Backscatter-Assisted High-Speed Rail Communications in Straight Tunnel Environments: Effects of Tag Number and Phase Control

TL;DR

This paper analyzes how the number of tags and phase control affect backscatter communication performance in tunnels, providing mathematical models and simulation results to guide system design.

Contribution

It introduces a detailed analysis of channel gain improvements with phase-adjustable tags and identifies optimal tag deployment strategies in tunnel environments.

Findings

Phase-adjustable tags significantly enhance channel gain.

An upper threshold exists for the number of effective tags.

Derived tractable expressions for link gain probabilities.

Abstract

Backscatter communication is a promising technology to enhance the signal strength received by the receiver in straight tunnel environments. The impact of the number of tags and their phase adjustment on system performance remains a challenging issue though. Therefore, in this paper, we investigate the channel gain of backscatter-assisted communication with multiple tags in straight tunnels. In particular, we derive the probabilities that the backscatter link gain is greater than the direct link under adjustable and random phase assumptions by applying the Gaussian and Gamma approximations to derive tractable expressions. The simulation results show that phaseadjustable tags significantly improve the channel gain of the backscatter links compared to the random phase case. Moreover, the number of tags has an upper threshold for an effective tag deployment pattern. These insights provide valuable guidelines for the efficient design of backscatter communication systems in tunnel environments.