Resource allocation for mixed numerology NOMA

6G wireless networks will require the flexibility to accommodate an extremely diverse set of service types. Accommodating different quality of service (QoS) requirements for these service types necessitates the use of mixed numerologies, where services using different subcarrier spacings or symbol durations coexist in the same frequency band. Non-orthogonal multiple access (NOMA) techniques can potentially be used to accommodate users with different numerologies while also gaining the performance benefits associated with NOMA. To achieve the full performance benefits of a mixed numerology NOMA (MN-NOMA) system, resource allocation is paramount. However, the coexistence of mixed numerologies changes the nature of the interference that each user experiences. In this letter, we approach the problem of optimizing subcarrier and power allocation for maximizing the spectral efficiency of MN-NOMA. In particular, we propose a two-stage sub-optimal approach to solve this problem. Numerical results show that the proposed approach provides performance gains over existing benchmark schemes of up to 14% and 12% in spectral efficiency and fairness, respectively