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Digital multimedia broadcasting service has been at the center of developing issues in mobile environment. in contrast to traditional multimedia broadcasting systems, mobile devices have limit of information handling capacity. In order to solve the problem, this paper presents a personalized channel recommendation system at client side in mobile environment. The system includes four modules: client manager agent, monitoring agent, data preparation agent and recommendation agent. Within the recommendation agent, we develop a recommendation algorithm using users' preference transitions for the channels. Also, we design and implement the prototype system on the Wireless Internet Platform for Interoperability. In the experiment, we compare the proposed algorithm with a conventional method. The experimental results show that the proposed recommendation system can provide better performance than the conventional method. [ABSTRACT FROM AUTHOR]

Smart antenna technology can greatly improve the coverage radius of wireless systems by focusing the transmitted signal (beam) toward desired users. However, beamforming has an important side effect as it creates a region, herein referred to as the complementary region, where some users in the network cannot sense the directional signals (beams). We have referred to this as the hidden beam problem in Tarokh et al.. From a physical layer perspective, beamforming reduces cochannel interference (CCI). However, in systems that use medium access-control techniques such as the carrier-sense multiple access (CSMA) protocol in wireless local area networks, during a busy period of the channel, the users in the complementary region may wrongly decide that the medium is idle and transmit packets. This may cause CCI, unnecessary retransmissions, subsequent backoff, and increased network latency. We introduced the concept of complementary beamforming (CBF) to address this issue in Throkh et al. In this paper, we propose two new methods, called "subspace complementary beamforming" (SCBF) and "complementary superposition beamforming" (CSBF). The SCBF uses dummy data to ensure a controlled level of received energy in all directions of eigenvectors unused by downlink beamforming. The technique works in multipath fading channels. The approach achieves similar results to those reported in Tarokh et al.. However, it enables the second technique (CSBF) which can also send data content in the complementary beam. This allows passive nodes in the network to receive "broadcast" information, while the active nodes are engaged in the exchange of user-specific data. It is shown that CBF effects can be achieved simply by increasing the transmit power of only one of antenna elements when space-division multiple access is not applied. Simulations are provided in order to quantify overall network performance improvements when using CBF, confirming significant throughput and delay performance enhancements. [ABSTRACT FROM AUTHOR]

This paper analyzes the multiuser capacity of Gaussian frequency-selective wireline multiaccess channels. Both the uplink (multiple-access channel) and downlink (broadcast channel) capacity regions are considered. The concept of balanced capacity is introduced to characterize the multiuser channel performance. Algorithms for the computation of the balanced multiuser capacity (and the associated power allocations) are proposed for an arbitrary number of users. The optimal power allocation in a K-user memoryless Gaussian channel is analyzed in detail, and an extension to intersymbol interference channels is given with various kinds of power constraints. Results are provided for a wireline access network with 20 users. [ABSTRACT FROM AUTHOR]

PN-sequence padding (PNP) TDS-OFDM transmission scheme has recently been proposed as an appealing alternative to the traditional Cyclic Prefix (CP) OFDM technology as it can provide significant improvement in the spectrum efficiency. In this paper, an iterative method is introduced to subtract the PN sequence. padding for the TDS-OFDM systems to mitigate the residual inter symbol interference (ISI) from the imperfect channel estimation, and the inherent channel estimation techniques are also performed to track the channel changes. Results show that this iterative algorithm can effectively remove the impact from the residual ISI on the slow-fading broadcast channels, even in the presence of very large channel delays in the single-frequency simulcast networks (SFN). [ABSTRACT FROM AUTHOR]

Digital video broadcasting-terrestrial (DVB-T) is an important multimedia technology capable of high data-rate transmission. Orthogonal frequency division multiplexing (OFDM) has been the backbone technique in the current DVB-T systems adopted by Europe and Japan. However, since the OFDM system is very sensitive to the frequency synchronization and phase errors, which will induce the intercarrier interference (ICI), the ongoing research has been dedicated to this ICI problem in the presence of the Doppler frequency drift and the fading channels. A means to deal with the ICI problem is called the ICI self-cancellation or polynomial cancellation coding scheme. In this paper, we establish the complete simulation environment for the physical layer of the DVB-T system and then evaluate the effectiveness of the ICI self-cancellation coding scheme compared with the existing convolutional coding scheme for different fading channels and different Doppler frequencies. According to our simulation results, we conclude that the ICI self-cancellation scheme significantly outperforms the convolutional coding scheme which is adopted by the existing DVB-T standard for the AWGN and the frequency non-selective fading channels, but both schemes have the similar performance in the frequency-selective fading channels. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel audio-visual feature-based framework for event detection in broadcast video of multiple different field sports. Features indicating significant events are selected and robust detectors built These features are rooted in characteristics common to all genres of field sports. The evidence gathered by the feature detectors is combined by means of a support vector machine, which infers the occurrence of an event based on a model generated during a training phase. The system is tested generically across multiple genres of field sports including soccer, rugby, hockey, and Gaelic football and the results suggest that high event retrieval and content rejection statistics are achievable. [ABSTRACT FROM AUTHOR]

Periodic broadcasting is known as an efficient technique to support near Video-on-Demand services for delivering popular videos, since it can reduce the bandwidth requirement for transmitting streaming video to simultaneous viewers. The channel transition problem is an issue to be concerned about the variability of popularity of video. In this paper, we present a novel channel transition scheme based on the fast broadcasting. In most conditions, our proposed scheme has less bandwidth waste than the existing SFB scheme. In addition, no extra startup latency and client buffer are needed in our scheme. [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]

Sensor networks usually operate under very severe energy restrictions. Therefore, sensor communications should consume the minimum possible amount of energy. While broadcasting is a very energy-expensive protocol, it is also widely used as a building block for a variety of other network layer protocols. Therefore, reducing the energy consumption by optimizing broadcasting is a major improvement in sensor networking. In this paper, we propose an optimized Broadcast Protocol for Sensor networks (BPS). The major novelty of BPS is its adaptive-geometric approach that enables considerable reduction of retransmissions by maximizing each hop length. BPS adapts itself and gets the best out of existing radio conditions. In BPS, nodes do not need any neighborhood information, which leads to low communication and memory overhead. We analyze the worst-case scenario for BPS and show that the number of transmissions in such a scenario is a constant multiple of those required in the ideal case. Our simulation results show that BPS is very scalable with respect to network density. BPS is also resilient to transmission errors. [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]

Broadcasting has been widely used in mobile Ad hoc networks as a communication means to disseminate information to all reachable nodes. Because radio signals are likely to overlap with others in a geographical area, straightforward broadcasting by flooding becomes very costly and results in serious redundancy, contention and collision, to which we refer as the broadcast storm problem. In this paper we propose the Relative Degree Adaptive flooding Broadcast (RDAB) algorithm for Ad hoc networks to efficiently reduce the broadcast overhead in the network. Based on the current situation of the network and the degree of the nodes, RDAB calculates the relative degree of the nodes, decides which nodes need to re-transmit and which nodes only need to receive. The higher the neighbor node's relative degree, the more uncovered nodes it can cover, hence these nodes can be selected to re-transmit broadcasting packets in the networks. We analyze the reliability and the validity of the RDAB algorithm to prove that the RDAB algorithm is a valid flooding broadcast algorithm. Simulation results show that the RDAB strategy outperforms the Ordinary Flooding Broadcast Method (OBM) and the Multipoint Relaying (MPR) protocol for Ad hoc networks. [ABSTRACT FROM AUTHOR]

Although the Ungerboeck's TCM (Trellis Coded Modulation) is attractive in terms of high efficiency with low descending data rate by coding and high coding gain, it is difficult to implement To remove this complexity, a pragmatic approach to the TCM, which is realized by employing the defacto convolutional code (constraint length K= 7 and rate 1/2), was proposed. In this paper, a simpler realization of the TCM of rectangle type 2N QAM (N is even number; ≥ 4) by using the pragmatic approach is presented. We will show the convolutional coding and the Viterbi decoding by the decomposition from two-dimensions into each one-dimension independently. By this decomposing, it is possible to apply the pragmatic approach to minimize hardware and cost Therefore it is very useful for 64 QAM or 256 QAM applications such as digital video broadcasting over digital cable TV (ITU-T J.83) and Fixed Wireless Access (IEEE802.16) systems. It can be applied not only to single carrier QAM but also to multi-carrier QAM like OFDM. [ABSTRACT FROM AUTHOR]

Localization is one of the substantial issues in wireless sensor networks. Several approaches, including range-based and range-free, have been proposed to calculate positions for randomly deployed sensor nodes. With specific hardware, the range-based schemes typically achieve high accuracy based on either node-to- node distances or angles. On the other hand, the range-free mechanisms support coarse positioning accuracy with the less expense. This paper describes a range-free localization scheme using mobile anchor points. Each anchor point equipped with the GPS moves in the sensing field and broadcasts its current position periodically. The sensor nodes obtaining the information are able to compute their locations. With the scheme, no extra hardware or data communication is needed for the sensor nodes. Moreover, obstacles in the sensing fields can be tolerated. The localization mechanism has been implemented in the network simulator ns-2. The simulation results show that our scheme performed better than other range-free mechanisms. [ABSTRACT FROM AUTHOR]

Broadcast is an efficient and scalable way of transmitting data to an unlimited number of clients that are listening to a channel. Cyclically broadcasting data over the channel is a basic scheduling technique, which is known as flat scheduling. When multiple channels are available, a data allocation technique is needed to assign data to channels. Partitioning data among channels in an unbalanced way, depending on data popularities, is an allocation technique known as skewed allocation. In this paper, the problem of data broadcasting over multiple channels is considered, assuming skewed data allocation to channels and flat data scheduling per channel, with the objective of minimizing the average waiting time of the clients. First, several algorithms, based on dynamic programming, are presented which provide optimal solutions for N data items and K channels. Specifically, for data items with uniform lengths, an 0(NK log N) time algorithm is proposed, which improves over the previously known 0(N2K) time algorithm. When K ≤ 4, a simpler 0(NlogN) time algorithm is exhibited which requires only 0(N) time if the data items are sorted. Moreover, for data items with nonuniform lengths, it is shown that the problem is NP-hard when K = 2 and strong NP-hard for arbitrary K. In the former case, a pseudopolynomial algorithm is discussed whose time is O(NZ), where Z is the sum of the data lengths. In the latter case, an algorithm is devised with time exponential in the maximum data length, which can optimally solve, in reasonable time, only small instances. For larger instances, a new heuristic is devised which is experimentally tested on some benchmarks whose popularities are characterized by Zipf distributions. Such experimental tests reveal that the new heuristic proposed here always outperforms the best previously known heuristic in terms of solution quality. [ABSTRACT FROM AUTHOR]

In this paper, we consider the communications involved by the execution of a complex application, deployed on a heterogeneous platform. Such applications extensively use macrocommunication schemes, for example, to broadcast data items. Rather than aiming at minimizing the execution time of a single broadcast, we focus on the steady-state operation. We assume that there is a large number of messages to be broadcast in pipeline fashion, and we aim at maximizing the throughput, i.e., the (rational) number of messages which can be broadcast every time-step. We target heterogeneous platforms, modeled by a graph where resources have different communication and computation speeds. Achieving the best throughput may well require that the target platform is used in totality: We show that neither spanning trees nor DAGs are as powerful as, general graphs. We show how, to compute the best throughput using linear programming, and how to exhibit a periodic schedule, first when restricting to a DAG, and then when using a general graph. The polynomial compactness of the description comes from the decomposition of the schedule into several broadcast trees that are used concurrently to reach the best throughput. It is important to point out that a concrete scheduling algorithm based upon the steady-state operation is asymptotically optimal, in the class of all possible schedules (not only periodic solutions). [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]

The LInear amplification using Nonlinear Components (LINC) technique is a well-known power amplifier linearization method to reduce out-of-band interferences in a nonconstant envelope modulation system, such as Digital Video Broadcasting (DVB) system, which is based on a very sensitive to nonlinear distortions OFDM modulation scheme. The major drawback of LINC transmitters is the inherited sensitivity to gain and phase imbalances between the two amplifier branches. In this paper, a novel full-digital base band method, which corrects any gain and phase imbalances in LINC transmitters mainly due to the un-matching of the two amplifier paths, is described. Amplifiers are characterized by a level-dependent complex gain using a memoryless model. The method uses adaptive signal processing techniques to obtain the optimal complex coefficients to to direct gain and phase imbalances. Its main advantage is the ability to track the input signal variations and adapt to the changes of amplifier nonlinear characteristics. Other effects are included in the analysis such as quadrature modulator and demodulator impairments. A computer simulation has been carried out to verify method functionality. [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]

Data dissemination by the use of periodic broadcast is a viable sc bible mechanism due to the explosion of information services in wireless networks. Many research works have exploited the data broadcast methodologies, however, upon the premise that the broadcast traffic is static on a single broadcast channel. In practice, the broadcast traffic changes dynamically and multiple broadcast channels can be utilized for efficient data dissemination. Accordingly, in this paper we devise an adaptive multichannel data dissemination mechanism, including two components: the multichannel traffic-awareness and the deterministic balance search techniques. The multichannel traffic-awareness technique performs a cyclic estimation of dynamic access frequency distribution in response to traffic dynamics. With the measured estimation, he deterministic balance search technique adjusts channel allocation and item classification to further minimize and balance the push access and the pull response time. The experimental results show that the proposed mechanism is able to attain the result of channel partition and item classification very close to the optimum and, thus, minimize the mean access time in both push and pull channels simultaneously. Therefore, the reliability of broadcast contents is guaranteed. [ABSTRACT FROM AUTHOR]

Broadcast has often been used to disseminate frequently requested data efficiently to a large volume of mobile units over single or multiple channels. Since mobile units have limited battery power, the minimization of the access and tuning times for the broadcast data is an important problem. There have been many research efforts that focus on minimizing access and tuning times by providing indexes on the broadcast data. In this paper, we have studied an efficient index allocation method for broadcast data with skewed access frequencies over multiple physical channels which cannot be coalesced into a single high bandwidth channel. Previously proposed index allocation techniques have one of two problems. The first problem is that they require equal size for both index and data. The second problem is that their performance degrades when the number of given physical channels is not enough. These two problems will result in an increased average access time for the broadcast data. To cope with these problems, We propose a tree-structured index allocation method. Our method minimizes the average access time by broadcasting the hot data and their indices more frequently than the less hot data and their indexes over the dedicated index and data channels. We present an in-depth experimental and theoretical analysis of our method by comparing it with other similar techniques. Our performance analysis shows that it significantly decreases the average access and tuning times for the broadcast data over existing methods. [ABSTRACT FROM AUTHOR]

MPEG-4 video streaming service is being regarded as a de facto standard service for current mobile multimedia video streaming services such as video conferencing, voice over IP, and even state-of-the-art digital multimedia broadcasting technology. There have been many illegal users who have used copyrighted material without getting permission and/or paying for its use. Therefore, much attention has been paid for Digital Rights Management (DRM) for digital media. We constructed a protection scheme for MPEG-4 video file format, which can be applied, to the video services that are exploiting the MPEG-4 standard In this protection scheme, minimum segments of every Video Object Plane in a MPEG-4 video file could be encrypted with a symmetric cryptography system like a DES (Data Encryption Standard) so that people who have not received permission and/or paid to use the contents would not be able to view them. We applied this scheme to all kinds of MPEG-4 VOP (Video Object Plane) types, that is I-, P-, and B-VOPs respectively. The prototype system was developed for proofing the feasibility of this scheme for hand-held devices and for mobile multimedia service environment. The efficiency of this scheme is reported at the end of this paper. [ABSTRACT FROM AUTHOR]

This paper introduces T-DMB transmission system in Korea based on Eureka-147 DAB and presents a new architecture of transmission system for digital multimedia services. For transmission of the digital multimedia contents in mobile environment by using the existing DAB, we developed a T-DMB processor which performs T-DMB encoding and insertion of the media stream into the existing DAB transmission system. After the implemented T-DMB processor can be connected to the front of the commercial Eureka-147 DAB system, and the performance of the T-DMB system is confirmed through the T-DMB experimental broadcasting in Korea. [ABSTRACT FROM AUTHOR]

Due to advances in fiber-optics and VLSI technology, interconnection networks that allow multiple simultaneous broadcasts are becoming feasible. Distributed-shared-memory implementations on such networks promise high performance even for applications with small granularity. This paper presents the architecture of one such implementation, called the Simultaneous Optical Multiprocessor Exchange Bus, and examines the performance of augmented DSM protocols that exploit the natural duplication of data to maintain a recovery memory in each processing node and provide basic fault tolerance. Simulation results show that the additional data duplication necessary to create fault-tolerant DSM causes no reduction in system performance during normal operation and eliminates most of the overhead at checkpoint creation. Under certain conditions, data blocks that are duplicated to maintain the recovery memory are utilized by the underlying DSM protocol, reducing network traffic, and increasing the processor utilization significantly. [ABSTRACT FROM AUTHOR]

In this paper, we propose a family of structures, namely, κ-localized minimum spanning tree (LMSTκ) for topology control and broadcasting in wireless ad hoc networks. We give an efficient localized method to construct LMSTκ using only O(n) messages under the local-broadcast communication model, i.e., the signal sent by each node will be received by all nodes within the node's transmission range. We also analytically prove that the node degree of the structure LMSTκ is at most 6, LMSTκ is connected and planar and, more importantly, the total edge length of the LMSTk is within a constant factor of that of the minimum spanning tree when κ ≥ 2 (called low weighted hereafter). We then propose another low weighted structure, called Incident MST and RNG Graph (1MRG), that can be locally constructed using at most 13n messages under the local broadcast communication model. Test results are corroborated in the simulation study. We study the performance of our structures in terms of the total power consumption for broadcasting, the maximum node power needed to maintain the network connectivity. We theoretically prove that our structures are asymptotically the best possible for broadcasting among all locally constructed structures. Our simulations show that our new structures outperform previous locally constructed structures in terms of broadcasting and power assignment for connectivity. [ABSTRACT FROM AUTHOR]

Self-pruning is an effective scheme for efficient broadcasting in ad hoc wireless networks. In a self-pruning broadcast protocol, a node may not forward a broadcast packet if a certain self-pruning condition is satisfied based on the neighborhood information. In a static network with an ideal MAC layer, only a subset of nodes forward the broadcast packet and still guarantee the complete network delivery. Various protocols have been proposed with different self-pruning conditions. Recently, a generic self-pruning protocol was proposed by Wu and Dai [21], which combines the strength of previous conditions and is more effective. In this paper, we first propose an enhanced version of the generic protocol, which is more elegant in interpreting existing protocols and has a simpler correctness proof. Then, we evaluate the performance of the family of self-pruning protocols under various network situations with ns2. The objective is to observe the efficiency and reliability of these protocols as a function of network density, congestion, and mobility, and provide a guideline of implementation in the "real world." Our performance analysis reveals that the protocol reliability is barely affected by packet collision. However, most self-pruning protocols suffer from low delivery ratio in highly mobile networks. We further explore various techniques that improve the delivery ratio and show that both high efficiency and reliability can be achieved in highly mobile networks. [ABSTRACT FROM AUTHOR]

The growing interest in the relation between electromagnetic fields and human health forces the assumption of national and international regulations on emission levels. In order to reduce the risks, restricted access around transmitting antennas have to be defined according with those regulations. This paper offers a guideline to determine the boundary of the potentially risky volumes around radio broadcasting antennas for AM-MF and FMSVHF services. With the proposed method, a complete reference volume is defined by just five parameters. [ABSTRACT FROM AUTHOR]

Manly essential multimedia applications rely on video-on-demand technology to deliver a video to different users. A number of periodic broadcast techniques have been proposed for the cost-effective implementation of such systems. Most of these techniques I would either try to minimize the server band- width, user bandwidth, user storage, user access latency to the video, or a combination of some of the aforementioned parameters. On the other hand, the implementation strategies of these broadcast schedules would necessitate a minimum bandwidth requirement for all users. Multi-resolution techniques address the heterogeneity problem by sacrificing user video quality. In this paper, we consider a different approach that does not possess this disadvantage. using an incremental channel design at the server side, and a specific broadcast schedule, users can choose among a range of band widths to use to download the video at the cost of their access latency and not to the video quality. We prove the correctness of the proposed solution; provide mathematical analysis to demonstrate its heterogeneous behavior, and present performance studies to illustrate its efficiency. [ABSTRACT FROM AUTHOR]

The harmonic data broadcasting scheme provides the best user latency. However, it has a drawback of not providing the video data always in time to view. This drawback has been overcome in some schemes. These schemes share common organizational structure to the harmonic scheme and hence may be called its variants. The main variants include cautious, quasi-harmonic, and polyharmonic schemes. The polyharmonic scheme has better performance for user latency in comparison to the cautious and quasi-harmonic schemes. But this scheme works by constraining a user for a fixed delay after receiving his/her request During that delay period, some appropriate portion of the video data is stored in the buffer storage at the client's site and it can be read from the buffer, whenever it is needed. In the polyharmonic scheme, two main parameters constrain its practicability. First, it needs the videos to be divided into the large number of subsegments that increases complexity of management Second, it requires huge amount of storage space at the client's site, increasing thus the cost of the end system. In this paper, the partially prestored harmonic scheme has been proposed, which requires less storage space than the polyharmonic scheme without affecting the user waiting time. Further, the number of subsegments of the video is considerably less, while maintaining the same user latency. [ABSTRACT FROM AUTHOR]

A new national standard for Digital Multimedia Broadcasting (DMB) has been announced in Korea to provide high quality digital audio, video, and data broadcasting services to fixed, mobile, and portable receivers. We have developed the world's first DSP/FPGA implementation of the portable DMB receiver, complete with an RF receiver, a 6.4-inch LCD display, and audio/video/data decoders. In this paper, we present the design, implementation, and performance of this portable DMB receiver. First, we provide a brief overview of the DMB system and the audio/video coding tools supported by it, i.e., MPEG-4 BSAC and MPEG-4 Part 10 A VC/H. 264. We discuss the low-power high-performance design of the DMB receiver, focusing particularly on the audio/video decoding parts. Finally, we illustrate the performance of the portable DMB receiver that operates in real-time at the overalifrequency of 25 MHz. [ABSTRACT FROM AUTHOR]

We consider multiaccess, broadcast, and interference channels with additive Gaussian noise. Although the set of rate pairs achievable by time-division multiple access (TDMA) is not equal to the capacity region, the TDMA achievable region converges to the capacity region as the power decreases. Furthermore, TDMA achieves the optimum minimum energy per bit. Despite those features, this paper shows that the growth of TDMA-achievable rates with the energy per bit is suboptimal in the low-power regime except in special cases: multiaccess channels where the users' energy per bit are identical and broadcast channels where the receivers have identical signal-to-noise ratios. For the additive Giussian noise interference channel, we identify a small region of interference parameters outside of which TDMA is also shown to be suboptimal. The effect of fading (known to the receiver) on the suboptimality of TDMA is also explored. [ABSTRACT FROM AUTHOR]

The development of technologies and standards intended to enable and organize a variety of innovative services over the infrastructure that supports digital TV requires a parallel evolution of the techniques to manage its main information media: digital video. Particularly, as TV broadcasters confront the provision of dynamic value-added content-based services over the audio-visual information that is being transmitted, they require online annotation of the received digital channels. In order to achieve it, apart from high levels of success in video temporal segmentation--a great resource-consuming task previous to most video annotation techniques--a faster than real-time performance is crucial. This paper describes a software module for video temporal segmentation which is able to detect both abrupt transitions and all types of gradual transitions in real time, with levels of recall and precision not reported up to date for such a large and varied set of video sequences. [ABSTRACT FROM AUTHOR]

OFDM has been applied in the current wireless local-area networks and digital video broadcasting systems since it has the advantage over the conventional single-carrier modulation schemes when the frequency-selective fadings are present. Nevertheless, intercarrier-interference (ICI) due to Doppler frequency drift, phase offset, local oscillator frequency drift, and multipath fading will be a severe problem in OFDM systems. Previous ICI self-cancellation coding schemes can greatly reduce the ICI, but they are very sensitive to the phase ambiguity, which is due to the composite effect of the phase offset, the multipath fading and the local frequency drift. In this paper, the phase ambiguity and amplitude ambiguity problems in ICI self-cancellation coded OFDM receivers will be formulated and discussed. Then, a novel receiver which combines the current ICI self-cancellation coding techniques with a new expectation-maximizations-based joint phase/amplitude estimation and symbol detection scheme is proposed. The outstanding performance of this proposed scheme is shown and compared with other existing methods at different noise levels through OFDM simulations. [ABSTRACT FROM AUTHOR]

A high-quality three-dimensional (3-D) broadcast service (3-D TV) is becoming increasingly feasible based on various recent technological developments combined with an enhanced understanding of 3-D perception and human factors issues surrounding 3-D TV. In this paper, 3-D technology and perceptually relevant issues, in particular 3-D image quality and visual comfort, in relation to 3-D TV systems are reviewed. The focus is on near-term displays for broadcast-style single- and multiple-viewer systems. We discuss how an image quality model for conventional two-dimensional images needs to be modified to be suitable for image quality research for 3-D TV. In this respect, studies are reviewed that have focused on the relationship between subjective attributes of 3-D image quality and physical system parameters that induce them (e.g., parameter choices in image acquisition, compression, and display). In particular, artifacts that may arise in 3-D TV systems are addressed, such as keystone distortion, depth-plane curvature, puppet theater effect, cross talk, cardboard effect, shear distortion, picket-fence effect, and image flipping. In conclusion, we summarize the perceptual requirements for 3-D TV that can be extracted from the literature and address issues that require further investigation in order for 3-D TV to be a success. [ABSTRACT FROM AUTHOR]

Conditional Access System (CAS) is one of the key techniques in digital television (DTV) broadcast which is used to charge the subscriber for subscribing fee by scrambling the program information. Scrambling algorithm and key distribution are the most important parts for CAS. In this paper, we proposed a new key distribution scheme based on hierarchical access control for conditional access system in digital television broadcast. Our key distribution scheme can greatly reduce the encrypting computation and acquire higher efficiency and security. Moreover, the proposed scheme is more flexible in processing joining and leaving of subscriber, which is very important for service provider to manage the subscriber. [ABSTRACT FROM AUTHOR]

One of the enablers for new consumer electronics based products to be accepted in to the market is the availability of inexpensive, flexible and multi-standard chipsets and services. DVB-T, the principal standard for terrestrial broadcast of digital video in Europe, has been extremely successful in leading to governments reconsidering their targets for analogue television broadcast switch-off. To enable one further small step in creating increasingly cost effective chipsets, the ODFM deterministic equalizer has been presented before with its application to DVB-T. This paper, discusses the test set-up of a DVB- T compliant baseband simulation that includes the deterministic equalizer and DVB-T standard propagation channels. This is then followed by a presentation of the found inner and outer Bit Error Rate (BER) results using various modulation levels, coding rates and propagation channels in order to ascertain the actual performance of the deterministic equalizer. [ABSTRACT FROM AUTHOR]

We obtain in this paper generic expressions in M for the exact bit-error rate of the generalized hierarchical 2/4/ . . . /M-phase-shift keyed constellations over additive white Gaussian noise (AWGN) and fading channels. For the AWGN case, these expressions are in the form of a weighted sum of Pawula F-functions and are solely dependent on the constellation size M, the carrier-to-noise ratio, and a constellation parameter which controls the relative message importance. The mathematical expressions are illustrated with some select numerical examples. [ABSTRACT FROM AUTHOR]

Considers a multiuser multiple-input multiple-output (MIMO) Gaussian broadcast channel, where the transmitter and receivers have multiple antennas. MIMO capacity region; Computational complexity required for obtaining the dirty paper achievable region.

Due to their low computational requirements, two-dimensional semiempirical wave propagation algorithms are still indispensable tools for terrestrial mobile communications and radio broadcasting coverage predictions in the very high and ultrahigh frequency bands. In this paper, we discuss various improvements of an algorithm based on digital terrain data. The algorithm combines the basic empirical propagation curves of Okumura et al. [1] with terrain adaptive propagation curves derived from Freshet zone clearance analyses of several terrain subsections. Also, a multiple knife-edge diffraction algorithm with approximate evaluation of the Kirchhoff diffraction integrals is applied when the line of sight is obstructed. Prediction quality is further improved by a robust algorithm for determination of effective transmitter antenna heights, and land usage along the terrain profile different from "open terrain" is considered by a multilevel Fresnel zone blockage evaluation. Prediction errors with standard deviations of about 6 to 7 dB were found for a great variety of measurements th ilar and moderately undulating terrain. Transmitter stations with very high antennas (more than 200 m) caused larger standard deviations of the prediction errors. However, improvements of the predictions could be achieved in these cases by evaluating street orientations with respect to the direct path. [ABSTRACT FROM AUTHOR]

This paper presents an orthogonal frequency division multiplexing (OFDM) system, which through the use of sub-optimal PTS combined with a preset threshold, achieves low computational complexity to find optimum weighting factors. A specific bit in weighting factor that leads to a smaller peak-to-average power ratio (PAP) is identified from the sub-optimum method. And a specific threshold, which found from the OFDM frame probability, is also applied to reduce computational complexity. The performance of the proposed method was slightly degraded compared to that of optimum method, PTS. However, the complexity of the proposed method was remarkably lower than that of optimum method. [ABSTRACT FROM AUTHOR]

One way to broadcast a popular video is to use multiple channels, each broadcasting a portion of the video periodically. Among the many schemes falling in this category, this paper focuses on several representative schemes (such as FB [15], [18], Pagoda [22], [24], and RFS [26]), which all share a FSFC property by repeatedly broadcasting the First Segment of the video on the First Channel. We propose a general Borrow-and-Return model can be immediately applied to any scheme owning the FSFC property to reduce the viewer's waiting time without increasing the number of channels required. Given a group of videos, the basic idea is to lend the free time slots of videos without viewers to those videos with viewers to speedup the latter's transmission. By so doing, some bandwidth may be vacated by the borrowing videos to benefit others' transmission. Effectiveness of this model is analyzed by applying it to the FB scheme. [ABSTRACT FROM AUTHOR]

In a multihop mobile ad hoc network, broadcasting is an elementary operation to support many applications. In [15], it is shown that naively broadcasting by flooding may cause serious redundancy, contention, and collision in the network, which we refer to as the broadcast storm problem. Several threshold-based schemes are shown to perform better than flooding in that work. However, how to choose thresholds also poses a dilemma between reachability and efficiency under different host densities. In this paper, we propose several adaptive schemes, which can dynamically adjust thresholds based on local connectivity information. Simulation results show that these adaptive schemes can offer better reachability as well as efficiency as compared to the results in [15]. [ABSTRACT FROM AUTHOR]

A site broadcasting its local value to all other sites in a fault-prone environment is a fundamental paradigm in constructing reliable distributed systems. Time complexity lower bounds and network connectivity requirements for reliable broadcast protocols in point-to-point communication networks are well known. In this paper, we consider the reliable broadcast problem in distributed systems with broadcast networks (for example, Ethernets) as the basic communication architecture. We show how properties of such network architectures can be used to effectively restrict the externally visible behavior of faulty processors. We use these techniques to derive simple protocols that implement reliable broadcast in only two rounds, independent of the failure upper bounds. [ABSTRACT FROM AUTHOR]

Communication in a broadcast protocol multiprocessor (BPM) is inherently different from that in distributed systems formed by explicit links between processors. A message broadcast by a processor in a BPM is received directly by all other processors in the network instead of being restricted to only one processor. Broadcasting is an inexpensive way of communicating with a large number of processors on a BPM. In this paper I will describe a new approach to user-level distributed programming called broadcast programming, i.e., distributed programs written as cooperating broadcasting sequential processes (BSP). Existing concurrent programming languages do not provide facilities to exploit the broadcast capability of a 8PM. The idea of distributed pro- grams written as BSP is tailored to exploiting a BPM architecture but is not restricted to such an architecture-however, implementation of the broadcast capability may not be as efficient on other architectures. I will illustrate the utility and convenience of broadcast programming with many examples. These examples will also be used to explore the suitability and advantages of BSP and to determine appropriate facilities for BSP. [ABSTRACT FROM AUTHOR]

Describes the above-named upcoming conference event. May include topics to be covered or calls for papers. [ABSTRACT FROM AUTHOR]

This paper considers multiple-antenna broadcast channels (BCs) with multi-dimensional space-time modulation schemes, created by various allocations of signal dimensions to transmit antennas. The signal dimensions are divided into disjoint subsets, where one is shared between all users, and each of the others are assigned to different users. This model encompasses several practical single point to multi-point wireless communication systems employing multiple antennas. Assuming space and time dispersive channels, we consider the transmission rates that are achieved by applying dirty paper coding (DPC) at the transmitter, present inner and outer bounds for the DPC rate region, and study the effects of space-time modulation formats. At high SNR, we consider the limit form of these bounds, derive an achievable multiplexing gain region, and study the effects of sharing signal dimensions between users. [ABSTRACT FROM PUBLISHER]

A broadcast encryption scheme enables a center to distribute keys and/or broadcast a message in a secure way over an insecure channel to an arbitrary subset of privileged recipients. In this paper, an ID-based broadcast encryption scheme is proposed, by which a center can distribute keys over a network, so that each member of a privileged subset of users can compute a specified key. Then a conventional private-key cryptosystem, such as DES, can be used to encrypt the subsequent broadcast with the distributed key. Because a key distribution can be done in an encrypted broadcast without any key pre-distribution, re-keying protocols for group membership operations can be simplified, a center can use the ID-based broadcast encryption scheme again to distribute a new and random session key. The ID-based broadcast encryption scheme from bilinear pairings is based on a variant of the Boneh-Franklin identity based encryption scheme. [ABSTRACT FROM AUTHOR]

Describes the above-named upcoming conference event. May include topics to be covered or calls for papers. [ABSTRACT FROM AUTHOR]

This letter presents the author's appreciation of all those people who volunteered their time and talents during 2003 to the peer review and publication of the journal "IEEE Transactions on Broadcasting." The author extends special thanks to IEEE Broadcast Technology Society Publications chairman and associate editors who shared their valuable time and broadcast engineering expertise in managing a steady flow of papers and evaluating manuscripts through the peer review process. The author says that numerous engineering professionals have volunteered their time expertise as peer reviewers during 2003 and these reviewers are critical to the peer review process and ensure that the journal publishes high quality and timely papers.