# A Review on Millimeter-Wave Hybrid Beamforming for Wireless Intelligent Transport Systems
###### Abstract
The reliable transmission of sensor data, including temperature readings, geographic information, and atmospheric data, contributes to improved spatial awareness, resource management, and decision-making in various sectors. The integration of millimeter-wave technology in UAV communications enables efficient, high-speed, and reliable data transfer, supporting a wide range of applications across aerial photography, surveillance, and remote sensing domains. By establishing mmWave access links through ground-based or satellite connections, UAVs can effectively communicate with core networks, facilitating the seamless transfer of visual, sensor, and other data for enhanced operational capabilities and situational awareness [11]. In this systematic review, we aim to provide a comprehensive roadmap for hybrid beamforming techniques applicable to mmWave MIMO communications, with an emphasis on wireless fidelity. We considered the following research questions while developing this unique systematic review. * How can we use the techniques and metrics in hybrid beamforming to design better wireless systems that work well with modern technology? * What factors affect the success of mmWave hybrid beamforming in wireless communication, and how can we optimize them to make systems work better? * How can the latest research trends in hybrid beamforming help us create more efficient and effective wireless communication systems using new millimeter-wave technologies? * How can we address the challenges, implement solutions, and focus on future research directions to improve the use of hybrid beamforming in wireless networks, considering the needs of today's technology and industry? To provide answers to the above research questions, we developed a database consisting of 350 articles from various reputable sources and then we finally selected 132 articles to develop this unique systematic review. The salient contributions are highlighted as follows:  
* A detailed literature review of algorithms/techniques used in hybrid beamforming along with performance metrics, characteristics, limitations, as well as performance evaluations are provided to enable communication compatible with modern trends. * An in-depth analysis of the mmWave hybrid beamforming landscape is provided based on user, link, band, scattering, structure, duplex, carrier, network, applications, codebook, and reflecting intelligent surfaces to optimize system design and performance across diversified user scenarios. * The current research trends for hybrid beamforming are provided to enable the development of advanced wireless communication systems with optimized performance and efficiency. * Challenges, solutions, and future research directions are provided to equip researchers with a deep understanding of the current state of the art and thereby enable the development of next-generation communication systems. Figure 3 illustrates the organization of this systematic review, which consists of five sections starting from Section 1, which constitutes a foundation stone; Section 2 contributes by providing critical knowledge; Section 3 contributes by providing comprehensive insights; Section 4 provides a thorough examination as well as an expert review; and finally Section 5 serves as an executive summary.