Digital Television Terrestrial Multimedia Broadcasting Research Articles

Channel Equalization With Phase Error Mitigation for the Chinese Digital Television Terrestrial Broadcasting Systems

OFDM is extensively used in modern digital television terrestrial broadcasting (DTTB) systems to support high performance bandwidth-efficient multimedia services, such as the Digital Video Broadcasting for Terrestrial Television (DVB-T) proposed as the European DTTB standard and the Digital Television/Terrestrial Multimedia Broadcasting (DTMB) proposed as the Chinese DTTB standard. System based on OFDM is sensitive to the phase error produced due to not only the tuner phase noise but also the phase deviation of residual sampling clock offset, frequency offset estimation error and Doppler spread in the mobile applications. In this paper, a channel equalization with phase error mitigation scheme is proposed for the time domain synchronous OFDM (TDS-OFDM) based Chinese digital television terrestrial broadcasting systems. In the proposed channel equalization scheme, the influence of the phase error on the performance of the TDS-OFDM based Chinese DTTB systems is split into a multiplicative part (which is common to all sub-carriers and is referred to as the common phase rotation (CPR)) and an additive part (which is referred to as the inter-carrier interference (ICI)). Both the CPE and the ICI are estimated and compensated in the proposed scheme. Simulation results for system with phase error and under mobile environment are presented to illustrate the effectiveness of the proposed scheme.

Low cost VLSI architecture of resisting long echo channel estimation for DTMB system

Digital television/terrestrial multimedia broadcasting (DTMB) was announced as the Chinese digital television terrestrial broadcasting (DTTB) standard in August, 2006. It adopts TDS-OFDM (time-domain synchronous-orthogonal frequency division multiplexing) as the baseline modulation technology. There is not pilot information in order to avoid reduction of channel throughput. It uses pseudo-noise (PN) sequence as guard interval (GI) and the training sequence for both multi- and single-carrier block transmissions which makes the synchronization faster than CP-OFDM (cyclic prefix-orthogonal frequency division multiplexing) systems. It can resist the inter-symbol interference (ISI) and can be used for channel estimation and synchronization. In this paper, a full-mode channel estimation scheme for DTMB demodulator is developed. This method utilizes the PN sequence to obtain channel estimation and equalization both in three kinds of frame head (FH) mode as well as in single and multi-carrier modulation transmission mode. To implement on hardware realization, interference cancellation is predigested, then equalization and filter for channel impulse response are optimized. A low cost VLSI architecture for channel estimation and equalization is proposed which works effectually and achieves low complexity as well. Computational simulation results show that the proposed scheme has little BER loss in performance.

Technology and standards of digital television terrestrial multimedia broadcasting [Topics in Wireless Communications

The digital television terrestrial multimedia broadcasting standard was ratified on August 18, 2006, and is the mandatory digital television terrestrial broadcasting standard in China. DTMB defines the signal frame structure, the coding and modulation schemes, and adopts time-domain synchronous orthogonal frequency-division multiplexing technology using pseudo random sequence as both the guard interval of the OFDM block and the training symbol. It can deliver fast system synchronization, accurate channel estimation, high spectrum efficiency, and excellent single-frequency network performance. This article covers the major features of the DTMB standard, its industrialization, current deployment status, and various applications based on the DTMB standard.

Phase Noise Correction Based on TPS Symbols for the Chinese DTTB System

In orthogonal frequency division multiplexing (OFDM) system, phase noise (PHN) from oscillator can severely reduce the performance by causing: common phase error (CPE) and inter-carrier interference (ICI). The impact of PHN on received signal can be characterized by the circular convolution of the transmitted signal and the discrete Fourier transform (DFT) of PHN signal in frequency domain. Digital television/terrestrial multimedia broadcasting (DTMB), announced as the Chinese digital television terrestrial broadcasting (DTTB) standard, adopted the time-domain synchronous OFDM system (TDS-OFDM) system which has 36 continuous transmission parameter signaling (TPS) symbols in frequency domain which be used for PHN suppression. Based on a linearized parametric model for PHN, least squared (LS) estimation and fast Fourier transform (FFT) approaching method for PHN correction are proposed in this paper. The effects of the PHN on channel estimation in both TDS-OFDM system and conventional cyclic prefix OFDM (CP-OFDM) are also investigated. Simulations show that the proposed algorithm can effectively reduce the PHN and improve the symbol error rata (SER) of TDS-OFDM systems over both additive white Gaussian noise (AWGN) and broadcasting multipath channel. In practice, the FFT-approaching method can be applied to the DTMB receiver-chip design directly with low implementation cost.

Novel channel estimation method based on PN sequence reconstruction for Chinese DTTB system

Digital television/terrestrial multimedia broadcasting (DTMB), announced as the Chinese digital television terrestrial broadcasting (DTTB) standard, uses pseudo-noise (PN) sequence as guard interval (GI) and the training sequence for both multi- and single-carrier block transmissions. The conventional channel estimation methods can be performed through either the subtraction of the PN sequence or the cancellation of residual inter-symbol interference (ISI). In this paper, a novel iterative method is introduced to estimate the overlapping part of PN sequence, meanwhile the channel impulse response (CIR) estimation can be obtained and updated via the reconstruction of the PN sequence in an iterative manner. Simulations show that the proposed algorithm can effectively reduce the ISI and improve the symbol error rata (SER) of DTMB system over slowvarying broadcasting multipath channel even with long delay spread. In practice, the proposed algorithm can be applied to the DTMB receiver-chip directly with low-complexity cost.

A Transmit Diversity Scheme for TDS-OFDM System

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Transmit diversity is especially important in broadcasting network. In this paper, a transmit diversity method is proposed for the Chinese National Digital Terrestrial Television Broadcasting (DTTB) Standard. The transmit diversity scheme is based on the design of orthogonal sequences which have perfect crosscorrelation and almost perfect autocorrelation characteristic. The characteristics of the proposed sequences can help for synchronization and channel estimation in time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) system. Simulations using space-time codes (STCs) in Digital Terrestrial/Television Multimedia Broadcasting (DTMB) system with low density parity check coding (LDPC) show that the proposed transmit diversity method has about 1–2 dB signal-to-noise ratio (SNR) gain comparing with no diversity for QPSK and 16 QAM constellations at <formula formulatype="inline"> <tex Notation="TeX">${\rm BER}=10^{-4}$</tex></formula>, and it can avoid the appearance of BER floor for 64QAM constellation. </para>

A New Paradigm for Mobile Multimedia Broadcasting Based on Integrated Communication and Broadcast Networks

This article provides a new paradigm to integrate the Chinese digital television/terrestrial multimedia broadcasting (DTMB) systems with existing mobile communication systems, which can support mobile multimedia broadcasting services with carrier-grade quality. By dividing the services into four categories -digital TV, video on demand, data on demand, and Internet access - a complete design of the layered structure and signaling protocols are presented. Specifically, a subnetwork data unit layer and a modified hybrid ARQ signaling protocol have been proposed. A testbed at Tsinghua University based on DTMB and WLAN/CDMAlx has been successfully implemented, and the experimental results clearly show the effectiveness of the proposed signaling protocols.