Cooperative Non-Orthogonal Multiple Access for Future Wireless Communications

Abstract

There is a huge demand for increased connectivity and reliability of devices in the fifth generation and beyond of wireless communications so as to ensure massive connectivity and high spectral efficiency. Recently, powerdomain non-orthogonal multiple access (NOMA) has received considerable attention as a promising multiple access scheme to improve spectrum efficiency. It allows multiple users to share both time and frequency resources by adjusting the power allocation ratio. However, with ever-increasing mobile users and machines in future wireless environments, NOMA still suffers from some challenges such as a limited connectivity, channel uncertainty and a trade-off between throughput and user fairness. Therefore, an opportunity exists for developing NOMA features in a cooperation of such devices. In this paper, we focuses on exploring cooperative power-domain NOMA systems to maximize potential and develops an effective multiple access for next generation wireless systems. To explore the trade-off of the cooperative NOMA system between its performance and the network complexity, several NOMA systems along with various techniques are introduced. Firstly, a joint NOMA and partial relay selection is introduced to improve both system throughput and user fairness. Secondly, a cooperative NOMA scheme which uses a cognitive radio network as an underlay is also introduced. In this work, a cooperative scheme is used to enhance the outage performance at a cell-edge user for user fairness and NOMA aims to improve spectral efficiency. Finally, an opportunistic NOMA under unreliable wireless backhauls and fronthaul channel uncertainty is introduced and two opportunistic selection rules are applied to a joint NOMA scheme and cooperated transmission. In this work, the impact of unreliable wireless backhauls and fronthaul channel uncertainty on the coordinated NOMA system is examined.

Performance Analysis for RF Energy Harvesting Mobile Edge Computing Networks with SIMO/MISO-NOMA Schemes

“…This technique allows multiple users to share the same resource (e.g., a time/frequency domain) and separate the users in the power domain by exploiting successive interference cancellation (SIC) scheme at the receiver. Recently, many studies on the advancements needed in the transmitter and receiver sides for adopting NOMA schemes have been published [4][5][6][7].…”