CRB Minimization for RIS-aided mmWave Integrated Sensing and Communications

Fuente: arXiv
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Auteurs principaux: Lyu, Wanting, Yang, Songjie, Xiu, Yue, Li, Ya, He, Hongjun, Yuen, Chau, Zhang, Zhongpei
Format: Preprint
Publié: 2024
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author Lyu, Wanting
Yang, Songjie
Xiu, Yue
Li, Ya
He, Hongjun
Yuen, Chau
Zhang, Zhongpei
author_facet Lyu, Wanting
Yang, Songjie
Xiu, Yue
Li, Ya
He, Hongjun
Yuen, Chau
Zhang, Zhongpei
contents In this paper, reconfigurable intelligent surface (RIS) is employed in a millimeter wave (mmWave) integrated sensing and communications (ISAC) system. To alleviate the multi-hop attenuation, the semi-self sensing RIS approach is adopted, wherein sensors are configured at the RIS to receive the radar echo signal. Focusing on the estimation accuracy, the Cramer-Rao bound (CRB) for estimating the direction-of-the-angles is derived as the metric for sensing performance. A joint optimization problem on hybrid beamforming and RIS phaseshifts is proposed to minimize the CRB, while maintaining satisfactory communication performance evaluated by the achievable data rate. The CRB minimization problem is first transformed as a more tractable form based on Fisher information matrix (FIM). To solve the complex non-convex problem, a double layer loop algorithm is proposed based on penalty concave-convex procedure (penalty-CCCP) and block coordinate descent (BCD) method with two sub-problems. Successive convex approximation (SCA) algorithm and second order cone (SOC) constraints are employed to tackle the non-convexity in the hybrid beamforming optimization. To optimize the unit modulus constrained analog beamforming and phase shifts, manifold optimization (MO) is adopted. Finally, the numerical results verify the effectiveness of the proposed CRB minimization algorithm, and show the performance improvement compared with other baselines. Additionally, the proposed hybrid beamforming algorithm can achieve approximately 96% of the sensing performance exhibited by the full digital approach within only a limited number of radio frequency (RF) chains.
format Preprint
id arxiv_https___arxiv_org_abs_2401_01113
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle CRB Minimization for RIS-aided mmWave Integrated Sensing and Communications
Lyu, Wanting
Yang, Songjie
Xiu, Yue
Li, Ya
He, Hongjun
Yuen, Chau
Zhang, Zhongpei
Signal Processing
In this paper, reconfigurable intelligent surface (RIS) is employed in a millimeter wave (mmWave) integrated sensing and communications (ISAC) system. To alleviate the multi-hop attenuation, the semi-self sensing RIS approach is adopted, wherein sensors are configured at the RIS to receive the radar echo signal. Focusing on the estimation accuracy, the Cramer-Rao bound (CRB) for estimating the direction-of-the-angles is derived as the metric for sensing performance. A joint optimization problem on hybrid beamforming and RIS phaseshifts is proposed to minimize the CRB, while maintaining satisfactory communication performance evaluated by the achievable data rate. The CRB minimization problem is first transformed as a more tractable form based on Fisher information matrix (FIM). To solve the complex non-convex problem, a double layer loop algorithm is proposed based on penalty concave-convex procedure (penalty-CCCP) and block coordinate descent (BCD) method with two sub-problems. Successive convex approximation (SCA) algorithm and second order cone (SOC) constraints are employed to tackle the non-convexity in the hybrid beamforming optimization. To optimize the unit modulus constrained analog beamforming and phase shifts, manifold optimization (MO) is adopted. Finally, the numerical results verify the effectiveness of the proposed CRB minimization algorithm, and show the performance improvement compared with other baselines. Additionally, the proposed hybrid beamforming algorithm can achieve approximately 96% of the sensing performance exhibited by the full digital approach within only a limited number of radio frequency (RF) chains.
title CRB Minimization for RIS-aided mmWave Integrated Sensing and Communications
topic Signal Processing
url https://arxiv.org/abs/2401.01113