Efficient Hybrid Beamforming with Anti-Blockage Design for High-Speed Railway Communications

TL;DR

This paper proposes an efficient hybrid beamforming approach with an anti-blockage scheme for high-speed railway mmWave communications, significantly improving data rates under blockage conditions.

Contribution

It introduces a two-stage hybrid beamforming algorithm and an adaptive anti-blockage scheme tailored for high-speed railway scenarios, addressing blockage challenges effectively.

Findings

Anti-blockage scheme improves effective rate by 20% in blocked scenarios.

Proposed algorithms maintain low outage probability.

Simulation results validate performance under various conditions.

Abstract

Future railway is expected to accommodate both train operation services and passenger broadband services. The millimeter wave (mmWave) communication is a promising technology in providing multi-gigabit data rates to onboard users. However, mmWave communications suffer from severe propagation attenuation and vulnerability to blockage, which can be very challenging in high-speed railway (HSR) scenarios. In this paper, we investigate efficient hybrid beamforming (HBF) design for train-to-ground communications. First, we develop a two-stage HBF algorithm in blockage-free scenarios. In the first stage, the minimum mean square error method is adopted for optimal hybrid beamformer design with low complexity and fast convergence; in the second stage, the orthogonal matching pursuit method is utilized to approximately recover the analog and digital beamformers. Second, in blocked scenarios, we design an anti-blockage scheme by adaptively invoking the proposed HBF algorithm, which can efficiently deal with random blockages. Extensive simulation results are presented to show the sum rate performance of the proposed algorithms under various configurations, including transmission power, velocity of the train, blockage probability, etc. It is demonstrated that the proposed anti-blockage algorithm can improve the effective rate by 20% in severely-blocked scenarios while maintaining low outage probability.