Cost-Aware Resource Allocation for Hybrid Multiple Access in Cell-Free MIMO System

In this letter, we investigate the resource allocation problem for multiple access in the cell-free multiple-input multiple-output (CF MIMO) system. To fully utilize multi-dimensional resources and meet the diverse demands of users, we extend the hybrid multiple access technology into the CF MIMO system based on its user-centric architecture, which unifies space division multiple access, non-orthogonal multiple access and orthogonal multiple access. Considering distinct expenses of different multiple access modes at receivers, we design a cost-aware utility function as the metric and develop a cost-aware utilization maximization optimization problem. To address this non-convex combinatorial optimization problem, an iterative resource allocation algorithm is proposed. This algorithm consists of a subchannel allocation algorithm based on matching theory and a power allocation algorithm based on Lagrange dual method. Simulation results validate the superiority of proposed scheme over fixed multiple access schemes.