  In the fifth generation and beyond (B5G) technologies, delay constrains
emerge as a topic of particular interest for ultra reliable low latency
communications (e.g., enhanced reality, haptic communications). In this report,
we study the performance of a two user uplink non orthogonal multiple access
(NOMA) network under quality of service (QoS) delay constraints, captured
through each user delay exponents in their effective capacity (EC). We propose
novel closed form expressions for the EC of the NOMA users and validate them
through Monte Carlo simulations. Interestingly, our study shows that in the
high signal to noise ratio (SNR) region, the strong NOMA user has a limited EC
no matter how large the transmit SNR is, under the same delay constraint as the
weak user. We show that for the weak user OMA achieves higher EC than NOMA at
small values of the transmit SNR and that NOMA become more beneficial at high
values of the transmit SNR. For the strong user, we show that NOMA achieves a
higher EC than OMA at small values of the transmit SNR and that at high values
of the transmit SNR OMA becomes more beneficial. By introducing user pairing
when more than two NOMA users are present, we show that NOMA with user pairing
outperforms OMA in term of the total link layer EC. Finally, we find the set of
pairs which gives the highest total link-layer in the uplink for NOMA with
multiple user-pairs.
