The concept of a joint optimization of multiuser (MU) operation from both transmitter and receiver's perspective has
the potential to further improve MU system capacity even if the transmission/precoding is non-orthogonal which could
come from, for example but not limited to, the simultaneous transmission of a large number of non-orthogonal
beams/layers with the possibility of more than one layer of data transmission in a beam. Such non-orthogonal
transmission could allow multiple users to share the same resource elements without spatial separation, and allow
improving the MU system capacity for networks. An example of such joint Tx/Rx optimization associated with adaptive
Tx power allocation and CW-IC receiver is recently a remarkable technical trend, including schemes based on
superposition coding. Joint Tx/Rx optimization might require standardization effort. Hence it is important to study the
trade-off, in terms of system performance, complexity, and signalling overhead.
The present document captures the results and findings of the study item "Study on Downlink Multiuser Superposition
Transmission". The purpose of this TR is to document the identified LTE enhancements to enable downlink
multiuser superposition transmission and corresponding evaluation results in the target deployment scenarios.
This document defines evaluation methodology and target deployment scenarios for the study on downlink multiuser
It identifies LTE enhancements and potential specification impacts to enable downlink multiuser
It contains an assessment of feasibility and performance of the identified LTE enhancements to enable
downlink multiuser superposition transmission.