Performance Analysis of STAR-RIS Aided Short-Packet NOMA Network Under Imperfect SIC and CSI

Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) and nonorthogonal multiple access (NOMA) are promising solutions for next-generation wireless networks with massive connectivity, ultra-low latency, ultra-high reliability, and spectral efficiency. This article analyzes the performance of the downlink STAR-RIS-aided short-packet (SP)-NOMA (STAR-RIS-SP-NOMA) network under the constraint of imperfect successive interference cancellation (ipSIC) and imperfect channel state information (ipCSI) by using a Nakagami-$m$ fading environment. To characterize the system performance, first, we derive the statistical distribution of cascaded Nakagami-$m$ channels using the Laguerre polynomial series approximation. Second, the approximate closed-form expressions in terms of average block error rate (ABLER), system throughput, goodput, latency, and reliability are derived. Third, the asymptotic analysis is also done at a high signal-to-noise ratio to gain further insights. Finally, the Monte Carlo simulations are performed to verify the correctness of the theoretical results. Numerical results validate the superiority of STAR-RIS-SP-NOMA over STAR-RIS-SP-orthogonal multiple access (OMA) (STAR-RIS-SP-OMA) and the conventional cooperative communication scenarios, such as decode and forward relay-assisted half-duplex-SP-OMA and fixed-gain amplify and forward relay-assisted half-duplex-SP-OMA. We have compared the ABLER expression for all three STAR-RIS operating protocols. Also, the effect of various parameters, such as the ipCSI correlation factor, ipSIC factor, blocklength, information bits, and number of STAR-RIS elements on the system performance is examined.