ta 16*16 array antenna of size 35*35cm are also described. Itsgain is over 28dB in the frequency range of 11.7~12.0GHz DBS band. The measured NHK broadcasting C/N ratio of 16816 array antenna is over 10dB in Pusan. It is expected that good picture quality of C/N .GEQ. 12dB can be obtained for domestic use if this microstrip antenna is used in KOREASAT broadcasting receiving system.