Alocação adaptativa de potência entre fluxos de mensagens privadas e comum em sistemas RSMA multiportadoras

Abstract

The Rate-Splitting Multiple Access (RSMA) technique has emerged as a promising technology for future generations of mobile networks. RSMA is based on the principle of dividing a user’s message into private parts, intended for specific users, and a common part, decoded by all users, allowing for more efficient interference management. This flexibility makes RSMA capable of handling multiple users and increased interference, offering a robust solution for the challenging scenarios of modern mobile networks. This work considers a Multiple-Input Single-Output (MISO) scenario based on multicarrier RSMA where two users are multiplexed per subcarrier. We study the weighted sum rate maximization problem, where user matching, subcarrier assignment, power allocation among subcarriers, and power allocation among streams should be defined. Given the complexity of the full formulated problem, a three-step algorithm is applied where user matching and subcarrier assignment, power allocation among subcarriers, and power allocation among private and common streams are solved in steps 1, 2, and 3, respectively. State-of-the-art solutions are applied for steps 1 and 2, and a new closed-form solution is provided in the context of weighted sum rate maximization for step 3. According to the simulation results, the proposed solution enables significantly higher data rates when compared with several benchmarks. Additionally, we analytically show how RSMA unifies, outperforms, and specializes in Spatial Division Multiple Access (SDMA), Orthogonal Multiple Access (OMA), Non-Orthogonal Multiple Access (NOMA), and multicasting in a multicarrier context as a function of the user weights and Signal-to-Noise Ratio (SNR) conditions. From a system design perspective, we highlight the relevance of adaptive power allocation among streams over adaptive power allocation among subcarriers.