BER and Outage Performance for Multi-hop User-Relays NOMA with Imperfect SIC and CSI

This paper examines a downlink multi-hop user relays assisted non-orthogonal multiple access (NOMA). The system is used to combat channel disorders, extend the coverage area, and improve the quality of service (QoS). Both imperfect successive interference cancellation (SIC) and channel state information (CSI) are taken into consideration. Under imperfect SIC and CSI, we obtain the bit error rate (BER) and outage probability (OP) expressions for the helper user. Then, when imperfect CSI is available at all hops, we compute the end-to-end BER and OP for far user message at each hop. Theoretical analyses are validated by computer simulations. The findings indicate that the BER and OP performance deteriorate as the hops increase. Additionally, at the high signal-to-noise ratio (SNR), the erroneous SIC and CSI create an error floor and impact the BER and OP performance at all hops.