Uplink Non-Orthogonal Multiple Access with Fractional Power Control

Abstract

As a promising radio access technology for 5G cellular network, non- orthogonal multiple access (NOMA) has attracted extensive research attention recently. Compared with orthogonal multiple access (OMA), NOMA possesses the potential to further improve system spectrum efficiency. To perform uplink NOMA successfully, the received signal of each user equipment (UE) within a NOMA group at base station needs to be decodable. On the other hand, fractional power control (FPC) is widely applied in the existing wireless networks to mitigate inter-cell interference by giving cell center and cell edge users different target receiving signal power levels. NOMA can exploit this difference in the received powers and group cell edge UEs and cell center UEs into a NOMA group so that further spectrum efficiency can be realized. In this paper, an analytical framework on uplink NOMA with FPC is developed and performance on the system coverage and average user achievable rate is evaluated. The analysis on an OMA access scheme with FPC is also provided for comparison. The analytical results are validated by simulations. The performance study demonstrates that NOMA with FPC can bring considerable capacity gain compared to OMA with FPC.