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The 2010 Scott Helt Memorial Award was awarded to Bogdan Ciubotaru, Gabriel-Miro Muntean, and Gheorghita Ghinea for their paper, "Objective Assessment of Region of Interest-Aware Adaptive Multimedia Streaming Quality," which appeared in the IEEE Transactions on Broadcasting, vol. 55, pp. 202-212, June 2009. [ABSTRACT FROM AUTHOR]

The new ways to consume and deliver media content in a wireless environment have led to a significant increase in the demand for spectrum resources. In addition, the arrival of next-generation wireless communication technologies has encouraged the creating of new verticals targeting novel applications, such as industry IoT, e-health, distance learning, smart city, smart-metering. All these new use cases are centred on an IP-based infrastructure. A promising alternative to satisfy the demand for resources is to incorporate a new delivery mechanism that can alleviate the congestion of classical cell-based point-to-point broadband wireless infrastructures. The best-positioned candidate is the next-generation Digital Terrestrial Television system, which offers a very spectrum efficient one-to-many PHY, and for the first time, native IP support. In ATSC 3.0, the whole system was designed with an IP-centric view, whereas DVB has created standards to deliver services to generic IP devices (DVB-I). Nevertheless, there is still a last missing piece to bring the broadcast infrastructure to the IP-connected world: a Broadcast Core Network (BCN). In this paper, the basics of a BCN are presented with new use cases that are attractive to Broadcast Network Operator (BNO). A possible roadmap towards implementation is described, and a service-based architecture for a BCN is presented and discussed. [ABSTRACT FROM AUTHOR]

In this correspondence, we show that solutions to the multiple description coding problem and the broadcast channel coding problem share a common encoding procedure: successive source encoding. We use this connection as the basis for establishing connections between the achievable multiple description rate region and Marton's region for broadcast channels. Specifically, we show that Marton's encoding scheme can be viewed as a multiple description coding procedure. We also explore the dual problem, namely, the relationship between successive channel decoding in multiple access communication and distributed source coding. By illuminating these connections to multiple description, we hope to motivate a solution to what remains a mostly unsolved problem. [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]

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]

Self-healing key distribution schemes allow group managers to broadcast session keys to large and dynamic groups of users over unreliable channels. Roughly speaking, even if during a certain session some broadcast messages are lost due to network faults, the self-healing property of the scheme enables each group member to recover the key from the broadcast messages he has received before and after that session. Such schemes are quite suitable in supporting secure communication in wireless networks and mobile wireless ad-hoc networks. Recent papers have focused on self-healing key distribution, and have provided definitions, stated in terms of the entropy function, and some constructions. The contribution of this paper is the following. • We analyze current definitions of self-healing key distribution and, for two of them, we show that no protocol can achieve the definition. • We show that a lower bound on the size of the broadcast message, previously derived, does not hold. • We propose a new definition of self-healing key distribution, and we show that it can be achieved by concrete schemes. • We give some lower bounds on the resources required for implementing such schemes, i.e., user memory storage and communication complexity. We prove that the bounds are tight. [ABSTRACT FROM AUTHOR]

Wireless broadcasting systems employ multiple retransmissions to guarantee the correct reception of each packet. The traditional hybrid automatic retransmission request (HARQ) protocol retransmits one packet per slot. Hence, a large amount of retransmissions is required to correctly receive all the packets, which leads to low spectrum efficiency. In this paper, we propose a Network-coding-and-distributed-Turbo-Coding-based type-III HARQ (NTC-HARQ) protocol, including an xoring Network Coding Combined (XNCC) retransmission strategy at the access node (AN) and a joint network–turbo decoding (JNTD) strategy at the user equipment (UE). Specifically, to reduce the overall number of retransmissions, lost packets of different UEs are network coding (NC) combined at the AN by utilizing the XNCC strategy. The soft information of the lost packet at each UE can be recovered from the received network-coded retransmission packet by using the proposed xoring soft network decoder. The recovered soft information of the UE's lost packet is combined with the local undecodable soft information of the same packet to form a distributed turbo code. A Chase-combining-based distributed turbo decoder is proposed to perform turbo decoding, which introduces coding gain and improves packet-error-rate (PER) performance. Theoretical analyses and simulation results show that the average-number-of-transmission performance of the proposed NTC-HARQ protocol outperforms that of the XNCC-based type-I HARQ protocol, the traditional NC-based HARQ protocol, and the JNTD-based protocol. [ABSTRACT FROM PUBLISHER]

In this paper, a downlink system in which a single-antenna base station communicates with K single antenna users over a time-correlated fading channel is considered. It is assumed that each receiver knows its own channel state, while the rate of the channel variation for all users and the corresponding initial fading gains are known to the base station. The average (per channel use throughput of the system is studied by applying various adaptive signaling schemes. Assuming a large number of users in the system, it is shown that using a scheduling scheme in which the base station transmits to the user with the maximum initial fading gain while using a fixed codeword length for all users, achieves the order of the maximum throughput. Moreover, an alternative scheduling scheme is proposed (by accounting for users' delays) and shown to achieve the optimum long-term fairness, while preserving the order of the maximum throughput. [ABSTRACT FROM AUTHOR]

This paper studies capacity bounds for discrete memoryless broadcast channels with confidential messages. Two private messages as well as a common message are transmitted; the common message is to be decoded by both receivers, while each private message is only for its intended receiver. In addition, each private message is to be kept secret from the unintended receiver where secrecy is measured by equivocation. Both inner and outer bounds are proposed to the rate equivocation region for broadcast channels with confidential messages. The proposed inner bound generalizes Csiszár and Körner's rate equivocation region for broadcast channels with a single confidential message, Liu et al.'s achievable rate region for broadcast channels with perfect secrecy Marton's and Gel'fand-Pinsker's achievable rate region for general broadcast channels. The proposed outer bounds, together with the inner bound, help establish the rate equivocation region of several classes of discrete memoryless broadcast channels with confidential messages, including the less noisy, deterministic, and semideterministic broadcast channels. Furthermore, specializing to the general broadcast channel by removing the confidentiality constraint, the proposed outer bounds reduce to new capacity outer bounds for the discrete memory broadcast channel. [ABSTRACT FROM AUTHOR]

With the increasing popularity of wireless networks and mobile computing, data broadcasting has emerged as an efficient way of delivering data to mobile clients having a high degree of commonality in their demand patterns. This paper proposes an adaptive wireless push system that operates efficiently in environments characterized by high broadcasting speeds and a-priori unknown client demands for data items. The proposed system adapts to the demand pattern of the client population in order to reflect the overall popularity of each data item. We propose a method for feedback collection by the server so that the client population can enjoy a performance increase in proportion to the broadcasting speed used by the server. Simulation results are presented which reveal satisfactory performance in environments with a-priori unknown client demands and under various high broadcasting speeds. [ABSTRACT FROM AUTHOR]

This paper describes a highly accurate carrier-frequency synchronization scheme for actively, automatically locking multiple, remotely located AM broadcast transmitters to a common frequency/timing reference source such as GPS. The extremely tight frequency lock (to ~1 part in 109 or better) permits the effective elimination of audible and even sub-audible beats between the local (desired) station's carrier signal and the distant stations' carriers, usually received via skywave propagation during the evening and nighttime hours. These carrier-beat components cause annoying modulations of the desired station's audio at the receiver and concurrent distortion of the audio modulation from the distant station(s) and often cause listeners to "tune out" due to the low reception quality. Significant reduction or elimination of the beats and related effects will greatly enlarge the effective (interference-limited) listening area of the desired station (from 4 to 10 times as indicated in our tests) and simultaneously reduce the corresponding interference of the local transmitter to the distant stations as well. In addition, AM stereo (CQUAM) reception will be particularly improved by minimizing the phase shifts induced by co-channel interfering signals; hybrid digital (HD) signals will also benefit via reduction in beats from analog signals. The automatic frequency-control hardware described is inexpensive ($1000-$2000), requires no periodic recalibration, has essentially zero long-term drift, and could employ alternate wide-area frequency references of suitable accuracy, including broadcasts from WWVB, LORAN-C, and equivalent sources. The basic configuration of the GPS-disciplined oscillator which solves this problem is extremely simple. The main oscillator is a conventional high-stability quartz-crystal type. To counter long- term drifts, the oscillator is slightly adjusted to track a high-precision source of standard frequency obtained from a specialized GPS receiver (or other source), usually at 10.000 MHz. This very stable local reference frequency is then used as a clock for a standard digitally implemented frequency synthesizer, which is programmed to generate the specific carrier frequency desired. The stability of the disciplining source, typically ~1 part in 109 to 1011,is thus transferred to the final AM transmitter carrier output frequency. [ABSTRACT FROM AUTHOR]

This paper aims to combine adaptive modulation and coding with layered video coding to improve the quality of video services to users experiencing differing radio conditions, in the context of broadcast and multicast standards such as MBMS and BCMCS. We propose an optimal radio resource allocation algorithm which maximizes a general performance metric for a video session in polynomial time. We show that system-wide optimal resource allocation can be obtained by combining our algorithm with a simple two-step decomposition of the system. In some configurations frequent re-allocations of resource are required, so we also present a sub-optimal allocation algorithm which runs in near linear time. Simulation results show better video quality than existing resource allocation schemes over a range of conditions, and also suggest that the difference between the performance of optimal and sub-optimal solutions is less than 3%. [ABSTRACT FROM AUTHOR]

Convergence between broadcasting services and telecommunication services and provisioning of rich media services are two major requirements that recent mobile broadcast TV services try to satisfy. Although there exist independent technologies and international standards for each of the requirements, few efforts have been paid for providing solutions supporting these requirements together. In this paper, we present a standard-based implementation for mobile handsets in support of rich media enabled mobile broadcast TV services. [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]

Video-on-demand (VoD) is an essential technology for many multimedia applications. However, it remains challenging to efficiently deliver on-demand streams to a large number of receivers in a heterogeneous network environment. Although a number of VoD broadcasting protocols have been proposed for heterogeneous receivers, these protocols considers only single-bit-rate VoD services, which cannot satisfy the diverse quality-of-service requirements of heterogeneous receivers. In this paper, we propose a unified approach to heterogeneous VoD broadcasting, called unified heterogeneous broadcasting (UHB). As a unified approach, UHB is design to integrate different VoD broadcasting protocols and different scalable video coding schemes. The main merits of UHB are threefold. First, unlike conventional VoD broadcasting protocols, UHB supports multiple-bit-rate VoD services. Second, UHB is capable of adapting to network bandwidth fluctuations. Third, UHB enables each heterogeneous receiver to obtain the best visual quality by selecting the optimum system joining time. Our performance evaluation results indicate that UHB is superior to conventional heterogeneous VoD broadcasting protocols under various network conditions. [ABSTRACT FROM AUTHOR]

This paper presents a bidirectional interactive ontents player for Terrestrial Digital Multimedia ~roadcasting (T-DMB). The presented player is capable of ending user requests to a proper return channel server using nformation included in a scene presentation. The player rovides functionality to combine requested data received via ommunication networks with the initially broadcasted ,ontents to present additional information to users. The result a request transmitted back through the broadcasting ietwork can also be presented properly using the presented ilayer'. [ABSTRACT FROM AUTHOR]

To support large-scale Video-on-Demand (VoD) services in a heterogeneous network environment, either a replication or layering approach can be deployed to adapt the client bandwidth requirements. With the aid of the broadcasting and caching techniques, it has been proved that the overall performance of the system can be enhanced. In this paper, we explore the impact on the broadcasting schemes coupled with proxy caching and develop an analytical model to evaluate the system performance in a highly heterogeneous network environment. We develop guidelines for resources allocation, transmission strategies as well as caching schemes under different system configurations. The model can assist system designers to study various design options as well as perform system dimensioning. Moreover, a systematic comparison between replication and layering is performed. From the results, it can be seen that the system performance of layering is better than that of replication when the environment is highly heterogeneous even if the layering overhead is higher than 25%. In addition, it is found that the system blocking probability can be further reduced by exploring the broadcast capability of the network if the proxy server cannot store all the popular videos. [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]

In this paper, we introduce a new communications paradigm, namely, reliable neighborcast, and present a reliable neighborcast protocol (RNP) that operates as an overlay on the existing reliable broadcast protocols. The protocol is intended for vehicle-to-vehicle communications networks that communicate the speed, position, and state of nearby vehicles to coordinate or control their operation. The implementation of RNP that we describe operates on top of overlapping groups that use the mobile reliable broadcast protocol and provides the guarantees and characteristics of that protocol to each neighborhood. The efficiency of the overlays—defined as the fraction of the received messages that apply to a neighborhood—widely varies. We present an efficient overlay for 1-D networks, which is implemented in many highway applications. The characteristics of mobility are considered, and techniques are presented to eliminate delays as vehicles change neighborhoods and to move the underlying broadcast groups with the general flow of traffic. [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]

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

In this paper, we develop optimization techniques for linear zero-forcing (ZF) multiple-input, multiple-output (MIMO) broadcast (BC) precoders. A computationally efficient technique based on QR-update algorithms for implementing this optimization is then proposed. The application of the proposed ZF precoders and decoders to systems with both large and small numbers of users is considered. The proposed optimization technique is also shown to perform very well in conjunction with nonlinear Tomlinson- Harashima precoding. Both coded and uncoded performances are considered. [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]

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]

Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to carrier frequency offset and symbol timing error. This paper deals with estimation method of integer frequency offset (IFO) without the aid of pilot symbols. The proposed IFO estimator exploits two consecutive identical OFDM data symbols with only change of phase. In order to improve the accuracy of the IFO estimator, receive diversity is adopted. To demonstrate the efficiency of the proposed IFO estimators, comparisons are made with other existing estimators in terms of error performance, estimation range, and complexity. [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, 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]

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 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 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]

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]

It has been demonstrated that turbo codes substantially outperform other codes, e.g., convolutional codes, both in the non-fading additive white Gaussian noise (AWGN) channel as well as multiple-transmit and multiple-receive antenna fading channels. Moreover, it has also been reported that turbo codes perform very well in fast fading channels, but perform somewhat poorly on slow and block fading channels of which the broadband fixed wireless access (FWA) channel is an example. In this paper, we thoroughly compare the performance of turbo-coded and convolutional-coded broadband FWA systems both with and without antenna diversity under the condition of identical complexity for a variety of decoding algorithms. In particular, we derive mathematical expressions to characterize the complexity of turbo decoding based on state-of-the-art Log-MAP and Max-Log-MAP algorithms as well as convolutional decoding based on the Viterbi algorithm in terms of the number of equivalent addition operations. Simulation results show that turbo codes do not offer any performance advantage over convolutional codes in FWA systems without antenna diversity or FWA systems with limited antenna diversity. Indeed, turbo codes only outperform convolutional codes in FWA systems having significant antenna diversity. [ABSTRACT FROM AUTHOR]

In a world driven by the accessibility of data for business, for communication and entertainment, but one populated by an increasingly nomadic society, it is no surprise that the appetite for wireless services continues to grow. The limitations of existing technologies however, particularly for wireless multi-casting and broadcasting, suggest that new approaches are needed to allow users to access services in the all wireless world. A popular approach for improving wireless services proposes to equip Mobile Terminals (MTs) with more than one radio interface to enable access to services in an always best connected paradigm. One such architecture envisages a co-operating overlay network, or inter-network, that comprises of a cellular telephony network and a digital broadcasting network. MTs in the inter-network have two corresponding radio interfaces and co-operation between the networks provide the user with seamless access to diverse services across the inter-worked platform. In this paper, we introduce novel location management proposals for co-operating overlay networks that incorporate a unidirectional broadcast overlay and provide a cost and latency analysis of the schemes. Our cost analysis demonstrates the soundness of the techniques and the value of the analyses as comparative evaluation tools. In particular, it is shown that there are a wide range of realistic operating conditions where the novel proposals presented here provide an optimum performance in cost terms. [ABSTRACT FROM AUTHOR]

Video broadcasting has been proved to be an efficient technique to increase the scalability of a video-on-demand (VoD) system. In this paper, we address the problems in providing interactive functions for VBR encoded videos in a broadcast VoD system. A traffic smoothing scheme is proposed to support the VCR functions in delivering VBR videos over CBR channels by the staggered broadcasting protocol. By introducing a small buffering delay, the customers are able to join back to the broadcasting groups after the interactive functions. A system model is then developed to determine the optimal parameters such that the system can meet the delay requirement as well as provide the expected quality of service to the customers. The results show that the proposed system framework is very efficient in terms of bandwidth requirement and buffering delay to provide interactive VoD services. [ABSTRACT FROM AUTHOR]

In this paper we present the results of a study that examines the user's perception—understood as both information assimilation and subjective satisfaction—of multimedia quality, when impacted by varying network-level parameters (delay and jitter). In addition, we integrate eye-tracking assessment to provide a more complete understanding of user perception of multimedia quality. Results show that delay and jitter significantly affect user satisfaction; variation in video eye path when either no single/obvious point of focus exists or when the point of attention changes dramatically. Lastly, results showed that content variation significantly affected user satisfaction, as well as user information assimilation. [ABSTRACT FROM AUTHOR]

Necessary and sufficient conditions for Logd(N, m, p) network to be point-to-point strictly nonblocking are known. Recently, Kabacinski and Danilewicz obtained necessary and sufficient conditions for the Log2 (N, 0, p) network to be broadcast strictly nonblocking. In this paper, we give necessary and sufficient conditions for Logd(N, m, p) to be f-cast strictly nonblocking for every f, thus covering the point-to-point case (f = 1) and the broadcast case (f = N) as special cases. [ABSTRACT FROM AUTHOR]

Commercial terrestrial digital multimedia broadcasting (T-DMB) service was launched on December 1st, 2005, in the Seoul metropolitan area of the Republic of Korea. As the world's first commercial terrestrial mobile multimedia broadcasting service, T-DMB garnered huge attention in the field of mobile broadcasting. This paper presents the history, system, and services of T-DMB. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel protocol for disseminating data in broadcast environments such that view consistency, a useful correctness criterion for broadcast environments, is guaranteed. Our protocol is based on concurrency control information that is constructed by the server and is broadcasted at the beginning of each broadcast cycle. The concurrency control information mainly captures read-from relations among update transactions. A salient feature of the protocol is that the concurrency control information is small in size, but precise enough for reducing unnecessary abortion of mobile transactions. The small-sized concurrency control information implies low communication overhead on broadcasting system. In addition, the computation overheads imposed by the algorithm on the server and the clients are low. We also address the reliability issue of wireless communication and the incorporation of a prefetching mechanism into our protocol. Simulation results demonstrate the superiority of our protocol in comparison with existing methods. Furthermore, we have extended our protocol to deal with local view consistency which requires that all mobile transactions submitted by the same client observe the same serial order of update transactions. [ABSTRACT FROM AUTHOR]

In this paper, we present the architecture of the interactive terrestrial digital multimedia broadcasting (T- DMB) system using the code division multiple access (CDMA) network for the new interactive broadcasting services. We also propose the novel structure of the novel platform based on Wireless Internet Platform for Interoperability (WIPI), which is the standard specifications for the mobile platform in Korea, to co-operate broadcasting and telecommunication. The proposed extended WIPI platform is implemented as an emulator on PC, and an integrated browser which shows multimedia broadcasting data including A V contents and interactive data returned through the telecommunication network, is developed to carry on with it. And then to verify the proposed platform and the interactive mobile broadcasting services, we implemented the integrated receiver as well as the data broadcasting server and the return channel server. Users can get interactive services or more information about broadcasting contents through CDMA network by using the proposed platform. This shows a possibility of new interactive services in digital broadcasting by using mobility of T-DMB and CDMA. [ABSTRACT FROM AUTHOR]

With the increasing demand of users in the broadcasting and communication services, coverage and interference prediction techniques need to be more accurate and applicable under different conditions. No single propagation model satisfies all the variations observed by the signal. Tuning of the existing models and development of new models are continuing and ongoing processes. With this objective in the present study path loss exponents have been deduced from various VHF/UHF measurements conducted over different regions of Indian subcontinent. These have been compared with the model of Perez-Vega and Zamanillo. The suitability of the model and the deviations has been presented in the paper. [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]

The staircase broadcasting scheme has optimal performance for the buffer storage and the disk transfer rate. However, this scheme sometime fails to provide the video data to the users in time. This limitation has been overcome in the conservative staircase scheme developed recently. In this scheme, the video segments are downloaded and stored at the client's site in their entirely before they are required for viewing. It does overcome the non-delivery of the video data to the users in time, but at the cost of extra resources. In this paper, we propose a new scheme named as generalized conservative staircase scheme, which requires less amount of resources and does not suffer from the problem of non-delivery of video data. The proposed scheme requires less amount of bandwidth by downloading the video data at slower rate. Thus this scheme has better performance for the viewer's waiting time and requires less amount of buffer storage and the disk transfer rate as compared to the conservative staircase scheme. [ABSTRACT FROM AUTHOR]

In Beyond Third Generation (B3G) wireless communications, multiple overlays of wireless access networks may cooperate to allow a user access to novel services, the future demands of which will significantly increase the load on location management systems within the networks. In this paper, we introduce the reader to our novel proposals for providing efficient Mobile Terminal (MT) Location Discovery and Paging across an inter-worked network consisting a Digital Video Broadcast (DVB) network and Universal Mobile Telecommunication System (UMTS) network. We further present numerical and simulation analyzes of our scheme. The numerical and simulation results allow broadcast and cellular network operators to configure their inter-worked system to reduce location management and paging costs whilst controlling average latency. Our .results demonstrate that our UMTS LA plus DVB paging schemes offer promise for efficient MT discovery in an inter-network environment that includes uni-directional broadcast network such as DVB; under realistic scenarios we achieve a minimum 4 times reduction in paging cost across the inter-network compared with independent paging systems. Furthermore, we briefly introduce further aspects of research that must be addressed in order to fully evaluate our proposals. [ABSTRACT FROM AUTHOR]

The allocation of certain frequency bands to both the broadcasting satellite service and the fixed service on a primary basis raises the issue of coexistence, whenever the two types of services are located in the same area and no coordination/agreement is effected. Although regulatory institutions have issued general guidelines concerning future systems, the effect of frequency sharing by numerous operating satellite earth terminals should be examined. The present paper provides an analytical methodology for the prediction of the carrier-to-noise plus interference ratio (CNIR) of broadcasting satellite systems, suffering from interference from an adjacent terrestrial link at frequencies above 10 GHz. The proposed model takes into account the aggravation of intersystem interference due to the spatial inhomogeneity of precipitation. A simplified version of the analytical model, useful for back of the envelope computations is also presented. Some interesting case studies are finally examined. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a new partial transmit sequence (PTS) orthogonal frequency division multiplexing (OFDM) scheme with low computational complexity. In the proposed scheme, 2n-point inverse fast Fourier transform (IFFT) is divided into two parts. An input symbol sequence is partially transformed using the first l stages of IFFT into an intermediate signal sequence and the intermediate signal sequence is partitioned into a number of intermediate signal subsequences. Then, the remaining n - l stages of IFFT are applied to each of the intermediate signal subsequences and the resulting signal subsequences are summed after being multiplied by each member of a set of W rotating vectors to yield W distinct OFDM signal sequences. The one with the lowest peak to average power ratio (PAPR) among these OFDM signal sequences is selected for transmission. The new PTS OFDM scheme reduces the computational complexity while it shows almost the same performance of PAPR reduction as that of the conventional PTS OFDM scheme. [ABSTRACT FROM AUTHOR]

It is well known that HPAs (High Power Amplifiers) are inherently nonlinear devices and many researches have focused on the predistortion for memoryless HPAs. However, memory effects of HPAs can no longer be ignored when communication systems have wider bandwidth. Memoryless predistortion techniques proposed previously seldom have satisfactory effectiveness for typical wideband applications such as OFDM (Orthogonal Frequency Division Multiplexing) systems. In this paper, an improved adaptive predistortion method called 2D LUT (2-dimension look-up table) with different accuracy levels is presented to linearize HPAs with memory effects. Simulation and experimental results show that 2D LUT implements excellent performance in mitigating the signal deterioration caused by memory effects, both rectifies the signal constellation distortion and suppresses the spectrum emission. Large scale matrix computation is also avoidable in these adaptive algorithms, which makes them feasible when a real-time system is necessary. [ABSTRACT FROM AUTHOR]

For the single-carrier M-ary differential phase-shift keying (MDPSK), the multiple-symbol differential detector, or the noncoherent maximum-likelihood sequence detector (NSD), and its three special cases, namely, the noncoherent one-shot detector, the linearly predictive decision-feedback (DF) detector, and the linearly predictive Viterbi receiver are reviewed based on a hierarchical interpretation. For the multicarrier transmission, the differential orthogonal frequency division multiplexing (OFDM) systems with diversity reception are discussed. It is well known that there are two types of differential OFDM systems, namely, the time domain differential OFDM (TD-OFDM) and the frequency domain differential OFDM (FD-OFDM). In this paper, the NSD and its special cases are incorporated to the differential OFDM systems. Furthermore, we provide a simple closed-form bit-error-rate (BER) expression for the differential OFDM systems utilizing the noncoherent one-shot detector with diversity reception in the time-varying multipath Rayleigh fading channels. Numerical results have revealed that, with multi-antenna diversity reception, the performance of the noncoherent one-shot detector is improved significantly. However, when only one or two receive antennas are available, the implementation of the linearly predictive DF detector or the linearly predictive Viterbi receiver is necessary for achieving better and satisfactory performance. [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]

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]

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]