Search

The Chinese digital television terrestrial broadcasting (DTTB) standard uses pseudo-noise (PN) sequence as guard interval (GI) and the training sequence. This PN sequence is used to do channel estimation and synchronization in the system. The existing channel estimation methods often have to adopt iterative scheme when the length of channel impulse response (CIR) is long, which will increase the receiver complexity dramatically. In this paper, a channel estimation scheme for time domain synchronous OFDM (TDS-OFDM) systems is proposed. Interference free CIR information can be obtained by constructing special correlation windows, rather than removing interference from the time domain sequences through iteration. Moreover, the estimation can be achieved by using correlation process. Comparing to conventional schemes, the proposed algorithm greatly reduces the computational complexity. Simulation results show that the proposed method can meet the requirement of the Chinese DTTB systems. And the scheme is also suitable for other communication OFDM systems with time domain sequence headers. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 re- suits of PN595 + C1 are also presented to demonstrate the satisfactory performances in fixed reception and high speed mobile reception. [ABSTRACT FROM AUTHOR]

A channel estimation method based on frequency-domain pilots and time-domain processing (FPTP) is proposed for OFDM systems in time-varying channels. Through Discrete Fourier Transform (DFT), the channel impulse response (CIR) is estimated by using the frequency-domain pilots, which is equivalent to the CIR estimated by cyclic correlation using time-domain pilot sequence. Hence, the channel estimation error, caused by the spectral leakage of the DFT, can be reduced by canceling the non-idea auto-correlation property of the pilot sequence in time-domain. At the same time, the complicated cyclic correlation computation in time-domain is evitable. The theoretical analysis and simulation results show that the proposed method outperforms the traditional DFT-based method and Wiener filter algorithm in time-varying multi-path fading channels. Moreover, the uncoded bit error rate (BER) performance of proposed algorithm is very close to that with perfect channel knowledge, especially in fast fading channels. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]