Subcarrier Selection and User Matching Technique for Downlink NOMA System

As a method for bettering resource allocation, Non-Orthogonal Multiple Access (NOMA) is a feature of 5G radio access. By Power domain NOMA users onto the transmission of power with the same time and spectrum resources, NOMA improves spectrum efficiency. In order to boost the downlink NOMA system's spectral efficiency, fairness, and weak user data rate, a subcarrier selection and user matching technique (SSUMT) has been proposed. This SSUMT uses the low gain subcarrier first based adaptive user selection (LGSF-AUS) algorithm. The LGSF-AUS algorithm works on the selection of the available subcarriers based on the least gain user and then pairs the users to provide the service by the subcarrier. One strong and one weak user are selected with respect to their channel gain value and these two users are paired for assigning to the subcarrier. The power allocation of the selected users is based on their power coefficients, weak users assigning more power and less power is assigned to strong user. This LGSF-AUS algorithm enhances the data rate of the weak users, so the spectral efficiency and fairness among the users is significantly improved in comparison with other existing methods.