RELIABLE BEAM TRACKING ON HIGH-ALTITUDE PLATFORM FOR MILLIMETER WAVE HIGH-SPEED RAILWAY

• Main Author: Paso Salmeno, Amran
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76201
• Institution: Institut Teknologi Bandung

Owing to the dominant line-of-sight (LOS) component of high-altitude platform (HAP) communications, tracking the high-speed railway (HSR) uplink channel is commonly performed by forming received beam based on the estimated direction-of-arrival (DOA) of the LOS path. Although DOA estimation accuracy is increased by using smaller angle resolution, but the DOA-based beam tracking is not computationally efficient when large antenna array size is involved, as recognized in mmWave communications. Moreover, maintaining link reliability becomes very challenging since beam misalignments arises frequently due to the high-speed user. In this paper, we propose a learning-based framework aiming to achieve reliable connectivity for HSR data transmission using HAP infrastructure employing uniform planar array (UPA) antenna configuration. Specifically, we employ the mulit-armed bandit (MAB) beam tracking, which is carried out in between two initial access (IA) phases of the fifth generation (5G) radio frame and follows the existing modify exponential weight (EXP3) algorithm. The proposed scheme results in outage probability approaching that of the DOA-based scheme but with complexity which only scales linearly with the codebook size and independent on the number of antenna elements. Furthermore, performing beam tracking prolongs the interval between two IA phases yet with negligible deterioration in outage performance which translates to more room available for data transmission.