Joint antenna and transmission design improves near-field multicast sensing and communication
Joint Antenna Geometry and Transmit Covariance Design for Near-Field Multicast ISAC with Pinching Antenna Arrays
Information Theory
Summary
Sending messages and sensing targets at the same time can be tricky, especially up close. This paper looks at a special antenna setup where many small antennas are arranged along waveguides that lose some signal strength. The researchers figured out how to place these antennas and control the transmitted signals to best sense the nearby targets while still sending messages to multiple users. They wrote mathematical formulas to measure how well this can be done and created an algorithm to find the best antenna positions and transmission settings that balance sensing accuracy and message delivery.
What this means in practice
- •For wireless network engineers: Design and optimize antenna arrays and signals for simultaneous message broadcasting and target sensing in close-range wireless networks.
- •For radar system integrators: Implement compact antenna arrays with waveguide architectures to improve joint communication and sensing capabilities in cluttered or indoor environments.
Authors
Hui Yang, Hao Feng, Ebrahim Bedeer, Ming Zeng, Mengyao Wang, Gaojian Huang, Mengyan Huang
Abstract
PASS provide a flexible waveguide-based architecture for reconfiguring wireless propagation environments and creating geometry-dependent radiating apertures. This paper investigates a near-field multicast ISAC system enabled by a lossy multi-waveguide PASS, where a base station transmits a common message to multiple communication users while simultaneously sensing one or multiple targets. The PA positions along the waveguides and the feed-domain transmit covariance matrix are jointly designed to improve sensing accuracy under multicast communication constraints. We first develop a near-field multicast ISAC signal model that accounts for waveguide attenuation, equal-radiated-power operation, geometry-dependent free-space propagation, and monostatic sensing. Then, we derive the FIM for target parameter estimation and obtain a compact projected-Jacobian representation by exploiting the block-diagonal PA transfer structure. This representation reveals how the PA geometry and transmit covariance jointly affect the CRB. Based on this structure, we further characterize the per-waveguide and cross-waveguide FIM contributions, the loss-aperture tradeoff, the identifiability condition, and the communication-sensing phase conflict. To minimize the CRB, we formulate a joint PA-position and transmit-covariance optimization problem subject to a multicast rate constraint, a feed-power budget, and PA deployment constraints. An alternating optimization algorithm is developed, where the covariance subproblem is solved as a semidefinite program and the PA-position subproblem is handled by waveguide-wise block coordinate descent.