Layer-division Multiplexing Research Articles (Page 1)

Delivering geographically segmented local content remains one of the key challenges in Single Frequency Networks (SFNs). By leveraging Layered Division Multiplexing (LDM), Local Content Insertion (LCI) can be achieved through Geographically Segmented Localcasting (GSL) for both multimedia and datacasting applications. This paper introduces a solution where region-wide broadcast services are carried by the Core Layer (CL) of the LDM, while local content is transmitted through the Enhancement Layer (EL). This approach also benefits network design and transmitter deployment, as new transmitters can be positioned freely within the intended broadcast service area. Each additional site enhances the reception quality of the regional component (LDM CL) while simultaneously delivering geographically specific multimedia and datacasting services to its local coverage zone. Since the localcasting signal on the EL operates at a lower transmission power, co-channel interference among local transmitters is minimized. A co-channel interference mitigation technique, Iterative Joint Detection and Decoding (IJDD), is also introduced. The paper outlines a roadmap for deploying LCI/GSL systems. Leveraging LDM enables any terrestrial television platform to adopt this approach in SFN or High-Power High-Tower (HPHT) configurations while remaining compatible with existing receivers. Furthermore, any cell-based wireless systems (5G/6G) can exploit this method, efficiently integrating broadcast, multicast, and unicast service delivery.

Mobile edge computing (MEC)-assisted non-orthogonal multiple access (NOMA) network has great potential to support real-time computing with the lower power consumption and network latency, since it leverages the computation capacities at the access point and power domain multiplexing technique. However, with the explosive growth of users in massive access, the power consumption and network latency for data offloading will inevitably increase. Conventional network ignoring the specific service requirement from different levels of users could severely jeopardize quality of service for the massive access NOMA network. To fill this gap, this work adopts the layered-division-multiplexing (LDM) structure, and jointly optimizes the beamforming, computation frequency, and power allocation to minimize the system power consumption under the alternating minimization framework. Simulation results demonstrate the convergence behavior of the proposed algorithm, and the performance gains from the proposed MEC-assisted NOMA network with LDM technique over the other benchmark networks.

An integrated satellite and aerial network (ISAN) is considered a promising candidate to provide seamless connectivity for future wireless communication systems. In this paper, we propose a multi-objective based robust beamforming (BF) scheme for an ISAN to support heterogeneous services with high flexibility, where the satellite network serves various heterogeneous satellite terminals through multicast non-orthogonal multiple access (MC-NOMA), while the aerial network offers services to many internet of things devices using layered division multiplexing (LDM). Specifically, we first formulate a multi-objective optimization problem (MOOP) to achieve a good trade-off between sum rate maximization and total transmit power minimization. To tackle this mathematically intractable problem, we exploit the weighted Tchebycheff approach to transform the MOOP into a single-objective problem. Since only the angular information based channel state information is available, we exploit the angular discretization method and sequential convex approximation to design a robust BF algorithm to obtain the Pareto optimal solutions. Finally, simulation results demonstrated that our proposed scheme can achieve a optimal trade-off between multiple performance metrics with high spectrum and energy efficiency, so as to support heterogeneous services in the ISAN and fill the gap of only single type of serivce in the existing ISAN works.

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.

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.

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 most recent standard for broadcast services, Advanced Television System Committee—Third Generation (ATSC 3.0), has adopted co-located multi-antenna schemes and Layered Division Multiplexing (LDM) in order to increase the capacity and reliability compared to former Digital Terrestrial Television (DTT) systems. ATSC 3.0 has adopted both technologies separately, but no combination of them is planned yet. Compared to baseline LDM case, use of several antennas allows for diverse parametrization for each layer. This paper analyzes the potential combination of co-located Multiple-Input–Multiple-Output (MIMO) schemes with LDM. A trade-off analysis between complexity constraints and performance benefits is evaluated.

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.

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.

The next-generation U.S. digital terrestrial television (DTT) standard ATSC 3.0 is the most flexible DTT standard ever developed, outperforming the state-of-the-art digital video broadcasting-terrestrial 2nd generation (DVB-T2) standard. This higher flexibility allows broadcasters to select the configuration that better suits the coverage and capacity requirements per service. Regarding the selection of pilot patterns, whereas DVB-T2 provides eight different patterns with a unique pilot amplitude, ATSC 3.0 expands up to 16, with five different amplitudes per pattern. This paper focuses on the pilot pattern and amplitude performance and optimization for time and power multiplexing modes, time division multiplexing and layered division multiplexing (LDM), respectively, of ATSC 3.0. The selection of the optimum pilot configuration is not straightforward. On the one hand, the pilots must be sufficiently dense to follow channel fluctuations. On the other hand, as long as pilot density is increased, more data overhead is introduced. Moreover, this selection is particularly essential in LDM mode, because the LDM implementation in ATSC 3.0 requires that both layers share all the waveform parameters, including pilot pattern configuration. In addition, there is an error proportional to the channel estimate of the top layer that affects to the lower layer performance.

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<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>

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.