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On the Performance of Uplink Pinching Antenna Systems (PASS)

Tianwei Hou, Yuanwei Liu, Arumugam Nallanathan

TL;DR

This work investigates uplink PASS in indoor LoS environments by deploying PAs along a ceiling-edge waveguide to enhance channel gains. It analyzes three deployment paradigms—MPSU, SPSU, and SPMU—deriving closed-form, analytical, and high-SNR ergodic-rate expressions, along with optimized PA positions (including NZ and FZ regimes) and, for SPMU, an optimized PA placement strategy for two-user cases. The results show that PASS can significantly outperform conventional networks, with gains scaling with the number of PAs in high-SNR regimes and notable improvements from optimized PA positioning; in particular, MPSU yields the largest ergodic-sum-rate gains and exhibits asymptotic antenna gains proportional to the number of PAs. These findings highlight the practical potential of reconfigurable PA-based Indoors wireless architectures for improved rate performance and energy efficiency, while also identifying trade-offs in PA hardware complexity and deployment geometry.

Abstract

Pinching antenna (PA) is a flexible antenna composed of a waveguide and multiple dielectric particles, which is capable of reconfiguring wireless channels intelligently in line-of-sight links. By leveraging the unique features of PAs, we exploit the uplink (UL) transmission in pinching antenna systems (PASS). To comprehensively evaluate the performance gains of PASS in UL transmissions, three scenarios, multiple PAs for a single user (MPSU), a single PA for a single user (SPSU), and a single PA for multiple users (SPMU) are considered. The positions of PAs are optimized to obtain the maximal channel gains in the considered scenarios. For the MPSU and SPSU scenarios, by applying the optimized position of PAs, closed-form expressions for analytical, asymptotic and approximated ergodic rate are derived. As the further advance, closed-form expressions of approximated ergodic rate is derived when a single PA is fixed in the SPMU scenario. Our results demonstrate the following key insights: i) The proposed PASS significantly outperforms conventional Multiple-input Single-output networks by exploiting the flexibility of PAs; ii) The PA distribution follows an asymmetric non-uniform distribution in the MPSU scenario; iii) Optimizing PA positions significantly enhances the ergodic sum rate performance.

On the Performance of Uplink Pinching Antenna Systems (PASS)

TL;DR

This work investigates uplink PASS in indoor LoS environments by deploying PAs along a ceiling-edge waveguide to enhance channel gains. It analyzes three deployment paradigms—MPSU, SPSU, and SPMU—deriving closed-form, analytical, and high-SNR ergodic-rate expressions, along with optimized PA positions (including NZ and FZ regimes) and, for SPMU, an optimized PA placement strategy for two-user cases. The results show that PASS can significantly outperform conventional networks, with gains scaling with the number of PAs in high-SNR regimes and notable improvements from optimized PA positioning; in particular, MPSU yields the largest ergodic-sum-rate gains and exhibits asymptotic antenna gains proportional to the number of PAs. These findings highlight the practical potential of reconfigurable PA-based Indoors wireless architectures for improved rate performance and energy efficiency, while also identifying trade-offs in PA hardware complexity and deployment geometry.

Abstract

Pinching antenna (PA) is a flexible antenna composed of a waveguide and multiple dielectric particles, which is capable of reconfiguring wireless channels intelligently in line-of-sight links. By leveraging the unique features of PAs, we exploit the uplink (UL) transmission in pinching antenna systems (PASS). To comprehensively evaluate the performance gains of PASS in UL transmissions, three scenarios, multiple PAs for a single user (MPSU), a single PA for a single user (SPSU), and a single PA for multiple users (SPMU) are considered. The positions of PAs are optimized to obtain the maximal channel gains in the considered scenarios. For the MPSU and SPSU scenarios, by applying the optimized position of PAs, closed-form expressions for analytical, asymptotic and approximated ergodic rate are derived. As the further advance, closed-form expressions of approximated ergodic rate is derived when a single PA is fixed in the SPMU scenario. Our results demonstrate the following key insights: i) The proposed PASS significantly outperforms conventional Multiple-input Single-output networks by exploiting the flexibility of PAs; ii) The PA distribution follows an asymmetric non-uniform distribution in the MPSU scenario; iii) Optimizing PA positions significantly enhances the ergodic sum rate performance.

Paper Structure

This paper contains 15 sections, 19 theorems, 71 equations, 10 figures.

Table of Contents

  1. Introduction
  2. Motivation and Contribution
  3. Organization and Notations
  4. System Model
  5. Antenna and Channel Model
  6. Signal Model
  7. Performance Analysis
  8. Using Multiple PAs for a Single User (MPSU)
  9. Using A Single PA for A Single User (SPSU)
  10. Using A Single PA for Multiple Users (SPMU)
  11. Optimized PA position for SPMU Scenario
  12. Numerical Results
  13. MPSU Scenario
  14. SPSU Scenario
  15. Conclusions

Key Result

Lemma 1

In the UL transmission, when multiple PAs are deployed for an individual user in the LoS channels, if ${d_0} > N \lambda$ holds, the optimized position of the $n$-th PA of the $i$-th user can be expressed as: where ${d_0} = \sqrt {y_{ui}^2 + {h^2}}$.

Figures (10)

  • Figure 1: Illustration of the PASS, where multiple users are randomly deployed in the indoor environments.
  • Figure 2: Top view of the asymmetric non-uniform PAs in the MPSU scenario.
  • Figure 3: Spacing of PAs in the MPSU scenario, where the analytical results are derived from \ref{['lemma_equ_massive_PAs_position_FA']}. The number of PAs is set to $N=10$.
  • Figure 4: Ergodic rate of the $i$-th user in the MPSU scenario, where the analytical results and asymptotic results are derived from \ref{['theorem new1_equ_massive_PAs']} and \ref{['corro2_new_MUSU_high-SNR_appro']}, respectively.
  • Figure 5: Ergodic rate of the $i$-th user in the MPSU scenario in both NZ and FZ cases. The number of PAs is set to $N=10$.
  • ...and 5 more figures

Theorems & Definitions (46)

  • Lemma 1
  • proof
  • Proposition 1
  • proof
  • Proposition 2
  • proof
  • Remark 1
  • Proposition 3
  • proof
  • Remark 2
  • ...and 36 more