Near-Field Integrated Sensing, Positioning, and Communication: A Downlink and Uplink Framework

• Published in: IEEE journal on selected areas in communications Vol. 42; no. 9; pp. 2196 - 2212
• Main Authors: Li, Haochen, Wang, Zhaolin, Mu, Xidong, Zhiwen, Pan, Liu, Yuanwei
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Communication; Communications systems; Convexity; Cramer-Rao bounds; Cramér-Rao bound; Design optimization; Downlink; Downlinking; Minimization; Near field communication; Near fields; near-field communications; Optimization; Precoding; Radio frequency; sensing and positioning; Transmission line matrix methods; Uplink; Uplinking
• ISSN: 0733-8716; 1558-0008
• DOI: 10.1109/JSAC.2024.3413956

A near-field integrated sensing, positioning, and communication (ISPAC) framework is proposed, where a base station (BS) simultaneously serves multiple communication users and carries out target sensing and positioning. A novel double-array structure is proposed to enable the near-field ISPAC at the BS. Specifically, a small-scale assisting transceiver (AT) is attached to the large-scale main transceiver (MT) to empower the communication system with the ability of sensing and positioning. Based on the proposed framework, the joint angle and distance Cramér-Rao bound (CRB) is first derived. Then, the CRB is minimized subject to the minimum communication rate requirement in both downlink and uplink ISPAC scenarios: 1) For downlink ISPAC, a downlink target positioning algorithm is proposed and a penalty dual decomposition (PDD)-based double-loop algorithm is developed to tackle the non-convex optimization problem. 2) For uplink ISPAC, an uplink target positioning algorithm is proposed and an efficient alternating optimization algorithm is conceived to solve the non-convex CRB minimization problem with coupled user communication and target probing design. Both proposed optimization algorithms can converge to a stationary point of the CRB minimization problem. Numerical results show that: 1) The proposed ISPAC system can locate the target in both angle and distance domains merely relying on single BS and limited bandwidths; and 2) the positioning performance achieved by the hybrid-analog-and-digital ISPAC approaches that achieved by fully digital ISPAC when the communication rate requirement is not stringent.