• Journal of Satellite, Information and Communications
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• v.3 no.2
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• pp.1-6
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• 2008

Space-time codes (STC) can achieve the diversity gain in a multi-path environment without additional bandwidth requirement. Recent study results reported that satellite systems can also achieve this diversity gain by using space-time codes in a cooperative network with terrestrial repeaters. Due to uni-directional nature of satellite DMB services, transmit diversity can be considered as one of the most effective ways to improve the performance. In this paper, we demonstrate various simulations results of STC schemes which can contribute to improve performance of future satellite DMB services. The STC schemes introduced in this paper provides diversity gains by combing independent coded signal from the satellite as well as from the terrestrial repeaters. In addition, we discuss a few points which should be considered to develop and implement these STC schemes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.221-227
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• 2013

In this paper, Satellite DMB/WiBro antenna and PCS/WiBro antenna improving indoor coverage for mobile services are designed and fabricated. Satellite DMB/WiBro bands repeater antenna and PCS/WiBro bands repeater antenna are proposed as a simple radiator with loading capacitor to generate LHCP(Left Hand Circular Polarization). The proposed antenna for Satellite DMB/WiBro and PCS/WiBro bands communication are fabricated by copper plate uploader type and substrate uploader type. The designed and fabricated antenna has a bandwidth of 70MHz at 1.816GHz~1.886GHz and bandwidth of 107MHz at 2.247GHz~2.354GHz. Maximum gain of radiation pattern was up to 5dBi.

• 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.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.32-39
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• 2012

In this paper, the implementation of location based services (LBS) using S-DMB (satellite-digital multimedia broadcasting) system was proposed. In S-DMB System, the frequency of transmitted signal is about 2 GHz which has a characteristics of strong straightness but weak diffraction so that there are many shade areas such as indoors and underground spaces. Therefore the signal transmitted from the satellite should be retransmitted by the earth repeaters called as gap filler. Because each gap filler has its own identification value, the gap filler ID introduces the area in which the gap filler was installed. Generally, the 51st data symbols of S-DMB pilot signal transmitted from the satellite are padded by dummy value and gap filler ID is embedded in this pilot symbol by the gap filler when S-DMB signals are retransmitted by gap fillers. So using gap filler ID of S-DMB system, LBS such as region registration, distance and time to destination, alarm of local area information could be implemented. In the experiment to prove the performance of the proposed LBS system using the gap filler ID of the S-DMB system, the firmware of S-DMB chip composing of RF and baseband parts was lightly modified so that application processor was able to manipulate the gap filler ID and the its related regional information.

• Journal of Satellite, Information and Communications
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• v.3 no.1
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• pp.22-28
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• 2008

In this paper, Korean digital radio services is introduced and utilized by the analysis of digital radio broadcasting and the standard model of DMB based disaster broadcasting

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.169-177
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• 2005

The Conditional Access System is a complete system for ensuring that broadcasting services be accessible to only those who are entitled to receive them. Secure key management and efficient delivery mechanism are very important design factors to this system. In this paper, we propose secure and efficient protocols which would be well fitted to a Pay TV system including the satellite DMB. Further. by applying our protocol to the existing conditional access system, we propose a new system that properly enables the control of conditional access to the Pay TV in satellite DMB environment.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.106-113
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• 2006

With the rapid development of digital technology, the satellite DMB service is able to provide chance to watch on TV, movie and listen on the Radio to their subscriber with moving. From the mid 2005, Korean people can get the satellite DMB service which includes In many kinds of new telecommunication services such as watching on tv, movie, and listening the music on service charge. The objective of this study is to grasp the factors which affecting the use satellite DMB service on the consumers who pay service charge, and to make an analysis on the structure relationship between such factors with consumer satisfaction and consumer royalty.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.58-62
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• 2012

Emergency alerting broadcasting of T-DMB is being serviced to deliver the event of a disaster to the people quickly and effectively through a T-DMB network. DGPS has been developed in order to improve the accuracy of the GPS receiving data and transmitting of DGPS information through the T-DMB network is being studied for a wide range of usage. Because DGPS information and AEAS message are sent through the same T-DMB network, if DGPS information is applied to AEAS message disaster area can be specified more precisely and the exact location of the disaster can be measured in the terminal. In this paper, a implementation method of T-DMB emergency alerting broadcasting system based on a DGPS including a new structure of AEAS message was proposed to identify the location of disaster accurately.

• 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.