Stacked Intelligent Metasurfaces for Integrated Sensing and Communications

TL;DR

This paper proposes a SIM-aided system that jointly optimizes beamforming and power allocation to enhance integrated sensing and communication, demonstrating improved interference mitigation and target detection capabilities.

Contribution

It introduces a novel optimization framework for SIM-based integrated sensing and communications, including a gradient ascent algorithm for joint phase shift and power design.

Findings

Effective interference mitigation in multi-user scenarios

Enhanced beam pattern generation for sensing tasks

Significant spectrum efficiency gains

Abstract

Stacked intelligent metasurfaces (SIM) have recently emerged as a promising technology, which can realize transmit precoding in the wave domain. In this paper, we investigate a SIM-aided integrated sensing and communications system, in which SIM is capable of generating a desired beam pattern for simultaneously communicating with multiple downlink users and detecting a radar target. Specifically, we formulate an optimization problem of maximizing the spectrum efficiency, while satisfying the power constraint of the desired direction. This requires jointly designing the phase shifts of the SIM and the power allocation at the base station. By incorporating the sensing power constraint into the objective functions as a penalty term, we further simplify the optimization problem and solve it by customizing an efficient gradient ascent algorithm. Finally, extensive numerical results demonstrate the effectiveness of the proposed wave-domain precoder for automatically mitigating the inter-user interference and generating a desired beampattern for the sensing task, as multiple separate data streams transmit through the SIM.