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Audience research is a vital part of TV and radio broadcasting, as well as of the more recent forms of media content delivery, such as the Internet, IPTV, mobile phones, Personal Video Recorders (PVRs) and portable media viewers. The uses of audience research range from self-promotion to refining service offerings and setting advertising rates. Without reliable audience data, many businesses will be reluctant to participate in the new platforms. This paper describes an end-to-end system for convergent audience measurement focused on IPTV but covering also terrestrial, cable, satellite and mobile broadcasting. We created the audience measurement system from the elaboration of a logical architectural model and a common data model which can be applied to any media scenario. We implemented this logical and data model in stationary and mobile media receivers (in the paper the particular case of IPTV is extensively explained). In addition user consumption is modeled and metrics are provided for user media consumption profiling and impact quantification in IPTV environments. [ABSTRACT FROM AUTHOR]

The requirements for future DVB-TIH networks demand that broadcasters design and deploy networks that provide ubiquitous reception in challenging indoors and other obstructed situations. It is essential that such networks are designed cost-effectively and with minimized environmental impact. The EC funded project PLUTO has since its start in 2006 explored the use of diversity to improve coverage in these difficult situations. The purpose of this paper is to investigate the performance of Transmit Delay Diversity (DD) with two antennas to improve the reception of DVB-TIH systems operating in different realistic propagation conditions through a series of tests using a SPIRENT SR5500 dual channel emulator. The relationship between correlation coefficient between channels, receiver velocity and diversity gain is investigated. It is shown that transmit delay diversity significantly improves the quality of reception particularly in simulated fast fading mobile broadcasting applications. This paper documents research conducted by Brunel University and Broadreach Systems. [ABSTRACT FROM AUTHOR]

Low-density parity-check (LDPC) codes are playing more and more important role in digital broadcasting standards due to their excellent error correction performance. In this paper, we study the combination of LDPC codes over GF(q) with q-ary modulations for bandwidth efficient transmission over AWGN channel and consider the design of the codes. Specifically, we develop the concept of quasi-regular codes, and propose an improved Monte Carlo method to optimize the quasi-regular codes. To justify the performance of our proposed scheme, simulation results are presented and analysed. [ABSTRACT FROM AUTHOR]

The objective of this work is to research and analyse the performance of Cyclic Delay Diversity (CDD) with two transmit antenna on DVB-H systems operating in spatially correlated channel. It is shown in this paper that CDD can achieve desirable transmit diversity gain over uncorrelated channel with or without receiver diversity. However, in reality, the respective signal paths between spatially separated antennas and the mobile receiver is likely to be correlated because of insufficient antenna separation at the transmitter and the lack of scattering effect of the channel. Under this spatially correlated channel, it is apparent that CDD cannot achieve the same diversity gain as obtained under the uncorrelated channel. In this paper, a new upper bound on the pairwise error probability (PEP) of the CDD with spatial correlation of two transmit antennas is derived. The upper bound is used to study the CDD theoretical error performance and diversity gain losses over a generalized spatially correlated Rayleigh channel. This theoretical analysis is validated by the simulation of DVB-H systems with two transmit antennas and the CDD scheme. Both the theoretical and simulated results give the valuable insight that the CDD ability to perform well with a certain amount of channel correlation. [ABSTRACT FROM AUTHOR]

Broadcasting is a prospective approach to support near video-on-demand services with light communication overhead. By letting clients share channels, such approaches involve partitioning a video into segments and repeatedly broadcasting these segments in multiple channels. An early paper proposed a broadcasting scheme called RFS (recursive frequency splitting), which can significantly reduce clients' waiting time. While efficient, RFS suffers from a high computational complexity of O(n log n), where n is the number of segments of the video, which is typically very large. This paper proposes an efficient segmentation scheme, which can significantly reduce the computational overhead by slightly sacrificing the number of segments that can be arranged as compared to RFS. [ABSTRACT FROM AUTHOR]

The use of 3D models for progressive transmission and broadcasting applications is an interesting challenge due to the nature and complexity of such content. In this paper, a new image format for the representation of 3D progressive model is proposed. The powerful spectral analysis is combined with the state of art Geometry Image(GI) to encode static 3D models into spectral geometry images(SGI) for robust 3D shape representation. Based on the 3D model's surface characteristics, SGI separated the geometrical image into low and high frequency layers to achieve effective Level of Details(LOD) modeling. For SGI, the connectivity data of the model is implicitly encoded in the image, thus removing the need for additional channel bits allocated for its protection during transmission. We demonstrated that by coupling SGI together with an efficient channel allocation scheme, an image based method for 3D representation suitable for adoption in conventional broadcasting standard is proposed. The proposed framework is effective in ensuring the smooth degradation of progressive 3D models across varying channel bandwidths and packet loss conditions. [ABSTRACT FROM PUBLISHER]

For broadcast networks, the Single-Frequency Network (SFN) mode is an alternative to the well-known Multi-Frequency Network (MFN) mode, where instead of transmitters operating at different frequencies, all base stations use the same frequency. Besides the optimal frequency reuse, it is usually expected that the more homogeneous distribution of received signal strength reception in an SFN will improve the quality of service. Nevertheless, it should be noted that not all the locations within the service area will benefit from the SFN configuration. Some areas will show a degraded quality caused by the SFN echoes. In this paper, the SFN gain is defined as a parameter describing potential gain or interference. An unambiguous methodology to obtain the actual SFN gain is presented and the variation of the gain is investigated for a DVB-H network as a function of the signal strength difference received from different transmitters. This SFN gain can be used for coverage planning of future broadcast networks. [ABSTRACT FROM AUTHOR]

Due to the recent popularization of digital broadcasting systems, selective contents, i.e., watching contents selected by users themselves, have attracted great attention. For example, in a news program, after a user selects an interesting content, he/she watches it. In selective contents broadcasting, since the server needs to deliver many contents, the necessary bandwidth for continuously playing the data increases. Conventional schemes reduce the necessary bandwidth by producing an effective broadcast schedule. However, they do not consider the upper limit in the bandwidth. When an upper limit exists in the bandwidth, users may wait to play the data. In this paper, we propose a broadcasting scheme that reduces waiting time by considering available bandwidth. In our proposed scheme, by acquiring the channel bandwidth that is the same as the data consumption rate, we effectively reduce the waiting time. [ABSTRACT FROM AUTHOR]

LDPC codes are state-of-art error correcting codes, included in several standards for broadcast transmissions. Iterative soft-decision decoding algorithms for LDPC codes reach excellent error correction capability; their performance, however, is strongly affected by finite-precision issues in the representation of inner variables. Great attention has been paid, in recent literature, to the topic of quantization for LDPC decoders, but mostly focusing on binary modulations and analysing finite precision effects in a disaggregrated manner, i.e., considering separately each block of the receiver. Modern telecommunication standards, instead, often adopt high order modulation schemes, e.g. M-QAM, with the aim to achieve large spectral efficiency. This puts additional quantization problems, that have been poorly debated in previous literature. This paper discusses the choice of suitable quantization characteristics for both the decoder messages and the received samples in LDPC-coded systems using M-QAM schemes. The analysis involves also the demapper block, that provides initial likelihood values for the decoder, by relating its quantization strategy with that of the decoder. A new demapper version, based on approximate expressions, is also presented, that introduces a slight deviation from the ideal case but yields a low complexity hardware implementation. [ABSTRACT FROM AUTHOR]

One way to broadcast a popular video is to partition the video into segments, which are transmitted on several channels currently and periodically. The approach lets multiple users share channels, and thus obtains high bandwidth utilization. Many previous studies such as the recursive frequency-splitting (RFS) and harmonic broadcasting schemes focus on decreasing clients' waiting time. Another issue on reduction of clients' buffer demands is also important, especially for the goal to provide video services using limited-capability client devices such as PDAs and set-top boxes (STBs). Related work includes the skyscraper broadcasting (SkB), client-centric approach (CCA), greedy disk-conserving broadcasting (GDB), and reverse fast broadcasting (RFB) schemes. By combining RFS and RFB, this paper designs a hybrid broadcasting scheme (HyB), which exhibits a good tradeoff between client buffering spaces and waiting time. In comparison with SkB, CCA, GDB, RFB, and RFS, HyB requires smallest buffers, only 25% of video size. For waiting time, the scheme also outperforms all the schemes, except RFS. [ABSTRACT FROM AUTHOR]

After coarse synchronization in orthogonal frequency division multiplexing (OFDM) systems, there might still be a residual frequency offset (RFO) and a sampling clock frequency offset (SFO), which seriously degrade the performance of the systems. This paper suggests a simple way of estimating the SFO in OFDM-based digital radio mondiale (DRM) system. To demonstrate the efficiency of the proposed SFO estimator, comparisons are made with other existing estimators in terms of mean square error (MSE) performance, estimation range, and complexity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Due to the recent popularization of mobile multi- media broadcasting, broadcasting continuous media data such as audio and video has attracted great deal of attention. In general continuous media data broadcasting, since clients have to wait to receive data before playing it, various schemes to reduce waiting time have been studied. Some reduce the waiting time by dividing the data into several segments and broadcasting preceding segments frequently with a single channel. However, by dividing the data into numerous segments and producing an effective broadcast schedule, the waiting time can be further reduced. In this paper, we propose a scheduling protocol to reduce waiting time with large-scale data segmentation. [ABSTRACT FROM AUTHOR]

The Hybrid Fiber Coax (HFC) is a modern broadband access network, providing advanced interactive services such as Internet access, digital interactive television and cable telephony. The edge costs dominate the cost of launching new services, at the time of deployment (CapEx) as well as for maintenance (OpEx). Therefore next-generation edge devices aim at the convergence of these services and their platforms into a single multi-service infrastructure, thus sharing resources and bandwidth. The focus of this paper is on the HFC access network design for bandwidth-intensive TV services, bringing standard as well as switched broadcast technologies into play. Standard broadcast TV service deployments, offered through the Digital Video Broadcast (DVB) platform, require low installation costs, but the bandwidth consumption increases linearly with the number of available TV channels, even for very unpopular channels. Switched broadcast TV channels, offered on the (Euro-) DOCSIS platform together with other interactive unicast services such as Video on Demand, are only streamed to a node on the HFC access network if they are requested locally, thus limiting bandwidth consumption for less popular channels. We present an access network design tool, based on an analytical TV traffic model, minimizing the installation cost on the edge devices and study the influence of the most important traffic and content parameters. [ABSTRACT FROM AUTHOR]

This paper presents an up to date study on external noise levels in the medium wave band based on field trials carried out in Spain and Mexico during years 2004 and 2005 respectively. External noise levels predicted by the ITU-R P.372 recommendation are based on measurements carried out more than 30 years ago and no updated results for the medium wave band have been published in this time. An increment on these noise levels have been measured, which leads to a significant impact on the minimum usable field strength requirements for the broadcasting systems used in this frequency band, such as the new Digital Radio Mondiale (DRM) and In-Band/On-Channel (IBOC) systems. [ABSTRACT FROM AUTHOR]

In this paper, we propose a differential space-frequency block code—orthogonal frequency division multiplexing (DSFBC-OFDM) scheme as a multiple-input multiple-output (MIMO) transmission technique for next generation broadcasting system. A linear decoding method for DSFBC, which performs comparably to the ML decoding method, is derived for the cases of two or four transmit antennas. A simple table lookup method is proposed to improve the efficiency of the encoding/decoding process of DSFBC for the case of non-constant modulus constellations. This not only reduces the computational load, but also removes the necessity of channel estimation. Also, synchronization techniques with a DSFBC-encoded phase reference symbol (PRS) are discussed. Finally, an MIMO channel model for the next generation broadcasting system is developed by extending the 3GPP MIMO model to fit broadcasting environments. The MIMO channel model is then used to compare BER performances of differential space block code schemes for various channel environments. Simulation results show that the DSFBC-16QAM scheme using either four transmit antennas with one receive antenna or two transmit antennas with two receive antennas achieves a performance gain of 12 dB, with a data rate twice faster than that of the conventional DQPSK scheme. [ABSTRACT FROM AUTHOR]

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 10-8 which can result in the extended coverage area of the T-DMB system. [ABSTRACT FROM AUTHOR]

In this paper, we describe how the transmission technologies developed for over-the-air Digital Television broadcasting could be used to offer Interactive Television and Internet Multimedia Service. We propose to use the ATSC-DTV system for the downlink and DVB-RCT standard to implement a wireless return channel. This paper will also present some technical aspects of the system implementation. [ABSTRACT FROM AUTHOR]

In this paper, novel and yet simple techniques are presented to minimize the error propagation caused by the large precursors and postcursors of the decision feedback equalizer (DFE) in 8VSB DTV system. A technique that selects a reference tap (symbol timing of DFE) from an estimated channel impulse response (CIR) is presented to minimize the effect of the large precursors. Another technique that selects the reference tap position, i.e., decision delay in a feedforward filter (FFF), from the estimated CIR and the amplitude of the selected reference tap is proposed to minimize the effect of large postcursors. The combined structure of a feedback filter (FBF) and Viterbi decoder for use in 8VSB DTV system is also proposed to replace the past unreliable decision symbols in FBF as well as to reduce the decision error probability. Simulation results show that our proposed DFE can prevent effectively the error propagation, in particular, by changing the reference tap and its position in FFF according to the channel condition. It is also shown that an echo removing capability of the proposed DFE, where 400 and 620 taps are used for the FFF and FBF, respectively, is greater than that of conventional DFEs by about -20 μs in the single pre-echo of -10 dB channel and by about 10 μs in the single post-echo of -1 dB channel. [ABSTRACT FROM AUTHOR]

In cellular environments, video broadcasting is a challenging problem in which the number of users receiving the service and the average successfully decoded video data-rate have to be intelligently optimized. When video is broadcasted using the 3G packet data standard, 1xEV-DO, the code space may be divided among the multiple layers if scalable video coding is employed. In this paper, we propose a novel, multi-objective optimized video broadcasting scheme for 1xEV-DO and investigate the feasibility of using multiple layers for transmission. The multi-objective optimization aims to find the best compromise between maximizing the average decodable video data-rate and minimizing the basic quality video outage probability. Simulations conducted for the ITU Pedestrian A and Vehicular B channels show that high data-rates with low outages are possible when 1xEV-DO is used for video broadcasting, however, it may not be desirable to use scalable video coding for this purpose. [ABSTRACT FROM AUTHOR]

Technical details of the recently announced Chinese Digital Terrestrial Television Broadcasting Standard which defines the physical layer transmission protocol including the frame structure, channel coding and modulation schemes are discussed in this paper. The major differences between Chinese DTV standard in multi-carrier working mode and DVB-T standard, all occupying the same 8 MHz baseband bandwidth, are addressed. The measurement results of several working modes showing satisfactory receiving performance of high and standard definition TV signals under both indoor and outdoor environments for the fixed and mobile reception are also presented. [ABSTRACT FROM AUTHOR]

Periodic broadcast is an effective paradigm for large-scale dissemination of popular videos. Considerable research efforts have gone into designing many excellent periodic broadcast protocols in terms of minimizing the server network bandwidth and the client resources. However, there are only few implementations of periodic broadcast protocols available. In this paper, we present a Generalized Periodic Broadcast Server (GPBS) architecture that supports many periodic broadcast protocols. Based on this architecture, we use mathematical analysis to formulate and solve a new optimization problem whose solution provides insights into the server's memory and disk resources allocation. We also discuss our implementation of a video server which embodies the GPBS architecture and analysis. The video server implements three representative broadcast protocols. Our work facilitates implementation and deployment of many other periodic broadcast protocols. [ABSTRACT FROM AUTHOR]

The performance of the orthogonal frequency division multiplexing (OFDM) systems may be severely deteriorated when passing through wireless channels with the spectral nulls. Zero-Padding (ZP) for the OFDM signal guarantees the symbol recovery regardless of the channel spectral nulls if complicated ZP-OFDM-MMSE equalizer is used. In this paper we first establish a connection between ZP-OFDM and DFT codes and then two novel signal reconstruction schemes, signal projection and low-complexity signal reconstruction, are presented to deal with the spectral nulls based on the frames theory. The simulation results demonstrate that significant performance improvement can be achieved using our proposed methods over the so-called ZP-OFDM overlap and add (ZP-OFDM OLA) scheme. [ABSTRACT FROM AUTHOR]

Transmit diversity can be applied to OFDM systems by adopting space time code. Since the received signal is the overlapped signals transmitted from different transmit antennas, channel estimation is a rather challenging task for space time coded OFDM (ST-OFDM) systems. Pilot structure can help the receiver to effectively separate the overlapped signals and perform accurate channel estimation. In this paper, we propose three different channel estimation algorithms based on specially designed comb type pilots inserted in frequency domain. One of our proposed algorithms is performed in frequency domain and the other two are performed in time domain. Such comb type pilot based algorithms can provide higher bandwidth efficiency than common significant-tap-catching algorithm using training block pilots. Numerical analyzes and computational simulation show that our proposed estimation schemes have the same good performance while the time domain methods have relatively simple structure. [ABSTRACT FROM AUTHOR]

With the introduction of Digital Television Broad- casting (DTV) the use of UHF Taboo channels and the first adjacent channels plus those already allotted to a community has become necessary due to spectrum scarcity. Most of the UHF Taboos are due to nonlinear interference mechanisms, which were, and still are characteristic of consumer receivers. Those mechanisms result in third and higher odd-order Intermodulation products some of which fall in the desired TV channel. Crossmodulation is a lesser problem than Intermodulation. Broadcasters need to understand these interference mechanisms to minimize their loss of service area. This knowledge may help them in choosing the future channel they will use for DTB broadcasting. This paper attempts to quantify these interference problems. [ABSTRACT FROM AUTHOR]

DVB-H networks allow high data rate broadcast access for hand-held terminals. A method to analyze the performance is developed. The influence of different MPE-FEC rates and modulation schemes on the performance of a DVB-H network is analyzed in this paper for 9 different reception conditions. Portable (indoor and outdoor) and mobile reception (car, train, tram, bus) are investigated. This analysis enables better estimations of the performance of DYB-H systems and an optimized DVB-H performance model. The percentage of valid reception, MPE-FEC gains, carrier to interference-plus-noise ratios, and minimal signal strengths for the different reception conditions and modulation schemes are presented. [ABSTRACT FROM AUTHOR]

Based on the standard of Digital Audio Broadcasting (DAB) Eureka 147 system to improve structures of transmitter/receiver, this paper proposes a physical layer transmission technique capable of boosting the spectrum efficiency up to two times of that of the DAB-Eureka 147 system while the backwards compatibility is guaranteed. The proposed transmission technique comprises the development of both the modulation and demodulation schemes. In the developed modulation scheme, differential 16-level amplitude! phase shift keying (D16APSK) is adopted to replace the differential quadrature-phase-shift-keying (DQPSK) used in the DAB Eureka 147 system. In the developed demodulation scheme, on the other hand, a detector for two-level differential amplitude-shift-keying (DASK) signal is proposed which can be implemented with rather low hardware costs. The performance is presented by the Simulink platform in multipath fading channel model. [ABSTRACT FROM AUTHOR]

Current broadcast networks make use of either a Single Frequency Network (SFN) or a Multi Frequency Network (MFN) approach. In this paper a new scheme is presented which combines the strength of both MFNs and SFNs. Considerations to- wards the implementation with Digital Video Broadcasting-Hand- held (DVB-H) are also given. The applicability of this concept is shown by a signal propagation simulation and an efficiency study. [ABSTRACT FROM AUTHOR]

Digitization of AM radio systems promises a revival of the currently underutilized broadcasting bands below 30 MHz. Its prospects are near-FM sound quality, automatic tuning, and interference-free reception. Using skywave propagation in some of the bands, a potentially very large area can be covered by a single transmitter if the appropriate frequency and power are chosen. In this paper, we compare mobile and stationary reception at various frequencies, investigate the correlation between solar sunspot activity and reception quality, and analyze how non-audio data service can efficiently be broadcast with digital radio systems in the AM bands. Restrictions regarding the antenna size together with varying ionospheric conditions and and man-made noise make the reception of radio transmissions below 30 MHz in a car a challenging problem. Using the Digital Radio Mondiale (DRM) system, a total of 58 measurements were conducted both in rural and urban environments in fall 2005, most of them in the 49 m, 41 m and 17 m short wave bands, but also in long wave and medium wave bands. A stationary reference receiver recorded data of the same transmission in parallel with the mobile measurements. Comparison of both data sets allowed for a detailed analysis of the impact of mobility on the reception quality. The results show that particularly in rural areas, mobile reception is indeed reliable and perceived as high quality. Only when ionospheric disturbances push signals to just above the required Signal-to-Noise Ratio (SNR), in-car reception fades more frequently than at a stationary receiver. In urban and industrial areas, shadowing effects (tunnels, large buildings) and man-made noise (power lines, etc.) cause even more frequent dropouts. Thus most of the problems known from analog AM reception in cars will remain the same for digital broadcasting. However, where it works, the digital audio quality is clearly superior to that of analog AM. Therefore, we believe that digital radio in the AM bands is a valuable complement to other digital broadcast services, e.g. by augmenting their coverage in rural areas, where network deployments for higher frequencies may economically not be feasible. Further, the data features—although limited—make digital broadcasting in the AM bands an interesting candidate for telematics and traffic information services covering very large areas. [ABSTRACT FROM AUTHOR]

In this paper, a super-imposed scheme for timing and frequency synchronization is proposed for orthogonal frequency division multiplexing (OFDM) systems. The proposed architecture includes a pre-defined pseudo-noise (PN) sequence, which is added to both the OFDM symbol and the cyclic prefix (CP) in time domain. In contrast to existing synchronization schemes, the proposed architecture has the advantage of better bandwidth utilization since it does not require extra pilot symbols. The peak-to-average power ratio (PAPR) is also significantly decreased. Both the timing and frequency offset estimators are derived using the maximum likelihood (ML) criterion. Efficiencies of the estimators are analyzed mathematically in AWGN channels. Simulation experiments are also conducted in frequency selective fading channels. Moreover, the optimal power allocation factor of the PN sequence is determined by minimizing the bit error rate using simulation experiments. [ABSTRACT FROM AUTHOR]

In this paper, a new broadband, vertically polarized, circular switched parasitic antenna array, appropriate for portable DVB-T applications at the IV UHF band, is developed with the aid of a proposed genetic algorithm approach. The array consists of a central fixed parasitic element and four peripheral ones. At any given time, only two adjacent peripheral elements are active, while each of the remaining two is short-circuited. By appropriately selecting active and short-circuited elements, a set of four radiation patterns can be formed, covering the horizontal plane alternately. Design considerations and results are presented, while array measurements are demonstrated for a single switching mode. [ABSTRACT FROM AUTHOR]

In this paper, we describe a new 1/4 rate robust modulation techniques for Enhanced-xVSB system which is fully backward compatible with ATSC 8-VSB standard. 1/4 rate mode Enhanced-xVSB system provides broadcasters with a wide choice of trade-offs of data rate vs amount of robustness of enhanced data for pedestrian/mobile services. Lab test results of proposed Enhanced-xVSB 1/4 rate mode robust stream is a significantly improved multipath as well as AWGN reception performance for Enhanced-xVSB receiver. We suggest an Enhanced-xVSB terrestrial broadcasting system for ATSC HDTV and pedestrian/portable TV simultaneous broadcasting service providing. [ABSTRACT FROM AUTHOR]

A new mobile multimedia broadcasting service using a geostationary satellite was launched on May 2005 in Korea. The Satellite Digital Multimedia Broadcasting (S-DMB) system provides high quality audio, video and data broadcasting services to handheld and mobile receivers. S-DMB is a personal digital media which can provide bidirectional and interactive services via the convergent platform of broadcasting and communication. At present, TU Media, the only S-DMB service provider in Korea, provides 15 TV channels, 19 audio channels, and 3 data channels. The number of subscribers is about 890,000 by Nov. 2006. Thousands of low power gap fillers (repeaters) have been installed in the shadowed or blocked reception areas in the metropolitan Seoul. This paper presents the system requirements, standards and specifications, architecture, and service status of S-DMB in Korea. Comparisons with other satellite broadcasting systems and the services are also presented. Link budget analysis on the direct path down-link (satellite to receivers) and relay path feeder link (gap fillers to receivers) are carried out in order to ensure the satisfactory QoS. [ABSTRACT FROM AUTHOR]

This paper presents propagation measurement results in the UHF Digital Television (DTV) band, using an ATSC DTV signal as a channel sounding signal to investigate the characteristics of a wideband single-input multiple-output (SIMO) under mobile reception conditions. A series of DTV dual channel signal measurements were conducted in the Ottawa region to characterize the transmission of ATSC 8-VSB signals under different propagation environments. A dual channel receiver was used to record SIMO signals: these were used to provide channel impulse response estimates. From the recorded time-varying impulse responses and their correlation functions, average power delay profiles, scattering functions were computed to analyse the joint spatial fluctuations of the received signals. The DTV channel characterization study is aimed at broadcast system designers involved in data transmission of terrestrial digital television signals over mobile channels with diversity reception. [ABSTRACT FROM AUTHOR]

As different types of wireless networks are converging into an all-IP network, i.e., the Internet, it can be expected that in the near future video-on-demand (VoD) will be widely applied to many interesting services, and users can access these services using heterogeneous terminals via heterogeneous wired/wireless access networks. Many periodic broadcasting protocols have been proposed to reduce the implementation cost of VoD systems. However, most of the protocols assumed homogeneity for user terminals, while in practice, user terminals are usually quite different in their processing power, buffer space, and power. To address this problem, a few periodic broadcasting protocols providing the same video quality for all heterogeneous clients have been proposed recently. In this paper, we proposed a novel heterogeneous VoD broadcasting technique called Catch and Rest (CAR) to accommodate bandwidth heterogeneity without sacrificing user video quality. Then, we provide mathematic analysis to calculate the client bandwidth and buffer space requirements of CAR. Finally, we present our performance evaluation results for CAR. Our results show that under the same system resources (i.e., server and network bandwidth), CAR provides more uniform and acceptable service latency for all heterogeneous clients compared to previous works. [ABSTRACT FROM AUTHOR]

This paper deals with objective quality monitoring for digital broadcasting networks. Several video quality assessment methods are described and discussed regarding the scope of applications. A no reference method for video quality assessment is proposed, based on the detection of mismatched blocks. [ABSTRACT FROM AUTHOR]

As an effective technique for combating multipath fading and for high-bit-rate transmission over wireless channels, orthogonal frequency-division multiplexing (OFDM) is extensively used in modern digital television terrestrial broadcasting (DTTB) systems, such as the cyclic prefix OFDM (CP-OFDM) based DVB-T DTTB systems and the lime domain synchronous OFDM (TDS-OFDM) based DMB-T DTTB systems, to support high performance bandwidth-efficient multimedia services. OFDM-based DTTB systems are very sensitive to the nonlinear distortion at the transmitter and the imperfect parameters estimation at the receiver. In this paper, the combined effects of nonlinear distortion and imperfect parameters estimation on the performance of the OFDM-based DTTB systems are investigated, a closed form of symbol error probability of the OFDM-based DTTB systems with nonlinear distortion and imperfect parameters estimation is derived. Theoretical results show closely matching with those obtained by simulations for both the CPOFDM based DVB-T DTTB systems and the TDS-OFDM based DM13 T DTTB systems. [ABSTRACT FROM AUTHOR]

This paper presents the physical layer functions powering a new wireless data broadcasting system over analog television signals, referred to as dNTSC system (for data over National Television System Committee (NTSC) standard). Novel data insertion techniques at the transmitter and data extraction techniques at the receiver allow data rates of 1-4 Mbps that coexist with existing analog transmission but do not adversely affect normal television reception. Novel digital signal processing (DSP) techniques include a video abatement system that reduces data-to-video crosstalk for unimpaired analog television reception, adaptive nonlinear amplifier compensation, and advanced video cancellation and adaptive data equalization methods in the receiver. An analysis of the dNTSC system through noisy, multipath channels reveals the subtleties of the dNTSC system, compared to a conventional, dedicated digital communication link. [ABSTRACT FROM AUTHOR]

An important issue for video transmission over IP networks is preservation of perceived video quality despite packet loss. Packet loss can be detrimental to compressed video. However, reducing packet loss to a very low level Is difficult with current loss control techniques. Furthermore, even a very low objective loss probability can still seriously distort perceived video quality. This paper presents two buffer management schemes using video characteristics. They increase maximum loss tolerance for a desired level of video quality, providing better quality at equal loss ratios, when compared to a conventional buffer management scheme. Meanwhile, service fairness and network efficiency are also improved. [ABSTRACT FROM AUTHOR]

Addresses the issue of optimal bit rate allocation among digital television (DTV) and Internet protocols (IP) services within the digital terrestrial broadcasting system (DVB-T) multiplex. Demonstration of novel configurations providing real time sharing of the available bandwidth ; Use of an algorithm based on service hierarchy and perceptual quality assessment; Presentation of the architecture of a functionable DVTB-T.

In this correspondence, we comment on the proposed phase modulation scheme described in the above paper. We also suggest revising Table Ito eliminate possible confusion. [ABSTRACT FROM AUTHOR]

IPTV is becoming a serious alternative to traditional broadcast schemes, such as cable, satellite or terrestrial, to deliver TV to the home. However, the expectation of the user is that IPTV provides the same or even better Quality of Experience (QoE). An important part of QoE for linear TV services is the Channel Change Time (CCT) also known as zapping time. Due to its relevance many ideas and concepts have been published which describe how to optimize or speed up the CCT. First, to be able to judge the challenges and benefits of the available concepts, a common understanding of the contributors to the CCT is necessary. This article provides an overview of all elements in the IPTV end-to-end chain influencing the CCT from the head end down to the Set-Top Box (STB) and finally to the display. Second, various techniques for reducing the CCT are presented and discussed. [ABSTRACT FROM AUTHOR]

The International Telecommunications Union has defined the frequency band in which Broadcasting Satellite Systems (BSS) and Multi-channel Multipoint Distribution Systems (MMDS) should coexist. With the development of MMDS working on the same frequency band as the BSS, and theoretically with identical technical parameters, an important question arises of how to set up the parameters of terrestrial distribution systems so that their coexistence with satellite systems is enabled while at the same time terrestrial systems are not made technically too limited. In this article, we summarize the results of extensive research work that sought to answer the above question. Results of practical measurements performed on MMDS and BSS are presented. The calculations were performed according to the ITU-R Regulations. In addition to measuring professional commercial systems, we constructed a transmitting/receiving system to simulate a worst-case scenario-having the BSS and MMDS transmitters and receiver (measurement system) on the same line (Fig. 1). From the analysis of the empirical measurements and calculations, we determined how the parameters should be set up so as to enable the quality coexistence of BSS and MMDS. We focused on those parameters that significantly influence such a coexistence: the geographical position of BSS and MMDS transmitters, Symbol Rate, Code Rate, MMDS Transmitter Frequency, and MMDS Transmitter Power. [ABSTRACT FROM AUTHOR]

Hierarchical modulation can be effectively used to enhance terrestrial digital multimedia broadcasting (T-DMB) or digital audio broadcasting (DAB) systems in response to both the demand for higher data-rate and the need to be backward compatible with legacy receivers. QAM-type modulations are well-liked for hierarchical transmission but require coherent detection based on pilot symbol aided channel estimation. In the T-DMB or the DAB system using DQPSK modulation, however, any available pilot symbols except for the phase reference symbol do not exist. Differential amplitude phase shift keying (DAPSK) modulation is easily applied to the T-DMB system for a hierarchical modulation but may be susceptible to fast fading. As a good candidate for a hierarchical modulation of T-DMB to solve the above problems, we propose an amplitude differential phase shift keying (A-DPSK) modulation which is robust to fast fading by estimating only amplitude coefficients of the channel transfer function with the use of amplitude pilots. To raise the accuracy of channel estimation, we arrange the amplitude pilots in a come-type and introduce a noise-reduction scheme of averaging estimated channel coefficients. Simulation results show that the proposed A-DPSK provides a good choice for achieving a higher data-rate over other possible modulation schemes for advanced T-DMB or DAB systems. [ABSTRACT FROM AUTHOR]

An encoding system was implemented purely in software for sending H.264 video multicast to mobile devices. The H.264 encoder is a multi-threaded parallel-GOP encoder. It is capable of running in real-time with an AMD Opteron 1.8 GHz dual-core platform in baseline profile at CIF resolution at 1 Mbps. Real-time video encoding is accomplished with aggressive Single Instruction Multiple Data assembly code optimizations and advanced algorithms. A Time Control algorithm was developed to quell the mode decision process from spending too much time per frame. Transmission of the audio and video streams is on an IP layer over WiFi and DVB-H. DVB-H is chosen for its power saving and reliability features. Using the IP network, the encoder can be repurposed for applications other than mobile broadcast video. [ABSTRACT FROM AUTHOR]

Intercarrier interference (ICI) self-cancellation schemes were often employed in many OFDM systems as a simple and effective approach to suppress ICI caused by carrier frequency errors. The same procedure, however, can not perform very well at high frequency offsets. We propose a simple decision feedback scheme based on the general ICI self-cancellation scheme to perform estimation and tracking of the carrier frequency offsets. A system with the scheme does not consume additional bandwidth since it used the same data symbols employed for ICI cancellation for the estimation. After an initial estimation is completed, the scheme switches to the tracking mode to carry out the estimation of deviations in the frequency offsets. Finally this fine-tuned estimate is applied to the ICI self-cancellation scheme concurrently for frequency offset correction and hence improved the system performance greatly. Simulation results showed that our scheme allowed up to 9% of random variations in the frequency offset. The effectiveness of our scheme is further verified by calculating the bit error rate performance of various OFDM receivers. [ABSTRACT FROM AUTHOR]

Raptor codes have been standardized as application layer forward error correction (FEC) codes for Multimedia Broadcast and Multicast Services (MBMS) and Digital Video Broadcast (DVB) due to their extraordinary advanced FEC protection and performance. Raptor codes are known to have characteristics very close to ideal and provide a wide range of operating flexibility and efficiency unmatched by other codes, and in particular they are an excellent implementation of fountain codes. Until now, investigations of the application of Raptor codes to UMTS and EPGRS have used an overall system model that does not accurately model the physical channel and user mobility, simplistically assuming independent random packet losses at the application layer. We investigate MBMS in UMTS in a much more realistic and complete simulation environment by considering advanced and complete channel models that simulate the physical channel and user mobility in a cellular network. We use this realisitic simulation environment to determine optimal system parameters under different mobility models, with different bearer parameters, and without and with selective combining. More specifically, we investigate joint settings of the Raptor code rate, the Turbo code rate, transmission power, etc., to find settings which provide reliable download delivery of files using minimal transmission energy. One of our main results is that optimal system-wide operating points use low transmission power and a modest amount of Turbo coding that results in relatively large radio packet loss rates that is compensated for by using a substantial amount of Raptor coding. These optimal operating points use far less transmission energy for download delivery of files than possible operating points without Raptor. [ABSTRACT FROM AUTHOR]

DVB-H (Digital Video Broadcasting-Handheld) is the digital broadcast standard for transmitting broadcast content to handheld terminal devices, developed by the International DVB (Digital Video Broadcasting) Project. DVB-H is based on the DVB-T standard for digital terrestrial television but tailored to the special requirements of the pocket-size class of receivers. The IP Datacast specification, which was also recently standardized, contributes the higher layer protocols to build a complete end-to-end system. This article presents an overview of the DVB-H and IP Datacast systems with respect to features and technology. An outlook on DVB-H network deployment is given. [ABSTRACT FROM AUTHOR]

A popular video can be broadcast by partitioning the video into segments, which are broadcast on several channels simultaneously and periodically. This method allows multiple users to share channels, leading to higher bandwidth utilization. Previous studies mainly focus on reducing viewers' waiting time. This work studies another important issue, namely client buffer' savings. A reverse fast broadcasting (RFB) scheme is proposed to alleviate the buffer problem. There are two specific properties for RFB. First, this scheme arranges the segments in descending order of their numeric indices on each channel at the server end. Second, RFB requires a client to receive segments as late as possible, such that the client buffers the smallest number of segments. RFB has the same waiting time as the fast broadcasting (FB) scheme, but just needs a half of buffer spaces required by FB. RFB also requires smaller client buffers than the pyramid broadcasting (PB), skyscraper broadcasting (SkB), greedy disk-conserving broadcasting (GDB), BroadCatch, and recursive frequency-splitting schemes. Moreover, if we apply the same changes to the PB, SkB and GDB schemes, their buffer requirements decrease by 25% to 75%. [ABSTRACT FROM AUTHOR]

An embedded space-time coding method is proposed for wireless multimedia broadcast with heterogeneous receivers. In the proposed system, a transmitter sends out multi-layer source signals by encoding different layers with different space-time codes. Then, a receiver can retrieve a different amount of information depending on the number of its antennas. The receiver with only one antenna can decode only the base layer information with a low complexity while the receiver with more antennas can retrieve more layers of information. We also investigate a differential design of the embedded space-time system, which is used when the channel state information (CSI) is unknown to the receiver. Both analytic and experimental results are provided to demonstrate the performance of the proposed system. Differential detection with Kalman filtering is also investigated to help improve performance. [ABSTRACT FROM AUTHOR]