  The development of the industrial Internet of Things (IoT) calls for higher
spectrum efficiency (SE). Faster than Nyquist (FTN) and non-orthogonal multiple
access (NOMA) are both promising paradigms to improve the SE without any extra
spectrum resources required. The combination of FTN and NOMA is an interesting
issue and has been focused on recently. In the NOMA technology, user pairing
and power allocation are key algorithms determining system capacity. This paper
first proposes a joint user pairing and power allocation algorithm for the
FTN-based single-carrier (SC) NOMA system. Then, the FTN-based
multiple-input-multiple-output (MIMO) NOMA is studied and a dynamic user
pairing and power allocation scheme is presented. In both scenarios, the
maximum available sum rate (ASR) is the target. While based on the fairness
principle, the user's SE in the NOMA system is guaranteed to be no less than
that in the OMA system. Simulation results show the advantage of the FTN-based
NOMA with the proposed scheme in ASR and quality of service (QoS) performance.
As far as we know, this paper is the first solution to the issue of user
pairing and power allocation in FTN-based NOMA, which proves the great
advantage of the combination of these two state-of-the-art technologies.
