Using Layered-Division-Multiplexing to Achieve Enhanced Spectral Efficiency in 5G-MBMS

3GPP is pursuing a multimedia broadcast multicast service subsystem in 5G (5G-MBMS) based on the latest LTE further evolved MBMS (feMBMS) system in Rel. 14. In this paper, Layered Division Multiplexing (LDM) is proposed as a new addition to the 5G technology toolbox for achieving significantly enhanced spectral efficiency for the 5G-MBMS to efficiently deliver mixed broadcast and unicast services. A capacity analysis is first conducted to derive the capabilities of an LDM-based 5G-MBMS system to deliver broadcast and unicast services in the different signal layers, under the conditions with severe co-channel interference (CCI). It is shown that using LDM can provide a nearly full-capacity unicast network on top of high-quality broadcast network. The broadcast capacity is mainly determined by the power allocations between the two signal layers. The unicast capacity can be maximized by deliberately operating the system in a CCI-limited mode. Simulation results are presented to demonstrate the capacity gain that can be achieved by incorporating LDM in the 5G-MBMS system. This study shows that LDM is one of the enabling technologies to close the gap between the LTE feMBMS capability and the 5G-MBMS requirements.