Orthogonal versus Non-Orthogonal multiplexing in Non-Coherent Massive MIMO Systems based on DPSK

The lack of orthogonal resources to increase the capacity of the communication networks has led to research on new ways to non-orthogonally multiplex the signals of several users. In this paper, we study the viability of multiplexing users' signals by non-orthogonal constellation-based schemes against orthogonal classical multiple access techniques, such as time-or frequency-division multiple access, in non-coherent massive MIMO (NC mMIMO) systems, where the channel state information (CSI) is not required. We use the block error rate (BLER) and the throughput to analyze the behavior of the proposed multiuser NC mMIMO system based on DPSK. We assess the performance of multiplexing the users in the constellation against using other physical resources such as time or frequency. Based on this analysis, we propose a combination of both orthogonal and non-orthogonal schemes to reduce the complexity and increase the system throughput and capacity.