Phase-Aware Localization in Pinching Antenna Systems: CRLB Analysis and ML Estimation
2026-02-24 • Information Theory
Information Theory
AI summaryⓘ
The authors study a new way to locate a device using special antennas called pinching antenna systems (PASS). Unlike past methods that only used signal strength, their approach also uses the signal's phase (timing) to improve accuracy. They create a mathematical model that includes how signals fade and change phase over distance and derive formulas to understand the best possible accuracy. They also design an algorithm that first roughly guesses and then fine-tunes the device's location, showing better results than before. This means their method can locate devices more precisely by using more information from the signals.
pinching antenna systemslocalizationamplitudephase informationcomplex baseband signalFisher information matrixCramer-Rao lower boundmaximum likelihood estimatorLevenberg-Marquardt algorithmposition error bound
Authors
Hao Feng, Ebrahim Bedeer, Ming Zeng, Xingwang Li, Shimin Gong, Quoc-Viet Pham
Abstract
Pinching antenna systems (PASS) have recently emerged as a promising architecture for high-frequency wireless communications. In this letter, we investigate localization in PASS by jointly exploiting the received signal amplitude and phase information, unlike recent works that consider only the amplitude information. A complex baseband signal model is formulated to capture free-space path loss, waveguide attenuation, and distance-dependent phase rotation between the user and each pinching antenna. Using this model, we derive the Fisher information matrix (FIM) with respect to the user location and obtain closed-form expressions for the Cramer-Rao lower bound (CRLB) and the position error bound (PEB). A maximum likelihood (ML) estimator that jointly considers the received signal amplitude and phase is developed to estimate the unknown user location. Given the non-convexity of the estimation problem, a two-stage solution combining coarse grid search and Levenberg-Marquardt refinement is proposed. Numerical results demonstrate that the proposed phase-aware estimator outperforms existing amplitude-only method in terms of positioning accuracy.