Improving Spectrum Efficiency in CR-NOMA over Rician Fading Channel Under Imperfection CSI

We present a downlink secondary network over Rician fading model since cognitive radio (CR) based non-orthogonal multiple access (NOMA) is adopted. Due to interference constraint, performance analysis of secondary destinations has further parameter to adjust performance as needed. We derive the closed-form expressions of outage probability for the case of two users in a group. Especially, we need to consider how system performance could be better in the case of imperfect channel state information. Then, we find main system parameters such as power allocation factor, condition of wireless channels as controlling factors of outage probabilities of two destinations. We perform Monte Carlo simulations to check the derived analytical expressions.