Rate-Splitting Multiple Access Scheme Based on Frequency Diverse Array

A rate-splitting multiple access (RSMA) scheme based on frequency diverse array (FDA) is proposed in this letter. With the fixed frequency offsets, the proposed scheme adopts the 1-layer rate-splitting (RS) strategy to cancel the intra-group interference when multiple users exist within a user group. Based on the proposed scheme, a max-min fairness optimization problem (OP) is formulated to maximize the minimum achievable rate among users, where the user grouping, digital precoding matrix, and RS vector are jointly optimized. A suboptimal two-step algorithm is proposed to solve the above OP. First, a K-means-based user grouping method is designed by using the location information of each user. Second, given the user grouping result, the OP is reformulated and solved by the semidefinite relaxation method. Simulation results illustrate that the designed user grouping method is effective in the FDA-based wireless communication system, and RSMA can better cancel interference than space division multiple access and non-orthogonal multiple access.