A Multi-Threshold Detector for Uplink Non-Orthogonal Multiple Access Systems with Analytical Probability of Error Evaluation

Document Type : Original Article

Authors

Department of Electrical Engineering, University of Isfahan, Isfahan, Iran

Abstract

In this paper, we modify the Multi-Threshold (MTh) Detector for detection of uplink non-orthogonal multiple access (NOMA) signals in the Ricean fading channels. Non-orthogonal multiple access system using the superposition principle can share resources to multiple users, which improves system capacity and spectral performance. The multi-threshold method is proposed as opposed to the successive interference cancellation (SIC) method. The multi-threshold method detects users' signals directly and without detecting other users' signals. We also obtain the MTh decision regions to detect the received signal at the base station (BS). Then, we compute the analytical probability of error (Pe) expression for the MTh and SIC methods. Computer simulations are performed which confirm the obtained analytic expressions.. The results obtained from the comparison of the MTh detector and SIC method shows that the performance of the MTh detector is superior to that of SIC in the uplink non-orthogonal multiple access system, because the MTh detector has less delay and probability of error than those of the SIC method. The better error probability of the MTh can be deduced from the simulation and analytic results. The MTh method has lower delay than SIC because it can detect every users' signals directly and without priority, while, the SIC method must detect the stronger users before detection of weaker users.

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