Performance evaluation of multiple-PLP based LDM systems for the next generation terrestrial broadcasting

In ATSC 3.0 physical layer standard, a layered division multiplexing (LDM) scheme has newly accepted as one of the multiplexing schemes in order to improve the reception performance when multiple broadcasting contents are simultaneously delivered through a single RF channel. This paper presents comparison results of LDM and time division multiplexing (TDM) schemes under fixed reception environments, and analyzes the performance gain of LDM over TDM. From the field test results, it was confirmed that the LDM gain in the theoretical analysis is still maintained in the actual field.

Layered Division Multiplexing (LDM) has demonstrated increased data rate capacity for wireless applications where the service bitrates being multiplexed are unbalanced. Current Direct-To-Home (DTH) broadcasting satellite standards (DVB-S2 and DVB-S2X) include Variable Coding and Modulation (VCM) mode. VCM provides the opportunity to deliver different services on a Time Division Multiplexing (TDM) basis and in consequence target different reception conditions with a single carrier. This article proposes the combination of the tools provided by DVB-S2X with LDM for satellite broadcast and communication systems. This article describes use cases where multiplexing schemes can be beneficial in comparison with VCM (TDM) approach. The use cases include the delivery of High Definition (HD) and Ultra High Definition (UHD) TV services to customers as well as additional communication services. The performance of the proposal is evaluated with simulations under different channels, including the impact of satellite equipment non-linearities. Analysis shows that LDM provides considerable gain in comparison with VCM in both AWGN and non-linear satellite channels.

The Advanced Television System Committee (ATSC) is currently developing the next-generation U.S. Digital Terrestrial Television (DTT) standard, known as ATSC 3.0. Two disruptive technologies for the physical layer are being evaluated, Layer Division Multiplexing (LDM) and Time Frequency Slicing (TFS). LDM consist in the transmission of a signal composed of two independent signals (layers) which are superimposed together at different power levels. These two layer can be configured with the desired robustness and capacity. LDM enables the efficient provision of services addressed to mobile and fixed reception in a more efficient way than the classical Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM) since full bandwidth and transmission time are used in both layers. However, practical operation is restricted due to several implementation constraints such as the use of common parameters and transmitter blocks for both layers (e.g. a common time interleaver). The use of TFS allows for an improved frequency diversity by the distribution of the service data across multiple Radio Frequency (RF) channels instead of using a single RF channel. The paper investigates the potential gains provided by the increased frequency diversity with TFS in conjunction with LDM.

In this paper, we present an efficient transmission method of multiple broadcasting services using layered division multiplexing (LDM) and scalable high efficiency video coding (SHVC) based on the next generation terrestrial digital broadcasting standard, advanced television systems committee 3.0. In a two-layer LDM system, each layer forms a physical layer pipe that carries base layer and enhancement layer video streams of SHVC, respectively. This combination of physical and presentation layers technologies can maximize channel utilization when multiple broadcasting services are delivered in a single radio frequency channel with different robustness and reception conditions. An intensive performance analysis is provided when the proposed combination of LDM and SHVC is compared with other approaches, such as time division multiplexing and/or high efficiency video coding simulcast broadcasting. Several performance measurements are also introduced, such as constant data rate measurement and constant quality measurement, which are used to evaluate the performance of video codecs in conjunction with different physical layer system parameters. A prototype hardware system with LDM and SHVC capable of selecting different parameter combinations is tested in the laboratory and in real field environments to verify the performance and feasibility of the proposed LDM and SHVC combination. Results show that the proposed LDM and SHVC combination provides significant gains on video service quality as well as reception robustness.

An ATSC 3.0 physical layer frame consists of a bootstrap immediately followed by a preamble containing layer 1 control signaling and then one or more subframes carrying payload data. Subframes within a particular frame may be of the same or different types, with different subframe types being configured for different classes of receivers (e.g., mobile versus fixed). This paper focuses on the subframe structure, configuration, and contents, including subframe boundary symbols which carry additional pilots to assist with channel estimation at the receiver and cell multiplexing which maps physical layer pipe (PLP) payload data to physical layer resources within each subframe. Various methods for cell multiplexing multiple PLPs within a subframe are discussed and described, including time division multiplexing, frequency division multiplexing, time-frequency division multiplexing, and layered division multiplexing. Frequency interleaving, pilot insertion, and guard interval insertion are also covered, including a method of distributing extra samples to guard intervals in order to obtain frame lengths equal to an integer number of milliseconds.

<p>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.</p>

Layered Division Multiplexing (LDM) is a Non-Orthogonal Multiple Access (NOMA) scheme initially proposed for application in digital terrestrial television standards (ATSC 3.0) providing increased system performance, robustness, throughput and flexibility. Lately, its use on satellite communications has been studied. Results confirm throughput gains with respect to Time Division Multiplexing if services being multiplexed have unbalanced data rates and reception thresholds. This paper targets a deeper insight on the impact of the injection level on the LDM system performance. The paper proposes a system evaluation prototype and a carefully designed simulation methodology. The results show gains ranging from 10% to 65% depending on the injection level applied.

Layer-division multiplexing (LDM) system has developed with significant improvement in spectrum efficiency and service diversity. LDM technology, that superposes multiple signals with different transmit powers, has been adopted by ATSC 3.0 to deliver robust high-definition services. However, due to the high mobility of devices, the wide signal coverage, and the uneven geographical channel condition, there exists under-utilized energy and significant potential of enhancing communication capacity in the LDM system. In this paper, we employ reconfigurable intelligent surface (RIS) to improve the reception quality in the LDM system, especially the SINR performance of the terminals in the edge area. We formulate a problem of maximizing the minimum SINR among all the terminals by jointly optimizing the power control and pairing mechanism, which is a Mixed-integer Nonlinear Programming (MINLP) problem. To solve it, we use the convex-concave procedure (CCCP). We further explore the high-mobility scenario with the limited channel state information (CSI) and the missing knowledge of detailed prediction of terminals’ mobility. We use Brownian Motion to model the possible variation of the terminals’ positions in the high mobility scenario to guarantee the successful reception probability. The analysis shows the RIS can bring obvious SINR gain to the LDM system, and the mobility modification could greatly help improve the successful reception probability.

In this paper, we introduce spatial modulation (SM) in the layered division multiplexing (LDM) system for digital TV scenarios. To analyze the achievable spectral efficiency (SE) performance of the proposed SM-LDM system, we calculate its mutual information (MI) through the Monte Carlo method. Considering both Gaussian and finite alphabet inputs, we derive the MI's computational-efficient lower bounds as well as their asymptotic values. Simulation results confirm both the advantages and our SE analysis of the proposed SM-LDM system.

Cloud transmission (Cloud-Txn) with layer-division-multiplexing (LDM) was proposed as a candidate Physical Layer (PHY) technology for the next generation digital TV broadcasting system. In this paper, we investigate the performance of the upper-layer signal cancellation with DFT-based channel estimation techniques, due to their capability of providing near-optimal performance for challenging channels with long delay spread at low Signal to Noise Ratio (SNR). Both Pilot-Aided (PA) and Decision-Directed (DD) techniques are investigated and their performances are compared. The major issue with DFT-based techniques is the “edge effect” for OFDM systems with Null spectrum on either side of the useful spectrum, which serves as guard band. A Cloud-Txn/LDM system usually requires very accurate channel estimation to achieve very low residual upper-layer signal after the cancellation. In this case, the “edge effect” becomes a significant impairment. In this paper, we evaluate different data-padding methods to reduce the “edge effect”, which fill the Null spectrum with Virtual Pilots (VP). It is shown that, with proper data-padding technique, 30 to 40 dB signal cancellation can be achieved.

Recently advanced time sharing scheme which is characterized as Variable Coding and Modulation (VCM) in satellite broadcasting system was adopted as a countermeasure for heavy rain fading in order to improve link availability in DVB-S2x (Digital Video Broadcasting — Satellite 2nd Generation eXtention) standard. Furthermore, we propose Layer Division Multiplexing (LDM) scheme to satellite broadcasting system for higher spectral efficient transmission and compare it with VCM.

California wild and forest fires in 2017 resulted in over 100 fatalities. While WEA alerts were transmitted to mobiles in selected areas, the power and network outages limited their delivery. WEA is similar to the SMS Broadcast system used elsewhere. It does not require subscription, and can be geotargeted, usually by map polygon. There are already available and in development other alerting technologies. The Emergency Alert System on radio and TV in the U.S. has been in use for many years. It is a broadcast break-in system the overrides program content. This was used in one location for the wildfires, but not elsewhere as geotargeting is not possible with this system. It is and analog broadcast technology architecture. AM and FM Broadcast in the U.S. now has HD Radio that is mixed analog and digital. A limited data message can be carried and used for selective delivery of messages. DAB, DAB+ and DRM also can carry a message payload, which can be used for a selective delivery mechanism when the receiver has location position. This may be in a vehicle radio/navigation system. The current digital television system in the U.S. and some other countries is now being replaced by ATSC 3.0. This provided a superior modulation format, Layered Division Multiplexing (LDM) for delivery of program content and alerts to suitable mobiles. An IC for UHF reception and prototype mobiles have been developed. No external antenna is required. Bothe of these new technologies are tested as delivering alerts independently of the mobile network. Within the limitations of radio and TV propagation, such capabilities would provide technology redundancy. The television signal propagation may be limited in rural areas, but ATSC 3.0 is capable of having on frequency repeaters to make a single frequency network for improved coverage of program content and alerting. Multilingual alerts based on the CAP Event Terms list with Message Formats are being provided for.

The authors propose a new multiplexing and demultiplexing technique based on return-to-zero (RZ) duty cycle division, which is called absolute polar duty cycle division multiplexing (APDCDM). The new technique allows for more efficient use of time slots as well as spectrum. In this paper three users operating at the same speed of 2.5 Gb/s are multiplexed in electrical domain. The performance comparison is made against 7.5 Gb/s return-to-zero time division multiplexing (TDM) system. The experimental simulation results show that although APDCDM has the same receiver sensitivity as TDM but it is able to support higher distance and higher bit rate than TDM.

A novel Layered Division Multiplexing (LDM) With Index Modulation (LDM-IM) system is proposed in this paper. It employs the Index Modulation (OFDM-IM) technology to enhance the transmission performance of the original LDM system by transmitting extra bits through the Orthogonal Frequency Division Multiplexing (OFDM) subcarriers indices. The proposed system is based on a two-layer, Upper Layer (UL) and Lower Layer (LL), LDM system that serves two independent data services for at least two User Equipment(s) (UE) simultaneously. Besides this, by exploiting the Index Modulation (IM), each UE can receive the extra bits by decoding the subcarriers activation patterns. To map the extra bits to the subcarriers, a simple random codebook is designed in the proposed system based on the concept of OFDM-IM. To proof the availability and reliability of the proposed system, two metrics are chosen to evaluate the system performance, the average Symbol Error Rate (SER) and the transmission rate. In this paper, the architecture of the proposed system is introduced firstly. After that, the average SER of it is analyzed and verified by the Monte Carlo simulation. Finally, the transmission rate of the proposed system and the original LDM system is compared and evaluated.

Planar lightwave circuits (PLCs) are waveguide devices that integrate fiber-matched optical waveguides on Silicon or glass substrate to provide an efficient means of interaction for the guided-wave optical signals. The most prominent feature of the silica waveguides is their simple and well defined waveguide structures. This allows us to fabricate multi-beam or multi-stage interference devices such as arrayed-waveguide gratings and lattice-form programmable dispersion equalizers. PLCs provide various important and functional devices for optical wavelength division multiplexing (WDM), time division multiplexing (TDM) systems and subscriber networks. This paper reviews the recent progress and future prospects of PLC technologies including arrayed-waveguide grating multiplexers, optical add/drop multiplexers, programmable dispersion equalizers and hybrid optoelectronics integration technologies.