Using Layered Division Multiplexing for Mixed Unicast-Broadcast Service Delivery in 5G

Point-to-multipoint (PTM) transmission is a key enabler for a wide range of emerging 5G New Radio (NR) applications and use cases. For more efficient use of spectrum, 3GPP is working on a 5G multimedia broadcast multicast service (5G-MBMS) subsystem, aiming at providing effective mixed unicast/multicast/broadcast services on a unified transmission platform. This paper shows that, in many cases, especially high-density small cell deployments, capacity of the current single frequency multi-cell unicast service in the 4G/5G infra-structure is limited by co-channel interference. Using a reduced transmission power to a certain extent will not impact the system performance and throughput. Meanwhile, for broadcast services using single frequency network (SFN), there is no co-channel interference. Signals from adjacent cells are identical, which enhances the reception quality. Slightly reducing the broadcast service SFN emission power will not impact the system quality of service (QoS). This provides a good opportunity to apply layered division multiplexing (LDM), a power-based non-orthogonal multiplexing (P-NOM) technology, to combine broadcast and unicast services in one RF channel by power sharing. This study demonstrates that, in a 5G-MBMS with two-layer P-NOM/LDM, broadcast SFN and multicell unicast services can be efficiently and effectively delivered using the same spectrum resource.