Abstract
In this paper, we investigate the outage performance in secondary network of cognitive radio (CR) employing non-orthogonal multiple access (NOMA) wireless networks over Rayleigh fading channels. The considered system model adopts device-to-device (D2D) transmission together with traditional communication to form a new system model, namely CR-D2DNOMA network. The specific user is selected from multiple D2D-Tx users (D2Ds) to communicate with far NOMA users to form qualified D2D connection with assistance of the Relay user (). The main metric in such CR-D2DNOMA network needs to be considered and we particularly introduce the closed-form expressions for outage probability in the secondary network where it is designed to serve two far NOMA users. The perfect Successive Interference Cancellation (SIC) and imperfect SIC can be further examined at the second NOMA user who detects signal based on the ability of SIC. The results show the positive impact of increasing the fading parameters on the system performance. More importantly, numerical results are provided to verify the correctness of our derivations. Additionally, the effects of asymptotic expressions on insights evaluation are also further analyzed.
Highlights
To improve current statistic spectrum use, cognitive radio (CR) is proposed as a spectrum-sharing technique in which a primary user (PU) permits a secondary user (SU) to occupy idle spectrum assigned to such PU
If the energy statistic is less than the threshold, the PU is detected to be absent [4,5,6,7]. detection probability and false alarm probability are two factors affecting the performance of energy detection. highly reliable detection of the idle channel can be achieved as low false alarm probability happened, while highly accurate detection on the presence of the PU results from high detection probability
The other cooperative non-orthogonal multiple access (NOMA) assisted underlay cognitive radio network is considered through approximate expressions for the outage probability and a relay is known as selected secondary user [24]
Summary
To improve current statistic spectrum use, cognitive radio (CR) is proposed as a spectrum-sharing technique in which a primary user (PU) permits a secondary user (SU) to occupy idle spectrum assigned to such PU. The other cooperative NOMA assisted underlay cognitive radio network is considered through approximate expressions for the outage probability and a relay is known as selected secondary user [24]. By assuming that the primary source’s interference is considered to be a constant, two metrics including the outage probability and the ergodic capacity to highlight performance of underlay cognitive radio network using cooperative NOMA [25]. The traditional cognitive radio network can further serve D2D users with improved outage performance while remaining quality for normal cellular users. These results can be useful in many practical applications, for example, evaluating the traditional channel model in CR-D2DNOMA network such as Rayleigh fading is resulted from this paper.
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