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Non-uniform constellation (NUC) is an advanced technology in digital terrestrial television broadcasting (DTTB) systems to reduce the shapping gap of BICM capacity to Shannon theoretical limit and provide performance gain. Two-dimensional NUC (2D-NUC) is a kind of NUC providing more gain but bringing higher demapping complexity at the receiver, which hinders its application prospects, especially in power limited systems. This paper proposes three novel demapping algorithms with reduced complexity for low to medium code rate 2D-NUCs in Advanced Television Systems Committee 3rd Generation (ATSC 3.0) standard. The proposed algorithms are based on the introduction of virtual points, the strategy of condensed symbols reduction and some reasonable approximations. There is a trade-off between the demapping complexity and performance. These three algorithms have different degrees of reduction in complexity and performance degradation, so they accommodate for different practical requirements. Theoretical analysis and simulation results are also given in this paper to prove the efficiency of the proposed demapping algorithms with reduced complexity. [ABSTRACT FROM AUTHOR]

In this paper, a novel demapper for 2-D non-uniform constellations (2D-NUCs) is proposed, exploiting the characteristics of these constellations. It represents the combination of two underlying demapping techniques targeting the ATSC 3.0 compliant OFDM transceiver. On the one hand, for low code rates, we define a metric to perform condensed demapping. On the other hand, for high code rates, adaptive sub-region demapping is proposed. In this paper, a combination of both demapping methods is designed showing comparable performance to the classical ML demapper. The gap does not exceed 0.1 dB for all code rates of the ATSC 3.0 standard. Higher complexity reduction, from 79.2% to 95.4%, than state of art 2D-NUC demappers is obtained for 2D-256NUCs. These results are validated for ideal and non-ideal channel state information over additive white noise Gaussian and Rayleigh independently and identically distributed channels. Results are extended to 2D-1kNUCs and 2D-4kNUCs showing demapping complexity reduction from 96% to 99.7% with a negligible impact on performance. [ABSTRACT FROM AUTHOR]

STiMi is a mobile multimedia broadcasting trade standard that was released by the Chinese State Administration of Radio Film and Television in 2006. This paper details the algorithm research and development work on the acquisition for STiMi. First, the STiMi physical layer is briefly reviewed. secondly, individual algorithms, including time slot detection, fractional frequency offset estimation, integer frequency offset estimation and fine timing synchronization are discussed with simulation results presented. An implemented STiMi receiver prototype is also introduced with a focus on the acquisition algorithms implementation. Finally, the whole acquisition procedure is summarized. Acquisition algorithms and structures presented in this paper are adopted for prototyping and perform well. [ABSTRACT FROM AUTHOR]

This paper presents a modified partial transmit sequence (PTS) algorithm for peak-to-average power ratio (PAPR) reduction of M-QAM orthogonal frequency division multiplexing (OFDM) signals by partitioning an OFDM block into non-disjoint OFDM sub-blocks. Since an M-QAM constellation can be written as sum of several QPSK constellations, we can then apply different disjoint partitions on the QPSK OFDM blocks, which result in an equivalent non-disjoint partition on the M-QAM OFDM block. Compared to a disjoint sub-block partition in conventional PTS, simulation results show that the modified PTS with a non-disjoint partition achieves better PAPR reduction in adjacent, interleaved, and random partitioning schemes. [ABSTRACT FROM PUBLISHER]

Layered transmission is studied in this paper to accommodate various device capabilities and channel conditions. The problem of efficiently broadcasting a common set of layer-encoded data from a single base station to multiple users over quasi-static fading channels is examined. Considering the maximum tolerable delay, a block-level utility is defined in terms of average probability of successful reception of each layer. Based on non-orthogonal multiple access scheme, we propose a complete algorithm to jointly optimize power allocation and transmission rates. By utilizing the idea of opportunistic scheduling, we first derive the success probability of one single layer in homogeneous scenarios, then extend the results to heterogeneous scenarios where users are subject to different channel statistics. The multi-layer optimization is realized by iteratively repeating the single-layer operations. Starting from the base layer, we first choose an optimal subset of users as the corresponding target group, then apply the single-layer allocation process until no power resources are left. Computer simulation and discussion confirm that our method maximizes the block-level utility at the same time balances the tradeoff between multiuser diversity gain and multicast gain. [ABSTRACT FROM AUTHOR]

This paper presents an aggregate wavelet-predominant algorithm to measure the distortions in THz security images. The algorithm integrates a spectral-based sharpness estimator, a noise estimator derived alpha-stable model and an overall viewing experience estimator based on free-energy principle. Among them, the greater weight is assigned to the spectral-based sharpness estimator considering that the main quality factor in THz security image is sharpness. To verify the feasibility of the proposed metric, we construct the THz security image dataset including a total of 181 THz security images, and each image has the mean opinion score (MOS) collected via subjective quality evaluation experiment. Quantitative experimental results on the constructed THz security image dataset show that the aggregate wavelet-predominant estimator produces the promising overall performance for the estimation of MOS values, with PLCC, SROCC, and RMSE of 0.900, 0.873, and 0.386, respectively. This performance is superior to other opinion-unaware approaches, viz., FISBLIM, SISBLIM, NIQE, CPBD, SINE, S3, FISH, and noise estimator. The determination coefficient (${R} ^{{2}}$) of linear regression between reference and predicted MOSs is 0.81. The result of Bland–Altman analysis further validates that the aggregate wavelet-predominant estimator can substitute for the subjective IQA of THz security image, with approximately 94.5% of data points locating within the limits of agreement. For usability identification, the wavelet-predominant estimator gives the satisfactory results, with accuracy, precision, recall rate, and false positive rate of 84.0%, 79.8%, 95.0%, and 29.6%, respectively. Furthermore, the potential application perspectives of the proposed metric can refer to commercial applications (guarantee THz security images of good quality) and scientific researches (assist in software development for THz security image analysis). The dataset is available at https://doi.org/10.6084/m9.figshare.7700123.v3. Possible researches on this dataset may include the development of THz quality standards, the selection of the best display mode, the enhancement of images, the modeling of image noise, and the detection of prohibited goods. [ABSTRACT FROM AUTHOR]

Digital television (DTV) signal has been recognized as a promising signal for navigation and positioning. However, due to the single frequency network (SFN) transmission within the European standard digital video broadcasting terrestrial (DVB-T) system, emitter confusion problem occurs in navigation and positioning, resulting in that a receiver is unable to know from which emitter a received signal comes. In this paper, we consider the wireless positioning with emitter confusion problem in DVB-T SFN networks. A joint wireless positioning and emitter identification algorithm is proposed, which is based on the expectation maximization (EM) method. The proposed algorithm is tested in a scenario, where signals are received from three to five emitters. Simulation results show that, relying on more than three emitters used in the tests for 2-D positioning, the EM-assisted positioning algorithm is feasible to achieve accurate positioning results in the existence of the emitter confusion problem. Our studies show that the performance achieved by the proposed algorithm approaches the Cramér-Rao bound. Furthermore, the proposed algorithm is effective to identify the DTV emitters, and the positioning performance is robust to the emitter identification error. Additionally, our methodology is general, and can be employed for time of arrival-based positioning in any SFNs. [ABSTRACT FROM PUBLISHER]

Due to multi-layer encoding and Inter-layer prediction, Scalable High Efficiency Video Coding (SHVC) has extremely high coding complexity. It is very crucial to improve its coding speed so as to promote widespread and cost-effective SHVC applications. In this paper, we propose a new probability-based fast Intra prediction algorithm for spatial SHVC. More specifically, first, we integrate depth probabilities with textural based all-zero blocks and all-nonzero blocks through Lagrange Interpolation Polynomial (LIP) to derive thresholds to early skip unlikely depths and early terminate depth selection. Second, to early skip Intra mode prediction, we combine mode probabilities with Jarque-Bera test through LIP to test the residual coefficients of Inter-layer reference (ILR) mode. Third, we adopt the difference of Hadamard Costs (HCs) of horizontal, vertical and diagonal directional modes to predict candidate directional modes (DMs), and then exploit both the percentages of gradient amplitudes and HCs for DM early termination. Experimental results demonstrate that the proposed algorithm can achieve a speed up gain of more than 61% with 0.03% decrease in Bjøntegaard Delta Bit Rate on average. [ABSTRACT FROM AUTHOR]

Immersive media, such as free view point video and 360° video, are expected to be dominant as broadcasting services. The light field (LF) imaging is being considered as a next generation imaging technology offering the possibility to provide new services, including six degree-of-freedom video. The drawback of this technology is in the size of the generated content thus requiring novel compression systems and the design of ad-hoc methodologies for evaluating the perceived quality. In this paper, the relation between depth map quality and overall quality of LF image is studied. Next, a reduced reference quality assessment metric for LF images is presented. To predict the quality of distorted LF images, the measure of distortion in the depth map is exploited. To test and validate the proposed framework, a subjective experiment has been performed, and a LF image quality dataset has been created. The dataset is also used for evaluating the performance of state-of-the-art quality metrics, when applied to LF images. The achieved results evidence that the estimated quality score by the proposed framework has a significant correlation with subjective quality rating. Consequently, reference data can be delivered to the clients thus allowing the local estimation of the perceived quality of service. [ABSTRACT FROM AUTHOR]

In this paper, spatial modulation (SM) is introduced to layered division multiplexing (LDM) systems for enlarging the spectral efficiency (SE) over broadcasting transmission. First, the SM aided LDM (SM-LDM) system is proposed, in which different layered services utilize SM for terrestrial broadcasting transmission with different power levels. Then a SE analysis framework for SM-LDM systems is proposed, which is suitable for the SM-LDM systems with linear combining. Moreover, the closed-form SE lower bound of SM-LDM systems with maximum ratio combining (MRC) is derived, which is based on this framework. Since the theoretical SE analysis of single transmit antenna (TA) LDM systems with MRC and spatial multiplexing (SMX) aided LDM systems with MRC lacks a closed-form expression, the closed-form SE is also derived for these systems. Monte Carlo simulations are provided to verify the tightness of our proposed SE lower bound. Furthermore, it can be shown via simulations that our proposed SM-LDM systems always have a better SE performance than single-TA LDM systems, which can even outperform the SE of SMX aided LDM (SMX-LDM) systems. [ABSTRACT FROM AUTHOR]

This paper describes a channel estimation algorithm for the advanced terrestrial digital multimedia broadcasting (T-DMB) transmission system which is fully backward compatible with the conventional T-DMB standard. The advanced T-DMB has enhanced features which provide higher transmission data rate for increasing program channel capacity and better multimedia A/V service quality than the conventional T-DMB system by adopting a hierarchical modulation and scalable audio/video CODEC. To support the higher data rate transmission for the advanced T-DMB, high performance channel estimation and equalization techniques should be adopted into the advanced T-DMB receivers. In this paper, we propose a new channel estimation technique for the Advanced T-DMB to compensate channel distortion under dynamic multipath environment. [ABSTRACT FROM AUTHOR]

Channel encoder, which includes a forward error correcting (FEC) code followed by an interleaver, plays a vital role in improving the error performance of digital storage and communication systems. In most of the applications, the FEC code and interleaver parameters are known at the receiver to decode and de-interleave the information bits, respectively. But the blind/semi-blind estimation of code and interleaver parameters at the receiver will provide additional advantages in applications, such as adaptive modulation and coding, cognitive radio, non-cooperative systems, etc. The algorithms for the blind estimation of code parameters at the receiver had previously been proposed and investigated for known FEC codes. In this paper, we propose algorithms for the joint recognition of the type of FEC codes and interleaver parameters without knowing any information about the channel encoder. The proposed algorithm classify the incoming data symbols among block coded, convolutional coded, and uncoded symbols. Further, we suggest analytical and histogram approaches for setting the threshold value to perform code classification and parameter estimation. It is observed from the simulation results that the code classification and interleaver parameter estimation are performed successfully over erroneous channel conditions. The proposed histogram approach is more robust against the analytical approach for noisy transmission environment and system latency is one of the important challenges for the histogram approach to achieve better performance. [ABSTRACT FROM PUBLISHER]

DASH, the Dynamic adaptive video streaming over hypertext transfer protocol (HTTP), has become the de-facto video delivery mechanism nowadays, which takes advantage of the existing low cost and wide-spread HTTP platforms. Standards like MPEG-DASH defines the bitstreams conformance and decoding process, while leaving the bitrate adaptive algorithm open for research. So far, most DASH researches focus on the constant bitrate video delivery. In this paper, various bitrate (VBR) video delivery is investigated in the on-demand streaming scenario. Detailed instant bitrates of future segments are exploited in the proposed adaptation method to grasp the fluctuation traits of the VBR video. Meanwhile, the adaptation problem is formulated as an optimization process with the proposed internal QoE goal function, which keeps a good balance between various requirements. Besides, the parameters within the internal QoE function can be tuned to guarantee the flexibility of meeting different preferences. The experimental results demonstrate that our proposed QoE-based video adaptation method outperforms the state-of-the-art method with a good margin. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a novel algorithm to generate multiple virtual views from a video-plus-depth sequence for modern autostereoscopic displays. To synthesize realistic content in the disocclusion regions at the virtual views is the main challenging problem for this task. Spatial coherence and temporal consistency are the two key factors to produce perceptually satisfactory virtual images. The proposed algorithm employs the spatio-temporal consistency constraint to handle the uncertain pixels in the disocclusion regions. On the one hand, regarding the spatial coherence, we incorporate the intensity gradient strength with the depth information to determine the filling priority for inpainting the disocclusion regions, so that the continuity of image structures can be preserved. On the other hand, the temporal consistency is enforced by estimating the intensities in the disocclusion regions across the adjacent frames with an optimization process. We propose an iterative re-weighted framework to jointly consider intensity and depth consistency in the adjacent frames, which not only imposes temporal consistency but also reduces noise disturbance. Finally, for accelerating the multi-view synthesis process, we apply the proposed view synthesis algorithm to generate the intensity and depth maps at the leftmost and rightmost viewpoints, so that the intermediate views are efficiently interpolated through image warping according to the associated depth maps between the two synthesized images and their corresponding symmetric depths. In the experimental validation, we perform quantitative evaluation on synthetic data as well as subjective assessment on real video data with comparison to some representative methods to demonstrate the superior performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Motion-compensated frame rate up-conversion (MC-FRUC) consists of two key elements: motion estimation and motion-compensated frame interpolation. The motion estimation algorithm presented in [1], which is used in the MC-FRUC method proposed in this paper, provides unidirectional motion trajectories. The advantage of this motion estimation algorithm, besides its accuracy, is that it provides information on occlusions. However, motion compensation along unidirectional motion trajectories yields overlaps, holes, and blocking artifacts. To solve these problems, this paper presents two new algorithms for unidirectional motion-compensated frame interpolation: irregular-grid expanded-block weighted motion compensation (DIEM) and block-wise directional hole interpolation (BUDDHISM). The DIEM is used to reduce the blocking artifacts and solve the problem of overlapping blocks. The BUDDHISM preserves local texture and edges while filling holes. Experimental results show that the DIEM outperforms conventional motion compensation, and the BUDDHISM is better than the repeated median filter that is often used to fill holes. The performance of the proposed MC-FRUC, that uses the two new algorithms and the unidirectional motion estimation algorithm, is evaluated against three existing MC-FRUC techniques: a typical bi-directional algorithm, an object-based algorithm, and a commercial plug-in product. Experimental results show that the quality of the pictures interpolated using the proposed MC-FRUC method is much higher than those interpolated using the three existing MC-FRUC techniques. [ABSTRACT FROM AUTHOR]

This paper presents a new Audio QUAlity monitoring algorithm: "AQUA" for assessing the performance of Digital Radio Mondiale (DRM) receivers. AQUA targets performance evaluation of consumer grade receivers in fading channels objectively. Consumer grade DRM receivers do not generally possess a Receiver Status and Control Interface (RSCI), which prohibits the possibility of analysing digitally decoded audio bit stream after reception. AQUA relies on the analysis of the received analog audio output signal instead. The paper describes the development of the AQUA algorithm and the measurement system used for receiver audio quality testing. The performance of AQUA is compared to conventional RSCI derived metrics like Bit Error Rate (BER) and Frame Error Rate (FER) of the decoded audio data. A series of tests are conducted in a variety of propagation conditions using a DRM dedicated testing system with a fading channel emulator. It is shown that FER estimates using AQUA are in good agreement with conventional FER figures derived from RSCI in different fading channel scenarios. This allows AQUA to be used as a reliable alternative to conventional FER performance analysis for automated objective testing of DRM receivers. [ABSTRACT FROM AUTHOR]

Providing VCR-like operations in Peer-to-Peer (P2P) environments is a significant challenge. This paper proposes a distributed Storage-assisted Data-driven overlay Network (SDNet) to support P2P Video-on-Demand (VoD) services. It integrates two networks: a Data-driven Overlay Network (DONet) and a multi-way tree. DONet is enhanced and used for the routine video distribution based on the buffer overlapping mechanism and gossip protocol. A novel algorithm which uses a multi-way tree structure and extra pre-fetching buffers at the nodes is proposed to support efficient VoD operations. Videos are divided into uniform segments, pre-fetched and stored in a distributed manner along the tree topology. The cooperation between DONet-based video delivery and the tree-located multimedia components enable multimedia streaming interactive commands to be performed efficiently. This paper presents and discusses the structure of SDNet and the distributed storage scheme and details the cooperation procedure. Simulation-based testing results show how the proposed SDNet is an efficient interactive streaming solution in a P2P environment. [ABSTRACT FROM AUTHOR]

The high efficiency video coding (HEVC) standard provides superior efficiency for encoding and improves the compression ratio by almost 50% compared with previous video coding standards, such as advanced video coding (AVC). However, more intensive computation complexity is introduced by implementing the flexible quad tree-structured coding model. In a typical HEVC encoder, coding units (CUs) in a coding tree unit (CTU) that is built as a quad-tree structure are recursively traversed each depth level (CU size) to select the optimal coding configuration. Therefore, most of the encoding time is spent searching for the optimal coding configuration. In this paper, an efficient and fast CU size decision algorithm is proposed to reduce HEVC encoder complexity by the spatiotemporal features. First, an adaptive depth-range prediction method minimizes the possible range depth level by observing previous frames and proximal CTUs. Second, an early termination method based on the boundary examination from the de-blocking filter (DBF) prevents unnecessary calculation on small CU sizes. Furthermore, according to the sum of absolution difference (SAD), a smooth area detection mechanism is triggered when the predictive depth range excludes the largest CU size. This mechanism increase the bitrate of the CU, which contains static objects with complex textures. Compared with the HM 16, the experimental results revealed that the proposed algorithm can achieve an average 59.73% and 64.98% reduction in encoding time along with a 0.68% and 1.27% Bjontegaard Delta bitrate (BDBR) penalty for various test videos under low-delay P and random-access conditions, respectively. [ABSTRACT FROM AUTHOR]

Quality of Experience (QoE) reflects end users’ overall experience and feeling with network services, but needs support in terms of end-to-end Quality of Service (QoS). Segment routing (SR) as a new routing paradigm can provide good end-to-end QoS guarantee, making traditional multimedia traffic routing more efficient and scalable. In this paper, we address two problems related to the new SR mechanism: enabling fine-grained end-to-end QoS routing under a complex network environment and constructing the multicast routing tree with branch node load balancing. To solve these problems, an Inaccurate information-based QoE-driven Routing algorithm (IQdR) and a Branch-aware Multicast Tree (BaMT) algorithm were proposed. Simulation test results that have compared the performance of our proposed solution against that of other algorithms show that the previous works were outperformed. Additionally, the results also show that our multicast architecture improves the scalability of the network in terms of the number of flows. [ABSTRACT FROM AUTHOR]

The paper presents an admission approach for IPTV service providers that is designed to minimize QoS violations whilst effectively utilizing available bandwidth. Central to the approach is an empirical method of estimating the effective bandwidth required to satisfy QoS targets for admitted traffic flows. The paper describes this method and specifies two admission control algorithms based on the use of effective bandwidth estimates. The first algorithm employs a simple evaluation of whether there is sufficient bandwidth available to ensure, with an appropriate degree of confidence, that QoS targets will not be violated if a requested flow is admitted. The second algorithm utilizes information relating to the cost, duration and request frequency of specific IPTV content to prioritize higher revenue flows within the admission control process. Results of a simulation study (employing real traffic traces of long-lived flows) indicate that the proposed algorithms ensure that an adequate, but not overly generous, amount of bandwidth is allocated to ensure that QoS targets for accepted flows are met. Furthermore, they demonstrate the potential advantage of using content specific information in the admission control process to maximize generated revenue. [ABSTRACT FROM AUTHOR]

This paper illustrates how to interpret the superimposed caption box (SCB) in broadcasted sports videos of which the SCB template is presumably not given as a priori. The embedded captions in sports video programs represent digested key information of the video content. Most of the previous studies assume that the SCB template and the character bitmaps are known. The major contributions of this paper are (1) caption template extraction and identification, (2) symbol extraction and modeling, and (3) semantic interpretation of the identified captions and symbols. Experimental results show that the algorithm performs the SCB con- tents understanding for several commercial sports video programs. [ABSTRACT FROM AUTHOR]

This paper presents a simple but effective IPTV channel control algorithm that keeps channel zapping time in the tolerable range with high network utilization. The proposed algorithm controls channel zapping time by adjusting the number of broadcasting channels that are located close to users over IP networks and the number of additional I-frames inserted into each channel, based on the user's channel preference information. Finally, experimental results are provided to show the performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Although patching has shown to be a simple and efficient technique for immediate media on-demand delivery, there is still much scope for further improvement compared with the lower bound of the server network-I/O bandwidth requirement. In this paper, a new technique of two-level patching scheme is proposed for the first time, in which patching channels are rearranged through merging and further patching. Simulation results show that the proposed two-level patching scheme outperforms the conventional patching technique by a significant margin. It even performs better than the dynamic skyscraper algorithm over a wide range of client request rates. Furthermore, it is reasonably competitive with hierarchical multicast stream merging (HMSM) at low to modest client request rates. Most importantly, the implementation complexity of our algorithm is much lower than the skyscraper and HMSM. [ABSTRACT FROM AUTHOR]

Time-varying channels destroy the orthogonality among subcarriers in orthogonal frequency division multiplexing (OFDM) systems, and introduce intercarrier interference (ICI). Lots of efforts have been devoted to mitigate ICI in OFDM systems, with different frame structures and channel models, but the computational complexity of the methods is usually very high. In multiple-input multiple-output (MIMO) systems, the complexity is even higher. In this paper, a low-complexity ICI mitigation method is proposed for MIMO-OFDM systems under the assumption of linear time-varying channels. It reduces the complexity of ICI compensation from O(K^3(N^3+MN^2+MN)+NK\log (K)) to O(K(N^3+2MN^2+2MN+2M^2+N\log (K))) , where K is the number of subcarriers, M the number of transmitters, and N the number of receivers. It requires channel estimation based on the linear time-varying channel model, and no transmission overhead is needed. The proposed algorithm applies to all OFDM systems as long as linear time-varying channel estimation is applicable. Time-domain synchronous-OFDM naturally suits for the proposed ICI mitigation algorithm because its receiver is able to easily estimate linear time-varying channels. Simulation with QPSK and 16QAM modulation demonstrates the performance of the proposed method, in comparison with no ICI mitigation case. It shows that 2 dB signal to noise gain is achieved when the uncoded bit error rate is 10^-3 and the normalized Doppler frequency is 0.1. [ABSTRACT FROM AUTHOR]

For an orthogonal frequency-division multiplexing (OFDM) system over a doubly selective channel, a large number of pilot subcarriers are needed to estimate the numerous channel parameters, resulting in low-spectral efficiency. In this paper, by exploiting temporal correlation of practical wireless channels, we propose a highly efficient structured distributed compressive sensing-based joint multisymbol channel estimation scheme. Specifically, by using the complex exponential basis expansion model (CE-BEM) and exploiting the sparsity in the delay domain within multiple OFDM symbols, we turn to estimate jointly sparse CE-BEM coefficient vectors rather than numerous channel taps. Then a sparse pilot pattern within multiple OFDM symbols is designed to obtain an ICI-free structure and transform the channel estimation problem into a joint-block-sparse model. Next, a novel block-based simultaneous orthogonal matching pursuit algorithm is proposed to jointly recover coefficient vectors accurately. Finally, to reduce the CE-BEM modeling error, we carry out smoothing treatments of already estimated channel taps via piecewise linear approximation. Simulation results demonstrate that the proposed channel estimation scheme can achieve higher estimation accuracy than conventional schemes, although with a smaller number of pilot subcarriers. [ABSTRACT FROM AUTHOR]

The performance of an orthogonal frequency division multiplexing system is degraded in the presence of narrowband interference (NBI). This degradation arises from spectral leakage of the interference power during demodulation, corrupting many subcarriers. There have been many attempts to mitigate the NBI, but most schemes need some prior information about the NBI or resources in frequency or time domain. Recently, compressive sensing (CS) theory has been introduced, and some researches show that CS theory can be applied to estimate the NBI effectively. However, they still need resources such as frequency domain known elements or time domain interference free region. Also, CS recovery algorithms require high computational complexity. In this paper, we propose an widely usable NBI estimation and mitigation scheme using CS theory without any requirement. We verified that the proposed scheme can sufficiently mitigate spectral leakage of the NBI. Then, we substantially reduce its computational complexity by introducing a neighborhood searching method by dominant samples based on sampling theory. [ABSTRACT FROM PUBLISHER]

Spectral efficiency improvement is essential for mobile systems development in the light of growing demand for high data transmission rate. The Time-domain synchronous OFDM transmission system increases bandwidth utilization by time-domain channel estimation without any support from frequency-domain pilot signals. Channel identification methods use a training sequence, added at the beginning of every OFDM symbol. Sparse nature of the channel impulse response, which manifests itself during wireless broadband transmission, enables one to implement compressed sensing techniques for channel identification. Channel sparsity reduces the number of measurement samples required in channel reconstruction procedure, but they should be taken from the inter-block interference (IBI) free part of the received training sequence. If maximum delay spread of the channel is comparable with the length of the training sequence, the number of measurements within the IBI-free region may be insufficient for accurate channel identification. This paper discusses a new iterative approach to sparse channels estimation, which uses the measurements from outside the IBI-free region. The proposed solution is examined for simulated transmission over randomly generated doubly-selective channels when compared with the conventional CS technique and perfect channel state information condition. The experiments reveal an enhancement of the transmission quality in terms of SER for slow-time selective channels when both delays and gains of the channel impulse response are estimated with the orthogonal matching pursuit algorithm. Further improvement, also for transmission over moderate varying channels, is observed when the path delays are found in advance. A suitable frame structure is proposed to do so. [ABSTRACT FROM PUBLISHER]

Image quality assessment (IQA) has been an active research area during last decades. Many existing objective IQA models share a similar two-step structure with measuring local distortion before pooling. Compared with the rapid development for local distortion measurement, seldom effort has been made dedicated to effective pooling schemes. In this paper, we design a new pooling model via the analysis of distortion distribution affected by image content and distortion. That is, distributions of distortion position, distortion intensity, frequency changes, and histogram changes are comprehensively considered to infer an overall quality score. Experimental results conducted on four large-scale image quality databases (LIVE, TID2008, CSIQ, and CCID2014) concluded with three valuable findings. First, the proposed technique leads to consistent improvement in the IQA performance for studied local distortion measures. Second, relative to the traditional pooling, the performance gain of our algorithm is beyond 15% on average. Third, the best overall performance made by the proposed strategy outperforms state-of-the-art competitors. [ABSTRACT FROM PUBLISHER]

Non-uniform constellations (NUCs) have been recently introduced in digital broadcasting systems to close the remaining gap to the unconstrained Shannon theoretical limit. Compared to uniform quadrature amplitude modulation (QAM) constellations, NUCs provide a signal-to-noise ratio (SNR) gain (i.e., a reduction in the required SNR), especially for high-order constellations. One-dimensional NUCs (1D-NUC) have a squared shape with non-uniform distance between the constellation symbols. Since the I and Q components remain as two independent signals, a 1D-demapper as for uniform QAM constellations is feasible. Two-dimensional NUCs (2D-NUC) provide a better performance than 1D-NUCs, since they are designed by relaxing the square shape constraint, with arbitrary shape along the complex plane. However, the main drawback of 2D-NUCs is the higher complexity at the receiver, since a 2D-demapper is needed. In this paper, we propose a demapping algorithm that reduces from 69% to 93% the number of required distances when using 2D-NUCs. The algorithm discards or replicates those constellation symbols that provide scarce information, with a performance degradation lower to 0.1 dB compared to the optimal maximum likelihood demapper. [ABSTRACT FROM PUBLISHER]

The field of assessing three-dimensional (3-D) visual experience is challenging. In this paper, we propose a new blind image quality assessment for stereoscopic images by using binocular guided quality lookup and visual codebook. To be more specific, in the training stage, we construct phase-tuned quality lookup (PTQL) and phase-tuned visual codebook (PTVC) from the binocular energy responses based on stimuli from different spatial frequencies, orientations, and phase shifts. In the test stage, blind quality pooling can be easily achieved by searching the PTQL and PTVC, and the quality score is obtained by averaging the largest values of all patch’s quality. Experimental results on three 3-D image quality assessment databases demonstrate that in comparison with the most related existing methods, the devised algorithm achieves high consistency alignment with subjective assessment and low-complexity pooling. [ABSTRACT FROM AUTHOR]

In this paper, we identify the potential of the television bands to be used for providing vehicular infotainment service. Specifically, content delivery from the roadside unit to vehicular users is conducted by exploiting the spectrum holes, which is also referred to as spatial spectrum reuse. In this manner, the spectrum utilization efficiency is improved and the digital television service is not interfered. We first give a thorough description on such vehicular content delivery network and indicate the major design issues. After that, we respectively develop user and resource models tailored for our scenario by considering their characteristics and formulate the resource allocation as a system throughput maximization problem based on these models. For practical implementation, we devise a vehicular content delivery protocol incorporating a dynamic spectrum access algorithm and a maximal frame size design method, both of which aim at throughput and spectrum efficiency enhancement. Extensive simulations are conducted and the numerical results show the system performance is improved with our approaches. [ABSTRACT FROM AUTHOR]

Cooperatively fetching video content with the help of other mobile nodes can release some of the pressure on storage and bandwidth of the constrained mobile devices in wireless networks and speeds up the localization process of video resources so as to support better quality of viewing experience. In this context, the discovery of the appropriate mobile cooperative node becomes a key factor and is also a challenge for the deployment of such a fetching scheme. In this paper, we introduce a novel cooperative content fetching-based strategy to increase the quality of video delivery to mobile users in wireless networks (CCF). By intelligently monitoring the real-time variation in the state of the one-hop neighbors (immediate-neighbors) of the video resource downloader, CCF employs an innovative estimation model to measure the stability of these immediate-neighbors. In order to enhance the cooperative fetching efficiency, CCF designs a communication quality forecast model to measure link reliability and forecast the available bandwidth. By making use of a newly proposed cooperative fetching algorithm, CCF can speed up fetching and disseminating of video resources with the help of cooperative neighbors selected in terms of stability and communication quality. Simulation results show how CCF obtains higher selection accuracy of cooperative neighbors, lower average end-to-end delay, lower average packet loss ratio, higher average throughput, higher video quality, and lower maintenance overhead in comparison with state-of-the-art solutions. [ABSTRACT FROM PUBLISHER]

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 \(8\times 8\) size coding units (CUs) from the \(64\times 64\) 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 \(\times\) 2N mode, an early MERGE mode decision is proposed for the root CUs (i.e., \(64\times 64\) size CUs). Then, an early MERGE mode decision is proposed for the children CUs (i.e., \(32\times 32\) , \(16\times 16\) , and \(8\times 8\) 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. [ABSTRACT FROM PUBLISHER]

The DVB standard does not mandate the use of authentication and integrity protection for transport streams. This allows malicious third parties to replace legitimate broadcasts by overpowering terrestrial transmissions. The rogue signal can then deliver a malicious broadcast stream to exploit security vulnerabilities on Smart TVs (STVs) in range. We implemented a proof-of-concept attack based on a malicious Hybrid Broadcast Broadband TV app, able to acquire permanent system-level access to an STV over the air, in less than 10 s. These attacks, however, are severely limited in range due to required co-channel protection ratios (CCPRs), which is in direct contradiction to previous publications. We present evidence for these limitations in form of laboratory experiments, extensive simulations, and field measurements. To this end, we developed an automated, low-cost method for CCPR determination, as well as a method for non-disruptive attack range measurements based on a gap filler and the resulting channel impulse response. [ABSTRACT FROM PUBLISHER]

Time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) has been widely recognized as a fundamental OFDM block transmission scheme because of its advantages in spectral efficiency. However, it suffers from severe performance loss under strong frequency selective channels and thus has difficulty supporting high-order modulations such as 256QAM. In this paper, we proposed a compressive sensing (CS)-based channel estimation (CE) algorithm for layer modulated TDS-OFDM (LM-TDS-OFDM). In the proposed CE algorithm, the low-order modulated symbols will be recovered and then sent to a feedback loop for precise CE. The priori-information hold subspace pursuit algorithm is investigated to achieve accurate estimation of channel. Analyses and simulations show that the proposed algorithm can successfully obtain high-accuracy CE and significantly reduce the computational complexity. Based on the proposed CE scheme, LM-TDS-OFDM can well support 256QAM transmission under severe channel conditions. [ABSTRACT FROM PUBLISHER]

When adopting transmit diversity in the Chinese digital television terrestrial broadcasting (DTTB) system, there exists two kinds of interference: training sequences (TSs) from different transmit antennas are overlapped; and the TSs are interfered with OFDM data due to multipath fading. In order to distinguish different TSs, this paper proposes a method to design orthogonal TS set, which also have good correlation characteristic. Subsequently, an iterative algorithm to eliminate the interference between TSs and data is proposed and theoretically analyzed. Finally, simulations are performed and the results show that the system with the proposed scheme can achieve great diversity gain under acceptable computational complexity. [ABSTRACT FROM PUBLISHER]

3D Video (3DV) with depth-image-based view synthesis is a promising candidate of next generation broadcasting applications. However, the synthesized views in 3DV are often contaminated by annoying artifacts, particularly notably around object boundaries, due to imperfect depth maps (e.g., produced by state-of-the-art stereo matching algorithms or compressed lossily). In this paper, we first review some representative methods for boundary artifact reduction in view synthesis, and make an in-depth investigation into the underlying mechanisms of boundary artifact generation from a new perspective of texture-depth alignment in boundary regions. Three forms of texture-depth misalignment are identified as the causes for different boundary artifacts, which mainly present themselves as scattered noises on the background and object erosion on the foreground. Based on the insights gained from the analysis, we propose a novel solution of suppression of misalignment and alignment enforcement (denoted as SMART) between texture and depth to reduce background noises and foreground erosion, respectively, among different types of boundary artifacts. The SMART is developed as a three-step pre-processing in view synthesis. Experiments on view synthesis with original and compressed texture/depth data consistently demonstrate the superior performance of the proposed method as compared with other relevant boundary artifact reduction schemes. [ABSTRACT FROM AUTHOR]

Multiple antenna orthogonal frequency division multiple access (OFDMA) is a promising technique for the high downlink capacity in the next generation wireless systems, in which adaptive resource allocation would be an important research issue that can significantly improve the performance with guaranteed QoS for users. Moreover, most of the current resource allocation algorithms are limited to the unicast system. In this paper, dynamic resource allocation is studied for multiple antenna OFDMA based systems which provide multicast service. The performance of multicast system is simulated and compared with that of the unicast system. Numerical results also show that the proposed algorithms improve the system capacity significantly compared with the conventional scheme. [ABSTRACT FROM AUTHOR]

This paper presents a feedback canceller (FC) for T-DMB repeaters. Though the conventional FC of T-DMB repeaters has a good feedback cancellation performance, it distorts the recovered signal's out-band spectrum. This spectrum distortion problem is very crucial for commercializing T-DMB repeaters. The feedback canceller with pre-whitening filters (PWFs), which estimates the feedback channel using whitened input signals, can compensate this spectrum problem. However the feedback canceling performance degradation occurs when the feedback channel varies with Doppler effects. To compensate the out-band spectrum distortion and cope with the variation of feedback channel, we propose a novel FC based on the convex combination algorithm. Simulation results show that the proposed FC can remove clearly the out-band spectrum distortion of the recovered signal with improved the feedback canceling performance in both time-invariant and time-varying feedback channels. [ABSTRACT FROM AUTHOR]

In this paper, a novel macroblock-based frequency selective weighting scalable video coding (MBFSW-SVC) algorithm is investigated by exploring the characteristics of the human visual system (HVS) in SVC H.264/AVC for improving the coding efficiency. Compared with previous SVC schemes, the MBFSW-SVC can extend the quality layer with different frequency weighting for each MB according to the size of region of interests. For reasonable adaptation of the frequency weighting into the quality layer extension, the spatial context characteristics and the motion activities in each picture are taken into account. The experiment results show that the proposed scheme can improve the coding performance up to a 10-20% reduction of the bit rate with almost the same subjective video quality. In particular, the subjective quality is significantly improved in lower scalable quality layers with a small number of the encoding bit budget. [ABSTRACT FROM AUTHOR]

This paper presents a new technique for Clock Recovery in MPEG-2 Transport Streams in DVB-IPTV environment. The amount of jitter in this environment is very high compared to DVB-S or DVB-T. Use of linear Regression algorithm for Clock synchronization over packet switched networks is suggested by researchers in the similar field. However, the stability of such a filter in Real Time set top box application posed a problem. The continuous adaptive feedback loop used with the Linear Regression Algorithm provides accurate clock synchronization even when subjected to jitter of half a second. This robustness is needed for IP environment because of the increasing network traffic. The algorithm was simulated and found to require low computation time, high jitter attenuation and fast response as needed for the IP network. It is auto-adaptive for both low and high jitter environments by analysing the jitter present in the stream. The algorithm was implemented for Real time application in IPTV set top box and tested to be stable in the RTOS environment. [ABSTRACT FROM AUTHOR]

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

High-throughput design approaches for quasi-cyclic (QC) low-density parity-check (LDPC) decoders are presented in this paper. Three novel schemes for the horizontal process in min-sum algorithm and its revisions are derived to reduce design and implementation complexity. The schemes can be directly applied for variant QC codes and easily pipelined to increase the operating frequency of the decoder. Some improvements of the semi-parallel architecture are proposed to enhance throughput performance and hardware efficiency. Employing the proposed approaches, QC-LDPC decoders for Chinese Digital Television Terrestrial Broadcasting (DTTB) standard are implemented using field programmable gate array (FPGA). As shown in the results, the proposed approaches can substantially improve the throughput performance, as well as the throughput-and-hardware tradeoff, of decoders with semi-parallel architecture. [ABSTRACT FROM AUTHOR]

The frequency assignment problem involves the assignment of discrete frequencies to the transmitters of a radio network, such as a radio broadcasting network. Frequency separation is necessary to avoid interference by other transmitters to the signal received from the wanted transmitter at the reception region. Here, it is of major importance to minimize the interference while at the same time using the spectrum efficiently. In this paper we present two original distributed algorithms implemented on clusters of PCs used to solve the frequency assignment problem in the field of radio broadcasting. The first one is based on the island distributed [1] implementation of our hybrid genetic algorithm [2]. The second one uses a distributed cooperative Tabu Search. Experimental results show that our algorithms, applied to several instances given by TDF-C2R, lead to important time performance improvements. [ABSTRACT FROM AUTHOR]

Currently no information about different shots is used in the H.264/AVC video coding standard. This kind of information can help us choose more optimally the size of the Group of Pictures (GOPs) used for encoding of video content. In this paper, we initially propose an MPEG-7 descriptor based shot detection technique with low computational cost for H.264/AVC. Then we propose an adaptive initial quantization parameter (QP) estimation method for each shot based on modeling, training according to the content of video sequences and the shot detection method of our previous step. This two step architecture can help us reduce the bit rate and PSNR fluctuation when video sequences have multiple shots. Our proposed scheme outperforms the rate control of the H.264/AVC significantly in terms of reducing the average bit rate fluctuation (variance) by 8.6%-99% and the average PSNR fluctuation (variance) by 5%-99% between shots. Experimental results also demonstrate that the proposed algorithm can achieve similar or even better Rate Distortion (R-D) performance than standard Rate Control algorithms. It is also applicable in computationally and memory restricted devices since it needs maximum 2 frames buffer space for MPEG-7 descriptor calculation, while the average amount of extra processing is only about 5.8% of the total CPU cycles. [ABSTRACT FROM AUTHOR]

The design of efficient packet scheduling algorithms, which play a key role in the radio resource management (RRM), is crucial for the multimedia delivery in the satellite digital multimedia broadcasting (SDMB) system. In this paper, a novel packet scheduling scheme, which uses the cross-layer approach in its design, is proposed. This scheme comprises a new service prioritization algorithm and a dynamic rate matching based resource allocation algorithm, aimed at utilizing both the applications' QoS attributes and the physical layer data rate information. The performance of the proposed scheme has been evaluated via simulation. In comparison with existing schemes, the proposed scheme achieves significant performance gain on delay, delay variation and physical channel utilization. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new scheme to generate region-of-interest (ROI) enhanced depth maps combining one low-resolution depth camera with high-resolution stereoscopic cameras. Basically, the hybrid camera system produces four synchronized images at each frame: left and right images from the stereoscopic cameras, a color image and its associated depth map from the depth camera. In the hybrid camera system, after estimating initial depth information for the left image using a stereo matching algorithm, we project depths obtained from the depth camera onto ROI of the left image using three-dimensional (3-D) image warping. Then, the warped depths are linearly interpolated to fill depth holes occurred in ROI. Finally, we merge the ROI depths with background ones extracted from the initial depth information to generate the ROI enhanced depth map. Experimental results show that the proposed depth acquisition system provides more accurate depth information for ROI than previous stereo matching algorithms. Besides, the proposed scheme minimizes inherent problems of the current depth camera, such as limitation of its measuring distance and production of low-resolution depth maps. [ABSTRACT FROM AUTHOR]

Historically, Error-Resilient (ER) video transmission and Super-Resolution (SR) image reconstruction techniques have evolved separately. In this paper, we propose a coordinated application of ER and SR to enhance the resolution of image transmitted over mobile ad-hoc networks. In order to combat error propagation, a flexible multiple description coding method based on shifted 3-D SPIHT (3-D Set Partitioning In Hierarchical Trees) algorithm is presented to generate variable independent descriptions (substreams) according to the network condition. And then, a novel unequal error protection strategy based on the priority level is provided to assign a higher level of error protection to more important parts of bitstream. Moreover, a robust SR algorithm is proposed in the presence of different kinds of packet loss rate to enhance the image resolution. Experimental results indicate that the proposed robust resolution-enhancement scheme outperforms the competing methods from the aspects of PSNR (Peak-Signal-to- Noise Ratio) and visual quality under different packet loss rates. [ABSTRACT FROM AUTHOR]

In this paper we present a Base-matrix based decoder architecture for multi-rate QC-LDPC codes proposed in broadband broadcasting system. We use the Modified Min-Sum Algorithm (MMSA) as the decoding algorithm in this architecture, which lowers the complexity of the LDPC decoder while keeping almost the same performance or even better. Based on this algorithm, we designed a novel check node processing unit to reduce the complexity of the decoder and facilitate the multiplex of the processing units. The decoder designed with hardware constraints is not only scalable in throughput, but also easily configurable to support different QC-LDPC codes flexible in code rate and code length. [ABSTRACT FROM AUTHOR]

Boundary matching algorithm (BMA) and decoder motion vector estimation (DMVE) are two well-known temporal error concealment methods using the matching-based approach. In these two methods, the motion vector of each missing block is estimated by choosing one among candidate motion vectors which minimizes a sum of absolute differences (SAD) between boundary pixels of the corrupted macroblock. In general, the performance of DMVE is better than that of BMA. However, depending on the location or pattern of the corrupted block, BMA produces higher visual quality than DMVE. In this paper, we propose two types of hybrid error concealment methods; switching method and blending method. The switching method chooses one of two results obtained by BMA and DMVE based on the normalized SAD values. In the blending method, the weighted sum of the results concealed by the aforementioned two methods is utilized to improve the performance of error concealment. In order to reduce blocking artifacts further, the modified overlapped-block motion compensation is adaptively applied to the concealed blocks. Simulation results show that the proposed methods outperform other techniques in terms of subjective visual quality as well as PSNR performance. [ABSTRACT FROM AUTHOR]