CR-NOMA Based Interference Mitigation Scheme for 5G Femtocells Users

In the last few years, we have witnessed an exponential increase in the popularity of Internet-enabled smart devices. In this era, various smart devices generate a huge amount of data during computing and communication. However, fixed infrastructure, especially in the dense population, have the issues of coverage and connectivity in this environment. But, 5G technology based femtocell emerges as one of the solutions for the aforementioned issues. Hence, in this paper, we investigate the non-orthogonal multiple access (NOMA) transmission with 5G enabled cognitive femtocell to attain higher spectral efficiency and to maximize the sum rate of femto users (FUs) with guaranteed QoS. A paring algorithm between strong and weak users has been proposed to reduce the NOMA interference between different FUs. To achieve higher data rates, the calculation of sum rate for an even/odd number of FUs in a femtocell is also proposed. Numerical results show that the proposed schemes effectively improve the sum rate of the cognitive femtocell under NOMA transmission to minimize the interference.