Abstract
In order to meet the explosive demand incurred by mobile applications, the downlink non-orthogonal multiple access (NOMA) has been regarded as a promising solution. Different from conventional orthogonal multiple access (OMA) technologies that different users are allocated to distinct orthogonal resources in either time or frequency domain, NOMA, which multiplexes multiple users in the same frequency resource, can enhance spectrum efficiency with the help of the use of superposition coding (SC) and successive interference cancellation (SIC). To be very practical, our system model takes non-zero outage probability at UEs and heterogeneity of resource blocks into account. We propose a joint user pairing and power allocation algorithm whose primary objective is to maximize the number of satisfied users and whose secondary objective is to maximize sum rate. Simulation results indicate that the proposed algorithm outperforms the compared algorithms significantly in terms of the number of satisfied users.