Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Fluid-Antenna-Enabled Integrated Bistatic Sensing and Backscatter Communication Systems

A. Abdelaziz Salem, Saeed Abdallah, Khawla Alnajjar, Mahmoud A. Albreem, Mohamed Saad, Hayssam Dahrouj, Hesham Elsawy

TL;DR

The paper tackles joint downlink communication, passive tag backscatter with energy harvesting, and bistatic sensing in a fluid-antenna-enabled ISABC network. It proposes an alternating-optimization framework that jointly optimizes BS transmit beamformers, sensing covariance, reader receive beams, tag reflection coefficients, and fluid-antenna positions, using SDR, MM, and SCA techniques to handle nonconvexities. The results show substantial transmit-power savings compared with fixed-position antennas and ZF baselines, and demonstrate convergence and scalability as the network grows in antennas, users, tags, and targets. This work demonstrates that fluid antennas can provide valuable spatial DoFs to balance multi-service demands in integrated sensing, backscatter, and communication systems, enabling energy-efficient IoT networks with environmental awareness.

Abstract

This paper studies a fluid-antenna-enabled integrated bistatic sensing and backscatter communication system for future networks where connectivity, power delivery, and environmental awareness are jointly supported by the same infrastructure. A multi-antenna base station (BS) with transmitting fluid antennas serves downlink users, energizes passive tags, and illuminates radar targets, while a spatially separated multi-antenna reader decodes tag backscatter and processes radar echoes to avoid the strong self-interference that would otherwise obscure weak returns at the BS. The coexistence of tags and targets, however, induces severe near--far disparities and multi-signal interference, which can be mitigated by fluid antennas through additional spatial degrees of freedom that reshape the multi-hop channels. We formulate a transmit-power minimization problem that jointly optimizes the BS information beamformers, sensing covariance matrix, reader receive beamformers, tag reflection coefficients, and fluid-antenna (FA) positions under heterogeneous quality of service constraints for communication, backscatter, and sensing, as well as energy-harvesting and FA geometry requirements. To tackle the resulting non-convex problem, we develop an alternating-optimization block-coordinate framework that solves four tractable subproblems using semidefinite relaxation, majorization--minimization, and successive convex approximation. Numerical results show consistent transmit-power savings over fixed-position antennas and zero-forcing baselines, achieving about 13.7% and 54.5% reductions, respectively.

Fluid-Antenna-Enabled Integrated Bistatic Sensing and Backscatter Communication Systems

TL;DR

The paper tackles joint downlink communication, passive tag backscatter with energy harvesting, and bistatic sensing in a fluid-antenna-enabled ISABC network. It proposes an alternating-optimization framework that jointly optimizes BS transmit beamformers, sensing covariance, reader receive beams, tag reflection coefficients, and fluid-antenna positions, using SDR, MM, and SCA techniques to handle nonconvexities. The results show substantial transmit-power savings compared with fixed-position antennas and ZF baselines, and demonstrate convergence and scalability as the network grows in antennas, users, tags, and targets. This work demonstrates that fluid antennas can provide valuable spatial DoFs to balance multi-service demands in integrated sensing, backscatter, and communication systems, enabling energy-efficient IoT networks with environmental awareness.

Abstract

This paper studies a fluid-antenna-enabled integrated bistatic sensing and backscatter communication system for future networks where connectivity, power delivery, and environmental awareness are jointly supported by the same infrastructure. A multi-antenna base station (BS) with transmitting fluid antennas serves downlink users, energizes passive tags, and illuminates radar targets, while a spatially separated multi-antenna reader decodes tag backscatter and processes radar echoes to avoid the strong self-interference that would otherwise obscure weak returns at the BS. The coexistence of tags and targets, however, induces severe near--far disparities and multi-signal interference, which can be mitigated by fluid antennas through additional spatial degrees of freedom that reshape the multi-hop channels. We formulate a transmit-power minimization problem that jointly optimizes the BS information beamformers, sensing covariance matrix, reader receive beamformers, tag reflection coefficients, and fluid-antenna (FA) positions under heterogeneous quality of service constraints for communication, backscatter, and sensing, as well as energy-harvesting and FA geometry requirements. To tackle the resulting non-convex problem, we develop an alternating-optimization block-coordinate framework that solves four tractable subproblems using semidefinite relaxation, majorization--minimization, and successive convex approximation. Numerical results show consistent transmit-power savings over fixed-position antennas and zero-forcing baselines, achieving about 13.7% and 54.5% reductions, respectively.
Paper Structure (15 sections, 1 theorem, 51 equations, 9 figures, 1 table)

This paper contains 15 sections, 1 theorem, 51 equations, 9 figures, 1 table.

Table of Contents

  1. Introduction
  2. Related works
  3. Contribution and paper organization
  4. System model
  5. Communication, BComs, and sensing models
  6. Energy harvesting model
  7. Problem formulation and proposed solution
  8. Optimizing the transmit beamformers and the sensing covariance
  9. Optimizing the reflection coefficients for the tags
  10. Optimizing the receive beamformers at the reader
  11. Optimizing the transmit antenna position at the BS
  12. Simulation Results and Discussion
  13. Conclusion
  14. Lower-bounding the intended communication signal (\ref{['FA_comm_useful_LB']})
  15. Communication interference terms (\ref{['FA_UB_comm_interf']})

Key Result

Lemma 1

The intended communication signal ${{\mathcal{S}}_{k}}$ can be lower-bounded as a quadratic expression of $\mathbf{z}$ as follows.

Figures (9)

  • Figure 1: FA-enabled bistatic ISABC system.
  • Figure 2: Transmit power versus the number of BS antennas, $M$.
  • Figure 3: Total transmit power versus $\Gamma_k^{\mathrm{th}}$.
  • Figure 4: Impact of increasing the number of users on the total transmit power.
  • Figure 5: Total sensing rate versus $\Gamma_{R,q}^{\mathrm{sens, th}}$.
  • ...and 4 more figures

Theorems & Definitions (2)

  • Lemma 1
  • proof