• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.22-28
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• 2013

In this paper, new LBS (location based service) are proposed using conventional DMB (digital multimedia/mobile broadcasting) system. LBS applications are proposed that can be suitable for the subway and ground transportation based on S-DMB (satellite-DMB) and T-DMB (terrestrial-DMB) respectively. In the shaded area such as subway, the broadcasting signal transmitted from the satellite of S-DMB system should be retransmitted by the earth repeater called the gap filler and each gap filler has its own identification value called the gap filler ID which introduces the area in which the gap filler was installed. Therefore, the LBS can be implemented by using the gap filler ID of S-DMB on the subway in which the GPS (global positioning system) can't be received. Unlike the LBS on the subway, the combination of T-DMB and DGPS (differential GPS) will be introduced as a way for ground transportation. Generally, DGPS has been designed to compensate the position value calculated from the GPS signal so that positioning error of about 1 meter can be obtained by using DGPS information. T-DMB system transmitting DGPS signal will be expected to be commercial in Korea and, if using DGPS information transmitted through T-DMB network, LBS with more precise positioning than GPS alone can be implemented in the ground vehicles.

• 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.

• ETRI Journal
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• v.22 no.4
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• pp.32-39
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• 2000

In low earth orbit (LEO) satellite communication systems, more severe phase distortion due to Doppler shift is frequently detected in the received signal than in cases of geostationary earth orbit (GEO) satellite systems or terrestrial mobile systems. Therefore, an estimation of Doppler shift would be one of the most important factors to enhance performance of LEO satellite communication system. In this paper, a new adaptive Doppler compensation scheme using location information of a user terminal and satellite, as well as a weighting factor for the reduction of prediction error is proposed. The prediction performance of the proposed scheme is simulated in terms of the prediction accuracy and the cumulative density function of the prediction error, with considering the offset variation range of the initial input parameters in LEO satellite system. The simulation results showed that the proposed adaptive compensation algorithm has the better performance accuracy than Ali's method. From the simulation results, it is concluded the adaptive compensation algorithm is the most applicable method that can be applied to LEO satellite systems of a range of altitude between 1,000 km and 2,000 km for the general error tolerance level, M = 250 Hz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5007-5014
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• 2010

Recently n Korea, the House of Commons and terrestrial broadcasting facilities integrated with FM radio and the satellite compulsory was amended to transfer MATV(Master Antenna Television) adjusted by SMATV(Satellite Master Antenna Television). While the SMATV was accepted by default in most other countries, our county did not accept it as the default for broadcast. Because domestic cable and satellite television service providers are conflicts with their interest. bAs a result, the hybrid amplifier for SMATV technology development and volume production for the state is insufficient. Therefore, terrestrial television broadcast bands (54 ~ 806Mhz) and FM radio broadcast band (88 ~ 108Mhz) band satellite with (950 ~ 2150Mhz) to amplify the development of a broadband amplifier with subsequent resolution of problems is also presented in this study.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.53-56
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• 2014

In the satellite system design, the design processes from the initial design to launch take about 5 years and the broadcasting satellite lifetime goes over 15 years. Furthermore, global warming phenomenon causes rainfall rate to increase more and more in some regions on the earth. Consequently, at the stage of the satellite link design, we need to consider the future rain attenuation over 20 years. In this paper, we investigated a time-series system model for forecasting to consider the future rainfall rate for the satellite broadcasting service. We found that rainfall rate of the future 20 years is increasing continuously.

• 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.

• ETRI Journal
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• v.24 no.3
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• pp.251-254
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• 2002

We developed a method for optimal superframe design in the multi-frequency time division multiple access (MF-TDMA) return-link of a satellite multimedia interactive network called a digital video broadcasting return channel over satellite (DVB-RCS) sub-network. To find the optimal superframe pattern with the maximum data throughput, we formulated the design problem as a non-linear combinatorial optimization problem. We also devised the proposed simple method so that it would have field applicability for improving radio resource utilization in the MF-TDMA return link.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.257-260
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• 2014

In this paper, a high gain waveguide array antenna combining horn antenna on slot radiator was designed. And the fabricated antenna showed enough gain, improved efficiency and broadband characteristics for receiving satellite signals, compare to conventional microstrip antenna which has dielectric loss and radiation loss on transmission line. For easy fabrication, the waveguide structure was composed by 3-stages of radiator, signal coupler and transmission line. By experiment, the array waveguide antenna of 4 by 16 showed 28.3[dBi] gain and 2:1 of VSWR. And by combining horn antenna structure, the gain was increased 1[dB]. The received signal from Koreasat 6 by measurement showed 16[dBc] of C/N on BS(Broadcasting Satellite)-band and 14[dBc] of C/N on CS(Communication Satellite)-band.

• Broadcasting and Media Magazine
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• v.15 no.1
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• pp.49-57
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• 2010

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.525-528
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• 2003

This paper describes the effective and rigorous analytic method of multipath effect which results from insufficient isolation characteristics between adjacent channels in communication payload system. It is very important to analyze the multipath effect for verifying the performance of transponder subsystem that especially is consist of multi channels. Finally the multipath effect are analyzed by calculating the GR and GDR for two adjacent channels of Ku-band transponder subsystem on the Communication & Broadcasting Satellite(CBS).