Adaptive Aquila optimized relay selection and power allocation in CR-NOMA model

Cooperative communication combining non-orthogonal multiple access (NOMA) and cognitive radio is a rapidly growing technique for wireless networks and beyond 5G Still, security is considered one of the primary issues due to overheard confidential details in wireless transmission platforms. Consequently, the replacement of encryption-based strategies for security must be done at the physical layer. The proposed method uses an enhanced Aquila optimization algorithm (EAO) to replace encryption methods to select the best joint relay and power allocation (PA). The method undergoes two stages to deliver the message to the secondary users (Ss). The first stage is the message transmitted from the secondary base station (BS) to the relay, and the second stage is relaying the message to the secondary users. Best joint relays are selected based on two objective functions to maximize throughput and the secrecy sum rate (SSR) with two factors delay and secrecy rate of CR-NOMA. To enhance the exploration and exploitation stages of the proposed algorithm, representative-based hunting (RH) is employed. The effectiveness of the proposed method is analyzed with other existing baselines on various performance metrics. The results showed that the proposed method performs well due to the inclusion of the NOMA strategy and maximizes the throughput and SSR of the network.