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Layered Division Multiplexing (LDM) is a Power-based Non-Orthogonal Multiplexing (P-NOM) technique that has been implemented in the Advanced Television System Committee (ATSC) 3.0 terrestrial TV physical layer to effectively multiplex services with different robustness and data rate requirements. As communication systems quickly evolve, the services to be delivered are becoming more diverse and versatile. Up to now, the LDM system adopted in the terrestrial TV system uses a uniform injection level for the lower-level (or Layer 2) signal injection. This paper investigates the non-uniform injection level LDM (NULDM). The proposed technique can explore the Unequal Error Protection (UEP) property of Low-Density Parity-Check (LDPC) codes and the flexible power allocation nature of the NULDM to improve the system performance and spectrum efficiency. NULDM enables the seamless integration of broadcast/multicast and unicast services in one RF channel, where the unicast signal can assign different resources (power, frequency, and time) based on the UE distance and service requirements. Meanwhile, more power could be allocated to improve the upper layer (or Layer 1) broadcast and datacast services. To make better use of the UEP property of LDPC codes in NULDM, the extended Gaussian mixture approximation (EGMA) method is used to design bit interleaving patterns. Additionally, inspired by the channel order of polar codes, this paper proposes an LDPC sub-block interleaving order (SBIO) scheme that performs similarly to the EGMA interleaving model, while better adapting to the diverse needs of proposed mixed service delivery scenarios for convergence of broadband wireless communications and broadcasting systems.

This paper demonstrates the feasibility of multi-antenna reception to facilitate mobile broadcasting for vehicular receivers. Starting from a dimension analysis estimating the spatial capacity of automobiles, we confirm multi-antenna embedding as a viable solution for vehicular broadcast receivers. Accordingly, a rolling prototype of an ATSC 3.0 multi-antenna diversity receiver (DivRx) is implemented and repeatedly tested on public roads. The field verification tests in this paper aim to evaluate the performance of DivRx in real broadcast environments, represented by an urban single-frequency network (SFN) with high-power transmissions using ultra-high frequencies. To this end, extensive field trials are drawn in an operating ATSC 3.0 network located in the Seoul Metropolitan Area, South Korea. Public on-air services of 1080p and 4K videos are tested, targeting inter-city journeys and trips in urban centroids, respectively. The mobile reliability gain of DivRx is empirically evaluated in terms of coverage probability and the field strength required for 95% receivability. The results show that leveraging four antennas can achieve 99% coverage of intra-city 4K service in the current network status, deriving 65% more gain over single-antenna systems. It is also exhibited that the signal strength requirement can be reduced by 13 dB or more. In addition to the empirical evaluation, we provide theoretical proofs aligning with the observations.