Power Allocation for NOMA with CSI Uncertainties and Imperfect Successive Interference Cancellation

Non-orthogonal multiple access (NOMA) employing multiple-input- single-output (MISO) is considered as one of the disruptive technologies introduced in the 5G systems to offer higher data rate. The performance of such techniques is heavily dependent on the availability of channel state information (CSI). Perfect CSI assumed in the current NOMA literature is difficult to realize, thus only high resolution CSI can be obtained at the base station (BS). In this paper we give a closed form optimal power allocation scheme that considers erroneous CSI with imperfect successive interference cancellation (SIC). Numerical results validate the derived expressions, showing that the proposed method outperforms conventional power allocation schemes that do not take into account the practical constraints of MISO-NOMA.