Performance of Low-Rate NOMA-based Uplink Underlay Networks

We analyze the performance of underlay networks in which non-orthogonal multiple access (NOMA) signalling is used for uplink signalling by low-rate users. The primary network imposes an interference temperature limit (ITL). Peak interference constraints are imposed on the secondary nodes to ensure compliance to the ITL. We show how opportunistic user selection can be performed for NOMA signalling, and demonstrate how the ITL can be apportioned between the users transmitting concurrently. The suggested scheme along with the evolved power control mechanism can double the spectrum utilization efficiency in many scenarios. Expressions are derived for outage probability and throughput. Computer simulations demonstrate accuracy of the derived expressions.