Performance analysis of NOMA based hybrid cognitive radio network assist by full-duplex relay

This paper examines the throughput and outage performance of secondary users in a hybrid cognitive radio network (CRN) based on non-orthogonal multiple access (NOMA) technology. Based on channel occupancy, secondary transmitters in a hybrid CRN immediately switch between overlay or underlay mode in response to sensing results. If the primary user (PU) is not active, they operate in overlay mode with the maximum permitted transmit power else they operate in underlay mode with a transmit power restriction. The secondary network employs the NOMA approach, in which the base station (BS) is assisted by a full-duplex (FD) relay network to send information to the secondary destinations. Secondary transmitters are equipped with energy detector and harvesting circuit which allows to sense and store energy from the radio frequency (RF) of the multiple primary users. The benefit of using multiple FD relays along with the hybrid operation of joint mode transmission enables to increase the system throughput. Finally, an analytical formulation including closed form for the outage probability as encountered by the secondary users (SUs) in the presence of self interference (SI) and imperfect successive interference cancellation (i-SIC) under hybrid mode has been derived and validated through MATLAB simulation.