Fractional Power Control for Small Cell Uplinks with Opportunistic NOMA Transmissions

Both small cells and non-orthogonal multiple access (NOMA) are cutting-edge technologies to boost the system capacity for the future wireless communications. In this paper, an analytical framework for small cell uplinks using NOMA transmissions is developed. To facilitate the detection of both near and far user signals, dual path loss compensation factors (PLCFs) are exploited for uplink power control. With the aid of stochastic geometry, the average successful transmission probability are derived for small cell networks with opportunistic NOMA transmissions and dual PLCFs. Based on the derived results, optimal PLCFs are obtained by two-dimension search methods. It is shown by simulation that the proposed NOMA scheme with optimal dual PLCFs outperforms the existing NOMA scheme with a unique PLCF in terms of both average successful transmission probability and spectrum efficiency.