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Popular Articles (April 2015)

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  • 1. Robust Preamble Design for Synchronization, Signaling Transmission, and Channel Estimation

    Publication Year: 2015 , Page(s): 98 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1153 KB) |  | HTML iconHTML  

    The European second generation digital video broadcasting standard introduces a P1 symbol. This P1 symbol facilitates the coarse synchronization and carries 7-bit transmission parameter signaling (TPS), including the fast Fourier transform size, single-input/single-output and multiple-input/single-output transmission modes, etc. However, this P1 symbol suffers from obvious performance loss over fading channels. In this paper, an improved preamble scheme is proposed, where a pair of optimal m sequences are inserted into the frequency domain. One sequence is used for carrier frequency offset (CFO) estimation, and the other carries TPS to inform the receiver about the transmission configuration parameters. Compared with the conventional preamble scheme, the proposed preamble improves CFO estimation performance and the signaling capacity. Meanwhile, without additional overhead, the proposed scheme exploits more active pilots than the conventional schemes. In this way, it can facilitate the channel estimation, improve the frame synchronization accuracy as well as enhance its robustness to frequency selective fading channels. View full abstract»

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  • 2. Channel estimation techniques based on pilot arrangement in OFDM systems

    Publication Year: 2002 , Page(s): 223 - 229
    Cited by:  Papers (494)  |  Patents (76)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (282 KB) |  | HTML iconHTML  

    Channel estimation techniques for OFDM systems based on a pilot arrangement are investigated. Channel estimation based on a comb type pilot arrangement is studied through different algorithms for both estimating the channel at pilot frequencies and interpolating the channel. Channel estimation at pilot frequencies is based on LS and LMS methods while channel interpolation is done using linear interpolation, second order interpolation, low-pass interpolation, spline cubic interpolation, and time domain interpolation. Time-domain interpolation is obtained by passing to the time domain by means of IDFT (inverse discrete Fourier transform), zero padding and going back to the frequency domain by DFT (discrete Fourier transform). In addition, channel estimation based on a block type pilot arrangement is performed by sending pilots in every sub-channel and using this estimation for a specific number of following symbols. We have also implemented a decision feedback equalizer for all sub-channels followed by periodic block-type pilots. We have compared the performances of all schemes by measuring bit error rates with 16QAM, QPSK, DQPSK and BPSK as modulation schemes, and multipath Rayleigh fading and AR based fading channels as channel models. View full abstract»

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  • 3. An Overview: Peak-to-Average Power Ratio Reduction Techniques for OFDM Signals

    Publication Year: 2008 , Page(s): 257 - 268
    Cited by:  Papers (219)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (764 KB) |  | HTML iconHTML  

    One of the challenging issues for Orthogonal Frequency Division Multiplexing (OFDM) system is its high Peak-to-Average Power Ratio (PAPR). In this paper, we review and analysis different OFDM PAPR reduction techniques, based on computational complexity, bandwidth expansion, spectral spillage and performance. We also discuss some methods of PAPR reduction for multiuser OFDM broadband communication systems. View full abstract»

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  • 4. Objective Video Quality Assessment Methods: A Classification, Review, and Performance Comparison

    Publication Year: 2011 , Page(s): 165 - 182
    Cited by:  Papers (70)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB) |  | HTML iconHTML  

    With the increasing demand for video-based applications, the reliable prediction of video quality has increased in importance. Numerous video quality assessment methods and metrics have been proposed over the past years with varying computational complexity and accuracy. In this paper, we introduce a classification scheme for full-reference and reduced-reference media-layer objective video quality assessment methods. Our classification scheme first classifies a method according to whether natural visual characteristics or perceptual (human visual system) characteristics are considered. We further subclassify natural visual characteristics methods into methods based on natural visual statistics or natural visual features. We subclassify perceptual characteristics methods into frequency or pixel-domain methods. According to our classification scheme, we comprehensively review and compare the media-layer objective video quality models for both standard resolution and high definition video. We find that the natural visual statistics based MultiScale-Structural SIMilarity index (MS-SSIM), the natural visual feature based Video Quality Metric (VQM), and the perceptual spatio-temporal frequency-domain based MOtion-based Video Integrity Evaluation (MOVIE) index give the best performance for the LIVE Video Quality Database. View full abstract»

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  • 5. An Indoor Broadband Broadcasting System Based on PLC and VLC

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1857 KB)  

    Visible light communication (VLC) using the light-emitting diode (LED) will become an appealing alternative to the radio frequency communication technology for indoor wireless broadband broadcasting. However, the LED lamps should access to the backbone information network and this requirement is not easily satisfied. Power line communication (PLC) systems utilize the ubiquitous power line network to power the LED lamps while serving as the backbone network for the VLC systems naturally. In this paper, we propose a novel and cost-effective indoor broadband broadcasting system based on the deep integration of PLC and VLC. The proposed scheme significantly reduces the complexity of the VLC network protocol, and requires much less modification to the current infrastructure, while providing better signal coverage. A two-lamp network demo is implemented and the performance evaluation for the proposed scheme is carried out in the laboratory. The proposed scheme is an appealing solution for the indoor family broadcasting, and could be well extended to the scenarios including the hospitals, shopping malls, stadiums, music halls, and etc. View full abstract»

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  • 6. Genetic Algorithm Aided Proportional Fair Resource Allocation in Multicast OFDM Systems

    Publication Year: 2015 , Page(s): 16 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (869 KB) |  | HTML iconHTML  

    The next-generation wireless communication networks are envisioned to offer many multimedia services such as audio/video clips, mobile TV, web browsing, video conference, etc., with diverse quality of service (QoS) requirements. Multicasting/broadcasting has been recognized as an emerging and enabling technique for such multimedia transmissions over wireless networks. By employing multicast transmission, a base station can transmit the same data content to several groups of users requiring flexible QoS. In this paper, we investigate subchannel and power allocation problems in an OFDM-based wireless multicast system. With the goal of maximizing the total system capacity, a low complexity, novel genetic algorithm aided efficient subchannel allocation scheme taking into account the constraints of total available bandwidth, proportional data rate fairness and total transmit power budget at the base station is proposed. The subchannel allocation is then followed by optimal power allocation. Unlike previous work where either no fairness or fairness based on number of subchannels allocated to the different groups was considered, we incorporate a set of system parameters in the problem formulation such that the ratio of the group data rates strictly follow the set of system parameters after resource allocation. Simulation results show that the proposed method obtains higher sum capacities while maintaining proportional data rate fairness among different multicast groups, without being awfully complex. View full abstract»

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  • 7. Blind Sharpness Prediction Based on Image-Based Motion Blur Analysis

    Publication Year: 2015 , Page(s): 1 - 15
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2154 KB) |  | HTML iconHTML  

    For high bit rate video, it is important to acquire the video contents with high resolution, the quality of which may be degraded due to the motion blur from the movement of an object(s) or the camera. However, conventional sharpness assessments are designed to find focal blur caused either by defocusing or by compression distortion targeted for low bit rates. To overcome this limitation, we present a no-reference framework of a visual sharpness assessment (VSA) for high-resolution video based on the motion and scene classification. In the proposed framework, the accuracy of the sharpness estimation can be improved via pooling weighted by the visual perception from the object and camera movements and by the strong influence from the region with the highest sharpness. Based on the motion blur characteristics, the variance and the contrast over the spectral domain are used to quantify the perceived sharpness. Moreover, for the VSA, we extract the highly influential sharper regions and emphasize them by utilizing the scene adaptive pooling. Based on the subjective results, we demonstrate that the VSA can measure the video sharpness more accurately than other sharpness measurements for high-resolution video. View full abstract»

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  • 8. Understanding the effects of phase noise in orthogonal frequency division multiplexing (OFDM)

    Publication Year: 2001 , Page(s): 153 - 159
    Cited by:  Papers (135)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Phase noise must be carefully considered when designing an OFDM-based communication system since an accurate prediction of the tolerable phase noise can allow the system and RF engineers to relax specifications. This paper analyzes the performance of OFDM systems under phase noise and its dependence on the number of sub-carriers both in the presence and absence of a phase correction mechanism. Besides some practical results are provided so as to give some insight into the phase noise spectral specifications that should be required of the local oscillator View full abstract»

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  • 9. Low-Complexity PTS-Based Schemes for PAPR Reduction in SFBC MIMO-OFDM Systems

    Publication Year: 2014 , Page(s): 650 - 658
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (909 KB) |  | HTML iconHTML  

    Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) is an attractive technique for high-data-rate transmission. However, MIMO-OFDM systems have an inherent drawback in that the transmitted signals may suffer from a high peak-to-average power ratio (PAPR). The conventional partial transmit sequences (PTS) scheme can be applied to each transmitting antenna directly to reduce the PAPR of MIMO-OFDM systems, but it has high computational complexity. In this paper, two types of low-complexity PTS schemes are proposed to reduce the PAPR for MIMO-OFDM systems that use space-frequency block coding (SFBC). The two proposed PTS schemes use the sample powers of subblocks to generate cost functions for selecting samples to estimate the peak power of each candidate signal, thus reducing the computational complexity. In addition, for one of the proposed PTS schemes, the similarity of the input signals from the various transmitting antennas is used to further reduce the computational complexity. Simulation results show that, as compared with other related works, the proposed PTS schemes can achieve a reduced PAPR performance and a bit error rate performance close to that of SFBC MIMO-OFDM systems, but at much lower computational cost. View full abstract»

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  • 10. Temporal Video Quality Model Accounting for Variable Frame Delay Distortions

    Publication Year: 2014 , Page(s): 637 - 649
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1677 KB) |  | HTML iconHTML  

    We announce a new video quality model (VQM) that accounts for the perceptual impact of variable frame delays (VFD) in videos with demonstrated top performance on the laboratory for image and video engineering (LIVE) mobile video quality assessment (VQA) database. This model, called VQM_VFD, uses perceptual features extracted from spatialtemporal blocks spanning fixed angular extents and a long edge detection filter. VQM_VFD predicts video quality by measuring multiple frame delays using perception based parameters to track subjective quality over time. In the performance analysis of VQM_VFD, we evaluated its efficacy at predicting human opinions of visual quality. A detailed correlation analysis and statistical hypothesis testing show that VQM_VFD accurately predicts human subjective judgments and substantially outperforms top-performing image quality assessment and VQA models previously tested on the LIVE mobile VQA database. VQM_VFD achieved the best performance on the mobile and tablet studies of the LIVE mobile VQA database for simulated compression, wireless packet-loss, and rate adaptation, but not for temporal dynamics. These results validate the new model and warrant a hard release of the VQM_VFD algorithm. View full abstract»

    Open Access
  • 11. eWU-TV: User-Centric Energy-Efficient Digital TV Broadcast Over Wi-Fi Networks

    Publication Year: 2015 , Page(s): 39 - 55
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2846 KB) |  | HTML iconHTML  

    This paper presents an innovative multifaceted architecture, named energy-efficient framework for DTV broadcast over Wi-Fi networks (eWU-TV), that provides an energy efficient, user-centric, adaptive digital television (DTV) broadcast over Wi-Fi. To cater to the varied properties of the user equipments (UEs), the proposed framework broadcasts DTV content in the form of scalable video coded content that is adapted to suit the subscribers' requirements. The user-centricity is in terms of UE device display size, user preferences for video quality profile based on device energy saving, and UE transmission technology support (DVB-T/H or Wi-Fi). Mathematical models on device battery discharge, quality of experience, and user preference are devised that closely approximate the results of device battery discharge experiments on DTV reception by heterogeneous devices over Wi-Fi/DVB-T, subjective video quality assessment study, and statistical survey of user preference. The proposed eWU-TV performance optimization framework is based on the developed models. The framework ensures that the adaptive scalable broadcast reception via Wi-Fi serves more number of users with higher quality of user experience and with provisions for significant device energy saving. View full abstract»

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  • 12. DVB-NGH: The Next Generation of Digital Broadcast Services to Handheld Devices

    Publication Year: 2014 , Page(s): 246 - 257
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8403 KB) |  | HTML iconHTML  

    This paper reviews the main technical solutions adopted by the next-generation mobile broadcasting standard DVB-NGH, the handheld evolution of the second-generation digital terrestrial TV standard DVB-T2. The main new technical elements introduced with respect to DVB-T2 are: layered video coding with multiple physical layer pipes, time-frequency slicing, full support of an IP transport layer with a dedicated protocol stack, header compression mechanisms for both IP and MPEG-2 TS packets, new low-density parity check coding rates for the data path (down to 1/5), nonuniform constellations for 64 Quadrature Amplitude Modulation (QAM) and 256QAM, 4-D rotated constellations for Quadrature Phase Shift Keying (QPSK), improved time interleaving in terms of zapping time, end-to-end latency and memory consumption, improved physical layer signaling in terms of robustness, capacity and overhead, a novel distributed multiple input-single output transmit diversity scheme for single-frequency networks (SFNs), and efficient provisioning of local content in SFNs. All these technological solutions, together with the high performance of DVB-T2, make DVB-NGH a real next-generation mobile multimedia broadcasting technology. In fact, DVB-NGH can be regarded the first third-generation broadcasting system because it allows for the possibility of using multiple input-multiple output antenna schemes to overcome the Shannon limit of single antenna wireless communications. Furthermore, DVB-NGH also allows the deployment of an optional satellite component forming a hybrid terrestrial-satellite network topology to improve the coverage in rural areas where the installation of terrestrial networks could be uneconomical. View full abstract»

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  • 13. Efficiency of Doherty RF Power-Amplifier Systems

    Publication Year: 1987 , Page(s): 77 - 83
    Cited by:  Papers (136)  |  Patents (69)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (923 KB)  

    A Doherty system combines the outputs of two or more linear RF power amplifiers (PAs) through an impedance-inverting coupler such as a quarter-wave transmission line. At low output levels, the first PA operates linearly, reaching saturation (and maximum efficiency) at some transition voltage below the system peak-output voltage. At higher output levels, the first PA remains saturated and the second PA operates linearly. The instantaneous efficiency and power characteristics of a Doherty system are derived using ideal class-B RF PAs so that the results can easily be scaled for use with real-world PAs. The average efficiency and maximum-efficiency transition points are then determined for a variety of amplitude-modulated signals. The Doherty amplifier can be considerably more efficient than a conventional class-B linear PA. For example, the 28-and 8.9-percent average efficiencies of a class-B PA with Rayleigh-distri buted envelopes with 10-and 20-dB peak-to-average ratios are improved to 60 and 48 percent, respectively, by a two-stage Doherty system. The addition of a third stage further improves the efficiencies to 70 and 66 percent, respectively. View full abstract»

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  • 14. Stereoscopic 3D-TV: Visual Comfort

    Publication Year: 2011 , Page(s): 335 - 346
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB) |  | HTML iconHTML  

    Among the key topics of discussion and research on three-dimensional television (3D-TV), visual comfort is certainly one of the most critical. This is because it is well known that some viewers experience visual discomfort when looking at stereoscopic displays. It is important to properly address the issue of visual comfort to avoid possible delays in the deployment of 3D-TV. Here we present a concise overview of the main topics relevant to comfort in viewing stereoscopic television and survey the key factors influencing visual comfort. Potential end users of 3D-TV, content creators, program providers, broadcasters, display manufacturers and researchers will find this overview useful. View full abstract»

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  • 15. Stereoscopic image generation based on depth images for 3D TV

    Publication Year: 2005 , Page(s): 191 - 199
    Cited by:  Papers (192)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3352 KB) |  | HTML iconHTML  

    A depth-image-based rendering system for generating stereoscopic images is proposed. One important aspect of the proposed system is that the depth maps are pre-processed using an asymmetric filter to smoothen the sharp changes in depth at object boundaries. In addition to ameliorating the effects of blocky artifacts and other distortions contained in the depth maps, the smoothing reduces or completely removes newly exposed (disocclusion) areas where potential artifacts can arise from image warping which is needed to generate images from new viewpoints. The asymmetric nature of the filter reduces the amount of geometric distortion that might be perceived otherwise. We present some results to show that the proposed system provides an improvement in image quality of stereoscopic virtual views while maintaining reasonably good depth quality. View full abstract»

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  • 16. Cloud Transmission: System Performance and Application Scenarios

    Publication Year: 2014 , Page(s): 170 - 184
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (20753 KB) |  | HTML iconHTML  

    Cloud transmission (Cloud Txn) is a flexible multilayer system that uses spectrum overlay technology to simultaneously deliver multiple program streams with different characteristics and robustness for different services (mobile TV, HDTV, and UHDTV) in one radio frequency channel. Cloud Txn is a multilayer transmission system like layered-division multiplexing. The transmitted signal is formed by superimposing a number of independent signals at desired power levels to form a multilayered signal. The signals of different layers can have different coding, bit rate, and robustness. The upper layer system parameters are chosen to provide very robust transmission that can be used for high-speed mobile broadcasting. The bit rate is traded for powerful coding and robustness so that the signal-to-noise ratio (SNR) threshold at the receiver is in the range of -2 to -3 dB. The top layer is designed to withstand combined noise, co-channel interference and multipath distortion power levels higher than the desired signal power. The lower-layer signal can be a DVB-T2 signal or another new system to deliver HDTV/UHDTV to fixed receivers. The system concept is open to technological advances that might come in the future: BICM/non uniform-QAM, rotated constellations, time frequency slicing or MIMO techniques can be implemented in the Cloud Txn lower (high data rate) layer. The system can have backward compatible future extensions, adding more lower layers for additional services without impact legacy services. This paper describes the performance of Cloud Txn broadcasting system. View full abstract»

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  • 17. A New Equalizer in Doubly-Selective Channels for TDS-OFDM

    Publication Year: 2015 , Page(s): 91 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (889 KB) |  | HTML iconHTML  

    Various factors contribute to the intercarrier interference (ICI) in orthogonal frequency-division multiplexing (OFDM), which violates the orthogonality among subcarriers and greatly degrades the performance. Traditional ICI compensation methods incorporate iterative estimation and cancelation for pilot subcarriers, bearing too much complexity and reducing the spectral efficiency. In this paper, a novel channel equalization method is proposed for time domain synchronous-orthogonal frequency-division multiplexing (TDS-OFDM), where fast and accurate channel estimation is achieved by utilizing the padded pseudo-noise sequence in consecutive blocks. The new equalizer refers to fast suboptimal-minimum mean square error structure, other than traditional overlap-add structure, inspired by the fact that linear convolution structure is better preserved than circular convolution structure in TDS-OFDM under time-varying channels. With the approximation of linear time-varying channel, the proposed equalizer achieves considerable performance with low complexity (linear) and no additional spectral overhead. View full abstract»

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  • 18. WVSNP-DASH: Name-Based Segmented Video Streaming

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    Video streaming from sensors and miniaturized devices is attractive for a wide range of web-based applications, e.g., remote surveillance. Existing web-based video streaming frameworks, such as the hypertext transfer protocol (HTTP) live streaming (HLS) and the motion picture experts group's dynamic adaptive streaming over HTTP (MPEG-DASH), have dependencies between the individual video segments and a manifest file that contains video metadata. Also, existing web-based video players are limited to fetching video segments over TCP/IP networks. The video segment dependencies complicate video segment distribution by resource-constrained source nodes, which may employ non-TCP/IP protocols, such as Zigbee. This paper proposes and evaluates a wireless video sensor network platform compatible DASH (WVSNP-DASH) framework and a WVSNP-DASH player (WDP) for flexible web-based access of video from sensors and other miniaturized source nodes. The WVSNP-DASH framework is based on independently playable video segments with a specific naming syntax that conveys elementary metadata so as to facilitate flexible search, transfer, distribution, and playback. The WDP employs elementary processes of version 5 of the hypertext markup language (HTML5) for video buffering and playback. Video segments are fetched into the HTML5 file system space, permitting flexible video fetching over a wide range of protocols, including sensor network protocols. Comparative evaluations of a WDP prototype with optimized HLS and MPEG-DASH players indicate that WDP has low client (receiver) load, while providing significant potential for power savings on the source node serving the video streams. View full abstract»

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  • 19. Clipping Noise Cancelation for OFDM Systems Using Reliable Observations Based on Compressed Sensing

    Publication Year: 2015 , Page(s): 111 - 118
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB) |  | HTML iconHTML  

    In this paper, a clipping noise cancelation scheme using compressed sensing (CS) technique is proposed for orthogonal frequency division multiplexing systems. The proposed scheme does not need reserved tones or pilot tones, which is different from the previous works using CS technique. Instead, observations of the clipping noise in data tones are exploited, which leads to no loss of data rate. Also, in contrast with the previous works, the proposed scheme selectively exploits the reliable observations of the clipping noise instead of using whole observations, which results in minimizing the bad influence of channel noise. From the selected reliable observations, the clipping noise in time domain is reconstructed and canceled by using CS technique. Simulation results show that the proposed scheme performs well compared to other conventional clipping noise cancelation schemes and shows the best performance in some cases. View full abstract»

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  • 20. The Evolution of Video Quality Measurement: From PSNR to Hybrid Metrics

    Publication Year: 2008 , Page(s): 660 - 668
    Cited by:  Papers (111)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (439 KB) |  | HTML iconHTML  

    This paper reviews the evolution of video quality measurement techniques and their current state of the art. We start with subjective experiments and then discuss the various types of objective metrics and their uses. We also introduce V-Factor, a "hybrid" metric using both transport- and bitstream information. Finally, we summarize the main standardization activities, such as the work of the video quality experts group (VQEG), and we take a look at emerging trends in quality measurement, including image preference, visual attention, and audiovisual quality. View full abstract»

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  • 21. Single Frequency-Based Device-to-Device-Enhanced Video Delivery for Evolved Multimedia Broadcast and Multicast Services

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2108 KB)  

    Despite of the undisputed benefits of the long term evolution-advanced (LTE-A) networks, offering support for group-oriented services challenges the evolved multimedia broadcast multicast services (eMBMS) design in LTE-A. This is especially important when delivering video content with high bitrate requirements. The conventional multicast scheme (CMS) is proposed as a radio resource allocation solution for eMBMS to serve all multicast group members with the data rate supported by the receiver with the worst channel conditions. In this paper, we propose a novel radio resource management approach, the device-to-device (D2D)-enhanced CMS with single frequency (D2D-SF). This proposal extends the CMS with additional D2D communications in order to increase the aggregate data rate of the cell, while also maintaining the typical CMS short-term fairness. D2D-SF makes use of one or more mobile subscriber devices as forwarding devices (FD) to retransmit the data received from the base station (BS) over direct local links to other members of the multicast group. The proposed solution supports both high-rate modulation and coding schemes on the downlink from BS to FDs, and reaches cell-edge devices (hence, experiencing worse channel conditions) through high-performing D2D links (improving this experience). Testing shows how the single frequency-based D2D CMS paradigm proposed, complemented by two novel strategies for selecting FDs, achieves significant enhancements of the overall performance when delivering video content compared to both the state-of-the-art multicast solutions and novel solutions that do not employ a single-frequency paradigm. View full abstract»

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  • 22. PAPR Reduction of OQAM-OFDM Signals Using Segmental PTS Scheme With Low Complexity

    Publication Year: 2014 , Page(s): 141 - 147
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6962 KB) |  | HTML iconHTML  

    In this paper, a novel segmental partial transmit sequence (S-PTS) scheme is proposed for the peak-to-average power ratio (PAPR) reduction in offset quadrature amplitude modulation based orthogonal frequency-division multiplexing (OQAM-OFDM) systems. The key idea of the S-PTS scheme is to divide the overlapped OQAM-OFDM signals into a number of segments, and then some disjoint subblocks are divided and multiplied with different phase rotation factors in each segment. Compared with the conventional PTS scheme directly employed in OQAM-OFDM sytems, the S-PTS scheme could offer better PAPR reduction with lower computational complexity. View full abstract»

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  • 23. Sparsity-Aware Adaptive Channel Estimation Based on SNR Detection

    Publication Year: 2015 , Page(s): 119 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (979 KB) |  | HTML iconHTML  

    Time domain synchronous orthogonal frequency division multiplexing OFDM (TDS-OFDM) has a higher spectral efficiency and faster synchronization than standard cyclic prefix OFDM, but suffers from the performance loss over multipath fading channels due to severe interblock-interference. Recently, compressive sensing (CS) is explored to solve those problems, but it heavily relies on the sparsity level of the channel, which is unknown in practice. In this paper, a signal-to-noise ratio-based sparsity estimation method is proposed to detect the sparsity level of the channel. Then we propose the priori aided subspace pursuit algorithm if the channel sparsity meets the theoretical CS model, otherwise we use an improved iterative channel estimation method with the help of the channel sparsity. Simulation results demonstrate that the proposed scheme could improve the robustness and performance of TDS-OFDM systems compared with the conventional iterative methods or recently proposed CS based methods. View full abstract»

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  • 24. Frame Rate Up-Conversion Method for Video Processing Applications

    Publication Year: 2014 , Page(s): 659 - 669
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3963 KB) |  | HTML iconHTML  

    In this paper, a new low-complexity frame rate up-conversion (FRUC) method is proposed for video processing applications. In the proposed FRUC method, true motion estimation (TME) is used to track motion trajectories by imposing smoothness constraints on block-matching algorithm (BMA). In order to produce high-quality interpolated frames, TME is performed in both forward and backward directions; then, the reliable dense motion vector field is obtained by using the multistage motion vector (MV) post-processing method. The constraints of low computational complexity and low memory bandwidth are also considered in our method. We use a histogram-based predictive search to impose smoothness constrains and reduce the number of search points. Furthermore, a complexity-simplified improvement of the proposed method is introduced to reduce computational complexity with slight quality degradation. In addition, a new scan order of BMA and a pipelining of MV post-processing are presented to guarantee the causality of the system and improve the pixel data reuse, which reduces the memory bandwidth. The experiment results show that the proposed FRUC method achieves not only better video quality, but also low computational complexity and memory bandwidth compared to the conventional methods. View full abstract»

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  • 25. DVB-T2: The Second Generation of Terrestrial Digital Video Broadcasting System

    Publication Year: 2014 , Page(s): 258 - 271
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (11979 KB) |  | HTML iconHTML  

    This paper provides a review of the second generation of terrestrial digital video broadcasting standard (DVB-T2). DVB-T2 is the evolution of DVB-T and, together with DVB-S2 and DVB-C2, inaugurated a new transition from the first-generation digital broadcasting systems, similar to the transition from analog-to-digital systems. In this paper, the most relevant features of DVB-T2 are explained in detail, along with their benefits and trade-offs. This paper also presents a comprehensive review of the laboratory and field trial results available so far. Especial emphasis is placed in the results of the measurements carried out to test the mobile reception and the novel technologies as multiple input single output and time frequency slicing. View full abstract»

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  • 26. A new standardized method for objectively measuring video quality

    Publication Year: 2004 , Page(s): 312 - 322
    Cited by:  Papers (282)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The National Telecommunications and Information Administration (NTIA) General Model for estimating video quality and its associated calibration techniques were independently evaluated by the Video Quality Experts Group (VQEG) in their Phase II Full Reference Television (FR-TV) test. The NTIA General Model was the only video quality estimator that was in the top performing group for both the 525-line and 625-line video tests. As a result, the American National Standards Institute (ANSI) adopted the NTIA General Model and its associated calibration techniques as a North American Standard in 2003. The International Telecommunication Union (ITU) has also included the NTIA General Model as a normative method in two Draft Recommendations. This paper presents a description of the NTIA General Model and its associated calibration techniques. The independent test results from the VQEG FR-TV Phase II tests are summarized, as well as results from eleven other subjective data sets that were used to develop the method. View full abstract»

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  • 27. Early MERGE Mode Decision Based on Motion Estimation and Hierarchical Depth Correlation for HEVC

    Publication Year: 2014 , Page(s): 405 - 412
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1791 KB) |  | HTML iconHTML  

    The high efficiency video coding (HEVC) is the latest video coding standard, which adopts the quadtree structure based coding tree unit (CTU) to improve the coding efficiency. In the HEVC encoding process, the CTU is recursively split into the 8×8 size coding units (CUs) from the 64×64 size CU. Along with the increased number of the sizes of the CUs, the number of coding modes has been greatly increased, which results in high computational complexity in the HEVC encoder. In this paper, we propose an early MERGE mode decision algorithm to reduce the computational complexity of the HEVC encoder. Firstly, based on the all-zero block (AZB) and the motion estimation (ME) information of the INTER 2N×2N mode, an early MERGE mode decision is proposed for the root CUs (i.e., 64×64 size CUs). Then, an early MERGE mode decision is proposed for the children CUs (i.e., 32×32, 16×16, and 8×8 size CUs) by considering the mode selection correlation between the root CU and the children CUs. To maximize the computational complexity reduction, when the root CUs are encoded in the non-MERGE modes, the AZB and the ME information are also used for early termination of the children CUs. Experimental results demonstrate that compared to the state-of-the-art published method, the proposed algorithm can achieve about 35% encoding time on average saving while the rate distortion performance degradation is negligible. View full abstract»

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  • 28. Assessments of Subjective Video Quality on HEVC-Encoded 4K-UHD Video for Beyond-HDTV Broadcasting Services

    Publication Year: 2013 , Page(s): 209 - 222
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2595 KB) |  | HTML iconHTML  

    In this paper, we present the experimental results with analysis for subjective quality assessment on 4K-ultra-high definition (UHD) video encoded by high efficiency video coding (HEVC) to investigate its feasibility for 4K-UHD TV broadcasting services. The subjective quality assessment on the HEVC-encoded (impaired) 4K-UHD video is conducted for the three target bitrates of 18, 23, and 36 Mb/s, the two color formats of YUV420 and YUV444, and the two viewing distances of 0.75 times the height of a display screen (H) and 1.5 H. The subjective quality assessment experiments on 4K-UHD test sequences show that the HEVC-encoded (impaired) YUV420 4K-UHD video even at the target bit of 18 Mb/s yields perceptual similar visual quality: 1) with MOS of 4.7 and 4.8 in 0.75 H and 1.5 H viewing distances, respectively, compared to the original YUV420 4K-UHD test video; and 2) with MOS of 4.8 in 1.5 H viewing distance, compared to the original YUV444 4K-UHD test video. This implies that the HEVC-encoded YUV420 4K-UHD video at the target bit rate of 18 Mb/s is perceptually good enough in the usage of legacy DTV broadcasting systems with single channel bandwidths of 6 MHz. It is also shown that the HEVC-encoded 4K-UHD test sequences mostly yield higher perceptual quality in the 420 YUV color format than in the YUV444 color format at the same target bitrates. View full abstract»

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  • 29. Three-Dimensional Displays: A Review and Applications Analysis

    Publication Year: 2011 , Page(s): 362 - 371
    Cited by:  Papers (20)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (622 KB) |  | HTML iconHTML  

    S. Benton published a definitive taxonomy of the first one hundred and seventy years of 3D displays covering the field up to the year 2000. In this article we review how display technologies have advanced in the last ten years and update Benton's taxonomy to include the latest additions. Our aim is to produce a display taxonomy suitable for content producers highlighting which displays have common requirements for image delivery. We also analyze key technical characteristics of 3D displays and use these characteristics to suggest the future applications for each category of display. View full abstract»

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  • 30. Efficient Linear Amplification Using Digitally Predistorted Overdriven Power Amplifiers

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2297 KB)  

    This paper investigates the effects of crest factor reduction and digital predistortion on the performances of communication and broadcasting systems. The overdrive of digitally predistorted power amplifiers is proposed for power efficient linear amplification of amplitude modulated signals having high peak to average power ratio. This is achieved by adding, at the input of the digital predistortion system, a clipping function to allow for an overdrive of the linearized power amplifier while meeting spectrum emission mask linearity requirements. The proposed technique is experimentally validated using a GaN Doherty power amplifier driven by long-term evolution (LTE) signals. Measurement results show that the overdriven power amplifier can deliver up to 2.5 dB extra output power, up to 80% enhancement in the power utilization factor, and up to 20% relative increase in the power efficiency while being compliant with the linearity requirements of the LTE standard. View full abstract»

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  • 31. Compressive Sensing Based Channel Estimation for OFDM Systems Under Long Delay Channels

    Publication Year: 2014 , Page(s): 313 - 321
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2113 KB) |  | HTML iconHTML  

    Time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) has advantages in spectral efficiency and synchronization. However, its iterative interference cancellation algorithm will suffer from performance loss especially under severely fading channels with long delays and has difficulty supporting high-order modulations like 256 QAM, which may not accommodate the emerging ultra-high definition television service. To solve this problem, a channel estimation method for OFDM under the framework of compressive sensing (CS) is proposed in this paper. Firstly, by exploiting the signal structure of recently proposed time-frequency training OFDM scheme, the auxiliary channel information is obtained. Secondly, we propose the auxiliary information based subspace pursuit (A-SP) algorithm to utilize a very small amount of frequency-domain pilots embedded in the OFDM block for the exact channel estimation. Moreover, the obtained auxiliary channel information is adopted to reduce the complexity of the classical SP algorithm. Simulation results demonstrate that the CS-based OFDM outperforms the conventional dual pseudo noise padded OFDM and CS-based TDS-OFDM schemes in both static and mobile environments, especially when the channel length is close to or even larger than the guard interval length, where the conventional schemes fail to work completely. View full abstract»

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  • 32. Transport Stream Analysis of a ISDB-T Signal Using an Embedded and Reconfigurable System

    Publication Year: 2015 , Page(s): 30 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2265 KB) |  | HTML iconHTML  

    Quality management is an important criterion to evaluate broadcaster's transmission system integrity, which can be affected by radiofrequency signal impairments and by coding, multiplexing, and/or modulation errors. The international system integrated services digital broadcasting - terrestrial (ISDB-T) was designed to provide a reliable reception, even with interferences inherent to radio wave propagation. However, channel noise, as well as problems in the transmission system, may corrupt the transport stream (TS), causing image failures and, depending on the error level, even a complete loss of signal. This paper presents a supervisory system consisting of an ISDB-T front-end with spatial diversity of four branches, associated with a system-on-chip (SoC) board, in order to analyze the TS of any broadcaster, identifying transmission errors in real-time. The system continuously searches received data for impairments such as cyclic redundancy check - 32 and continuity counter errors, table/section intervals, and program clock reference jitter. The SoC comprises a field programmable gate array that includes a hard-wired processor, used to compute and show the analysis results. View full abstract»

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  • 33. Two Dimensional Code Based on Low Density Parity Check and Reed–Solomon Codes for the Terrestrial Cloud Transmission System

    Publication Year: 2015 , Page(s): 75 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2358 KB) |  | HTML iconHTML  

    In this paper, we propose a two dimensional (2-D) code based on a vertical low-density parity check (LDPC) code and a horizontal Reed-Solomon code for the cloud transmission system. The proposed 2-D code shows superior performance under fading channels due to its inherent block-type interleaving feature. Furthermore, the proposed 2-D code can be adaptively decoded to reduce decoding latency and complexity because the vertical LDPC code has raptor-like rate-compatible feature. View full abstract»

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  • 34. New MPEG Transport Standard for Next Generation Hybrid Broadcasting System With IP

    Publication Year: 2014 , Page(s): 160 - 169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (818 KB) |  | HTML iconHTML  

    MPEG-2 transport system (TS) and ISO base media file format (ISOBFF) standards developed by MPEG have been widely used by various industries and applications including digital broadcasting systems. Recently MPEG has developed a new standard, MPEG Media Transport or MMT, for next generation broadcasting system considering the emerging convergence of digital broadcasting network and the Internet. MMT assumes HTML5 and Internet protocol (IP) as deployment environment and inherits major features of MPEG-2 TS while simplifying unnecessary complicated features in IP environments. It also considers hybrid delivery of multi-screen services. MMT defines an application layer protocol enabling packetization of opaque objects or files without considering the structure of data and media processing unit (MPU) format specific packetization. Synchronization technology of MMT providing flexible synchronization of multimedia components delivered through hybrid environment over multiple devices is built on top of HTML5. View full abstract»

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  • 35. ADT-Based UHDTV Transmission for the Existing ATSC Terrestrial DTV Broadcasting

    Publication Year: 2015 , Page(s): 105 - 110
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1215 KB) |  | HTML iconHTML  

    In this brief, we propose an augmented data transmission (ADT)-based ultrahigh definition (UHD) television transmission system for the existing advanced television systems committee terrestrial digital television (DTV) broadcasting. The proposed system can support a rate of 12 Mb/s using a moving pictures expert group-2 (MPEG-2)-based DTV signal and a rate of 12.5 Mb/s using High Efficiency Video Coding (HEVC)-based DTV and ADT signals. By combining properly an MPEG-2-based DTV signal, an HEVC-based DTV signal and an HEVC-based ADT signal, 4K (3840 × 2160 ) UHD video can be served while providing backward-compatible high-definition video service. View full abstract»

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  • 36. Coverage Optimization and Power Reduction in SFN Using Simulated Annealing

    Publication Year: 2014 , Page(s): 474 - 485
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2396 KB) |  | HTML iconHTML  

    An approach that predicts the propagation, models the terrestrial receivers and optimizes the performance of single frequency networks (SFN) for digital video broadcasting in terms of the final coverage achieved over any geographical region, enhancing the most populated areas, is proposed in this paper. The effective coverage improvement and thus, the self-interference reduction in the SFN is accomplished by optimizing the internal static delays, sector antenna gain, and both azimuth and elevation orientation for every transmitter within the network using the heuristic simulated annealing (SA) algorithm. Decimation and elevation filtering techniques have been considered and applied to reduce the computational cost of the SA-based approach, including results that demonstrate the improvements achieved. Further representative results for two SFN in different scenarios considering the effect on the final coverage of optimizing any of the transmitter parameters previously outlined or a combination of some of them are reported and discussed in order to show both, the performance of the method and how increasing gradually the complexity of the model for the transmitters leads to more realistic and accurate results. View full abstract»

    Open Access
  • 37. Simplified Detection for DVB-NGH MIMO Decoders

    Publication Year: 2015 , Page(s): 84 - 90
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1743 KB) |  | HTML iconHTML  

    Nowadays, communication systems need to satisfy very demanding constraints in order to cope with users new necessities. One of the most promising techniques to improve the system capacity is multiple input multiple output (MIMO). However, the use of MIMO implies a huge complexity increase in the detection process. In this paper, a method to reduce the aforementioned complexity is presented. Although the proposed method is analyzed for digital video broadcasting next generation for handhelds, its implementation is useful for any MIMO system that requires the computation of log likelihood ratios (LLRs), used by the low density parity check codes. The presented technique consists of applying a simplification when calculating the Euclidean distances needed by the LLRs. The simplification avoids almost all the multiplications, very area demanding when translated into hardware, and presents a performance loss under 0.1 dB. View full abstract»

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  • 38. A Piecewise Linear Companding Transform for PAPR Reduction of OFDM Signals With Companding Distortion Mitigation

    Publication Year: 2014 , Page(s): 532 - 539
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1443 KB) |  | HTML iconHTML  

    Companding is a well-known technique for the peak-to-average power ratio (PAPR) reduction of orthogonal frequency division multiplexing (OFDM) signals. However, as companding transform is an extra operation after the modulation of OFDM signals, companding schemes reduce PAPR at the expense of increasing the bit error rate (BER). In this paper, a new piecewise linear companding scheme is proposed aiming at mitigating companding distortion. In the design of the companding transform, we study the theoretical characterization of companding distortion. It demonstrates that companding larger signals with smaller amplitude increments are more favorable in reducing companding distortion. Based on the analysis results, a new piecewise linear companding transform is proposed by clipping the signals with amplitudes over a given companded peak amplitude for peak power reduction, and linearly transforming the signals with amplitudes close to the given companded peak amplitude for power compensation. With the careful design of the companded peak amplitude and the linear transform scale, the proposed transform can achieve enhanced BER and power spectral density performance, while reducing PAPR effectively. View full abstract»

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  • 39. New Depth Coding Techniques With Utilization of Corresponding Video

    Publication Year: 2011 , Page(s): 551 - 561
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1718 KB) |  | HTML iconHTML  

    With the development of 3D display and interactive multimedia systems, new 3D video applications, such as 3DTV and Free Viewpoint Video, are attracting significant interests. In order to enable these new applications, new data formats including captured 2D video sequences and corresponding depth maps have been proposed. Compared to conventional video frames, depth maps have very different characteristics. First, they typically consist of homogeneous areas partitioned by sharp edges representing depth discontinuities, while the sharp discontinuities play very important roles in view rendering. Second, there exists structure similarity between depth map and corresponding video, in which the edges in depth exhibit quite similar behaviors as the edges in the corresponding video. In conventional video coding techniques with transforms followed by quantization, there usually exist large artifacts along sharp edges and it costs significant more bits to represent the edges with higher accuracy. In order to suppress the coding artifacts while preserving edges, and to better compress depth information, we propose in this paper two new depth compression techniques: Trilateral Filter and Sparse Dyadic Mode. Both techniques utilize the structure similarity between depth and corresponding video while focusing on different aspects in depth compression. As a new in-loop filter, Trilateral Filter is designed to filter depth with coding artifacts based on the proximity of pixel positions, the similarity among depth samples, as well as the similarity among the collocated pixels in the video frame. While Sparse Dyadic Mode is used as an intra mode to reconstruct depth map with sparse representations of depth blocks and effective reference of edge information from video frames. With these two new coding tools, we can achieve up to about 1.5 dB gain on rendering quality as compared to depth sequences coded using MVC under the same coding rate. View full abstract»

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  • 40. 3D-TV Content Storage and Transmission

    Publication Year: 2011 , Page(s): 384 - 394
    Cited by:  Papers (29)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1398 KB) |  | HTML iconHTML  

    There exist a variety of ways to represent 3D content, including stereo and multiview video, as well as frame-compatible and depth-based video formats. There are also a number of compression architectures and techniques that have been introduced in recent years. This paper provides an overview of relevant 3D representation and compression formats. It also analyzes some of the merits and drawbacks of these formats considering the application requirements and constraints imposed by different storage and transmission systems. View full abstract»

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  • 41. Invertible Subset QC-LDPC Codes for PAPR Reduction of OFDM Signals

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB)  

    A type of invertible subset low density parity-check (IS-LDPC) codes was proposed to reduce the peak-to-average power ratio for orthogonal frequency-division multiplexing systems with low complexity recently, where the key idea is that each invertible subset can be independently inverted to generate other valid codewords of the LDPC code. In this paper, we firstly extend the idea of invertible subsets to quasi-cyclic LDPC (QC-LDPC) codes, and this new family of QC-LDPC codes is called as invertible subset QC-LDPC (IS-QC-LDPC) codes. Moreover, we propose two types of subset partitioning and deeply discuss the properties of IS-QC-LDPC codes with different subset partitioning. After declaring that interleaved partitioning is more appropriate for IS-QC-LDPC codes than the block partitioning, we propose a novel progressive edge graph-like algorithm to construct good IS-QC-LDPC codes with interleaved partitioning. The simulation results show that the IS-QC-LDPC codes exhibit good error-correcting performance, which is very close to that of the corresponding QC-LDPC codes of the IEEE 802.16e, for a wide range of subset number. View full abstract»

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  • 42. Joint Delivery of Unicast and E-MBMS Services in LTE Networks

    Publication Year: 2012 , Page(s): 157 - 167
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1203 KB) |  | HTML iconHTML  

    Long Term Evolution (LTE) standard enhances Multimedia Broadcast Multicast Services (MBMS) to provide highly efficient transmission of multicast/broadcast services. This paper aims at clarifying which is the best option for the Enhanced MBMS (E-MBMS) network configuration according to the operator needs. Besides, it describes the main technical features of the new E-MBMS LTE standard, for both streaming and file delivery, and derives optimum operation modes. Some relevant conclusions are drawn from a set of simulation results calibrated with International Telecommunication Union Radiocommunication (ITU-R) guidelines. Regarding streaming delivery, results show that increasing the MBMS over a Single Frequency Network (MBSFN) area size allows employing a higher modulation and coding scheme level, which entails more streaming channels per MBSFN area. Concerning file delivery, results show that the reduction in the mean throughput of unicast users matches exactly the percentage of stolen subframes. Besides, the hybrid approach suggested in this paper improves the file delivery efficiency while eliminating the dependency on a MBMS threshold. View full abstract»

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  • 43. A Low-Complexity Digital Predistortion Algorithm for Power Amplifier Linearization

    Publication Year: 2014 , Page(s): 670 - 678
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1942 KB) |  | HTML iconHTML  

    Transmission signals of modern communication systems, such as orthogonal frequency-division multiplexing signals, usually have large peak-to-average power ratio. These signals are sensitive to the power amplifier's nonlinearity, which generates both in-band distortion and out-of-band spectral regrowth. The adaptive digital predistortion (DPD) is an efficient linearization technique without sacrificing the power efficiency. To estimate the DPD coefficients, numerical instability and computational complexity are bottlenecks. In this paper, we propose a general approach to derive orthonormal basis functions, which can improve the numerical stability during the coefficients estimation. By applying the orthonormal basis functions, we further propose an adaptive algorithm that exhibits a low computation complexity of least mean squares algorithm while retaining the fast convergence speed of recursive least squares algorithm. Both simulation and experimental results validate the effectiveness of the proposed algorithm. View full abstract»

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  • 44. Effect of PAPR Reduction on Spectrum and Energy Efficiencies in OFDM Systems With Class-A HPA Over AWGN Channel

    Publication Year: 2013 , Page(s): 513 - 519
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    In this paper, we mainly analyze the relations between peak-to-average power ratio (PAPR) reduction, spectrum efficiency (SE), and energy efficiency (EE) in orthogonal frequency division multiplexing (OFDM) systems, respectively. Through PAPR reduction, the efficiency of high power amplifier (HPA) could be substantially improved, and the nonlinear distortion noise caused by the HPA could also be significantly reduced. As a result, the SE and EE are increased with a total transmit power constraint over additive white Gaussian noise (AWGN) channel. Moreover, we derive the quantitative relations between PAPR reduction, SE, and EE, respectively. Simulation results show that the OFDM system with PAPR reduction could achieve higher SE and EE than the system without PAPR reduction. View full abstract»

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  • 45. Depth Map Driven Hole Filling Algorithm Exploiting Temporal Correlation Information

    Publication Year: 2014 , Page(s): 394 - 404
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2782 KB) |  | HTML iconHTML  

    The depth-image-based-rendering is a key technique to realize free viewpoint television. However, one critical problem in these systems is filling the disocclusion due to the 3-D warping process. This paper exploits the temporal correlation of texture and depth information to generate a background reference image. This is then used to fill the holes associated with the dynamic parts of the scene, whereas for static parts the traditional inpainting method is used. To generate the background reference image, the Gaussian mixture model is employed on the texture information, whereas, depth maps information are used to detect moving objects so as to enhance the background reference image. The proposed holes filling approach is particularly useful for the single-view-plus-depth format, where, contrary to the multi-view-plus-depth format, only information of one view could be used for this task. The experimental results show that objective and subjective gains can be achieved, and the gain ranges from 1 to 3 dB over the inpainting method. View full abstract»

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  • 46. Joint Scalable Coding and Routing for 60 GHz Real-Time Live HD Video Streaming Applications

    Publication Year: 2013 , Page(s): 500 - 512
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1556 KB) |  | HTML iconHTML  

    Transmission of high-definition (HD) video is a promising application for 60 GHz wireless links, since very high transmission rates (up to several Gbit/s) are possible. In particular we consider a sports stadium broadcasting system where signals from multiple cameras are transmitted to a central location. Due to the high pathloss of 60 GHz radiation over the large distances encountered in this scenario, the use of relays might be required. The current paper analyzes the joint selection of the routes (relays) and the compression rates from the various sources for maximization of the overall video quality. We consider three different scenarios: (i) each source transmits only to one relay and the relay can receive only one data stream, and (ii) each source can transmit only to a single relay, but relays can aggregate streams from different sources and forward to the destination, and (iii) the source can split its data stream into parallel streams, which can be transmitted via different relays to the destination. For each scenario, we derive the mathematical formulations of the optimization problem and re-formulate them as convex mixed-integer programming, which can guarantee optimal solutions. Extensive simulations demonstrate that high-quality transmission is possible for at least ten cameras over distances of 300 m. Furthermore, optimization of the video quality gives results that can significantly outperform algorithms that maximize data rates. View full abstract»

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  • 47. Variable LLR Scaling in Min-Sum Decoding for Irregular LDPC Codes

    Publication Year: 2014 , Page(s): 606 - 613
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    Min-sum decoding is a low-complexity alternative to the so-called belief propagation and consists in simplification of the nonlinear operation on the log likelihood ratios (LLRs) in the check nodes. The resulting suboptimality may be tempered via appropriate scaling of the LLRs, e.g., the fixed optimal scaling in the normalized min-sum algorithm, and variable scaling algorithms gradually appearing in the literature. However, up to now, none of the papers studied variable scaling both as per iteration and as per different check node degree, due to the prohibitive complexity of multioptimization over space of too many parameters. In this paper, we propose a generalized mutual information (GMI) of LLRs as the criterion to search for the scaling factors for different check node degrees in every iteration in a 1-D thus low-complexity manner. This approach is first analyzed via density evolution, and in addition can be extended to practical LLRs based formulas via Monte Carlo tools to cope with the mismatch issue. Bit error rate simulation results on two low-density parity-check codes show that our proposed GMI metrics have a noticeable gain over the variable scaling schemes that appeared in the literature. View full abstract»

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  • 48. Adaptive Resource Allocation to Multicast Services in LTE Systems

    Publication Year: 2013 , Page(s): 658 - 664
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6211 KB) |  | HTML iconHTML  

    This paper addresses the design of an adaptive resource allocation policy for the efficient delivery of multicast services in Long Term Evolution (LTE) systems. The proposed approach overcomes the intrinsic inefficiencies of Conventional Multicast Scheme (CMS) related to the different channel quality experienced by the involved users. The basic idea is to split any multicast group into subgroups and apply subgroup-based adaptive modulation and coding schemes, which enable a more efficient exploitation of multi-user diversity. The distribution of users into subgroups is determined by the solution of an optimization problem, aiming to improve the network throughput while guaranteeing fairness among multicast members. View full abstract»

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  • 49. PAR reduction in OFDM via active constellation extension

    Publication Year: 2003 , Page(s): 258 - 268
    Cited by:  Papers (280)  |  Patents (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (761 KB) |  | HTML iconHTML  

    The high peak-to-average power ratio (PAR) in orthogonal frequency division multiplexing (OFDM) modulation systems can significantly reduce power efficiency and performance. Methods exist which alter or introduce new signal constellations to combat large signal peaks. We present a new PAR-reduction method that dynamically extends outer constellation points in active (data-carrying) channels, within margin-preserving constraints, in order to minimize the peak magnitude. This scheme simultaneously decreases the bit error rate slightly while substantially reducing the peak magnitude of an OFDM transmit block. Furthermore, there is no loss in data rate and, unlike other methods, no side information is required. PAR reduction for an approximated analog signal is considered, and about a 4.6 dB reduction at a 10-5 symbol-clip probability is obtained for 256-channel QPSK OFDM. The results show great promise for use in commercial systems. View full abstract»

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  • 50. Subjective Quality Assessment of Longer Duration Video Sequences Delivered Over HTTP Adaptive Streaming to Tablet Devices

    Publication Year: 2014 , Page(s): 707 - 714
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (891 KB) |  | HTML iconHTML  

    HTTP adaptive streaming facilitates video streaming to mobile devices connected through heterogeneous networks without the need for a dedicated streaming infrastructure. By splitting different encoded versions of the same video into small segments, clients can continuously decide which segments to download based on available network resources and device characteristics. These encoded versions can, for example, differ in terms of bitrate and spatial or temporal resolution. However, as a result of dynamically selecting video segments, perceived video quality can fluctuate during playback which will impact end-users' quality of experience. Subjective studies have already been conducted to assess the influence of video delivery using HTTP Adaptive Streaming to mobile devices. Nevertheless, existing studies are limited to the evaluation of short video sequences in controlled environments. Research has already shown that video duration and assessment environment influence quality perception. Therefore, in this article, we go beyond the traditional ways for subjective quality evaluation by conducting novel experiments on tablet devices in more ecologically valid testing environments using longer duration video sequences. As such, we want to mimic realistic viewing behavior as much as possible. Our results show that both video content and the range of quality switches significantly influence end-users' rating behavior. In general, quality level switches are only perceived in high motion sequences or in case switching occurs between high and low quality video segments. Moreover, we also found that video stallings should be avoided during playback at all times. 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