Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Multi-Antenna Broadband Backscatter Communications

Hao Chen, Zhizhi Huang, Ying-Chang Liang, Robert Schober

TL;DR

This paper proposes a bistatic broadband backscatter system (BBBC) that equips a multi-antenna backscatter device with cyclic delay diversity to combat frequency-selective fading in the backscattered link. A low-complexity receiver combines time-domain preprocessing, pilot-based channel estimation, and frequency-domain equalization to reliably recover backscattered data, and diversity is analyzed via the matched-filter bound under general Rayleigh fading and special LoS-forward-link conditions. The key contributions include the single-carrier block transmission with zero-padding, an overlap-add-based circulant-channel construction, LS channel estimation with two pilots, and a detailed outage-diversity analysis showing that increasing BD antennas yields both array and spatial diversity gains, particularly in LoS-forward-link scenarios. Simulations confirm significant reduction in outage probability and BER with more BD antennas and demonstrate superiority over conventional backscatter schemes, suggesting BBBC as a strong candidate for high-rate, long-range backscatter communications in IoT contexts.

Abstract

Backscatter communication offers a promising solution to connect massive Internet-of-Things (IoT) devices with low cost and high energy efficiency. Nevertheless, its inherently passive nature limits transmission reliability, thereby hindering improvements in communication range and data rate. To overcome these challenges, we introduce a bistatic broadband backscatter communication (BBBC) system, which equips the backscatter device (BD) with multiple antennas. In the proposed BBBC system, a radio frequency (RF) source directs a sinusoidal signal to the BD, facilitating single-carrier block transmission at the BD. Meanwhile, without requiring channel state information (CSI), cyclic delay diversity (CDD) is employed at the multi-antenna BD to enhance transmission reliability through additional cyclically delayed backscattered signals. We also propose a receiver design that includes preprocessing of the time-domain received signal, pilot-based parameter estimation, and frequency-domain equalization, enabling low-complexity detection of the backscattered signal. Leveraging the matched filter bound (MFB), we analyze the achievable diversity gains in terms of outage probability. Our analysis reveals that spatial diversity is achievable under general Rayleigh fading conditions, and both frequency and spatial diversity are attainable in scenarios where the forward link experiences a line-of-sight (LoS) channel. Simulation results validate the effectiveness of the proposed BBBC system. As the number of BD antennas increases, our results show that the proposed scheme not only enhances array gain but also improves diversity order, significantly reducing both outage probability and bit error rate (BER). Consequently, it outperforms conventional schemes that yield only minor gains.

Multi-Antenna Broadband Backscatter Communications

TL;DR

This paper proposes a bistatic broadband backscatter system (BBBC) that equips a multi-antenna backscatter device with cyclic delay diversity to combat frequency-selective fading in the backscattered link. A low-complexity receiver combines time-domain preprocessing, pilot-based channel estimation, and frequency-domain equalization to reliably recover backscattered data, and diversity is analyzed via the matched-filter bound under general Rayleigh fading and special LoS-forward-link conditions. The key contributions include the single-carrier block transmission with zero-padding, an overlap-add-based circulant-channel construction, LS channel estimation with two pilots, and a detailed outage-diversity analysis showing that increasing BD antennas yields both array and spatial diversity gains, particularly in LoS-forward-link scenarios. Simulations confirm significant reduction in outage probability and BER with more BD antennas and demonstrate superiority over conventional backscatter schemes, suggesting BBBC as a strong candidate for high-rate, long-range backscatter communications in IoT contexts.

Abstract

Backscatter communication offers a promising solution to connect massive Internet-of-Things (IoT) devices with low cost and high energy efficiency. Nevertheless, its inherently passive nature limits transmission reliability, thereby hindering improvements in communication range and data rate. To overcome these challenges, we introduce a bistatic broadband backscatter communication (BBBC) system, which equips the backscatter device (BD) with multiple antennas. In the proposed BBBC system, a radio frequency (RF) source directs a sinusoidal signal to the BD, facilitating single-carrier block transmission at the BD. Meanwhile, without requiring channel state information (CSI), cyclic delay diversity (CDD) is employed at the multi-antenna BD to enhance transmission reliability through additional cyclically delayed backscattered signals. We also propose a receiver design that includes preprocessing of the time-domain received signal, pilot-based parameter estimation, and frequency-domain equalization, enabling low-complexity detection of the backscattered signal. Leveraging the matched filter bound (MFB), we analyze the achievable diversity gains in terms of outage probability. Our analysis reveals that spatial diversity is achievable under general Rayleigh fading conditions, and both frequency and spatial diversity are attainable in scenarios where the forward link experiences a line-of-sight (LoS) channel. Simulation results validate the effectiveness of the proposed BBBC system. As the number of BD antennas increases, our results show that the proposed scheme not only enhances array gain but also improves diversity order, significantly reducing both outage probability and bit error rate (BER). Consequently, it outperforms conventional schemes that yield only minor gains.
Paper Structure (13 sections, 1 theorem, 41 equations, 10 figures, 1 table)

This paper contains 13 sections, 1 theorem, 41 equations, 10 figures, 1 table.

Table of Contents

  1. Introduction
  2. System Model
  3. Receiver Design for BBBC
  4. Preprocessing of Received Signal
  5. Pilot-Based Channel Estimation and Refined Interference Suppression
  6. Frequency-Domain Equalization
  7. Diversity Analysis of BBBC
  8. General Channel Conditions
  9. Single-Antenna Case
  10. Multi-Antenna Case
  11. Special Channel Conditions
  12. Simulation Results
  13. Conclusion

Key Result

Lemma 1

Considering the generalized-$K$ fading channel characterized by its parameters $k$, $m$, and $\Omega$, the diversity order of the BBBC system is equal to parameter $m$.

Figures (10)

  • Figure 1: Model of the BBBC system.
  • Figure 2: Block diagram of the information modulator at the BD.
  • Figure 3: Block diagram of the receiver design at the reader.
  • Figure 4: Channel matrix before and after overlap-add.
  • Figure 5: BER versus average SNR for perfect and estimated CSI.
  • ...and 5 more figures

Theorems & Definitions (2)

  • Remark 1
  • Lemma 1