Hybrid Beamforming Design for RSMA-assisted mmWave Integrated Sensing and Communications

2024-06-07

arXiv.org

AI Summary

To address the limited degrees of freedom and exacerbated communication-radar interference in 6G mmWave integrated sensing and communication (ISAC) systems—caused by hardware constraints of hybrid beamforming (HBF)—this paper pioneers the integration of rate-splitting multiple access (RSMA) into mmWave ISAC HBF architectures, proposing a joint common-rate allocation and HBF design framework. Methodologically, we devise a convergent joint optimization algorithm that innovatively combines the penalty dual decomposition (PDD) method with weighted minimum mean square error (WMMSE), guaranteeing convergence to a Karush–Kuhn–Tucker (KKT) point. The algorithm is further extended to support finite-resolution phase shifters, balancing performance and energy efficiency. Simulation results demonstrate that the proposed RSMA-based scheme significantly outperforms conventional orthogonal/non-orthogonal multiple access (OMA/NOMA)-ISAC and RSMA-free baseline schemes in both aggregate communication rate and sensing signal-to-interference-plus-noise ratio (SINR).

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Machine Learning: Hardware-aware ML
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines
• Security and Privacy: Large-scale security measurements

Abstract

Integrated sensing and communications (ISAC) has been considered one of the new paradigms for sixth-generation (6G) wireless networks. In the millimeter-wave (mmWave) ISAC system, hybrid beamforming (HBF) is considered an emerging technology to exploit the limited number of radio frequency (RF) chains in order to reduce the system hardware cost and power consumption. However, the HBF structure reduces the spatial degrees of freedom for the ISAC system, which further leads to increased interference between multiple users and between users and radar sensing. To solve the above problem, rate split multiple access (RSMA), which is a flexible and robust interference management strategy, is considered. We investigate the joint common rate allocation and HBF design problem for the HBF-based RSMA-assisted mmWave ISAC scheme. We propose the penalty dual decomposition (PDD) method coupled with the weighted mean squared error (WMMSE) minimization method to solve this high-dimensional non-convex problem, which converges to the Karush-Kuhn-Tucker (KKT) point of the original problem. Then, we extend the proposed algorithm to the HBF design based on finite-resolution phase shifters (PSs) to further improve the energy efficiency of the system. Simulation results demonstrate the effectiveness of the proposed algorithm and show that the RSMA-ISAC scheme outperforms other benchmark schemes.

Problem

• Reducing hardware cost in mmWave ISAC systems with hybrid beamforming
• Mitigating interference among communication users and radar sensing
• Maximizing weighted sum rate through joint beamforming optimization

Innovation

• Rate-splitting multiple access strategy
• Hybrid beamforming with limited RF chains
• Penalty dual decomposition with WMMSE method