Compact beamforming techniques for energy efficient wireless communication systems

Abstract

In this thesis, novel energy efficient beamforming techniques, for use in wireless communication systems, are proposed, investigated and analyzed. The techniques rely on utilizing the electronically steerable parasitic array radiator (ESPAR), and offer the advantages of a single radio frequency (RF) frontend as well as compact size. Applications in wireless communication include analog and hybrid beamforming. In the thesis investigations three novel ESPAR configurations are proposed, demonstrated and compared with benchmarks. In the first contribution, a novel analog beamforming technique is proposed for a multiple-input-single-output (MISO) system, utilizing compact-sized ESPAR. This technique is useful as it enables the straightforward formation of arbitrary beamformers within the beamspace domain. Additionally, channel state information (CSI) is carefully considered and addressed through an unconstrained load book optimization problem. By implementing this proposed approach, good spectral efficiency (SE) is achieved, while simultaneously achieving a notable enhancement in energy efficiency (EE). In the second contribution, a novel compact-sized beamforming technique is proposed for a massive multiple-input-multiple-output (MIMO) system, aiming to leverage ESPAR to enhance EE in millimeter wave (mmWave) band applications. By adopting the proposed technique, a larger number of antenna elements can be accommodated within a limited area compared to conventional planar arrays. This advantage leads to an improved SE compared to traditional hybrid beamforming techniques. Moreover, by eliminating the need for phase shifters in the proposed system, a significant improvement in EE is also achieved. In the third contribution, the aim has been to improve the practicality of compact-sized beamforming techniques by investigating quantized beamformers. Furthermore, a customized channel estimation method is proposed in the approach. The results demonstrate that a quantized beamformer with a limited number of resolution bits can achieve comparable SE to that without quantization. In addition, the tailored channel estimation approach attains SE close to that using conventional channel estimation. Consequently, by maintaining the SE of the quantized beamformer, the proposed system outperforms conventional techniques in terms of EE. All three contributions provide innovative solutions for compact-sized beamforming in energy-efficient wireless communication systems. In addition for all three techniques, simulation results are presented to validate the underlying theoretical assumptions and to compare their performance against traditional technologies. The techniques offer new approaches to beamforming for wireless communication systems and have potential for inclusion in future wireless systems.

Date of Award	2024
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Ross MURCH (Supervisor) & Chi Ying Tsui (Supervisor)