Effective capacity of finite-blocklength NOMA and OMA with heterogeneous latency requirements

In this work we present a performance comparison for the downlink of two-user NOMA and OMA systems, for applications with heterogeneous latency requirements and considering the finite blocklength scenario. The system performance is evaluated using the effective capacity (EC), that takes into account the effect of the delay and outage in the achievable rate. We evaluate the EC by numerical integration using the ordered statistics distributions for the case of Rayleigh fading and verify these results through Monte Carlo simulations. The performance of both access techniques is evaluated considering homogeneous and heterogeneous latency requirements and considering in particular the cases of the strong and weak users. We show that NOMA outperforms OMA when users have different latency demands. In particular, for large signal-to-noise ratios (SNRs) the difference between both access technologies is even more pronounced.