Performance Analysis of NOMA Enabled Hybrid Network With Limited Feedback

This paper investigates the coexistence of multi radio access technology (RAT) using Ultra High Frequency (UHF) small base station (SBS) and millimeter Wave (mmWave) SBS tier in a heterogeneous network (HetNet). To support large number of users, non-orthogonal multiple access (NOMA) is used in the SBS tier. For NOMA, the SBS needs to obtain users' channel state information (CSI) to determine their ordering. Acquiring CSI at the SBS is a challenging task due to the massively increased number of users. The existing literature uses limited feedback from the users as a potential solution to assist the SBS in user ordering, when perfect CSI is not known at the base station. The limited feedback from the users in the existing literature is used only for user ordering. However, in the proposed work, unlike using limited feedback only for user ordering, the usage of limited feedback from the users is twofold. The first one is for the user ordering and the second is for the RAT selection. The impact of the proposed feedback system is analyzed in a NOMA enabled hybrid UHF/mmWave downlink HetNet. Numerical results show that the proposed feedback system achieves significant improvement in the outage probability.