Terrestrial Digital Multimedia Broadcasting Research Articles

차세대 T-DMB 방송의 부가 서비스 제공을 위한 비트 분리 방법 및 Double Binary Turbo 부호 적용 연구

T-DMB(Terrestrial Digital Multimedia Broadcasting) system, is based on the Eureka-147 standard, provides various multimedia data services. However T-DMB system needs upgrades for more various services and better services. Therefore, we proposed advanced T-DMB system using unequal error protection system and hierarchical modulation in this paper while maintaing backward compatibility. And we simulated various bit split methods and double binary turbo code of DVB-RCS standard as method of LP data stream for additional service of advanced T-DMB. As the simulation results, double binary turbo code of proposed advanced T-DMB system have each coding gain of over 2 dB compared to conventional T-DMB.

Depth-image-based rendering for 3DTV service over T-DMB

In this paper, we present a depth-image-based rendering (DIBR) technique for three-dimensional television (3DTV) service over terrestrial-digital multimedia broadcasting (T-DMB). 3DTV service over T-DMB is very attractive because the single user environment of T-DMB is suitable to glassless 3D viewing. However, the bit budget for the transmission of additional data in 3DTV service is very limited in T-DMB. DIBR can resolve this problem because the depth information as the additional data can be compressed effectively. However, DIBR has also some problems such as the backward compatibility with the conventional T-DMB, a large computational cost for rendering virtual images and generation of holes by disocclusion. To solve these problems, we first present the service architecture for DIBR-based 3DTV service over T-DMB, which can maintain the backward compatibility with the conventional T-DMB. Second, we propose a new depth preprocessing method based on adaptive smoothing. In the proposed depth preprocessing method, two adaptive smoothing filters of the discontinuity-preserving smoothing and the gradient direction-based smoothing are sequentially conducted. As a result, both the reduction of bitrates required for the depth transmission and the reduction of the holes can be achieved. Finally, we present look-up table (LUT)-based simultaneous method for generating an auto-stereoscopic image so that problems of the limited memory and the large computational cost can be resolved in T-DMB player. Various experiments show that the proposed DIBR technique can be efficiently employed for 3DTV service over T-DMB.

T-DMB 시스템을 위한 E-OCR에서의 채널추정

This paper proposes noise reduction methods to improve the channel estimation performance in Equalization On-Channel Repeater (E-OCR) for Terrestrial-Digital Multimedia Broadcasting (T-DMB) system. In the E-OCR for T-DMB system, the channel estimation is performed by the pilot signal extraction and the channel coefficient estimation. Since the performance of the channel estimation highly depends on the estimated channel coefficients whose accuracy is associated with the received signal-to-noise ratio (SNR), it is important to reduce noise existing at the estimated channel coefficients. To reduce such noise components, various noise reduction methods of the estimated channel coefficients based on the M -point weighted moving average are proposed. Computer simulations show that the proposed methods improve the estimation performance by more than 2 to 3 dB in terms of the symbol error rate after equalization.

Compact Dipole Antenna for Terrestrial Digital Multimedia Broadcasting Service

A compact dipole antenna for the terrestrial digital multimedia broadcasting (TDMB) application is presented. The length of the antenna is about 0.06λ at the TDMB resonance frequency of 190 MHz. Miniaturization of the antenna is achieved by using meander structures and lumped elements. The proposed antenna has two resonance frequencies and covers the TDMB band from 174 MHz to 216 MHz in Korea. The antenna has good impedance bandwidth and radiation characteristics for the TDMB. The experimental results of the designed dipole antenna are presented and analyzed.

T-DMB의 SFN을 위한 등화형 동일채널 중계기

In this paper we consider technological requirements of the on-channel repeater to broadcast the terrestrial digital multimedia broadcasting (T-DMB) signals using single frequency networks (SFN) and propose the configuration and implementation method of the equalization on-channel repeater (OCR) that meet such requirements. The proposed equalization OCR not only has short time delay, but shows high output power and good quality of output signal by removing a feedback signal due to incomplete antenna isolation and multipath signal existing between the main transmitter and the OCR. In addition, computer simulations and laboratory tests results are provided to figure out performance of the proposed equalization OCR.

Remultiplexing Eureka-147 Ensemble With MPEG-2 TS for T-DMB Multimedia Service

This paper introduces a layered structure of the Korean terrestrial digital multimedia broadcasting (T-DMB) ensemble based on Eureka-147 and suggests a new transmission architecture for flexible T-DMB service. In the suggested transmission architecture, MPEG-2 transport stream (TS) for T-DMB multimedia service is inserted into the ensemble distributed via the ensemble transport interface (ETI). Thus, we propose a novel algorithm remultiplexing the ETI with MPEG-2 TS. The architecture of ETI remultiplexing algorithm is described as a four-step process, and implemented as real-time embedded software in an ETI remultiplexing system. The design and implementation of the interoperable ETI remultiplexing system available for a small-scale transmission system for T-DMB service is described in detail.

A Robust Symbol Synchronization Method for Terrestrial-DMB Receivers in the Hierarchical Modulation Mode

Recently, hierarchical modulation has been considered as a way to increase the payload data in terrestrial digital multimedia broadcasting (T-DMB) transmission systems. This paper proposes a robust symbol synchronization method for T- DMB receivers working in the hierarchical modulation mode. The proposed method employs a timing error detector (TED) which produces a timing phase error at OFDM symbol rate instead of the frame rate. This method thus results in the robust synchronization of symbol timing in the presence of a sampling frequency offset (SFO). Simulation results show that the proposed method outperforms the conventional one especially at a large SFO .

Bidirectional Interactive Contents Player for Terrestrial Digital Multimedia Broadcasting

This paper presents a bidirectional interactive contents player for terrestrial digital multimedia broadcasting (T-DMB). The presented player is capable of sending user requests to a proper return channel server using information included in a scene presentation. The player provides functionality to combine requested data received via communication networks with the initially broadcasted contents to present additional information to users. The result of a request transmitted back through the broadcasting network can also be presented properly using the presented player.

Detection of Hierarchically-Modulated Data for Advanced T-DMB Receivers

This paper proposes an efficient detection method of hierarchically-modulated data for an advanced terrestrial digital multimedia broadcasting (AT-DMB) receiver. Hierarchical modulation, where low-priority (LP) symbols are hierarchically added to the existing high-priority (HP) symbols, has been considered to be useful for increasing the data rate in AT-DMB systems. The distance between two neighboring LP symbols is limited by the noise margin of HP symbols and thus should be shortened to minimize the effect on the detection of HP symbols. To cope with the poor condition of LP symbols, we introduce a coherent detection method based on coded decision-directed (CDD) channel estimation (CE). CDD-CE may provide an accurate estimation result even under the infrequent pilot arrangement of the T-DMB system. Additionally, we propose a moving average (MA) method in frequency direction to reduce noise existing in the estimated channel coefficients. Simulation results show that the proposed method can be a good solution to successfully detect LP data.

계층변조 시스템에서 신호의 우선순위를 이용한 블라인드 등화

이 논문에서는 계층변조를 적용하는 AT-DMB (advanced terrestrial digital multimedia broadcasting) 시스템에 적용할 수 있는 블라인드등화 기법을 제시하고 그 성능을 살펴본다. AT-DMB 시스템은 기존 T-DMB의 DQPSK (differential quadrature phase-shift keying) 신호와 역방향 호환성을 보장하고 더 높은 데이터 전송률을 지원하기 위해 16-QAM (quadrature amplitude modulation) 계층변조 방식을 적용한다. 이 결과 SNR (signal to noise ratio)에 따라 기존 T-DMB 심볼과 추가된 심볼은 서로 다른 판정오율 (decision error rate)을 가진다. 따라서 판정한 신호로부터 채널을 추정할 때 판정오율이 낮은 선순위 심볼과 판정오율이 높은 후순위 심볼의 신뢰도에 따라 다른 가중치를 줌으로써 판정치의 전체적인 신뢰도를 향상시킬 수 있다. 이 논문에서는 계층변조에 따른 비트 오율(bit error rate) 성능의 악화정도를 분석하고, 모의실험을 통해 판정신호의 신뢰도에 따라 가중치를 주는 제안방식이 가중치를 주지 않은 경우에 비해 비트 오율 성능이 향상됨을 확인하였다. In this paper, we propose a blind equalization method for advanced terrestrial digital multimedia broadcasting (AT-DMB) systems which use hierarchical modulation. The AT-DMB system adopts hierarchical 16-ary quadrature amplitude modulation (16-QAM) to ensure backward-compatibly with the differential quadrature phase shift keying (DQPSK) signal of the legacy terrestrial digital multimedia broadcasting (T-DMB) systems and to support higher transmission rate. Due to the hierarchical modulation, the conventional T-DMB signal and the additional signal have different error rate at same signal to noise ratio (SNR). By weighting the decided symbols differently according to the reliability of the symbols, i.e., high priority symbol with low error rate and low priority symbol with high error rate, we can improve the channel estimation accuracy. In this paper, we analyze SNR loss by hierarchical modulation and confirm it through simulations. Moreover, through simulations, we verify that the proposed weighting method improve BER compared to the no-weighting method.

Optimal transmission policies for MOT in T-DMB

The Multimedia Object Transfer (MOT) protocol in Terrestrial Digital Multimedia Broadcasting (T-DMB) systems inherently does not facilitate return paths in data transmission and therefore additional policies are required to envision further efficient reliable media broadcasting. This letter proposes novel optimal transmission policies for MOT standard definition in T-DMB. The proposed broadcasting policies drastically enhance the capability of conventional MOT protocol.

Ex-ante simulation of mobile TV market based on consumers' preference data

Subscribers to mobile TV are able to watch programming via a mobile telecommunications network. While expectations for mobile TV are promising, it is at present a fledgling industry, and deployments of mobile TV networks have been driven largely by system implementation concerns rather than consumer demand and market considerations. In South Korea, mobile TV offerings are based on two competing standards: satellite digital multimedia broadcasting (S-DMB) and terrestrial digital multimedia broadcasting (T-DMB). Beginning with stated preference data drawn from a conjoint survey administered before the launch of commercial mobile TV services in South Korea, the authors use Bayesian estimation to investigate the effect of consumer preferences on the mobile TV market. Results indicate that consumers view subscription cost and media quality as the two most important attributes of mobile TV and that T-DMB-based service should presently occupy roughly 75% of the market. Moreover, the authors model the effects of varying the core attributes of the services on market share as well as the market share elasticity of each type of service. The authors test their modeled results against actual subscription data, and the model fairs well, leading to the conclusion that mobile TV broadcasters and policymakers alike will find use for the study's findings and the model itself.

A Wideband CMOS RF Front-End Using AC-Coupled Current Mirrored Technique for Multiband Multistandard Mobile TV Tuners

In this paper, a wideband CMOS radio frequency (RF) front-end for various terrestrial mobile digital TV applications such as digital video broadcasting-handheld, terrestrial digital multimedia broadcasting, and integrated services digital broadcasting-terrestrial is proposed. To cover VHF III, UHF, and L bands and reduce the silicon area simultaneously, it employs three low-noise amplifiers and single-to-differential transconductors and shares the rest of the RF front-end. By applying ac-coupled current mirrored technique, the proposed RF front-end has good wideband performance, high linearity, and precise gain control. It is fabricated in 0.18 mum CMOS process and draws 15 mA~20 mA from a 1.8 V supply voltage for each band. It shows a gain of more than 29 dB, noise figure of lower than 2.5 dB, IIP2 of more than 30 dBm, IIP3 of more than -10 dBm for entire bands.

A Low Profile Folded Inverted-L Antenna for T-DMB/UHF Handset Application

A novel low profile and dual-band antenna for terrestrial digital multimedia broadcasting (T-DMB) and ultra high frequency (UHF) applications is proposed in this paper. The proposed antenna consists of a folded inverted-L antenna and two open stubs. The designed low profile antenna occupies an antenna volume of 148 x 49 x 11 mm 3 . The length of the folded radiating element is about 0.09A at the resonant frequency of T-DMB application (180-210 MHz). The parasitic open stubs are utilized to obtain the wide bandwidth (50%) for UHF application (470-740 MHz). The maximum gains at the frequencies of T-DMB and DTV applications were -5 and +5 dBi, respectively. The radiation patterns are near omnidirectional at frequency of interest.

Active integrated antenna for mobile TV signal reception

AbstractThis paper proposes a small‐sized field‐effect transistor (FET) based active integrated antenna (AIA) for terrestrial digital multimedia broadcasting (T‐DMB) signal reception, which is one of the mobile TV services allocated to 200 MHz band. The commercially used T‐DMB antenna is a 120 mm long monopole, but the size of the proposed one is reduced to 50 mm by the method of active device integration. The active device integrated to the radiator influences not only on the current distribution at the radiator but also the input impedance, results in an antenna size reduction with an enhanced gain. In addition to this, a band‐pass filter is designed at the input port of the radiator. This plays a role as a matching circuit between a radiator and an active device as well as provides a band‐selection function simultaneously to be free of other high intensity signals existing around the T‐DMB band. The antenna effective length related to the same‐sized monopole and noise figure are measured to verify the validity of the proposed antenna. The performance of the proposed FET based AIA shows the feasibility of designing absolutely small‐sized antenna with active devices integrated compared to an operating frequency band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2998–3001, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22968

Development of T-DMB Receiver Linking with CDMA Network for Interactive Data Broadcasting Services

In this paper, we present the configuration diagram of the interactive Terrestrial Digital Multimedia Broadcasting (T-DMB) system using the Code Division Multiple Access (CDMA) telecommunication network for the interactive broadcasting services. The system consists of a T-DMB transmission system, an interactive receiver with a CDMA module, and a return channel server. We also describe the protocol stack for providing data broadcasting service in T-DMB and propose a variety of interactive broadcasting service based on it. In order to verify the proposed service, we design and implement an interactive T-DMB receiver with a CDMA module. And also a return channel server is operated to test it, which includes the interactive contents produced in advance, responding user's request. Under the constructed test environment, the proposed service and the newly designed receiver were verified. This means that new interactive services in digital broadcasting are possible on the move by using mobility of T-DMB and CDMA.1

On the Calculation of the Maximal MOT Throughput in T-DMB

Digital multimedia broadcasting (DMB) is one of burgeoning communication technologies, which can provide audio, video, and data services to mobile terminals using broadcasting infrastructures. Data services in terrestrial- digital multimedia broadcasting (T-DMB) inherently have the disadvantage of retransmitting a lot of data unnecessarily for reliability. This paper proposes a novel optimized transmission policy using segment size and repetition number variability, which maximizes the object- level throughput as well as improves reliability. The theoretical modeling and simulation results demonstrate that our policy provides a throughput gain over the conventional protocol.

A New Scheme to Predict Erasures for Reed-Solomon Decoder in T-DMB Receiver

In this paper, we introduce a new scheme to improve the performance of the terrestrial - digital multimedia broadcasting (T-DMB) system, which exploits the burst error characteristics at the output of the convolutional decoder and the properties of the Reed-Solomon (RS) decoder to correct more errors by predicting erasures in each RS packet in advance as many as possible before decoding in the RS decoder. Simulation results show that the proposed scheme yields performance gain of around 1 dB at BER of 10-R which can result in the extended coverage area of the T-DMB system.

지상파 DMB 방송웹사이트 서비스 송수신 정합 시험 도구 개발

본 논문에서는 지상파 DMB(Terrestrial Digital Multimedia Broadcasting, T-DMB) 데이터 서비스 중 하나인 방송웹사이트(Broadcast Web Site, BWS) 서비스에 대한 송수신 정합 시험 도구를 개발하였다. 먼저 지상파 DMB BWS 서비스를 위한 송신 측 및 수신 측 정합 시험 방법론을 수립하였다. 시험 도구는 BWS 비트스트림 분석기, BWS 참조 복호 모듈(소프트웨어) 그리고 BWS 시험 비트스트림 등의 세 가지로 구성된다. 송신 측 시험을 위해 BWS 비트스트림 분석기를 개발하였으며, 수신 측 시험을 위해 BWS 참조 복호 모듈을 개발하고 BWS 시험 비트스트림을 제작하였다. 이 시험 비트스트림의 적합성을 검증하는 데 본 논문에서 개발한 비트스트림 분석기가 실제로 사용되었다. 동일한 시험 비트스트림을 시험 대상 BWS 복호 모듈과 참조 복호 모듈에 동시에 입력하고, 이 두 모듈의 결과를 비교함으로써 수신 측 시험을 수행한다. 본 논문에서 개발한 시험 도구들은 MOT 프로토콜, HTML, PNG, MNG, JPEG, Ecma 스트립트 등 BWS에 포함된 모든 프로토콜 및 텍스트/이미지 규격에 대한 시험을 포함한다. In this paper, we presents conformance test tools for the broadcast web site (BWS) service which is one of the data services for terrestrial digital multimedia broadcasting (T-DMB). First, the methodology for the conformance test is established for both transmitters and receivers of T-DMB BWS services. The test tools consist of three parts: BWS bitstream analyzer, BWS reference decoder (software) module, and BWS test bitstreams. For testing transmitted BWS bitstreams, we developed the bitstream analyzer. For testing BWS receivers, we developed the reference Ifecoder module and created the test bitstreams. Actually the bitstream analyzer developed in this paper was used for the verification of the test bitstreams. The same test bitstreams are fed to a BWS decoder module under test and the reference decoder module and the results from the two are compared for verification. The test tools can be used for the test of all the protocol and textual/image specifications related to BWS including MOT protocol, HTML, PNG, MNG, JPEG, and Ecma Script.

T-DMB에서의 교통여행정보서비스 설계 및 구현

지상파 DMB(Digital Multimedia Broadcasting)에서 비디오 서비스에 이어, 본격적인 데이터 서비스가 시작되고 있는데, 교통여행정보 서비스는 그 중에서도 핵심적인 데이터 서비스로 간주되고 있다. 본 논문은 교통여행정보 서비스를 제공하기 위한 방송시스템의 설계와 구현방안을 제안하기 위한 것이며, 전체 시스템은 저작 시스템, DB 시스템, 송출 시스템 및 모니터링 시스템으로 구성되어 있다. 구현한 시스템은 국내 지상파 DMB 교통여행정보 서비스 표준인 TPEG(Transfer Protocol Expert Group) 프레임을 따른다. 본 시스템은 실시간 혼잡교통정보(CTT), 혼잡교통정보(CTT SUM)를 비롯하여 다양한 비실시간 관심지점정보(POI), 안전운전정보(SDI) 등을 저작 및 자동 송출할 수 있도록 설계하였으며, 양질의 콘텐츠를 효율적으로 제작하고 제작한 콘텐츠를 비디오 및 오디오와 함께 안정적으로 송출하는데 중점을 두어 구현하였다. 구현한 시스템은 다양한 수신기와의 실내외 정합실험을 통하여 그 성능을 검증하였으며, 지속적인 업그레이드를 거쳐 현재 방송 서비스에 활용하고 있다. DMB video/audio service was successfully launched. DMB data service is a matter of primary concern now. The TTI(Traffic and Travel Information) service is considered as a killer application of the data service. Tn this paper, we propose a method for design and implementation of the broadcasting system for TTI service. The proposed TTI service system consists of an authoring tool, the DB module, the Transmission module and Monitoring module. This system satisfies the national TTA standards of the Traffic and Travel Information data services for terrestrial DMB; TPEG(Transport Protocol Experts Group) platform. The system was designed to support real-time automatic transmission for CTT and CTT SUM, and non real-time authoring & automatic transmission for POI and SDI, and was focused on the capability to make high-quality contents efficiently and to send them to the data inserter reliably. The performance of the implemented system was proven through the conformance tests with the various commercial receivers. After the continuous upgrade, the system is being used in commercial service.