ATSC 3.0 LDM/TDM performance comparison in fixed reception environment

In this paper, we present performance evaluation of multiple physical layer pipe (PLP) based layered division multiplexing (LDM) systems for the next generation terrestrial broadcasting. In addition to a conventional multiple-PLP configuration, which is based on time division multiplexing (TDM), a variety of LDM configurations, which includes combinations of TDM and two-layer LDM, and three-layer LDM, are considered. Given three different broadcasting contents are delivered by three PLPs, performance comparison and analysis are provided when four different multiple-PLP configurations including TDM, two-layer LDM, and three-layer LDM are used.

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.

Recent broadcast standards support Layered Division Multiplexing (LDM) to achieve graceful degradation as signal quality degrades at the receiver. LDM is accomplished by using different constellations within the same Radio Frequency (RF) spectrum. LDM thus enables delivering multiple service tiers in a single broadcast channel. LDM when used in conjunction with scalable source coding codecs such as the Scalable extension of High Efficiency Video Coding (SHVC), further helps improve overall spectrum utilization and efficiency. In this paper we investigate a 2-tier broadcast LDM based service with one service tier aimed at lower video resolution such as 540p, 720p, 1080p for a mobile receiver (smaller/indoor antenna) and the other service tier targeting twice the video resolution of the lower tier, for stationary receivers (larger/outdoor antenna). The primary contribution of this paper is to identify 2-tier transmission configurations of interest to broadcasters and compare the spectrum and bitrate coding efficiency gains of an SHVC-based multi-tier service versus a simulcast (single layer) based multi-tier service for an Advanced Television Systems Committee (ATSC) 3.0 transmission system. Bitrate savings ranging from 38% and 57% is observed for the SHVC based layered system. For large coverage and pedestrian with a receiver test scenarios, channel utilization savings ranging from 23% to 46% is observed. For mobile and tablet in bedroom scenarios a smaller broadcast bandwidth savings ranging from 6% to 9% is observed.

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.

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.

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.

This paper presents Layered Division Multiplexing (LDM), a technology that may be used to provide a flexible multi-layer system transmission by means of spectrum overlay. This technology can be used to simultaneously deliver multiple program streams with different characteristics and robustness for different services (mobile TV, HDTV and UHDTV) in one RF channel. — In Layer Division Multiplex (LDM) the signal to be transmitted consists of a number of different independent signals superimposed together at different injection levels to form a multi-layer signal. Each layer can have its own characteristics. The top layer is the most robust one, which has a negative Signal to Noise Ratio (SNR) system threshold value, and can be used for robust mobile service. The lower layer(s) can be used to provide fixed high data rate services, such as multiple High Definition Television (HDTV) and Ultra High Definition Television (UHDTV). For example, DVB-T2, or an alternative design of a high data rate transmission system can be used for the second layer. The upper layer signal can be a separate program, or be used for delivering supplementary bit rate to be combined with the lower layer signal to provide additional features or achieve higher quality of service (e.g., scalable video coding and placing audio on upper layer for extra robustness).

A new wireless access system, called Infostations, has been proposed previously, for providing isolated pockets of high bandwidth connectivity for future data and messaging services. This paper address the problem of defining an efficient time division multiplexing (TDM) scheme for Infostations. The main focus is on suitable combinations of power control and modulation/transmission rate control, assuming an average power constraint and a bandwidth limitation.

The next generation digital TV (DTV) broadcast, namely Advanced Television System Committee (ATSC) 3.0, relies on substantial single frequency networks (SFN), each of which requires a studio to transmitter link (STL) to transmit data from the broadcast gateway (BG), leading to significant construction costs. Therefore, the wireless in-band distribution link (IDL) technology is proposed, which uses layered-division multiplexing (LDM) to transmit the STL data via wireless links from the BG to the SFN transmitters within the same spectrum as the broadcast services. In this paper, we propose the time synchronization and signal detection algorithm for wireless IDL systems with both unicast and broadcast signals. We introduce two multiplexing schemes, N-LDM and 3-LDM, and demonstrate their superiority over traditional frequency division multiplexing (FDM). To overcome the challenge of multi-access interference and synchronization errors caused by multipath, we develop a unique word (UW) design algorithm for transmitted signals and a double threshold correlation detection algorithm (DTCDA) that outperforms traditional ones. We employ a second threshold to enhance detection performance at low signal-to-noise ratios, and utilizes successive interference cancellation (SIC) to mitigate multiple-access interference. More importantly, our approach requires no knowledge of the unicast user number or channel state information. Simulation results validate the effectiveness of the proposed scheme.

In recent years, most of the research about distributed video coding focus on how to get the exact side-information and virtual channel estimation parameters in order to achieve better rate-distortion performance. However, there is quite few research about the practical transmission issue, i.e., no practical and effective transmission scheme has been proposed yet for distributed video coding (DVC). Feedback channel based DVC can usually achieve better rate-distortion performance, while leading to long delay because of feed-backs. The traditional video transmission scheme, which doesn't consider the characteristics of DVC, will introduce long delay since the encoder needs to wait until receiving the feedback information. As a result, the effective bandwidth of the network will be reduced greatly. In this paper, we have proposed an adaptive time division multiplexing video transmission scheme for the DVC which can reduce the delay due to waiting feed-backs. Experimental results show that our method can reduce transmission time effectively. And as a result, it can improve the effective bandwidth and the buffer utilization rate, thus higher transmission efficiency can be achieved.

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.

This letter describes a single RF channel using a fully integrated multiplex LNA (Low Noise Amplifier) with four input channels and a double-balanced mixer in a 0.35µm CMOS technology for SMILE (Spatial MultIplexing of Local Elements) applications. This technique is a front-end architecture which uses only one RF channel, carrying multiplexed information from multiple antennas. The performance characteristics of this single RF channel like gain, isolation, noise figure, IIP3, and matching are shown in this work. The specifications and performance are in close agreement, validating the proposed compact design.

We have devised a digital time-division multiplexing (TDM) scheme for minimizing the circuit complexity required for an array of sensors. As a proof-of-concept, we have designed, fabricated, and tested a four-channel digital TDM readout circuit. The proposed scheme can be generalized for a larger number of channels. The readout circuit comprises an array of ADCs to digitize sensor outputs, a multiplexing unit, a clock controller, and a counter with parallel-to-serial output interface. For demonstration purposes, we employed low-pass phase modulation–demodulation ADCs running in a synchronous mode of operation. To facilitate an independent verification of circuit operation, we also placed an on-chip pattern generator to apply a unique pattern to each channel. The multiplexing unit is based on an array of sequentially triggered switches, each controlling the flow of data from a single ADC to a common output bus. In our scheme, the switches are realized using RS-flip-flops with nondestructive (RSN) readout cells with only one RSN cell turned on at a time. Multiplexed output data were stored in ripple counter based on T-flip-flops and read out to room temperature electronics using a serial interface. The chip was immersed in liquid helium at 4.2-K temperature and extensively evaluated at sampling frequencies up to 12.8 GHz. By means of embedded pattern generators, we proved the correct operation of each channel and of all four channels combined. We also were able to perform reconstruction of a signal applied to individual ADC. The chip was fabricated using HYPRES’ 4.5-kA/cm2 process with four Nb metal layers. We briefly discuss the proposed scheme's scalability for higher current density and smaller feature size fab processes.

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.