Performance Analysis of NOMA Short-Packet Communications With QoS-Based SIC Detecting Order

In this letter, we perform an unified analysis of an uplink non-orthogonal multiple access (NOMA) system with short-packets over a wide range of fading channels, such as lognormal-Nakagami-
${m}$
, generalized
$K_{G}$
,
$\eta -\mu $
, Nakagami-
${q}$
(Hoyt),
$\kappa -\mu $
, Rician, Nakagami-
${m}$
, and Rayleigh fading. The system model consists of a high-priority user with low-rate, low-latency and high-reliability requirements, and a low-priority user with high-rate and delay-tolerant. We first derive closed-form expressions of the average block error-rate (BLER) and the asymptotic at the high signal-to-noise ratio (SNR) regime. Next, we optimize the power back-off level and the packet-length to maximize the throughput of the low-priority user subject to the quality-of-service (QoS) requirements of the high-priority user. Theoretical analysis is corroborated by simulation results.