User Fairness and Performance Enhancement for Cell Edge User in NOMA-HCN with Offloading

The explosion of cellular users and high demand for data has evolved the single-tier cellular network to multi-tier network. This paper analyses the gain of non-orthogonal multiple access (NOMA), an enabling technique for 5G, in a heterogeneous cellular network (HCN) consisting of a macro base station (MBS) tier and femto base station (FBS) tier. Offloading users to the FBS tier is performed to relieve the MBS tier of over congestion. In order to support offloaded user, the FBS tier employs NOMA. The results are plotted for different channel conditions while offloading the user to FBS tier. Benefits of NOMA (for e.g., higher ergodic rate, user fairness, performance enhancement at cell edge user) are observed for different channel conditions for the offloaded user. It is also observed that offloading to FBS tier with NOMA gives better performance as compared to offloading without NOMA.