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Phase-Aware Localization in Pinching Antenna Systems: CRLB Analysis and ML Estimation

Hao Feng, Ebrahim Bedeer, Ming Zeng, Xingwang Li, Shimin Gong, Quoc-Viet Pham

TL;DR

This letter investigates localization in pinching antenna systems by jointly exploiting the received signal amplitude and phase information, unlike recent works that consider only the amplitude information.

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.

Phase-Aware Localization in Pinching Antenna Systems: CRLB Analysis and ML Estimation

TL;DR

This letter investigates localization in pinching antenna systems by jointly exploiting the received signal amplitude and phase information, unlike recent works that consider only the amplitude information.

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.
Paper Structure (6 sections, 2 equations, 2 figures)

This paper contains 6 sections, 2 equations, 2 figures.

Table of Contents

  1. Introduction
  2. System Model
  3. CRLB Derivation and Analysis
  4. Maximum Likelihood Estimation of the User Location
  5. Numerical Results
  6. Conclusion

Figures (2)

  • Figure 1: Position error versus noise power under different number of PAs.
  • Figure 2: Position error map (m) for: a) PEB; b) Proposed solution and c) Benchmark from zhang2025. Here $N=8$ and the noise power is $-40$ dBm. Each point is obtained by averaging over 100 random trials for b) and c).