• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.1
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• pp.46-52
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• 2009

This paper design QHA(quadrifilar helical antenna) to receive efficiently Satellite-Digital Multimedia Broadcasting video signal. It is designed as quadrifilar structure with phase variation $0^{\circ}C$, $90^{\circ}C$, $180^{\circ}C$, $270^{\circ}C$ to obtain circular polarization. Upper gap, turn number and height of QHA are varied to obtain optimization dimensions. Optimization dimensions are gap=2.2mm, turn number=0.9, height=42mm and input reflection coefficient is approximately -5.8dB. Designed QHA can be applied to Satellite-DMB terminal.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.372-382
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• 2005

DS/CDM-QPSK (ITU-R Recommendation BO.1130-4 Annex 6, 'Digital System E'), which has been adoptedas a standard of Korean Satellite DMB (Digital Multimedia Broadcasting) system, is a satellite-based multimedia broadcasting service which transmits the multi-channel and high quality contents to the terrestrial users through a satellite or gap-fillers. The broadcast from a satellite is directly received in the plain terrain which are within line-of-sight, but in cities where the broadcast cannot be received directly due to the shadow of buildings, an attempt is being made to install 'Gap-Fillers' to improve the reception in those areas. The gap-fillers, however, may induce interference to service of adjacent band, when their output power is substantially higher compared to the received signal power of signal from a satellite of the adjacent service. In this paper, a link budget analysis is performed, and the optimal EIRP of a gap-filler to maximize the gap-filler coverage, while preventing adjacent band interference is derived.

• 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 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.

• Journal of Broadcast Engineering
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• v.11 no.3 s.32
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• pp.302-310
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• 2006

ITU-R B.O. 1130-4 Digital System E adopted for Korean satellite DMB service is a multimedia broadcasting system based on DS-CDM-QPSK technique which broadcasts audio and video contents via the satellite or terrestrial gap-filler. However, Digital System E can not provide full loading services because the multi-channel interference (MCI) is increased due to the loss of orthogonality between signature waveforms in multipath fading channels. In this paper a chip equalizer using tap selection algorithm that enhances the receiving performance is proposed and compared to the conventional rake receiver for the satellite DMB system.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.356-363
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• 2006

The demand for digital multimedia service using Ka band satellite communication are growing rapidly. So, in this paper, we have analyzed rain attenuation with typical model, and proposed prediction model of rain attenuation in high frequency(20 GHz). This paper illustrates Korea rain attenuation characteristics at the Ka band Koreasat beacon frequency based on the theoretical and empirical approaches and seek for efficient techniques by rain attenuation estimate and analyzed performance of adaptive modulation system. Propose prediction model of rain attenuation and parameter of satellite link can be available for the Ka band satellite communication.

• The Journal of Information Systems
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• v.14 no.3
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• pp.59-62
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• 2005

The recent broadcasting environment has shifted to embrace multimedia and multi-channel features through terrestrial, satellite and cable media. This has multiplied the number of broadcasting programs. With the information on a myriad of programs provided to TV viewers, information overload occurs, and thus, the TV viewing environment is shifting to one where viewers cannot select programs passively. Thus, a growing need is emerging to ensure a personalized electronic program guide (EPG) to help individuals select TV programs according to their taste. This paper presents a personalized EPG that enables a purpose-oriented broadcasting service to provide personalized broadcasting programs in tune with the user's requirements and preferences.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.744-748
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• 2003

Developing an interactive satellite multi­media system, such as a digital video broadcasting (DVB) return channel via satellite (RCS) system, is gaining popularity over the world To accommodate the increasing traffic demand we are motivated to investigate an alternative for improving return channel utilization We develop an efficient method for optimal packet scheduling in an interactive satellite multimedia system using hybrid CDMA/TDMA channels. We formulate the timeslot-code assignment problem as a binary integer programming (BIP) problem, where the throughput maximization is the objective, and decompose this BIP problem into two sub-problems for the purpose of solution efficiency. With this decomposition, we promote the computational efficiency in finding the optimal solution of the original BIP problem Since 2001, ETRI has been involved in a development project where we have successfully completed an initial system integration test on broadband mobile Internet access via Ku-band channels using the proposed resource allocation algorithm.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.494-498
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• 2011

Satellite digital multimedia broadcasting (S-DMB) systems use gap fillers (GFs) to provide wireless multimedia services to non-line-of-sight locations. GFs act as repeaters, and S-DMB systems require GF networks in order to guarantee mobile reception. Each GF covers a cell or sector. In order to provide contiguous coverage of an area comprising two or more cells or sectors, multiple GFs are needed. However, when multiple GFs are situated close to each other, interference is likely to occur. As a result, in this study, we have investigated system-level environments for planning the design of interference-free GF networks in S-DMB systems. Our investigations revealed that S-DMB services are unavailable because of quality deterioration caused by interference when the delay attributable to a GF and the satellite signals exceeds ${\pm}$256 chips and the distance between the GF and its reception terminal is greater than 4.6 km. On the basis of this analysis, we conducted a field test that confirmed that the above-mentioned time delay can be controlled in such a way as to ensure high quality S-DMB services.

• ETRI Journal
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• v.25 no.4
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• pp.211-218
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• 2003

This paper presents a dynamic resource allocation algorithm with multi-frequency time-division multiple access for the return link of interactive satellite multimedia networks such as digital video broadcasting return channel via satellite systems. The proposed timeslot assignment algorithm, called the very efficient dynamic timeslot assignment (VEDTA) algorithm, gives an optimal assignment plan within a very short period. The optimality and computational efficiency of this algorithm demonstrate that it will be useful in field applications.