Joint User Association and Resource Optimization for Multi-Cell NOMA Networks

In multi-cell networks, resource management becomes exceedingly complex as network density rises. Therefore, it is necessary to devise effective and low-complexity algorithms for resource management in multi-cell networks. This paper investigated the joint optimization problem of user association and resource optimization to improve the sum rate in multi-cell non-orthogonal multiple access (NOMA) networks. The problem is decomposed into three sub-problems. To address the coupling problem between user association and channel allocation, an iterative based method is employed. Firstly, the user association problem is addressed by proposed sum rate maximization matching (SRMM) algorithm. Then, the channel allocation problem is resolved by developed hypergraph coloring (HC) algorithm. After achieving convergence by iteratively solving the coupling problems, the power allocation problem is converted into an easily solved convex problem. Numerical results clarify that the proposed algorithm presents superior performance compared to both orthogonal multiple access (OMA) algorithm and signal-to-interference-plus-noise ratio maximization user association (SINRM-VA) algorithm.