Satellite Digital Multimedia Broadcasting System Research Articles

위성 DMB 시스템을 이용한 위치 기반 서비스 구현

본 논문에서는 위성 DMB (satellite-digital multimedia broadcasting, S-DMB) 송수신 시스템을 이용한 위치 기반 서비스 (location based services, LBS) 구현 방법에 대하여 제안한다. S-DMB 송출 신호는 2 GHz 대역의 주파수를 사용하므로 직진성은 강하지만 회절성이 약한 특징을 갖고 있다. 따라서 S-DMB 시스템에서는 실내 및 지하 공간 등의 음영 지역이 다수 존재하게 되는데, 이러한 음영지역에서는 갭필러 (gap filler)라는 음영지역 중계기를 통해서 S-DMB 신호를 수신하게 된다. 이러한 갭필러의 식별정보 (gap filler ID)를 확인하면 갭필러가 설치된 지역을 알 수 있다. 따라서 본 논문에서는 S-DMB 신호를 수신할 수 있는 단말기에서 S-DMB 파일럿 신호 중 갭필러 식별정보를 이용하여, 관심 위치 정보 등록, 목적지 도착 알림, 및 지역 정보 알림 기능 등의 LBS를 구현하는 방법을 제안한다. 제안한 LBS 구현 방법의 성능을 검증하기 위한 실험에서는 S-DMB 수신칩이 갭필러 식별정보를 애플리케이션 프로세서 (application processor, AP)로 전달하도록 단말기의 펌웨어 (firmware)를 수정하여 LBS 구현 테스트를 진행하였다. 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.

Planning of gap filler networks in satellite DMB systems for wireless multimedia services

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. Fach 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 ±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.

Combinational spreading and modulation technique for mobile satellite DMB services

Satellite digital multimedia broadcasting (S-DMB) service has been launched in Korea in May 2005. S-DMB can provide high quality broadcasting services (audio, video, and data) to handheld mobile receivers via the geostationary satellite. Due to multipath fading, incurred inter-code-interference limits the current S-DMB system to utilize only half the available Walsh code sequences, thereby decreasing channel utility. To maximize the use of broadcast channel resources, we propose a transmission method of combining spreading and code modulation. The efficient use of Walsh code sequences increases the capacity of the S-DMB system in an interference prone environment, without degrading quality of service.

두 개의 기생 패치를 갖는 고 이득.광대역 SAP 안테나

본 논문에서는 SDMB(Satellite Digital Multimedia Broadcasting) 시스템에서 동작하는 고 이득 광대역 안테나를 구현하였다. 제안된 안테나는 표면파를 억제하기 위한 SAP(Shorted Annular Patch) 구조와 이득, 대역폭 그리고 지향성을 개선시키기 위하여 <TEX>$0.25 {\lambda}_0$</TEX> 간격을 갖는 3차원 배열의 기생 SAP로 구성되었다. 원형 패치상의 서로 반대 방향으로 농인 두 개의 슬릿을 이용하여 RHCP(Right Hand Circular Polarization)로 동작하도록 하였다. 모의 실험 결과, 제안된 안테나의 최대 방사 이득은 기존의 마이크로스트립 패치 안테나에 비해서 5.22 dBi 개선된 12.6 dBi로 나타났다. 제작된 안테나는 동작 주파수 2.63 GHz에서 최대 방사 이득이 10.5 dBi로 나타났다. 측정된 임피던스 대역폭<TEX>$(VSWR{\leq}2)$</TEX>은 기존의 마이크로스트림 패치 안테나에 비해서 300 MHZ 개선된 <TEX>$360 MHz(2.488{\sim}2.848 GHz)$</TEX>이며, HPBW(Half Power Beam Width)는 <TEX>$45.8^{\circ}$</TEX>, FBR(Front Back Ratio)은 15.49dBi로 나타났다. 3dB 축비 대역폭은 220 MHz<TEX>$(2.54{\sim}2.76 GHz)$</TEX>를 얻었다. In this paper, the high gain and broadband antenna operating for SDMB(Satellite Digital Multimedia Broadcasting) system is realized, The proposed antenna consists of the SAP(Shorted Annular Patch) structure, which inhibits surface-wave and the parasitic SAP element with spacing of <TEX>$0.25 {\lambda}_0$</TEX> in order to improve gain, bandwidth and directivity. The RHCP(Right Hand Circular Polarization) is generated by two slits, which are made along the periphery of the circular patch at the diametrically opposite points, The simulated maximum gain of the proposed antenna is 12.6 dBi, which is better 5.22 dBi than maximum gain of the conventional microstrip patch antenna. The measured maximum gain is 10.5dBi at operating frequency 2.63GHz. Also, the measured impedance bandwidth<TEX>$(VSWR{\leq}2)$</TEX> of the proposed antenna is <TEX>$360MHz(2.488{\sim}2.848 GHz)$</TEX>, which is better 300 MHz than the bandwidth of the conventional microstrip patch antenna. The measured HPBW(Half Power Beam Width) of the proposed antenna is <TEX>$45.8^{\circ}$</TEX>, and the measured FBR(Front to Back Ratio) is 15.49 dBi, The 3dB axial ratio bandwidth is 220 MHz<TEX>$(2.54{\sim}2.76 GHz)$</TEX>.

A Cross-Layer Packet Scheduling Scheme for Multimedia Broadcasting via Satellite Digital Multimedia Broadcasting System [Advances in Mobile Multimedia

In recent years, multimedia content broadcasting via satellite has attracted increased attention. The satellite digital multimedia broadcasting (S-DMB) system has emerged as one of the most promising alternatives for the efficient delivery of multimedia broadcast multicast service (MBMS). The design of an efficient radio resource management (RRM) strategy, especially the packet scheduling scheme, becomes a key technique for provisioning multimedia services at required quality of service (QoS) in S-DMB. In this article, we propose a novel cross-layer packet scheduling scheme that consists of a combined delay and rate differentiation (CDRD) service prioritization algorithm and a dynamic rate matching (DRM)-based resource allocation algorithm. The proposed scheme considers multiple key factors that span from the application layer to the physical layer, aiming at simultaneously guaranteeing diverse QoS while utilizing radio resources efficiently under the system power and resource constraints. Simulation results demonstrate that the proposed cross-layer scheme achieves significantly better performance than existing schemes in queuing delay, jitter, and channel utilization.

Network architecture and radio resource management for satellite digital multimedia broadcast system [internetworking and resource management in satellite systems series

Network architecture and radio resource management for satellite digital multimedia broadcast system [internetworking and resource management in satellite systems series

Internetworking and Resource Management in Satellite Systems [Guest Editor's Introduction

Discusses the three articles that are part of a series on internetworking and resource management in satellite systems. The first article appears in the July 2007 Aerospace and Electronic Systems Magazine issue "Network architecture and radio resource management for satellite digital multimedia broadcast system"); the second article appears in the August 2007 issue ("PEPsal: A performance enhancing proxy for TCP satellite connections"); and the third article in the series appears in the September 2007 issue ("Advanced channel coding for Hap-based broadcast services").

Novel radio resource allocation strategy for multimedia content delivery over satellite multicast/broadcast systems

The provisioning of multimedia applications requires wireless networks to optimally allocate radio resource and efficiently adapt to dynamically changing wireless environment. Radio Resource Allocation (RRA) strategy is an important issue in the design of the Satellite Digital Multimedia Broadcasting (SDMB) system, aiming at providing more efficient and cost-effective delivery of broadcast/multicast (BC/MC) services to a wide range of audience. Based on the single-level channel multiplexing framework, the existing RRA strategy only performs transport channel multiplexing and assumes one-to-one ideal mapping between logical and transport channels. However, the bit rates of the logical channels do not always exactly match those of the transport channels, and this leads to inefficient usage of radio resource. To solve this problem, in this paper, a novel RRA strategy, which is capable of optimally performing both logical and transport channel multiplexing, is proposed for the SDMB system. In order to improve the resource utilisation and reduce the power consumption, two new algorithms, namely Optimum Estimation Algorithm (OEA) and Power-Oriented Adaptation (POA) algorithm, are developed to optimize the proposed 2-level channel multiplexing scheme. In comparison with the existing single-level channel multiplexing scheme, simulation results show that the proposed 2-level channel multiplexing scheme achieves significantly better performance in terms of transport/physical channel utilisation, transmission power consumption as well as total transmission capacity.

Demand Sensitive Model for Tuning Price Over Satellite Digital Multimedia Broadcast System

In this paper an integrated satellite-terrestrial network architecture offering SDMB (Satellite Digital Multimedia Broadcast) services to mobile users through the satellite or terrestrial UMTS segment, is studied to test a novel Demand Sensitive Model (DSM). The DSM is proposed for tuning price service over SDMB system to offer a price discount to large amount of users while maintaining profit for the service provider. The simulations have been carried out to show the goodness of the proposed model within the system architecture; moreover the model, based on simple parameters, is very flexible and can be easily integrated in a "Price Adapter" module making the offered service attractive for end users and in the same time profitable for the satellite operator

On the use of OFDM radio interface for satellite digital multimedia broadcasting systems

AbstractThe paper considers the application of Orthogonal Frequency Division Multiplexing (OFDM) techniques in the physical layer of a satellite system devoted to the provision of digital multimedia broadcasting (DMB) services, which are presently the focus of extensive research and development endeavours. In particular, the paper demonstrates that the inherently high spectrum efficiency of OFDM can be retained even in unfavourable propagation channels affected by heavy non‐linear distortion introduced by the on‐board high power amplifier. This encouraging performance is achieved through the proper design and application of coding and pre‐distortion techniques, as described in the paper. Based on these results, the paper considers also the comparison of OFDM and High Speed Downlink Packet Access (HSDPA) techniques. HSDPA is the standardized radio interface for 3G terrestrial mobile networks. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Demonstration with field trials of a satellite-terrestrial synergistic approach for digital multimedia broadcasting to mobile users

The close synergy between a satellite system and terrestrial mobile cellular networks for cost-efficient content delivery to mobile users lies at the core of the satellite digital multimedia broadcasting system concept. Having already rich research and design work behind it, much of which has been carried out in the framework of European R&D projects, the system has recently seen the end of its first field trials, which relied on an experimental platform representing the future operational system. The article reports the outcomes of these trials that confirmed the technical feasibility of the system concept and provided valuable hints for the subsequent system design stages.