User-Centric Multi-Dimensional Multiple Access in 6G Communications

The ever-increasing service heterogeneity and Quality-of-Service diversity call for multi-dimensional radio resource exploitation and utilization schemes in future 6-th generation (6G) wireless. To this end, we design a user-centric QoS provisioning framework assisted with multi-dimensional multiple access (MDMA) scheme, where two conflicting goals, i.e. user’s QoS preference and their utilization costs of multi-dimensional resources, are considered with different user-specific priority levels in the utility function for each user. To implement the user-centric MDMA with QoS fairness, the related problem is formulated as a Max-Min optimization. Due to the NP-hardness of the formulated problem, we first use bisection searching to examine the feasible solution set. Then, the tested feasible set is solved by addressing two sub-problems: user-subchannel mapping and power allocation, which are solved by matching theory and heuristic gradient descent algorithm. Simulation results verify the effectiveness of the proposed design that can significantly outperform the state-of-art scheme.