Novel Heuristic Subcarrier Allocation for Spectral: Energy Efficiency Tradeoff Improvement in Underlay Cognitive Radio Network

Cognitive radio (CR) technology has become an integral part of 5G and beyond systems owing to its ability to improve spectrum utilization. Allocation of resources to the cognitive secondary users with the aim of enhancing the total throughput will increase spectral efficiency (SE) only. Energy efficiency (EE) should also be given due consideration since huge power consumption may lead to various adverse effects such as increased operational costs among many others. In this work, a new heuristic approach called Indigent User Favouring Subcarrier Allocation (IUFSA) is proposed for efficient allocation of subcarriers to the SUs in an underlay CR network, with focus on improving the SE-EE tradeoff. Simulation results show that IUFSA improves the SE-EE tradeoff by a maximum of 59.2% compared to other conventional subcarrier allocation techniques considered. It also performs close to optimal Munkre's (Hungarian) assignment algorithm. The results are obtained by performing extensive Monte Carlo simulations. Simulation parameters are chosen as per 3GPP release 15 5G TR 138,901 specifications to ensure that the results are close to practical deployment scenarios.