Resource allocation for NOMA in multiuser multicarrier systems

In this paper, we propose a non-orthogonal multiple access scheme based on multiuser orthogonal frequency division multiplexing system to reduce the total transmit power. In this system, each subcarrier can be assigned to two users for data transmission and transmits data with a lower order of a modulation mode. Because the system is based on orthogonal frequency division multiple access, a primary user is more important than a secondary user, we ensure that all assigned subcarriers transmit data to the primary user in the system. The secondary user will transmit data with the primary user on some subcarriers. We discuss how the primary and secondary users perform resource allocation under different subcarriers and channel gains. Based on the development, using the non-orthogonal multiple access allocation idea to allocate bits and transmit power, the simulation results show that the proposed scheme outperforms the conventional OFDM system in terms of transmit power or capacity equivalently.