Generation Terrestrial Digital Video Broadcasting Research Articles

Quasi-Optimal Tone Reservation PAPR Reduction Algorithm for Next Generation Broadcasting Systems: A Performance/Complexity/Latency Tradeoff With Testbed Implementation

High peak-to-average power ratio (PAPR) of the transmitted signal is a serious issue in multicarrier communication systems, such as second generation terrestrial digital video broadcasting (DVB-T2) systems. These large fluctuations prevent feeding the high power amplifier at an operating point near its non-linear saturation region thereby lowering its power efficiency. In recent years, tone reservation (TR) PAPR reduction techniques have been deeply studied and included in the DVB-T2 and the American digital video broadcasting (ATSC 3.0) specifications. It is based on a gradient iterative approach where, at each iteration, a predefined kernel is used to reduce one peak in time domain. In this paper, a novel TR PAPR reduction technique namely individual carrier allocation for multiple peaks (ICMPs) that is based on a new kernel signal is proposed. This algorithm, compatible with the DVB-T2 standard, offers better performance than the gradient-based DVB-T2 algorithm but suffers with increased complexity for higher modes of DVB-T2 and ATSC 3.0 as the number of required iterations is equal to the number of reserved tones. To overcome this issue, we propose an improved ICMP technique, called grouped ICMP defined with this new kernel. The main principle of this new algorithm consists in dividing the reserved tones into $G$ groups. This highly reduces the number of iterations, now equal to the number of groups, and thereby the latency. An in-depth performance analysis has been done by implementing our algorithm on a testbed platform with real power amplifiers. Both the simulation and experimental results demonstrated that the proposed PAPR reduction algorithm offers very good performance/complexity/latency tradeoff.

Spectral Overlap Optimization for DVB-T2 and LTE Coexistence

In this paper, we analyze the spectral coexistence between the second generation terrestrial digital video broadcasting (DVB) and the long term evolution (LTE) networks. In particular, the global spectral efficiency (SE) of both systems is investigated when a partial spectral overlap between DVB and LTE signals occurs. Our contribution lies in twofold: 1) the interfering signal variance in each network is derived analytically according to the frequency overlap while taking into account the difference between the characteristics of LTE and DVB networks, especially the OFDM subcarrier spacing and then the OFDM symbol duration and 2) SE is derived with uniform and non uniform power allocation between overlapped and non overlapped subcarriers of the two networks. This derivation offers an analytical evaluation of the effect of the spectral overlap ratio variation and different power allocation scenarios and provides insightful results on the cooperation between the two networks.

Influence of the LTE System using Cognitive Radio Technology on the DVB-T2 System using Diversity Technique

In recent years, the development of advanced wireless communication systems has been rapidly progressing. In Europe, the 2nd Generation Terrestrial Digital Video Broadcasting (DVB-T2) and Long-Term Evolution (LTE) are the most promising techniques to provide multimedia services efficiently (in flexible quality and with high spectrum efficiency). The purpose of this work is to explore possible influences of the LTE uplink services, using cognitive radio (CR) technology, on the area which is covered by DVB-T2 services. In the case of DVB-T2, both single-input single-output (SISO) and multiple-input single-output (MISO) transmission techniques are considered. The defined coexistence scenarios are measured with an appropriate measurement testbed. The performance of the received TV signal is evaluated on its physical layer (PHY) level. The obtained results allow better understand the influence of LTE system on DVB-T2 which is using diversity technique in the same RF channel (co-channel coexistence). One of the main results is that there are the same requirements on the Forward Error Correction (FEC) decoding process in the DVB-T2 receiver, when power imbalances between TV transmitters (an both SISO and MISO modes) are considered at the interfering LTE signal. This finding was also proved by analysis of variance (ANOVA).

Performance Analysis of DVB- T2 using MIMO-OFDM Technique

Orthogonal Frequency Division Multiplexing (OFDM) is a powerful technique employed in communications systems to combat with the frequency selective channel. Combined with smart antennas (multiple antenna system) at the transmitter and receiver, OFDM proves to be robust against channel delay spread. Moreover, it leads to significant data rates with improved bit error performance over links having only a single antenna at both the transmitter and receiver. In this work, the performance of the 2 Generation Terrestrial Digital Video Broadcasting (DVB-T2) is analyzed, where high data rate is a must. To analyze this system, OFDM with Multiple-Input MultipleOutput (MIMO) systems have been used by applying an algorithm called Space-Time Block Code (STBC). Here, bit error rate (BER) of the system is analyzed in Additive White Gaussian Noise (AWGN) channel using QPSK modulation scheme. It has also been proved in this work that, the combination of OFDM-MIMO system is much more bandwidth efficient compared to normal OFDM system.

Simplified Rotated Constellation Demapper for Second Generation Terrestrial Digital Video Broadcasting

The constellation rotation and cyclic Q-delay technique has been adopted in second generation terrestrial digital video broadcasting to provide signal space diversity, improving the system performance under severe multipath propagation environments. The main drawback of this technique is the hardware complexity introduced in the demapping process compared to non-rotated constellations. In this brief, we present a simplified demapper that reduces up to 78% the number of required operations with almost no performance degradation compared to the results of the ideal max-log demapper.

Opportunistic Error Correction for OFDM-Based DVB Systems

DVB-T2 (second generation terrestrial digital video broadcasting) employs LDPC (Low Density Parity Check) codes combined with BCH (Bose-Chaudhuri-Hocquengham) codes, which has a better performance in comparison to convolutional and Reed-Solomon codes used in other OFDM-based DVB systems. However, the current FEC layer in the DVB-T2standard is still not optimal. In this paper, we propose a novel error correction scheme based on fountain codes for OFDM-based DVB systems. The key element in this new scheme is that only packets are processed by the receiver which has encountered high-energy channels. Others are discarded. To achieve a data rate of 9.5 Mbits/s, this new approach has a SNR gain of at least 10 dB with perfect channel knowledge and 11 dB with non-perfect channel knowledge in comparison to the current FEC layer in the DVB-T2standard. With a low-complexity interpolation-based channel estimation algorithm, opportunistic error correction offers us a QEF (Quasi Error Free) quality with a maximum DF (Doppler Frequency) of 40 Hz but the current DVB-T2 FEC layer can only provide a BER of 10?7 quality after BCH decoding with a maximum DF of 20 Hz.

An Improved Integer Frequency Offset Estimator using the P1 Symbol for OFDM System

This paper suggests an improved integer frequency offset (IFO) estimation scheme using P1 symbol for orthogonal frequency division multiplexing (OFDM) based the second generation terrestrial digital video broadcasting (DVB-T2) system. Proposed IFO estimator is designed by a low-complexity blind IFO estimation scheme, which is implemented with complex additions. Also, we propose active carriers (ACs) selection scheme in order to prevent performance degradation in blind IFO estimation. The simulation results show that under the AWGN and TU6 channels, the proposed method has low complexity than conventional method and almost similar performance in comparison with the conventional method. Keywords—OFDM, DVB-T2, P1 symbol, ACs, IFO.

Rotated constellation demapper for DVB-T2

The constellation rotation and cyclic Q-delay technique has been adopted in the second generation terrestrial digital video broadcasting (DVB-T2) standard. It improves the performance under fading channels, but introduces serious complexity problems in the hardware implementation of the demapper. Presented is a simplified demapper scheme that reduces up to 31% the number of required operations with almost no performance degradation.

Analysis of Physical Layer Signaling Transmission in DVB-T2 Systems

In this paper the robustness of the physical layer signaling in the new DVB-T2 (second generation terrestrial digital video broadcasting) system is studied and compared to corresponding robustness of data path with help of computer simulations. The robustness is studied in both static and mobile transmission channels.

Coarse time synchronisation for DVB-T2

A new coarse time synchronisation algorithm for second generation terrestrial digital video broadcasting (DVB-T2) receivers is presented. The proposed method provides not only an accurate coarse timing estimate but also a fast detection of DVB-T2 signals with slightly better robustness than the scheme presented in the DVB-T2 implementation guidelines.

Performance and Implementation Evaluation of TR PAPR Reduction Methods for DVB-T2

High Peak to Average Power Ratio (PAPR) is a critical issue in multicarrier communication systems using Orthogonal Frequency Division Multiplexing (OFDM), as in the Second Generation Terrestrial Digital Video Broadcasting (DVB-T2) system. This problem can result in large performance degradation due to the nonlinearity of the High Power Amplifier (HPA) or in its low power efficiency. In this paper, we evaluate the performance of different Tone Reservation-based techniques for PAPR reduction in DVB-T2 context. Also, we propose an iterative TR-based technique called “One Kernel One Peak” (OKOP). Simulation results and performance comparison of these techniques in terms of gain in PAPR reduction, mean power variation, and complexity will be given. Finally, we describe the implementation of a PAPR reduction algorithm in the DVB-T2 modulator.

Coded Decision Directed Demodulation for Second Generation Digital Video Broadcasting Standard

Second generation terrestrial digital video broadcasting (DVB-T2) standard aims at providing high definition television and high rate services for the same spectrum allocation of current DVB-T standard. This goal is achieved by adopting new physical layer features that increase the spectrum efficiency. In this respect, the insertion of pilot tones in the orthogonal frequency division multiplexed (OFDM) signal, though allowing an efficient channel estimation, decreases the spectral efficiency. In this paper we evaluate performance of the coded decision directed demodulation (CD3) technique for channel estimation in DVB-T2. In fact, by iterating between decoding and channel estimation, with the latter obtained by using previously decoded symbols, CD3 is able to provide an accurate channel estimation with very few pilots, even in the presence of highly frequency dispersive and time-variant channels. Numerical results are provided for a comparison in terms of achievable throughput between DVB-T2 with CD3 and current DVB-T. Moreover, multiple antennas at the base station are also considered to provide spatial diversity and hence further improve system performance.