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Terahertz User-Centric Clustering in the Presence of Beam Misalignment

Khaled Humadi, Imene Trigui, Wei-Ping Zhu, Wessam Ajib

TL;DR

This work tackles the reliability challenges of terahertz networks caused by beam misalignment by introducing adaptive user-centric BS clustering with joint transmission to enable macro-diversity. The authors develop a stochastic-geometry framework and use a central limit theorem-based approximation to characterize the aggregate interference, capturing THz-specific propagation and beam-alignment effects. The principal contributions include a Lambert W-based adaptive cluster radius, a tractable CLT-based coverage expression, and design insights on cluster size and beamwidth that enhance THz coverage under misalignment. The results demonstrate that user-centric cooperation can significantly improve THz system reliability, providing practical guidance for deploying high-rate THz networks in the presence of beam misalignment.

Abstract

Beam misalignment is one of the main challenges for the design of reliable wireless systems in terahertz (THz) bands. This paper investigates how to apply user-centric base station (BS) clustering as a valuable add-on in THz networks. In particular, to reduce the impact of beam misalignment, a user-centric BS clustering design that provides multi-connectivity via BS cooperation is investigated. The coverage probability is derived by leveraging an accurate approximation of the aggregate interference distribution that captures the effect of beam misalignment and THz fading. The numerical results reveal the impact of beam misalignment with respect to crucial link parameters, such as the transmitter's beam width and the serving cluster size, demonstrating that user-centric BS clustering is a promising enabler of THz networks.

Terahertz User-Centric Clustering in the Presence of Beam Misalignment

TL;DR

This work tackles the reliability challenges of terahertz networks caused by beam misalignment by introducing adaptive user-centric BS clustering with joint transmission to enable macro-diversity. The authors develop a stochastic-geometry framework and use a central limit theorem-based approximation to characterize the aggregate interference, capturing THz-specific propagation and beam-alignment effects. The principal contributions include a Lambert W-based adaptive cluster radius, a tractable CLT-based coverage expression, and design insights on cluster size and beamwidth that enhance THz coverage under misalignment. The results demonstrate that user-centric cooperation can significantly improve THz system reliability, providing practical guidance for deploying high-rate THz networks in the presence of beam misalignment.

Abstract

Beam misalignment is one of the main challenges for the design of reliable wireless systems in terahertz (THz) bands. This paper investigates how to apply user-centric base station (BS) clustering as a valuable add-on in THz networks. In particular, to reduce the impact of beam misalignment, a user-centric BS clustering design that provides multi-connectivity via BS cooperation is investigated. The coverage probability is derived by leveraging an accurate approximation of the aggregate interference distribution that captures the effect of beam misalignment and THz fading. The numerical results reveal the impact of beam misalignment with respect to crucial link parameters, such as the transmitter's beam width and the serving cluster size, demonstrating that user-centric BS clustering is a promising enabler of THz networks.
Paper Structure (12 sections, 25 equations, 4 figures)

This paper contains 12 sections, 25 equations, 4 figures.

Table of Contents

  1. Introduction
  2. System Model
  3. Network Model
  4. Beam Alignment Models
  5. Propagation Model
  6. BS Clustering Model
  7. User-Centric Coverage Analysis
  8. Received SINR
  9. Coverage Probability
  10. Numerical Results
  11. Conclusion
  12. Appendix

Figures (4)

  • Figure 1: Coverage probability versus the SINR threshold $\gamma$ for different values of the clustering parameter with $\sigma_b=\sigma_u=10^\circ$
  • Figure 2: Coverage probability versus BS antenna beamwidth $\theta_b$ for different values of the standard deviation of the alignment error in BSs, $\sigma_b$, with $\sigma_u=10^\circ$.
  • Figure 3: Coverage probability versus standard deviation of the alignment error in BSs, $\sigma_b$, for different values of the clustering parameter with $\sigma_u=10^\circ$.
  • Figure 4: Coverage probability versus BS density $\lambda_b$ for different BS antenna array configurations with $\delta=0.6$$\sigma_b=\sigma_u=5^\circ$, $N_u=8$.