Resource Allocation and Performance Analysis of Hybrid RSMA-NOMA in the Downlink

TL;DR

This paper explores a hybrid RSMA-NOMA system, optimizing resource allocation to enhance sum-rate and fairness, and analyzing the trade-offs involved in combining these multiple access techniques.

Contribution

It introduces a joint optimization framework for power and rate allocation in hybrid RSMA-NOMA, demonstrating its benefits over traditional methods.

Findings

Hybrid RSMA-NOMA improves system sum-rate and fairness.

The proposed optimization ensures convergence and feasible solutions.

Numerical results highlight trade-offs between sum-rate, fairness, and complexity.

Abstract

Rate splitting multiple access (RSMA) and non-orthogonal multiple access (NOMA) are the key enabling multiple access techniques to enable massive connectivity. However, it is unclear whether RSMA would consistently outperform NOMA from a system sum-rate perspective, users' fairness, as well as convergence and feasibility of the resource allocation solutions. This paper investigates the weighted sum-rate maximization problem to optimize power and rate allocations in a hybrid RSMA-NOMA network. In the hybrid RSMA-NOMA, by optimally allocating the maximum power budget to each scheme, the BS operates on NOMA and RSMA in two orthogonal channels, allowing users to simultaneously receive signals on both RSMA and NOMA. Based on the successive convex approximation (SCA) approach, we jointly optimize the power allocation of users in NOMA and RSMA, the rate allocation of users in RSMA, and the power budget allocation for NOMA and RSMA considering successive interference cancellation (SIC) constraints. Numerical results demonstrate the trade-offs that hybrid RSMA-NOMA access offers in terms of system sum rate, fairness, convergence, and feasibility of the solutions.