Spectrum Allocation for Non-Orthogonal Multiple Access Heterogeneous Networks

Non-orthogonal multiple access is a promising technology for improving the spectral efficiency in 5G networks and beyond. Also, the deployment of heterogeneous networks for densifying the existing networks enhances the capacity and the coverage. Spectrum allocation is very important for the in-band heterogeneous networks where different tiers operate at common frequencies. Hence, this paper proposes resource and power allocation solution for optimizing the utility of spectral efficiency of small cell users (SCUs). The considered constraints are the small cell base stations power budget and the condition for applying successive interference cancellation (SIC) on NOMA users. The proportional fairness utility is considered to guarantee fairness between SCUs of different channel conditions. We used the Kuhn-Munkres algorithm to optimize the spectrum allocation process with low complexity. The power allocation process for SCUs is solved through sequential convex programming (SCP) to maximize the spectrum efficiency utility of SCUs. The results show that the proposed algorithm based on the Kuhn-Munkres (CRA) algorithm for resource allocation outperforms the JSAPCA-1 algorithm in terms of the spectral efficiency achieved by SCUs beside achieving a comparable level of the interference experienced by MCUs.