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In this paper, we propose a channel estimation method using time domain training sequences. Most recent works generally use a correlation scheme for channel estimation in OFDM systems with time domain sequences. However, the performance of this method is affected dramatically by the correlation characteristics and suffers from multipath interference. Rather than correlation analysis, we provide a new method based on least mean square (LMS) theory. The selection of parameter and corresponding schemes in time-varying channels as well as multipath channels with long time delay spreads are discussed too. Simulations of the new scheme and comparisons show its superiority over the conventional method. Index Terms--Channels estimation, LMS, TDS-OFDM, time domain sequences.

For wireless video streaming, the three dimensional scalabilities (spatial, temporal and SNR) provided by the advanced scalable video coding (SVC) technique can be directly utilized to adapt video streams to dynamic wireless network conditions and heterogeneous wireless devices. However, the question is how to optimally trade off among the three dimensional scalabilities so as to maximize the perceived video quality, given the available resource. In this paper, we propose a low-complexity algorithm that executes at resource-limited user end to quantitatively and perceptually assess video quality under different spatial, temporal and SNR combinations. Based on the video quality measures, we further propose an efficient adaptation algorithm, which dynamically adapts scalable video to a suitable three dimension combination. Experimental results demonstrate the effectiveness of our proposed perceptual video adaptation framework. Index Terms--Human visual system, no-reference video quality assessment, perceptual video adaptation, scalable video coding.

In this paper, the effect of the Minimum-Mean-Square Error Decision Feedback Equalizer (MMSE-DFE) when combined with decoding that is applied to the coded transmission, is studied. When the length of MMSE-DFE is large, it is more realizable to use the decoding value as the decision value. Here, the DFE using the Nordstrom-Robinson (NR) decoding value is proposed. Through simulation and by testing results, the DFE combined with NR decoding shows better performance than the traditional DFE. Moreover, this paper supports an approach to cancel partial residual Inter-Symbol Interference (ISI) that is caused by decision delay when DFE is combined with NR decoding. Index Terms--DFE, DTTB, equalization, NR code, receiver.

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. Index Terms--Base-matrix, broadcast, channel coding, FPGA, MMSA, multi-rate, quasi-cyclic low-density parity-check codes (QC-LDPCC), scalable throughput.

A digital terrestrial television broadcasting (DTTB) standard named 'Frame structure, channel coding and modulation for digital television terrestrial broadcasting system' was published in China in August 2006. This is the first paper of a series that provide a complete and in depth description to the standard including laboratory and field measurement results, detailed analysis on technologies in achieving stable fixed reception and fast mobile reception, as well as methodologies in spectrum allocation, and principles and technologies in performing single frequency network operation. Among the hundreds of operation modes to support multi-program SDTV/HDTV terrestrial services in the standard, the key features and major applications of a series of modes named 'PN595 + C1' are described in detail. Measurement results of PN595 + C1 are also presented to demonstrate the satisfactory performances in fixed reception and high speed mobile reception. Index Terms--Chinese Standard, DTTB, PN595, single carrier.

Transmit diversity can be applied to OFDM systems by adopting space time code. Since the received signal is the overlapped signals transmitted from different transmit antennas, channel estimation is a rather challenging task for space time coded OFDM (ST-OFDM) systems. Pilot structure can help the receiver to effectively separate the overlapped signals and perform accurate channel estimation. In this paper, we propose three different channel estimation algorithms based on specially designed comb type pilots inserted in frequency domain. One of our proposed algorithms is performed in frequency domain and the other two are performed in time domain. Such comb type pilot based algorithms can provide higher bandwidth efficiency than common significant-tap-catching algorithm using training block pilots. Numerical analyzes and computational simulation show that our proposed estimation schemes have the same good performance while the time domain methods have relatively simple structure. Index Terms--Channel estimation, comb type pilot, frequency domain, OFDM, pilot design, space time code, time domain, transmit diversity.

Video communication with Quality of Service (QoS) is an important and challenging task. The transmitted video stream must be able to afford the bandwidth variance and unavoidable packet loss in the Internet. In particular, fine-granular-scalability (FGS) video coding has been adopted by the MPEG-4 standard as the core video-compression method for streaming applications. From this inception, the FGS scalability structure was designed to be packet resilient especially under unequal loss protection (ULP). In this paper, we use ULP to protect FGS compressed video, and under the restriction of the network bandwidth, joint source-channel rate-distortion based optimization is performed in bit allocation to minimize the end-to-end distortion. Simulation results demonstrate effectiveness of our approach. Index Terms--FGS, rate-distortion optimization, unequal loss protection.

In Digital TV Broadcasting, the Scheme of Single Frequency Network (SFN) has nontrivial advantages. By forming a SFN, a broadcasting system is able to serve an arbitrary large area with the same program within the same frequency block. At the mean time, the SFN structure provides the receiver with a potential of yielding the space diversity gain, while the power in every single transmitter is not increased. However, there are heavy artificial multipath propagation in the area covered by the SFN broadcasting. Traditionally, a transversal equalizer is used at the receiver to remove the SFN interference. The equalizer always cannot converge properly due to the over-long time delay and the over-large magnitude of the different paths from each transmitter of the SFN. To solve the problem, a new model based on the MIMO structure of the SFN is proposed in this paper, where the signal's space information is exploited. With the model in mind, a new receiving scheme is derived. By using a beamformer, signals with different incident angles are separated, so the problem caused by the over-long delay and the over-large magnitude is avoided. A bank of parallel sub-filters are used to remove the residual multipath spread. The space diversity gain is obtained at the output of a combiner. Index Terms--Beamformer, digital terrestrial television, equalizer, MIMO, SFN.

Motion compensated video format conversion (MC-VFC) needs true motion vectors, which have such features as spatial consistency and temporal extension. Based on these features, the temporal compensated motion estimation algorithm with the simple block-based prediction (TC-SBP) is presented in this paper. Making use of the spatial-temporal correlation, the simple block-based prediction needs only three neighboring candidate vectors for each block, so that its computational complexity is highly reduced. At the same time, three temporal compensated updating candidates are used to efficiently accelerate the convergence of the algorithm for the global motion field. Measured with the criteria relevant to the MC-VFC and video processing applications, the new TC-SBP algorithm is shown to get a superior performance over alternative ones. Index Terms--Motion compensated video format conversion, simple block-based prediction, spatial-temporal correlation, temporal compensated strategy, video processing.

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

Low-density parity-check (LDPC) codes are widely used as error correction codes in new generation digital TV standards, such as the second generation of terrestrial digital video broadcasting standard (DVB-T2), Advanced Television Systems Committee (ATSC) 3.0, etc. The nonlinear belief propagation (BP) algorithm has excellent decoding performance for LDPC codes, but is often simplified in hardware implementations by linear min-sum (MS) algorithm due to its high complexity. This simplification also leads to over-estimation problems, which can be corrected by adding factors in conventional algorithms (e.g., normalized min-sum (NMS), offset min-sum (OMS), and variable scaling normalized min-sum (VMS) algorithms). However, the correction factors of these modified MS algorithms cannot adapt to different channels and modulations, and the performance needs further improvement. In this paper, the concepts of over-estimation value (OEV) and over-estimation rate (OER) are introduced to describe the over-estimation problem of the MS algorithm. Then, under the guidance of OEV and OER, a polygonal line min-sum (PMS) algorithm with correction factors adapted to different channels and modulations is proposed according to LLR distribution. Following the properties of OEV and OER, PMS algorithm is further simplified into Simplified PMS (SPMS) algorithm. LDPC codes from ATSC 3.0 are adopted in this paper to evaluate SPMS algorithm in comparison with the conventional algorithms. Extensive simulation results show that the SPMS algorithm for ATSC 3.0 LDPC decoder has at most 1.61dB, 0.24dB and 0.36dB gain over NMS, OMS and VMS algorithms respectively when frame error rate (FER) is at 10−4 level over additive white Gaussian noise (AWGN) channel with QPSK modulation. More importantly, the simulation results show that the SPMS algorithm can achieve much better performance than these modified MS algorithms over AWGN and Rayleigh channel with higher-order modulations or under limited maximum iteration number. [ABSTRACT FROM AUTHOR]

In Multimedia Broadcast/Multicast Service(MBMS), Multicast/Broadcast Single Frequency Network (MBSFN) and Single-cell Point-to-multipoint Network (SC-PTM) are two essential ways to organize networks to provide multicast services. MBSFN shows its unique advantage of enhancing signals at the boundary of two cells, however, highly requiring synchronization of symbols. SC-PTM shows the advantage of the flexibility on the network deployment. The comparison and complementarity of these two modes are explored. In this paper, we analyze the reception performance of MBSFN and SC-PTM from multiple perspectives. We first compare the successful transmission probability (STP) of MBSFN with that of SC-PTM. Then, we consider optimal power control problems in MBSFN and SC-PTM. The corresponding power control optimization problems are with fraction and max-min forms and solved by the Dinkelbach algorithm. Furthermore, we propose a joint mode-selection and power-control method in the hybrid mode of MBSFN and SC-PTM, where each cell could select the multicast mode from MBSFN and SC-PTM. This is a mixed-integer nonlinear programming (MINLP) problem and solved by the concave-convex procedure (CCCP) and the Dinkelbach algorithm. To further improve the throughput, the appropriate successful reception proportion is selected under the opportunistic multicast. Finally, the numerical simulations show the performance of our algorithms and compare the throughput of two modes, which verify our analysis. [ABSTRACT FROM AUTHOR]

This article investigates the non-uniform constellation (NUC) optimization adapted for Hierarchical modulation (HM) without using Successive Interference Cancellation (SIC). This approach is promising to reduce system demod/decode delay in comparison to Layered Division Multiplexing (LDM). By maximizing the constellation constrained capacity of Enhanced Layer (EL) service in HM, while the capacity of Core Layer (CL) service are approximately the same in HM and LDM, the capacity achieved by HM using NUCs is comparable to LDM. Particle Swarm Optimization (PSO) algorithm is used to resolve this problem. To accelerate the optimization, initial constellation is selected from regular NUCs or the combination of CL and EL constellations of LDM in ATSC 3.0. The results imply that under certain capacity demands, especially when there is a large difference between the SNR thresholds of CL and EL or the power ratio of CL to EL is high (for example, 10 dB or higher), HM, with lower delay compared to LDM, can achieve the capacity comparable or even better than LDM with the help of NUCs. Even if the power ratio of CL to EL is relatively low (for example, 3 dB), the capacity loss can be reduced with properly designed NUCs and the SNR threshold loss of EL can be approximately 0.4 dB with respect to LDM. However, LDM is still superior to HM when the difference between the SNR thresholds of CL and EL is relatively low. [ABSTRACT FROM AUTHOR]