Jon Barrueco

LDM Core Services Performance in ATSC 3.0

Advanced Television Systems Committee (ATSC) 3.0, the new generation digital terrestrial television standard, has been designed for facing the new challenges of the future broadcasting systems. ATSC 3.0 has been built using the most recent cutting-edge technologies. Layered division multiplexing (LDM) is one of the major components of the new system baseline. LDM provides a tool to make flexible use of the spectrum for delivering simultaneous services to stationary and mobile services. This paper presents the performance evaluation of ATSC 3.0 core services in mobile scenarios using LDM. Simulation results are presented to analyze the influence of different LDM ensemble configuration modes for mobile reception. The simulation results have been also confirmed by laboratory tests under different channel models. The signal to noise ratio threshold values confirm the excellent behavior of ATSC 3.0 and LDM in mobile and portable scenarios.

SHVC and LDM techniques for HD/UHD TV indoor reception

This paper presents a study that combines LDM (Layer Division Multiplexing) and SHVC (Scalable High Efficiency Video Coding) techniques to offer HD/UHD TV services in indoor scenarios. First, a theoretical study of the optimal configuration parameters for the LDM signal (such as constellation, code-rate and injection level) for indoor reception will be presented. Next, the results of some laboratory measurements for testing the performance in indoor scenarios will be included. For this purpose, TU6, PI, IOA and IOB channel models will be considered, being the main objective to determine the minimum receiving signal to noise ratios (SNR). These results will be useful for broadcasters for planning purposes.

ATSC 3.0 interleavers influence in reception performance

This paper presents the performance study of the interleavers defined in the ATSC 3.0 physical layer. It must be noted that for single PLP configurations convolutional time interleaving and frequency interleaving can be used. Nevertheless, when multiple PLP configurations are used, cell interleaving, block time interleaving, frequency interleaving and subslicing can also be included. The ATSC 3.0 interleavers influence on the reception performance will be tested in stationary, pedestrian and mobile scenarios. The main objective of this paper is to measure the required signal to noise ratio (SNR) threshold for an error-free reception with and without interleavers. In addition, each interleavers parameter configuration impact on the performance is also discussed. Consequently, each interleaver performance gain will be noted for each type of scenario. The obtained results will be useful for planning purposes.

Low complexity and high order two-dimensional non-uniform constellations for high capacity broadcasting systems

Non uniform constellations have been recently included in the new terrestrial broadcasting system ATSC 3.0, providing better performance than the uniform ones. However, for high order constellations, the complexity in the demapper grows as the number of constellation points do, being necessary to reduce the number of degrees of freedom in the constellation design process. The goal of this paper is to present a set of optimal high order non uniform constellations which provide higher gain than the ones proposed for the ATSC 3.0 system with low demapping complexity.

Asynchronous N-Layered Division Multiplexing (N-LDM)

Layered Division Multiplexing (LDM) is a novel non-orthogonal multiplexing access (NOMA) technique, based on power allocation techniques, which has been recently included in the ATSC 3.0 Digital Television Terrestrial (DTT) standard. In the recent literature, the LDM capabilities have been studied just for the two layered case, mainly when one of the layers is targeting mobile/indoor services and the other one high throughput programs. The main objective of this paper is to extend the study of multilayer LDM potential applications to communication paradigms not analyzed so far. First of all, a study of the A-layered theoretical capacity is presented, and after that, new application scenarios that will take advantage of this case will be presented. Finally, several practical simulations to confirm the aforementioned theoretical results will be discussed.

Condensation methodologies for two-dimensional non-uniform constellations

Two-dimensional non-uniform constellations (2D-NUC) have been adopted for the most recent terrestrial broadcasting system called ATSC 3.0. They are known for being more efficient than one-dimensional non uniform constellations (1D-NUC) and uniform constellations (UC). They can be used in any communication system with the bit-interleaved coded modulation (BICM) structure. However, one of the main challenges of such constellations is their design for optimal behaviour in a wide range of cases and the design of a demapper that exploits their advantages. This paper presents two different condensation methodologies to design efficient 2D-NUCs simple in design and with limited demapping complexity. The proposal provides a complexity reduction of the design and demapping processes in the range from 13% to 94%. The demapping stage provides performance losses less than 0.1 dB if compared with standard 2D-NUC demapping.

New transmitter identification mechanism for DVB-T2

In the DVB-T2 digital terrestrial television standard a transmitter signature can be included in order to provide a unique identification to each of the transmitters in the network. This feature is optional and it can be exploited for many other applications. For instance, it is a very valuable tool for broadcasters intending to bring new a single frequency network onto air or troubleshooting a network that was already working. In the DVB-T2 physical layer standard, a couple of options are provided, and the network operators are the ones that should select the solution that copes better with their particular requirements. In this work, the main characteristics and drawbacks of the already existing solutions are studied comprehensively, and afterwards, a new transmitter identification mechanism which overcomes the previously identified challenges is presented. The proposed solution is based on the direct sequence spread spectrum modulation. The presented technical solution will be backwards compatible with current receivers, and what is more, its features will make easier the implementation of new application scenarios, such as WIB.

Improving LDPC decoding performance for ATSC 3.0 LDM profiles

ATSC 3.0 includes Layered Division Multiplexing (LDM) in addition to the traditional Time Division Multiplexing (TDM) technique in order to offer simultaneous stationary and mobile services. At the receiver side, Log-likelihood ratio (LLR) probability density functions are considered in the decoding process. The main objective of this paper is to analyze the performance of using different LLR PDF formulas for LDM signals in order to find the best trade-off between performance and implementation requirements, measuring the performance gain over TDM.

Constellation Design for Bit-Interleaved Coded Modulation (BICM) Systems in Advanced Broadcast Standards

This paper presents a generic methodology to optimize constellations based on their geometrical shaping for bit-interleaved coded modulation (BICM) systems. While the method can be applicable to any wireless standard design it has been tailored to two delivery scenarios typical of broadcast systems: 1) robust multimedia delivery and 2) UHDTV quality bitrate services. The design process is based on maximizing the BICM channel capacity for a given power constraint. The major contribution of this paper is a low complexity optimization algorithm for the design of optimal constellation schemes. The proposal consists of a set of initial conditions for a particle swarm optimization algorithm, and afterward, a customized post processing procedure for further improving the constellation alphabet. According to the broadcast application cases, the sizes of the constellations proposed range from 16 to 4096 symbols. The BICM channel capacities and performance of the designed constellations are compared to conventional quadrature amplitude modulation constellations for different application scenarios. The results show a significant improvement in terms of system performance and BICM channel capacities under additive white Gaussian noise and Rayleigh independently and identically distributed channel conditions.

LLR Reliability Improvement for Multilayer Signals

The limitations and rigidness of current use of spectrum resources have fostered the design of new power multiplexing techniques to improve frequency efficiency and flexibility. These techniques are based on the simultaneous transmission of different services on the same channel with different power distribution. At the receiver side Log-likelihood ratio (LLR) probability density functions have been so far optimized for single layer systems, so the reception quality of multilayer signals with the existing LLR algorithms is degraded. This paper proposes a new LLR probability density function, including corrections for the multilayer influence, in order to improve reception performance. Simulation results are also included to test the performance improvement in terms of the receiving SNR threshold.