Performance of Underlay Uplink NOMA over Nakagami-m Fading Channels with Imperfect SIC and CSI-Dependent Power Allocation

This paper examines the performance of an underlay uplink non-orthogonal multiple access (NOMA) network over Nakagami-m fading channels. With the help of NOMA signalling notions, two users are serviced in the secondary network concurrently with the primary user's transmission. The transmit powers of secondary users are determined such that the cumulative interference at the primary receiver from the two secondary transmitting nodes is within the interference temperature limit (ITL). Since hardware impairments and channel estimation errors cause imperfect successive interference cancellation (SIC) in practical scenarios, imperfect SIC is considered in the analysis. Channel state information (CSI) based ITL apportioning is proposed for the first time in such scenarios taking into consideration both decoding orders. Our results demonstrate the supremacy of the suggested scheme over underlay orthogonal multiple access. We derive expressions for the outage probability and throughput of both users. Monte Carlo simulations validate the analytical expressions.