As the next generation digital TV (DTV) standard, the ATSC 3.0 system is developed to provide significant improvements on the spectrum efficiency, the service reliability, the system flexibility, and system forward compatibility. One of the top-priority requirements for the ATSC 3.0 is the capability to deliver reliable mobile TV services to a large variety of mobile and indoor devices. Layered-division-multiplexing (LDM) is a physical-layer non-orthogonal-multiplexing technology to efficiently deliver multiple services with different robustness and throughputs in one TV channel. A two-layer LDM structure is accepted by ATSC 3.0 as a baseline physical-layer technology. This LDM system is capable of delivering robust high-definition (HD) mobile TV and ultra-HDTV services in one 6 MHz channel, with a higher spectrum efficiency than the traditional time/frequency-division-multiplexing (T/FDM)-based DTV systems. This paper presents a detailed overview on the LDM technology, and its application in the ATSC 3.0 systems. First, the fundamental advantages of the LDM over the traditional TDM/FDM systems are analyzed from information theory point of view. The performance advantages of the LDM are then confirmed by extensive simulations of the ATSC 3.0 system. It is shown that, LDM can realize the potential gain offered by superposition coding over the TDM/FDM systems, by properly configuring the transmission power, channel coding, and modulation, and using different multiple antenna technologies in the multiple layers. Next, the efficient implementation of LDM in the ATSC 3.0 system is presented to show that the performance advantages of the LDM are obtained with small additional complexity. This is achieved by carefully aligning the transmission signal structure and the signal processing chains in the multiple layers. Finally, we show that the LDM can be further integrated with different multiple antenna technologies to achieve further transmission capacity.

The industrial environment poses strict requirements to the infrastructure of good and service production and delivery. Communications are not an exception. Wired systems currently dominate in factory premises for their robustness in complex and noisy propagation conditions. They also present ruggedness in front of malicious attackers aiming to bring the communication system down or take over the system under control. Unfortunately, wired systems have severe maintenance, scalability, and operational flexibility limitations. Wireless systems constitute a solution, but they show performance weaknesses in reliability and security. This paper analyzes the security challenges of radio-frequency wireless systems in industrial use cases and aligns different categorization efforts from various sources, focusing on the lower layers of the OSI model (PHY/MAC). The analysis includes a detailed taxonomy of attacks and PHY/MAC countermeasure techniques required to make security compatible with the system requirements of industrial applications. Among the different industrial applications, the focus of this work is directed towards Factory Automation. Finally, based on the wide range of existing attacks and techniques, we propose a methodology for dissecting attack scenarios and designing tailored protection techniques and architectures. A wide diversity of attack situations are described, and the corresponding countermeasures are discussed. Finally, we propose a methodology for dissecting attack scenarios and designing tailored protection techniques and architectures.

In this paper, we propose novel transmitter and receiver architectures for low complexity layered division multiplexing (LDM) systems. The proposed transmitter architecture, which is adopted as a baseline technology of the Advanced Television Systems Committee 3.0, shares time and frequency interleavers, FFT, pilot patterns, guard interval, preamble, and bootstrap among different layers, so that the implementation of LDM receivers can be realized with less than 10% complexity increase compared to conventional single layer receivers. With such low complexity increment, we show simulation and laboratory test results that the proposed LDM system has significant performance advantage (3-9 dB) over traditional TDM systems, and maintains its performance up to the velocity of 260 km/h in mobile reception.

The expected growth in mobile video demand over broadband cellular networks is one of the key factors driving the wireless industry to develop the fifth generation of network technology. This scenario is fueling the need for group-oriented services (i.e., multicast and broadcast) in order to efficiently manage the radio resources, and consequently grant different groups of users simultaneous access to the same multimedia content with differentiated quality of service. The evolved multimedia broadcast multicast service (eMBMS), standardized by the Third Generation Partnership Project, is one of the technologies likely to be extended to 5G systems with the aim of addressing point-to-multipoint services. In addition, non-orthogonal multiple access (NOMA) techniques are also being considered as a driver to increase the efficient use of the spectrum in multi-user environments with asymmetric data delivery. The present article proposes the joint use of subgrouping multicast techniques and NOMA in an eMBMS-like scenario. Performance is evaluated in envisaged 5G environments, where different quality video services are delivered to a group of users interested in the same contents.

Smart Grids are becoming a reality all over the world. Nowadays, the research efforts for the introduction and deployment of these grids are mainly focused on the development of the field of Smart Metering. This emerging application requires the use of technologies to access the significant number of points of supply (PoS) existing in the grid, covering the Low Voltage (LV) segment with the lowest possible costs. Power Line Communications (PLC) have been extensively used in electricity grids for a variety of purposes and, of late, have been the focus of renewed interest. PLC are really well suited for quick and inexpensive pervasive deployments. However, no LV grid is the same in any electricity company (utility), and the particularities of each grid evolution, architecture, circumstances and materials, makes it a challenge to deploy Smart Metering networks with PLC technologies, with the Smart Grid as an ultimate goal. This paper covers the evolution of Smart Metering networks, together with the evolution of PLC technologies until both worlds have converged to project PLC-enabled Smart Metering networks towards Smart Grid. This paper develops guidelines over a set of strategic aspects of PLC Smart Metering network deployment based on the knowledge gathered on real field; and introduces the future challenges of these networks in their evolution towards the Smart Grid.

Cloud transmission (Cloud Txn) is a flexible multilayer system that uses spectrum overlay technology to simultaneously deliver multiple program streams with different characteristics and robustness for different services (mobile TV, HDTV, and UHDTV) in one radio frequency channel. Cloud Txn is a multilayer transmission system like layered-division multiplexing. The transmitted signal is formed by superimposing a number of independent signals at desired power levels to form a multilayered signal. The signals of different layers can have different coding, bit rate, and robustness. The upper layer system parameters are chosen to provide very robust transmission that can be used for high-speed mobile broadcasting. The bit rate is traded for powerful coding and robustness so that the signal-to-noise ratio (SNR) threshold at the receiver is in the range of ${-}{2}$ to ${-}{\rm 3}~{\rm dB}$ . The top layer is designed to withstand combined noise, co-channel interference and multipath distortion power levels higher than the desired signal power. The lower-layer signal can be a DVB-T2 signal or another new system to deliver HDTV/UHDTV to fixed receivers. The system concept is open to technological advances that might come in the future: BICM/non uniform-QAM, rotated constellations, time frequency slicing or MIMO techniques can be implemented in the Cloud Txn lower (high data rate) layer. The system can have backward compatible future extensions, adding more lower layers for additional services without impact legacy services. This paper describes the performance of Cloud Txn broadcasting system.