Higher frequency band beamforming scheme for high speed train

Abstract

With the increasing popularity of high speed trains (HSTs) and the traffic forecast for future cellular networks, the need to provide very high data rates using higher frequency bands (HFBs) for train passengers is becoming crucial. In this paper, we present a timer-based beamforming selection algorithm for HST, which exploits the prior knowledge of the position and direction of the HST. A sequential and hierarchical codebook is designed based on the array response vectors and linked to the line-of-sight (LOS) angle-of-arrival/departure base station (BS)-HST link. The effect of velocity feedback errors on the throughput performance was analyzed. The antenna deactivation and the sub-array approaches were considered to mitigate the effect of velocity feedback errors. Evaluation of our proposed beamforming scheme indicates a close performance to the optimal singular value decomposition (SVD) scheme when no velocity feedback error occurs and with the occurrence of velocity feedback errors, the sub-array approach proved to be an efficient way to reduce the effect of the errors.

A Fast Hybrid Beamforming Scheme for High-Speed Railway Communications

“…As can be observed from the figure, the proposed F-HBF scheme performs very close to the full digital beamforming. The HBF algorithm in [8,13,18] performance close to full digital beamforming and proposed algorithm at low SNRs, while the HBF algorithm in [8,13] has almost 5 dB gap compared with the full DBF when SNR increases. The algorithm in [13] only have ABF part, so we complement the DBF part.…”

“…Moreover, when ∆ t growths from 2 ms to 80 ms, the OPs do not increase very much at the same time point, i.e., OPs increase from 0.3 to 0.4 at 0.8 s. However, for ∆ t = 200 ms, the OP increase to 0.52 at 0.8 s. Consequently, even though the shorter the time interval can achieve better OP, it also brings higher beam-searching cost. Figure 5 shows the comparison of the proposed scheme with full digital beamforming and algorithms in [8,13,18] in terms of SE. The solid, star, rhombus, triangle, and square lines indicate the performances of full digital beamforming, the proposed F-HBF scheme, the compared HBF algorithms in [8,13,18], respectively.…”

“…Figure 5 shows the comparison of the proposed scheme with full digital beamforming and algorithms in [8,13,18] in terms of SE. The solid, star, rhombus, triangle, and square lines indicate the performances of full digital beamforming, the proposed F-HBF scheme, the compared HBF algorithms in [8,13,18], respectively. As can be observed from the figure, the proposed F-HBF scheme performs very close to the full digital beamforming.…”

“…Moreover, beam switching within BS also ensure a smoother switching between BSs. The authors in [13] proposed a timer-based beam selection algorithm for HSR. The algorithm used the prior knowledge of train position and direction in railway environment to estimate the angle of arrival and departure of propagation path.…”

“…The proposed scheme is a combination of fast analog beam-searching and digital beamforming algorithms. In contrast to [13], F-HBF does not need velocity feedback to calculate optimal beam pairs, but uses the improved fast beam-searching algorithm to carry on the periodic omni-directional search.…”