Joint Optimization for an Integrated Over-the-Air Computation and NOMA Communication System With MIMO Two-Way Relay Assistance

Integrated over-the-air computation (AirComp) and non-orthogonal multiple access (NOMA) systems can provide dual-functional services by sharing the same spectrum. This integration significantly enhances both spectrum efficiency and resource utilization within the system, which has recently attracted considerable attention. To further improve transmission reliability and expand the communication-computation performance region, we investigate a multi-input multi-output (MIMO) two-way relay (TWR) assisted integrated AirComp and NOMA system. With the aim of maximizing the sum achievable rate for all NOMA users while satisfying the AirComp requirement, we jointly optimize the transmit power factors, aggregation beamforming vector, and beamforming matrices at the access point (AP) and TWR. The formulated problem is highly nonconvex and challenging to solve due to the coupled variables. Therefore, we propose an inexact block coordinate descent method based path-following (IBCD-PF) algorithm, which can address the intractable problem effectively. Numerical results demonstrate that our proposed scheme can achieve superior performance compared to the benchmarks.