Digital Television Terrestrial Broadcasting System Research Articles

Review on 5G NR LDPC Code: Recommendations for DTTB System

The freezing of the 5th generation new radio (5G NR) Release 16 indicates that 5G development has stepped into a new stage. The application of a dedicated low-density parity-check (LDPC) code for channel coding is an important technical advance that distinguishes 5G NR from the 4th generation (4G) long-term evolution (LTE) and LTE-advanced. Although LDPC codes has been used in many different systems, the newly developed LDPC code in 5G NR integrates many cutting-edge technologies to provide better performance and attractive features. Thus, it can be a good reference for channel coding in other evolving systems headed by digital terrestrial television broadcasting (DTTB). In emerging applications, the DTTB system needs to carry information with higher density, while meeting the high requirements for real-time, coverage, and bit error rate of broadcasting. To provide a reference for DTTB channel coding that improves its performance and supports new services, a review of 5G NR LDPC code implementation is carried out from three aspects: code analysis and design, decoding algorithm, and decoder architecture. We thoroughly evaluate each solution and highlight some candidates for existing implementations or some directions for further development of the DTTB system.

IMPLEMENTATION OF FPGA-BASED DVB-T2 TRANSMITTER FOR A SECOND GENERATION DIGITAL TERRESTRIAL TELEVISION BROADCASTING SYSTEM

Nowadays, with strong development of Science and Technology, integrated circuits continue to dominate not only in the field of digital information. Over the last several years, Technological television industry has taken huge strides and powerful transformation to meet with government’s policy about digitization of television all over the country in period 2015 – 2020. Stemming from the practical needs of “localization of products” and mastering of technological design of DVB-T2 transmitter (Digital Video Broadcasting – Terrestrial for Second generation), the authors have made an effort to research in algorithm, designed and tested in Field Programmable Gate Array (FPGA) technology. DVB-T2 is mainly aimed to replace the current standard DVB-T. The main motivation of DVB-T2 is to provide broadcasters with more advanced and efficient alternative to DVB-T standards. In DVB-T2 transmitter system, digital audio, video, and other data are compressed into a single signal to be transmitted on a single RF channel, using orthogonal frequency-division multiplexing (OFDM) with concatenated channel coding and interleaving. The higher offered bit rate makes it a suited system for carrying HDTV signals on the terrestrial TV channel. The next generation broadcasting systems should be designed to make full use of spectral resources while providing reliable transmissions in order to enable services like multichannel HDTV (High Definition Television) and innovative data casting services. The efficient usage of the radio spectrum can be achieved by the introduction of Single Frequency Networks (SFN). Digital transmitter DVB-T2 implemented on FPGA using a software Xilinx System Generator for DSP tool and Xilinx ISE Design Suite 14.7. System Generator for DSP is in conjunction on environment MATLAB-Simulink that is capable of simulating the proposed hardware structures that is synthesized and implemented by the programmable elements in Field-programmable Gate Arrays. In this project, adaptative MPEG-TS bitrate converter is designed to allows to increasing or reducing the MPEG TS rate by adding or filtering NULL packets. The entire digital transmitter DVB-T2 is integrated in one chip Xilinx FPGA Kintex-7 XC7K325T-1FFG676. Experimental design on development Kit NetFPGA-1G-CML of Digilent Corporation is performed at design department of technology center of Vietnamese Communications Television Development JSC. Authors are continuing to improve products, put into practical applications to replace the digital terrestrial television broadcasting stations that are being used in Vietnam. The article named “Implementation of FPGA-based DVB-T2 transmitter for a second generation digital terrestrial television broadcasting system” presents the research results, design methods, test results to compare, evaluate the accuracy of algorithm implementation. The results open up new directions for technological television in Vietnam.

EFFICIENT IMPLEMENTATION OF FPGA-BASED FORWARD ERROR CORRECTING COMBINATION AND BIT TO CELL WORD DE-MULTIPLEXER FOR A SECOND GENERATION DIGITAL TERRESTRIAL TELEVISION BROADCASTING SYSTEM

This article focus on the implementation of FEC part. The motivation of the design is that FEC is an effective tool to mitigate problems associated with OFDM which stem from multipath fading channel, high speed data rate. One of the key features of BCH codes is that during code design, there is a precise control over the number of symbol errors that are correctable by the code. BCH coder proccesses parralelly with high-speed operation. 8-bit parallel data input and output helps to maximize the throughput. DVB-T2 used LDPC coder, as inner codes with word length up to 64,800 bits, enabling significant proximity to Shannon limit. This encoder supports all code rates and both normal and short frames. Output of LDPC encoder is interleaved with bit interleaver. This project was fully optimized for speed and memory area, fully synchronized by using a single clock. The design was coded in VHDL, synthesized by using Xilinx ISE Design Suite 14.7. The design has been tested on development Kit NetFPGA-1G-CML of Digilent Corporation and the bit map was downloaded into Xilinx Kintex-7 XC7K325T-1FFG676, which is integrated on experimental transmitter system DVB-T2. This research product belong to program “Research of experimental testing of second generation digital terrestrial television broadcasting system DVB-T2” of Vietnamese Communications Television Development JSC.

Radio-Optics Hybrid Single Frequency Network for DTTB: Principle, Technology, and Practice

The digital television terrestrial broadcasting (DTTB) system is one of the most important wireless broadcasting systems, but its indoor coverage performance is not satisfactory enough. The visible light communication (VLC) system works well for indoor scenarios and becomes a quite appealing technology that can realize indoor wireless communications. In this paper, we propose a hybrid system called the radio-optics hybrid single frequency network (SFN) with wide and reliable coverage for DTTB. The current SFN structure of DTTB is maintained, while the optical signal within visible wavelength is adopted to achieve seamless connection between outdoor and indoor. Based on the identical intermediate frequency, the hybrid receiver with antennas and photodiodes can not only receive radio and optical signals individually or simultaneously, but also combine the received signals from different transmitters in the analog/digital domain with various combination methods. The feasibility of the radio-optics hybrid system is verified by the experiment implemented in the laboratory. Furthermore, the proposed hybrid system has great potential to improve other extended applications of DTTB, including positioning, interactivity, scalable video coding, etc.

PN Signal as a New Illuminator of Opportunity for Passive Radar Applications

In this letter, we use the known pseudorandom noise (PN) signal in the digital television terrestrial multimedia broadcasting (DTMB) system as a new illuminator of opportunity for the passive radar. We propose a computationally efficient signal processing method for the PN-based passive radar (PNPR). The proposed method takes advantage of the distinctive structure of the PN signal and constructs a locally remapped PN signal. The circular cross-correlation between the remapped PN signal and the original PN signal is an ideal impulse function. Thus, the PNPR even does not need to do the clutter cancellation. The proposed method is validated via both the simulated and experimental data.

On the Interaction Between Joint Tx/Rx IQI and Channel Estimation Errors in DVB-T Systems

Digital video broadcasting terrestrial (DVB-T) systems use hierarchical modulation, which involve a “high-priority” and a “low-priority” (LP) bit stream. An inherent weakness of this scheme is the severe performance degradation of the less protected LP stream. In addition, the presence of inphase quadrature imbalance (IQI) at both transmitter/receiver front end may significantly reduce the detection accuracy. Here, we propose an improved receiver design for OFDM-based DVB-T systems confronting the effects of both imperfect channel estimation and IQI. First , we propose a specific pilot-symbol arrangement inside the OFDM symbol that facilitates derivation of the posterior distribution of the perfect channel conditioned on its maximum-likelihood (ML) estimate. The latter posterior distribution plays an important role toward an improved receiver design for taking into account channel estimation errors in the presence of IQI at the receiver side. Second , we derive the formulation of an improved and efficient detector under channel estimation errors when IQI is also present only at the receiver side. Third , we generalize our proposed improved detector for the case where IQI is present at both transmitter and receiver sides. The proposed approach is able to reduce the impact of channel uncertainty on the receiver's performance in the presence of IQI. Our results are compared to those achieved by the conventional mismatched ML detector, which uses the imperfect channel as perfect channel and to those obtained by the detector based on the expectation-maximization algorithm. Numerical results over a realistic COST 207 channel model show that significant performance improvement is achieved for bit error rate of the LP stream in the considered DVB-T system.

Progressive Matrix Growth Algorithm for Constructing Rate-Compatible Length-Scalable Raptor-Like Quasi-Cyclic LDPC Codes

With the worldwide deployment and rapid development of digital television terrestrial broadcasting (DTTB) systems, the demands of diversified multimedia services from the fixed/mobile receptions increase significantly. To satisfy the various requirements of quality of service, the forward error correction codes with multiple code rates and lengths become a trend for DTTB standards. In this paper, rate-compatible length-scalable raptor-like quasi-cyclic low density parity check (RL-QC-LDPC) codes are proposed for future DTTB systems, where a wide range of code rates and information/parity block lengths can be obtained with low implementation complexity. A low-complexity construction method, called progressive matrix growth (PMG), is also proposed for such kind of RL-QC-LDPC codes. Unlike conventional construction methods, PMG performs 2-D progressive extension of both information variable nodes and check nodes with limited computational complexity and memory resources. Based on the performance prediction provided by the tool of multi-edge type density evolution, several code families are constructed with PMG as examples, and careful discussions on design parameters are given. The numerical results show that the average gaps of SNR threshold to Shannon limit of binary-input additive white Gaussian noise channel are only 0.41~0.44 dB for the code families with information-bit puncturing.

Generalized Spatial Modulation-Based Multi-User and Signal Detection Scheme for Terrestrial Return Channel With NOMA

The terrestrial return channel provides interactive services in digital television terrestrial broadcasting systems to meet various consumers’ demands around the world. The extension of non-orthogonal multiple access and generalized spatial modulation multiple-input multiple-output to the terrestrial return channel improves both the spectral and energy efficiencies of the system, but it puts forward detection challenges. In this paper, a joint user activity and signal detection scheme based on the block-sparse compressive sensing (BS-CS) method in the terrestrial return channel is proposed, in which the generalized spatial modulation technology is used. By exploiting the structure and sparsity of the multi-user generalized spatial modulation signal, we formulate the detection problem into a block-sparse recovery problem. Then a BS-CS-based detection algorithm, enhanced structured block-sparse compressive sampling matching pursuit (ESB-CoSaMP), is proposed to detect the active users and transmitted data efficiently. Moreover, the information of active antennas at each user is exploited in ESB-CoSaMP to further improve the accuracy. Simulations show that the proposed detection scheme outperforms the conventional CS and BS-CS-based schemes.

FPGA implementation of RS codec with interleaver in DVB-T using VHDL

Digital television (DTV) provides a huge amount of information to many users at low cost. Recently, it can be packaged and fully integrated into completely digital transmission networks. Reed-Solomon code (RS) is one type of error correcting codes that can be used to enhance the performance of DTV. Interleaving/deinterleaving process enhances the performance of channel errors by spreading out random errors, very high-speed hardware description language (VHDL) is used in electronic design automation. It can be used as a general-purpose parallel programming language.This paper presents VHDL program for Reed-Solomoncodec (204, 188) and convolutional interleaver/deinterleaver, used in Digital Video Broadcasting-terrestrial system (DVB-T), according to ETSI EN 300 744 V1.5.1 standard. The VHDL programs are implemented on Xilinx 12.3 ISE and then simulated and tested via ISE simulator then the code is synthesized on FPGA device the results are compared with IP core for Xilinx 12.3 ISE, which gives the same results.

Efficient and reliable slice allocation for multi‐services in DVB‐T2 networks

Digital television terrestrial broadcasting (DTTB) networks can help to alleviate the congestion problem in cellular networks by delivering rich contents to a large number of clients simultaneously. In particular, recently, there is a strong interest of extending current DTTB systems to support multimedia broadcasting services. The lack of return channel and long transmission time interval however impose great challenge to the resource allocation for this application in DTTB networks. The reliable resource allocation is studied for multi-services with data delivery delay constraints in the second generation digital video broadcasting terrestrial (DVB-T2) system. To solve this challenging problem, the data cells of a T2-frame are divided into data slices which are indexed by binary numbers. These data slices are organised in a binary tree, and each node in the tree is associated with a certain number of non-adjacent data slices. Then a node can be allocated to a service by using the predefined policies. Based on this scheme, this study proposes a heuristic algorithm to allocate resources to multi-services. Simulation results validate the effectiveness of the proposed algorithm and demonstrate its advantage over the current resource allocation scheme in DVB-T2 networks.

Optimum Wavelet Selection for Orthogonal Wavelet Division Multiplex (OWDM) Based Broadcasting System

In the recent years Orthogonal Wavelet Division Multiplexing (OWDM) has been considered as an alternative of Orthogonal Frequency Division Multiplexing (OFDM). OWDM has lower computational complexity and higher flexibility compared to its OFDM counterpart. Wavelet is the most important element of an OWDM based system. Wavelets have been a much investigated topic in digital image processing for a long time. Recently they are being used in efficient communication system design. In this work we use wavelets in Digital Video Broadcasting-Terrestrial (DVB-T) system. Originally DVB-T system was designed based on OFDM. In this paper we use OWDM instead. We apply a number of wavelets namely Haar, Daubechies, Biorthogonal, Coiflets, and Symlets in OWDM design . The simulation results show that the Haar function outperforms other wavelets and hence this

Performances of Orthogonal Wavelet Division Multiplex (OWDM) System Under AWGN, Rayleigh and Ricean Channel Conditions

Orthogonal Wavelet Division Multiplexing (OWDM) has been considered as an alternative of Orthogonal Frequency Division Multiplexing (OFDM) in the recent years. OWDM has lower computational complexity and higher flexibility compared to its OFDM counterpart. The core component of OWDM is wavelet. Wavelet has been a much investigated and applied topic in digital image processing for a long time. Recently, it has drawn considerable attention of the researchers working in communication field. In this work we investigate the performances of OWDM under different channel conditions. We consider three channel conditions namely Additive White Gaussian Noise (AWGN), Rayleigh, Ricean, and frequency selective. We consider a number of wavelets namely Haar, Daubechies, Biorthogonal, Reverse Biorthogonal, Coiflets, and Symlets in OWDM design. For system model we choose Digital Video Broadcasting-Terrestrial (DVB-T). Originally DVB-T system was designed based on OFDM. In this work we use OWDM instead. The simulation results show OWDM outperforms OFDM in terms of bit error rate (BER), noise resiliency, and peak-to-average ration. The results also show that the Haar wavelet based OWDM outperforms other wavelets based OWDM system under all three considered three channel conditions.

Adaptive fuzzy assisted detector under impulsive noise for DVB-T systems

The main novel contribution of this paper is the improvement achieved on the Digital Video Broadcasting-Terrestrial (DVB-T) system by the addition of a fuzzy median filter to reduce the effect of impulsive components. The proposed detector includes the fuzzy median filter and can be adaptively adjusted according to the noise level and type of the noise. The system is studied under Gaussian and impulsive noise. Simulation results show that fuzzy assisted detector reduces the effect of impulsive noise and improves the performance of the system significantly while also working efficiently in Gaussian noise.

Coexistence Between DVB-T/T2 and LTE Standards in Common Frequency Bands

In the last decade, fulfilling the growing users' expectations on the quality of provided multimedia services is one of the biggest challenges for different wireless communication systems. However, many times, different kinds of wireless systems can operate in the same (shared) frequency band. Such coexistence generally negatively affects the performance of the systems colliding. This is especially true for the widely used Digital Video Broadcasting-Terrestrial (DVB-T) or upcoming DVB-2nd Generation Terrestrial (DVB-T2) and Long-Term Evolution (LTE) standards, operating in Europe. Hence, the aim of this paper is to explore the impact of interfering mobile telecommunication services on the mobile TV services provided by LTE and DVB-T/T2 systems in the same frequency band. For the simulation of the coexistence between the LTE and DVB-T/T2 services on the physical layer level, an appropriate method is proposed and complex simulation tools are coupled. The results, presented as a dependence of modulation error ratio at the receiver input and bit error ratio at the channel decoder input on the spectral level ratio, show comparable performances for DVB-T and DVB-T2 systems. Results from simulations are verified by laboratory measurements and should help to better understand the influence of co-channel interferences from LTE mobile networks on DVB-T/T2 networks for mobile transmission scenarios.

Comparative Analysis of DVB System for Different Encoding Techniques with Compressed Images

Objectives: In this paper encoding techniques used in the Digital Video Broadcasting-Terrestrial (DVB-T) system have been discussed. The paper focuses upon the comparison between the different types of encodings as a part of the DVB-T standard. Methods/Analysis: Different types of encoding methods which could be the part of the DVB-T standard have been considered .The system used is able to measure and analyze the performance by using different encoding techniques along with the Orthogonal Frequency-Division Multiplexing (OFDM). Findings: DVB-T was developed by the Digital Video Broadcasting (DVB) Project that was basically for broadcasting. The compressed images, digital audio, compressed videos and other forms of data in Moving Picture Expert Group (MPEG) transport stream, through OFDM modulation is transmitted by this DVB-T system. Novelty /Improvement: In the DVB-T Reed Solomon encoding is used to encrypt the data. Hybrid coding has been proposed as the way to improve the performance.

A Near-Capacity MIMO Coded Modulation Scheme for Digital Terrestrial Television Broadcasting

Multiple-input multiple-output (MIMO), which can provide ultrahigh data transmission rate, is one of the key technologies for the next generation digital terrestrial television broadcasting (DTTB) standards. This paper proposes a near-capacity MIMO bit-interleaved coded modulation scheme with either independent or iterative demapping (BICM/BICM-ID) for the DTTB system. First, the amplitude phase shift keying (APSK) constellation with Gray mapping is proposed to replace the conventional Gray quadrature amplitude modulation (QAM) counterpart. From the perspective of average mutual information analysis, Gray-APSK has certain shaping gain compared to Gray-QAM for both independent and iterative demapping schemes. Besides the APSK constellation, a novel bit interleaver named bit mapping, which takes into account the unequal error protection of both APSK constellations and low-density parity-check codes, is proposed to further improve the system performance. The tool of extrinsic information transfer chart is utilized to analyze and design the optimal bit mapping for the BICM/BICM-ID scheme. Bit error rate simulations are finally carried out to verify the superiority of the proposed MIMO coded modulation scheme.

Optimization of Spectrum Usage and Coexistence Analysis of DVB-T and LTE-800 systems

This paper investigates the possible coexistence issues between the digital video broadcasting-terrestrial (DVB-T) system and the long term evolution (LTE) that operate in adjacent frequency bands. The proposed methodology for interference assessment evaluates the DVB-T performance degradation in presence of aggregate LTE-800 interference targeting the territory of Macedonia as evaluation area. The simulation analysis quantifies the percentage of interference degraded pixels and obtains the probability of pixel DVB-T service degradation. Furthermore, a measurement trial complements the simulation analysis through the evaluation of the influence of active antenna usage by the DVB-T receivers. The simulation and measurement results in this particular case confirm that the alignment of the active DVB-T receiving antenna towards the LTE-800 base station can substantially increase the degradation whereas aligning of the active DVB-T receiving antenna towards the DVB-T transmitter maintains the efficient TV reception. Finally, this paper proposes a simple algorithm for optimal LTE frequency arrangement, resulting in significant reduction of the LTE interference towards the DVB-T system.

Backward Compatible Multiservice Transmission Over the DTMB System

In this paper, a backward compatible multiservice transmission scheme over the digital television terrestrial multimedia broadcasting (DTMB) system is proposed, which is based on embedded constellation and bit division multiplexing. With the proposed scheme, simultaneous transmission of original services and multiple augmented services can be supported in the DTMB system in a backward compatible manner. No additional RF spectrum is required and no additional complexity is introduced to the legacy DTMB receivers. Two schemes over the DTMB system are proposed toward two different requirements, which are maintaining the transmission rate of original services and maintaining the reception SNR-threshold of original services, respectively. Average mutual information analysis and bit error ratio simulations are performed. In both schemes, the increment in the throughput of the DTMB system can be over 7.6 Mb/s in typical mode.

Implementing a Standard DVB-T System using MATLAB Simulink

This paper describes the Simulink implementation of all functional blocks of a standard Digital Video Broadcasting Terrestrial (DVB-T) transmitter and receiver and presents the simulation model for DVB-T system according to ETSI EN 300 744 V1.6.1. The implemented model contains all channel coding and modulation building blocks with the parameters: 8K OFDM-mode, code rate (1/2, 2/3, and 3/4), and Modulation (64-QAM, 16-QAM). Realizing such system level implementation is required to study the effect of the channel on the transmission properties of the system and it helps getting the required quality of service by adjusting the system parameters. In addition, such model is the first step in software defined radio implementation. The bit error rate as a function of the signal to noise ratio C/N is evaluated to be used in the link budget calculations. General Terms DSP System, DVB-T, Computer Applications

An Urban-Rural Dual Structure for the Digital Terrestrial Television Broadcasting System of FOBTV

In this paper, the requirements of digital terrestrial television broadcasting are analyzed. One structure, named as urban-rural dual structure, is emphasized in the future broadcasting system, especially in those developing countries, such as China, Russia, and Brazil. A comparison between Shanghai and Fengyang in China is given to help understanding this unique structure. Some technical consideration on the structure is presented for the future of broadcast television.