Movable Antenna Empowered Downlink NOMA Systems: Power Allocation and Antenna Position Optimization

TL;DR

The paper studies movable antennas (MAs) integrated into a downlink MISO-NOMA system to enhance spectral efficiency by jointly optimizing the power allocation coefficient $\\alpha_s$ and MA positions $\\mathbf{r}_i$. It proposes an alternating-optimization framework with successive convex approximation to handle the resulting non-convex problem, yielding a stationary solution. Simulations show that MA-enabled NOMA significantly outperforms OMA and conventional NOMA in average sum rate and outage probability across region sizes and power regimes. This work highlights the potential of MA to exploit spatial degrees of freedom in NOMA and motivates future research on fairness and multi-user MA-NOMA designs.

Abstract

This paper investigates a novel communication paradigm employing movable antennas (MAs) within a multiple-input single-output (MISO) non-orthogonal multiple access (NOMA) downlink framework, where users are equipped with MAs. Initially, leveraging the far-field response, we delineate the channel characteristics concerning both the power allocation coefficient and positions of MAs. Subsequently, we endeavor to maximize the channel capacity by jointly optimizing power allocation and antenna positions. To tackle the resultant non-convex problem, we propose an alternating optimization (AO) scheme underpinned by successive convex approximation (SCA) to converge towards a stationary point. Through numerical simulations, our findings substantiate the superiority of the MA-assisted NOMA system over both orthogonal multiple access (OMA) and conventional NOMA configurations in terms of average sum rate and outage probability.

Figures (4)

• Figure 1: MA-assisted NOMA downlink communication system.
• Figure 2: Average sum rate versus normalized region size.
• Figure 3: Average sum rate versus transmit power.
• Figure 4: Outage probability versus transmit power.