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Broadcasting, IEEE Transactions on

Issue 2 • Date June 2003

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Displaying Results 1 - 15 of 15
  • 16QAM symbol timing recovery in the upstream transmission of DOCSIS standard

    Page(s): 211 - 216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (471 KB) |  | HTML iconHTML  

    This paper investigates the performance of the digital symbol timing recovery schemes for 16QAM upstream transmission of the DOCSIS standard. Two forms of nonlinearity are considered: the magnitude square operation and the delay multiplication operation, both of which generate the output signal that contains the symbol timing information. The detailed analysis for the magnitude square timing recovery is given in the digital domain, and consequently the symbol timing estimate can be directly obtained by the discrete Fourier transform. The simulation results show that the magnitude square timing recovery and delay multiplication timing recovery algorithms suffer from the same problem that the estimation error is reduced slowly at high signal-to-noise ratios due to the effect of self-noise. To this end, the third scheme, which is the magnitude square timing recovery with prefilter, is examined. This scheme shows a superior performance and a comparison with the results of the other two schemes is made. View full abstract»

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  • Implementation of HDTV PES combiner based on horizontal six-block segmentation

    Page(s): 217 - 220
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (307 KB) |  | HTML iconHTML  

    We present the hardware design of the packetized elementary stream (PES) combiner in the third generation HDTV encoder in China, which is a key part in the HDTV encoding system. In our design, the input HDTV video signal is divided into six sub-images, and a horizontal six-block segmentation method is implemented in the HDTV encoder. Each of the sub-images is coded by one MP@ML encoding ASIC, which works at a different bitrate. The PES combiner combines all the output bit streams into one HDTV PES. The coding parameters and timing stamps are modified according to the requirements of MPEG-2 MP@HL. All these PES combiner functions are implemented by one complex programmable logic device (CPLD), which makes the whole encoding system compact and stable. The detailed discussions of hardware design are also presented in this paper. Experimental results show that the quality of decoded image is improved over the past two generation encoders, and constant bitrate can be maintained at the same time. View full abstract»

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  • Analysis and optimization of DS-CDMA systems with time-limited partial response chip waveforms

    Page(s): 202 - 210
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (874 KB) |  | HTML iconHTML  

    Conventional direct sequence code division multiple access systems (DS-CDMA) using offset quadrature phase shift key (OQPSK) usually employ a strictly bandlimited partial response square-root raised cosine pulse as the chip waveform. They have the disadvantage of large envelope fluctuation that will incur performance degradation due to the intermodulation and bandwidth enlargement caused by post nonlinear processing. To improve the performance of DS-CDMA systems, the chip waveform and receiver should be properly selected. This paper presents a systematic performance analysis of a matched filter receiver and zero-forcing filter (ZF) receiver for DS-CDMA using a time-limited partial response chip waveform. Nevertheless the systematic performance analysis is applicable to bandlimited chip pulse as well. For the zero-forcing filters, we propose to select the frequency responses that satisfy the first Nyquist criterion. With this class of filters, we can choose the roll-off factor to minimize the total power of multiple access interference and noise power. The zero-forcing filter with proper choice of roll-off factor, referred to as optimum ZF, yields a performance better than the matched filter counterpart. The bit error rate (BER) performance of the optimum ZF with superposed quadrature amplitude modulation signal as the time pulse waveform is evaluated. It is shown that the optimum ZF provides better BER performance than conventional OQPSK and minimum shift keying, and its envelope uniformity is much better than that of OQPSK. View full abstract»

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  • Broadcasting video with the knowledge of user delay preference

    Page(s): 150 - 161
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    In designing a video broadcasting system, the delay preference of a user is traditionally regarded as unknown. In fact, such preference can be known upon user's arrival by employing some techniques such as: (i) delay-dependent charging, where users are offered different levels of pay-per-view (PPV) depending on the maximum delay they are willing to tolerate; or (ii) reservation, where a user specifies the exact play-time of a movie in advance, and he/she is charged according to the length of the reservation period. We explore, for the first time, the impact of such delay knowledge on request scheduling and system cost in terms of user loss and stream requirement. For delay-dependent charging, we propose "delay-aware broadcasting" (DAB) and its variant based on reservation (DAB-r), where allocation of server streams is driven by the delay tolerance of a user. DAB-r offers differentiated grade of services according to user PPV (and thereof classes). As compared with a system where user delay preference is not known, our schemes achieve substantially lower user loss rate, higher revenue, and better fairness. Regarding reservation system, we consider a scheme where clients can pre-buffer video data. Unicast streams are used to merge requests back to the on-going broadcast streams. We show that a reservation system achieves substantially lower stream requirement as compared to an on-demand system based on "patching". View full abstract»

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  • A scalable video-on-demand system using multi-batch buffering techniques

    Page(s): 178 - 191
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (685 KB) |  | HTML iconHTML  

    A video-on-demand (VoD) system delivers videos on demand over an installed network. Due to the large size of digitized videos, expensive video servers with high I/O capability are needed in order to provide VoD services in metropolitan areas. In addition, there is a great need for efficient networking distribution/interaction schemes so that the video servers can serve as many clients as possible. In particular, because of scalability problems, the classical unicast VoD system is not suitable for large-scale deployments. In this paper, a highly scalable VoD system with a low per-user cost is described and evaluated. We first analyze the performance degradation problems using recently proposed VoD systems, namely batched and centralized-buffer VoD systems that occur during the handling of interactions. Then a new system called the multi-batch buffer (MBB) system, which attempts to solve these problems, is proposed. The proposed system handles a majority of interaction requests by scalable buffering techniques employed in the buffer of the local servers and the set-top boxes (STB). We have performed extensive simulation for the analysis and performance evaluation of our proposed VoD system. The simulation results demonstrate that our VoD system is very scalable and outperforms related state-of-the-art VoD systems. View full abstract»

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  • A borrow-and-return model to reduce client waiting time for broadcasting-based VOD services

    Page(s): 162 - 169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (631 KB) |  | HTML iconHTML  

    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, Pagoda, and RFS ), 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 that 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. The effectiveness of this model is analyzed by applying it to the FB scheme. View full abstract»

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  • Effects of phase noise on performance of OFDM systems using an ICI cancellation scheme

    Page(s): 221 - 224
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (389 KB) |  | HTML iconHTML  

    This paper investigates the effects of phase noise on the performance of orthogonal frequency division multiplexing (OFDM) systems using an intercarrier interference (ICI) cancellation scheme. In this case, the common phase error (CPE) and ICI caused by phase noise depend on the overall spectrum of each weighted group of subcarriers rather than on the spectrum of each individual subcarrier. This means that the system performance can be improved by filtering the phase noise to fit a particular spectrum. It is shown that the ICI cancellation scheme can significantly improve the bit error rate (BER) performance in the presence of phase noise. View full abstract»

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  • Performance degradation of analog FM system due to spread spectrum overlay

    Page(s): 113 - 123
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3590 KB) |  | HTML iconHTML  

    The investigation of spectrum overlay of a spread spectrum system on the existing narrowband FM broadcasting system is presented. The overlaid spread spectrum (SS) system is assumed to utilize direct sequence (DS) spreading, using maximal length pseudorandom sequences. We studied the performance degradation of the analog FM system due to the interference produced by the SS signal, through laboratory subjective and objective measurements, for various types of spreading scenarios and for different carrier frequency differences (Δf). The RF protection ratios for the FM receivers are derived, along with SINAD measurements. Finally, these experimental results have been compared with the theoretical study of the FM receiver's audio frequency SNR output due to SS interference. View full abstract»

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  • Modeling of HPA and HPA linearization through a predistorter: Global Broadcasting Service applications

    Page(s): 132 - 141
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    This paper presents a technique to linearize the high power amplifier (HPA) through a predistorter (PD). The characteristics of the PD circuit are derived based on the extension of Saleh's model for HPA and a simple linear-log model. Numerical results are shown for Global Broadcasting Service (GBS) applications. View full abstract»

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  • Peak-to-average power reduction using partial transmit sequences: a suboptimal approach based on dual layered phase sequencing

    Page(s): 225 - 231
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (972 KB) |  | HTML iconHTML  

    A high peak-to-average power ratio (PAPR) is a major shortcoming in multicarrier systems, as it causes nonlinearity in the transmitter, degrading the performance of the system significantly. Partial transmit sequences (PTS) is one of the best methods in reducing PAPR, in which the information-bearing subcarriers are divided into M disjoint subblocks, each controlled by a phase rotation factor which brings PAPR down. Though PAPR reduction by PTS is more effective with more subblocks, there is a corresponding exponential increase in complexity. In this paper, a novel implementation of PTS is presented, in which a dual-layered approach is employed to reduce the complexity. View full abstract»

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  • SDRAM: a SD channel-based multicast scheme on ATM networks for multimedia transmissions

    Page(s): 192 - 201
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (538 KB) |  | HTML iconHTML  

    Multicast delivery has become more and more important in modern multimedia applications. VoD and videoconferences are two examples. Multimedia integrates texts, audios, videos and still images in a variety of applications. The data in this media can be time critical in terms of maximum delay and delay jitter. In order to satisfy all these applications, the network needs to have an efficient multicasting mechanism using the true capability of ATM networks. In the native solution, a separate connection can be set up from the source to each group node, also called full connectivity. The full connectivity needs O(N2) connections, where N is the number of nodes in a group. Instead, we can have one tree spanning all the participants. Multicast using a single shared tree has become the trend. In this paper, we propose a bi-directional multipoint-to-multipoint multicast scheme, a SD channel-based Multicast with Round-robin Access (SDRAM), for ATM networks, which uses a single tree for a multicast group consisting of multiple participants that are either senders, receivers, or a mix of both. We first discuss why the resequencer model will not be suitable for multimedia traffic, then propose the SDRAM scheme to solve the problems, and finally compare our scheme with the resequencer model through simulation. Results show the mean queuing delays and mean inter-PDU delays of our scheme are not sensitive to mean PDU size while the mean queuing delays and mean inter-PDU delays of the resequencer scheme are very sensitive to mean PDU size. View full abstract»

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  • Multi-carrier PAP reduction method using sub-optimal PTS with threshold

    Page(s): 232 - 236
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (333 KB) |  | HTML iconHTML  

    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 the optimum method. View full abstract»

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  • FFT and IMDCT circuit sharing in DAB receiver

    Page(s): 124 - 131
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2145 KB) |  | HTML iconHTML  

    This paper proposes a circuit-sharing approach to improve efficiency for the key digital audio broadcasting (DAB) techniques, i.e., MPEG1-audio decoding and orthogonal frequency division multiplexing (OFDM). Because OFDM's fast Fourier transform (FFT) requires heavy computational power for implementation, a single butterfly processing element (BPE) is adopted to reduce the chip area required for FFT. Furthermore, by modifying the BPE logical combinational circuit, both IMDCT (inverse modified discrete cosine transform) and FFT functions can be obtained simultaneously from a single VLSI chip. Therefore, the proposed technique reduces hardware overhead, enhances circuit efficiency and significantly reduces the cost of DAB receivers. The proposed circuit is simulated as a VLSI prototype chip using a 0.35 μm CMOS process, with a chip area of about 22.09 mm2 and a total gate count of approximately 10839 (excluding ROM and RAM). View full abstract»

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  • SER performance evaluation and optimization of OFDM system with residual frequency and timing offsets from imperfect synchronization

    Page(s): 170 - 177
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (507 KB) |  | HTML iconHTML  

    This paper deals with the effects of residual timing and frequency offsets on the symbol error rate (SER) performance of an orthogonal frequency division multiplexing (OFDM) system. The synchronization of an OFDM system generally consists of a coarse frequency and timing acquisition stage and a refine stage. Due to the presence of Gaussian noise, channel distortions and implementation losses of synchronization and equalization algorithms, residual frequency and timing offsets always exist for an OFDM receiver. The residual frequency and timing offsets are proven to be Gaussian distributed, with their corresponding variances determined. The reception process of an OFDM signal with frequency and timing offsets is analyzed. A closed-form analytical result on the SER of an OFDM system with residual synchronization errors is derived. Computer simulations and analyses show that the frequency and timing offsets affect the OFDM subcarriers differently. With this observation, a new technique is proposed to minimize the SER of the OFDM systems by adjusting the distribution of transmission power among the subcarriers. View full abstract»

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  • A comparative investigation on channel estimation algorithms for OFDM in mobile communications

    Page(s): 142 - 149
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (521 KB)  

    A comparative investigation on various channel estimation algorithms for OFDM system in the mobile communication environment is presented and analyzed in terms of computational complexity, mean square error, and bit error rate in this paper. As a result, Wiener filter estimation shows the best error performance. Concerning the computational complexity as well as the performance, however, the piecewise linear estimator is considered as a proper choice when the reference signal spacing is relatively narrow. And the cubic-spline estimator is a good alternative to the Wiener filter estimation if the reference signal spacing is wider than the coherent bandwidth of transmission channel. View full abstract»

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Aims & Scope

IEEE Transactions on Broadcasting covers the field of broadcast technology, including the production, distribution, transmission, and propagation aspects of broadcasting.

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Meet Our Editors

Editor-in-Chief
Yiyan Wu
Communications Research Ctr Canada