• Journal of Communications and Networks
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• v.12 no.6
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• pp.558-567
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• 2010

In this paper, we analyze the capability of satellite broadcasting systems to offer different levels of quality of service (QoS). We focus on the European telecommunications standards institute satellite digital radio and digital video broadcasting satellite handheld (DVB-SH) standards, which have recently been proposed for satellite broadcasting communications. We propose a strategy to provide different levels of QoS for the DVB-SH standard on the basis of an extension of the interleaving scheme, referred to as molded interleaver, which supports low latency service requirements for interactive services. An extensive analysis based on laboratory measurements shows the benefits of this solution. We also present a multilevel coding (MLC) scheme with multistage decoding designed for broadcasting communications as an alternative to the existing standards, where services with different levels of QoS are provided. We present a graphical method based on mutual information for the design and evaluation of MLC systems used for broadcasting communications. Extensive simulations for a typical satellite channel show the viability of the proposed MLC scheme. Finally, we introduce multidimensional constellations in the proposed MLC scheme in order to increase the number of different protection levels.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.48-51
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• 2016

Many studies have been carried out in order to develop a frequency efficient communication system than the current communication system for satisfying the increasing demands of wireless data services in mobile communication systems. Service providers must maintain a lot of base station equipments to meet the increasing demands of wireless data service. Therefore service provider needs a system or method to reduce maintenance costs. The amount of wireless data service are changed according to the time of day, geographical location and so on. Power consumption can be reduced if the supplied power of communication systems is controlled by the amount of wireless data traffics. In this paper, power management system of base station's equipment for mobile communication is designed and implemented. The proposed power management system controls the power supplied to the mobile communication infrastructures depending on the service amount of wireless data. Field test result of the implemented system shows the proposed system saves 26% of the power consumption in the base stations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2073-2082
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• 2010

The 4-th generation of mobile communication aims to realize global, fast and mobile communication service. The satellite communication charges a key role in this field. In this study, an OTM(On-The-Move) antenna which is mounted on ground vehicles and is used for mobile communication between vehicle and satellite was addressed. Since vehicles move during communication, active antenna line-of-sight stabilization is a core technology to guarantee high satellite communication quality. Stabilization of a satellite tracking antenna which consists of 2-DOF gimbals, an elevation gimbal over an azimuth gimbal, was considered in this study. Various disturbance torques such as static and dynamic mass imbalance torques, variation of moment of inertia according to elevation angle, friction torque related to vehicle motion, equivalent disturbance torque due to antenna roll motion, etc. were analyzed. As a robust stabilization control, rate feedback with sliding mode control and position feedback with proportional+integral control was suggested. To compensate antenna roll motion, a supplementary roll rate feed forward control was included beside of the feedback control loop. The feasibility of the analysis and the proposed control design were verified along with some simulation results.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.49-53
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• 2017

In this paper we present the combination of location based mobile advertisement services and dynamic digital signage markets has been developing recent days to provide consumer admired visual mobile advertisement on all kind transportation vehicles. In spite of that, the digital signage advertisement content management is still not that easy to manage the content dynamically as well operation is most time consuming to handle the contents dynamically in digital signage business. As location based services is most impactful service in shopping, the location responsive advertisement on vehicle signage will be most desirable mobile advertisement to help people migrate from one place to another place for travel or stay. This paper propose a mobile location responsive digital signage system for vehicles using the GPS and wireless infrastructure integrated with digital signage system. This proposed research use the centralized digital signage system architecture for the mobile advertisement application and this system can be expanded to different vehicles for digital advertisement including buses, trucks, train, air vehicle and any other form of mobile advertising vehicles. Also, this present an effective advertisement recommendation algorithm, by which the advertisement can be selected broadcasted for the right advertisement ventures more effectively as the service requested from advertiser. This paper present the emulated experimental result to evidence the proposed dynamic vehicle signage system performed better than compared with traditional signage random advertising. The emulated result proves that the advertisement recommendation algorithm can effectively works out the targeted key audiences in location responsive region the algorithm evaluated.

• Korean journal of communication and information
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• v.28
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• pp.141-169
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• 2005

This study considered the factor of the adoption of the satellite DMB. This study focus on the TV audience's demographic traits and media usage. The results are follows : 1) the elder-aged group, high-educated group and car driver group have high intention to be subscriber for the satellite DMB service. 2) the white collar group and the middle income group have high intention to be subscriber for the satellite DMB service. 3) the many media use group and the many function use of mobile phone group have high intention to be subscriber for the satellite DMB service. 4) the local TV audience like the entertainment genre in video and audio service and the information genre in data service 5) the local TV audience don't mind of the re-transmission territorial broadcasting by the satellite DMB service.

• Korean Journal of Remote Sensing
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• v.28 no.4
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• pp.467-475
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• 2012

Cloud computing services are known that they have many advantages from the point of view in economic saving, scalability, security, sharing and accessibility. So their applications are extending from simple office systems to the expert system for scientific computing. However, research or computing technology development in the geo-spatial fields including remote sensing applications are the beginning stage. In this work, the previously implemented smartphone app for image processing was first migrated to mobile cloud computing linked to Amazon web services. As well, parallel programming was applied for improving operation performance. Industrial needs and technology development cases in terms of mobile cloud computing services are being increased. Thus, a performance testing on a satellite image processing module was carried out as the main purpose of this study. Types of implementation or services for mobile cloud varies. As the result of this testing study in a given condition, the performance of cloud computing server was higher than that of the single server without cloud service. This work is a preliminary case study for the further linkage approach for mobile cloud and satellite image processing.

• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.40-47
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• 2006

The next-generation mobile communication system are required to provide high-data-rate and high quality transmission over hostile radio channels. Orthogonal Frequency Division Multiplexing(OFDM) technique regarded as a most promising solution in mobile environment. This paper considers the issue of efficient subcarrier allocation for OFDM system in multi-service application. Proposed algorithm can consider channel gain of each service and divide subchannel. Proposed method considers priority of service and divide more subchannels in high priority service. When proposed algorithm compares with existent algorithm, the convergence rate improves and the calculation amount is decreased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.85-91
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• 2004

The land mobile antenna for two-way communication using geostationary satellite consists of a transmitting and receiving systems. The transmitting system plays the role of sending the signal to the satellite while the receiving system does the role of receiving signal from the satellite and tacking the target satellite. Especially, the land mobile antenna for satellite communication must be met with the international regulation such as antenna pattern, transmitting power and tracking error to protect the damage of the neighbor satellites. On the other hand, this paper thoroughly examined a receiving system to satisfy a stable satellite tracking performance and antenna pattern specified by the international regulation for Ku-band geostationary satellite.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1807-1816
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• 1998

The interference probability between non-geostationary-statellite orbit mobile station is calculated when the two systems are sharing the frquency band below 1 GHz. The probability density function of a mobile earth station(MES) is calculated based on the established propagation model and then, a probability of exceeding the threshold level is derived. By changing the average transimission per unit time of total MSS(Moblie satellite service) area and the ratio of transmitters for specific area, we obtain the average transmission per unit time for the area under consideration. From this, the exceedance probability for the given pfd threshold level is evaluated. The exceedance probability is increased as the average transmissio per unit time and ratio become larger. Also the effect of filter isolation between channels is accounted for.