LAUSR

In this letter, an adaptive power allocation (APA) strategy is proposed for an uplink non-orthogonal multiple access (NOMA) with semi-grant-free (SGF) transmission, where one grant-based user (GBU) shares the same resource with other grant-free users (GFUs) using grant-based scheme and grant-free scheme, respectively. The proposed strategy is based on the fact that the quality of service for the GBU can be strictly guaranteed if its instantaneous data rate is larger than the target date rate. Compared to existing works, the derived analytical results for the proposed APA strategy in uplink NOMA-SGF networks show that the outage probability at a low signal-to-noise ratio for the GBU can be significantly reduced, and full diversity gain for the GFUs can be achieved. Finally, the accuracy of the theoretical results is validated using Monte Carlo simulations.