Digital Video Broadcasting-Second Generation Research Articles

Optimization of Multi-Frequency Network With DVB-T2 Services for Regions With Complex Geographies: A Case Study of Nepal

Planning for Multi-Frequency Network (MFN) with Digital Video Broadcasting-Second Generation Terrestrial (DVB-T2) services is particularly useful during the transition from analog to digital broadcasting. For efficient management of service area as well as resource allocation, it is necessary to administer the use of network parameters, e.g., transmit power, frequency channels, and antenna parameters. This article, therefore, proposes a coverage maximization scheme for the MFN with the DVB-T2 system by using the Genetic Algorithm. In order to effectively perform the optimization over regions with diverse geographical structures, a propagation prediction method considering the complex orography together with Digital Elevation Model is used to predict signal strength at each receiving location. Based on the received signal strength and standard Quality of Service criteria, the overall radio coverage of the network is maximized using the optimum values of transmit power levels, frequency channels, and antenna parameters. Although our analysis and simulations are based on the MFN network in Nepal, the methodology presented in this work can be applied in any region with some alterations in geographical and meteorological parameters.

Regional Contents in a National DVB-T2 SFN: A Novel Approach Based on DVB-SIS

To include regional contents in a national single-frequency network (SFN), the RAI Radiotelevisione Italiana has studied and tested a system configuration that benefits from the multiple physical layer pipes (PLPs) of Digital Video Broadcasting-Second Generation Terrestrial (DVB-T2) standard in a laboratory. According to the proposed solution, in each region, the national programs are transmitted in one PLP, whereas other k PLPs convey the regional contents of a macroregional SFN, formed by a region and the (k–1) surrounding ones. The DVB Single Illumination System standard can be a valid technical solution to distribute such complex signals to SFN transmitters via satellite or terrestrial contribution links in a cost-effective way. This article presents the rules adopted to map content into DVB-T2 PLPs and their application to the Italian case. Furthermore, it describes the end-to-end laboratory setup and the results of tests carried out, showing that a national SFN can broadcast both national and regional contents with high flexibility and spectrum efficiency.

Measurement of digital video broadcasting-second generation terestrial (DVB-T2) signal in Kuala Lumpur, Malaysia

<span style="font-size: 9pt; font-family: 'Times New Roman', serif;">DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial) is one of the latest technical standards being developed by the DVB Project for DTT (Digital Terrestrial Television). It is also known as digital broadcasting trough terrestrial system since 2006 and is an extension of the DVB-T system as a second generation program to improve efficiency of the total system. It is important to perform a research on the performance of DVB-T2 because Malaysia has launched the free-to-air digital TV project since 2016 hence there is a need to know how well the signal is being received by viewers. This research focuses on a DVB-T2 transmission process which involve the transmission from Menara Kuala Lumpur transmitter to receivers located at 100 different locations. The performance of DVB-T2 can be determined by measuring the field strength, MER (Module Error Ratio) and BERaLDPC (Bit Error Rate after Low Density Parity Check decoder), and then a comparison between DVB-T and DVB-T2 systems can be made. Equipments involved in the measurement are indoor antenna, distribution amplifier, waveform monitor, field strength meter, DVB-T2 decoder and TV set as the receiver. Results are recorded in Microsoft Excel and analyzed using MATLAB software. The result of the measurement shows92% of the test points had higher reading than the baseline value which means better reception of digital TV signal is delivered to the location.Comparison between DVB-T and DVB-T2 performance shows that field strength of the DVB-T2 system is slightly higher by 1.5 % – 3.8 % from DVB-T</span><p class="MsoNormal"><span style="font-size: 16.0pt; line-height: 107%; mso-bidi-font-style: italic;">Measurement of digital video broadcasting-second generation terestrial (DVB-T2) signal in Kuala Lumpur, Malaysia</span></p>

OFDM comparison with FFT and DWT processing for DVB-T2 wireless channels

Introduction: Recent studies on the FFT processing (Fast Fourier Transform) or DWT (Discrete Wavelet Transform) of the OFDM signal (Orthogonal Frequency Division Multiplexing) have shown pros and cons for DVB-T2 (Digital Video Broadcasting-Second Generation Terrestrial) radio communications; however, the benefits of both types of processing have yet to be compared for the same scenario.
 Objective: The objective of this research is to compare the response of the wireless channel with AWGN noise (Additive White Gaussian Noise Channel) and Rayleigh and Rician fading in the UHF (Ultra High Frequency) band.
 Methodology: The transmission of DVB-T2 information with OFDM modulation and FFT and DWT processing was simulated in Matlab®, specifically in Simulink.
 Results: The results of the study proved to be more efficient for DWT system than FFT system, due to the low rate of erroneous bits, spectral efficiency and reduction of the Peak-to-Average Power Ratio (PAPR), for Eb / No relations greater than 10dB.
 Conclusions: In this article, we present the designs of both systems and the results of the research experience; likewise, the practical applicability of these systems is discussed, and improvements are suggested for future work.

An unequal error protection scheme for non-binary LDPC using statistical QAM and prioritized mapping

Low Density Parity Check (LDPC) codes are among the most popular channel codes used nowadays because of their ability to achieve near channel capacity performances. However, with the ever-increasing demand for reliable transmission of data at higher data rates, there is a need to narrow down the gap between the performance of LDPC codes and the channel capacity. LDPC codes and Quadrature Amplitude Modulation (QAM) have been widely deployed in wireless communication standards such as the IEEE 802.11n and Digital Video Broadcasting-Second Generation Terrestrial (DVB-T2). Recently, several Unequal Error Protection (UEP) schemes have been used to enhance the performance of LDPC codes. In this paper an UEP scheme is proposed for Non- Binary LDPC codes with QAM. The scheme uses the statistical distribution of the source symbols to obtain a more efficient statistical QAM constellation. Additionally, it uses the degree distribution of the nodes of the LDPC codeword to achieve prioritized QAM mapping. Simulations revealed that the proposed scheme can provide Eb/N0 gains of up to 0.78 dB and 1.24 dB with 16-QAM and 64-QAM respectively in the range BER?10-2.

An Efficient FPGA Design and Performance Testing of the ACE Algorithm for PAPR Reduction in DVB-T2 Systems

Active constellation extension (ACE) is one of the common algorithms for peak-to-average power ratio reduction in digital video broadcasting-second generation terrestrial (DVB-T2) systems. In this paper, we study the implementation of the ACE algorithm for DVB-T2 on field programmable gate array (FPGA) platforms. For this purpose, a general hardware architecture with two parallel channels is first proposed. The proposed architecture is based on 16-bit fixed-point representation which can achieve a tradeoff between numerical accuracy and hardware cost. Moreover, the pipelining design is adopted in some units and arithmetic components of the proposed architecture, with respect to enhancement of working frequency. Aiming at a specific DVB-T2 system, the proposed architecture is implemented in a low-cost FPGA platform. Implementation results indicate that the fixed-point FPGA design involves less hardware overhead, and can run at a clock of up to 120.6 MHz and achieves a maximum throughput of 513 Kb/s. Finally, the performances of the fixed-point FPGA design are verified on a laboratory prototype. Experimental results demonstrate that the proposed fixed-point FPGA design provides an accuracy performance that is very close to that of floating-point simulation counterpart.

Low Complexity Switched Soft Demapper for Rotated QAM Constellations

In the digital video broadcasting-second generation terrestrial standard, the constellation rotation and cyclic Q-delay techniques have been adopted to improve the bit error rate performance in fading channels. However, they would lead to a substantially increased demapping complexity at the receiver. In order to reduce the demapping complexity, we propose a switched soft demapper, where different demapping algorithms with different level of complexities can be selected according to the in-phase (I) and the quadrature (Q) channel fading conditions. A decision block is applied to determine the demapping algorithm. Three kinds of decision criteria are discussed and compared to verify that the decision criterion has an impact on the performance of the soft demapper. In addition, the algorithm that determines the threshold in the decision block is presented. For the rotated 64-QAM, the performance loss of the proposed demapping scheme is proved to be negligible if a suitable threshold is applied, while the demapping complexity is reduced by up to 77% in Rayleigh fading channel without erasures. For the rotated 256-QAM, the complexity is reduced by up to 95% in Rayleigh fading channel without erasures.

Construction of Multiple-Rate QC-LDPC Codes Using Hierarchical Row-Splitting

In this letter, we propose an improved method called hierarchical row-splitting with edge variation for designing multiple-rate quasi-cyclic low-density parity-check (QC-LDPC) codes, which constructs lower-rate codes from a high-rate mother code by row-splitting operations. Consequently, the obtained QC-LDPC codes with various code rates have the same blocklength and can share common hardware resources to reduce the implementation complexity. Compared with the conventional row-combining-based algorithms, a wider range of code rates are supported. Moreover, each individual rate code could be separately optimized, making it easier to find a set of multiple-rate QC-LDPC codes with good performance for all different rates. Simulation results demonstrate that the obtained codes outperform the counterparts from digital video broadcasting-second generation terrestrial.

Maximum Likelihood Synchronization for DVB-T2 in Unknown Fading Channels

In this paper, we consider the timing and carrier frequency offset (CFO) estimation problem for digital video broadcasting-second generation terrestrial (DVB-T2) transmissions by utilizing the P1 symbol. Unlike previous studies, an unknown fading channel scenario is considered. Two maximum likelihood (ML) methods are derived by modeling the transmitted signal as a stochastic and, respectively, a deterministic unknown waveform. The proposed stochastic ML (SML) algorithm can jointly estimate the received signal power, time delay, and CFO. By ignoring the presence of null carriers in the P1 symbol, the SML method can be simplified with a lower complexity. Meanwhile, the proposed deterministic ML method is more flexible and computationally simpler compared with the SML method. Numerical results are presented to illustrate the performances of the proposed estimators along with several existing solutions for DVB-T2 signal synchronization. In addition, Cramer–Rao lower bounds are evaluated for the considered estimation problem.

Simplified log likelihood ratio calculation in soft ordered successive interference cancellation for multiple‐input multiple‐output digital video broadcasting‐second generation terrestrial receivers

This study proposes a soft ordered successive interference cancellation (OSIC) receiver accompanied by a simplified log-likelihood ratio calculation method for a dual-polarised multiple-input multiple-output (MIMO) digital video broadcasting-second generation terrestrial system. The future terrestrial transmission systems will be required to provide high data rates for ultra-high definition television service. For this purpose, dual-polarised MIMO techniques with a little cross-antenna interference and high-order modulation schemes have been considered. As the cross-antenna interference needs to be removed, a soft OSIC receiver can be used effectively. However, the receiver has to endure high computational complexity for calculating soft values. To reduce it, the authors simplified the calculation based on the decision threshold (DT) method. The main contribution of this study is to extend the conventional DT method, which is restricted to only low-order modulations, to an algorithmic process applicable to any modulation order. The proposed soft OSIC receiver has about 1 dB degradation from the soft OSIC receiver with the maximum-likelihood calculation of soft values. The degradation can be fully rewarded by the significantly reduced computational complexity. Furthermore, this study presents an additional possibility of improving the decoding performance by modelling the OSIC equaliser as a biased estimator.

Obtaining Diversity and Coding Gains for Digital Terrestrial Television by Using a Coded Cooperative MIMO Transmission Scheme

Digital terrestrial television is a modern broadcasting technology that has permitted broadcasters to offer television service with excellent image and sound quality. Many countries have been assigned a new digital television standardization process and many studies are underway regarding digital multimedia broadcasting technology. This paper investigates the utilization of a coded cooperative multiple-input and multiple-output (MIMO) transmission scheme in modern digital broadcasting systems to achieve additional transmit diversity and coding gains. The main idea of this work is the implementation of a coded cooperative MIMO scheme based on a low-density parity check code. A coded cooperative transmission can obtain a robust forward error correction. In this way, it is possible to achieve more stable system performance and improved mobility for next generation handheld systems. In order to show the potential for practical implementation, the performance of the proposed method is evaluated on the basis of the Digital Video Broadcasting-Second Generation Terrestrial (DVB-T2) system. The simulation results show that the proposed scheme can be utilized for the development of future DVB broadcasting systems that should support high mobility handheld devices, such as the Digital Video Broadcasting---Next Generation Handheld (DVB---NGH) system.

QoSatAr: a cross-layer architecture for E2E QoS provisioning over DVB-S2 broadband satellite systems

This article presents QoSatAr, a cross-layer architecture developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. Our design is developed at the satellite-independent layers, being in compliance with the ETSI-BSM-QoS standards. The architecture is set up inside the gateway, it includes a Re-Queuing Mechanism (RQM) to enhance the goodput of the EF and AF traffic classes and an adaptive IP scheduler to guarantee the high-priority traffic classes taking into account the channel conditions affected by rain events. One of the most important aspect of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator. In this article, we present evaluation metrics, extensive simulations results and conclusions about the performance of the proposed QoSatAr when it is evaluated over a DVB-S2 satellite scenario. The key results show that the implementation of this architecture enables to keep control of the satellite system load while guaranteeing the QoS levels for the high-priority traffic classes even when bandwidth variations due to rain events are experienced. Moreover, using the RQM mechanism the user’s quality of experience is improved while keeping lower delay and jitter values for the high-priority traffic classes. In particular, the AF goodput is enhanced around 33% over the drop tail scheme (on average).