# Modeling and Performance Analysis of mmWave and WiFi-Based Vehicle Communications
## 1 Introduction  
In recent years, there has been a significant pivot by automotive manufacturers towards the development of autonomous and driverless vehicles, a trend that has been catalyzed by the exponential growth in vehicular Internet of Things (IoT) applications [1]. Consequently, Vehicle-to-vehicle (V2V) communication has emerged as a focal area of research, attracting considerable interest from both the academic sphere and the automotive industry. The facilitation of communication among vehicles plays a pivotal role in augmenting traffic safety and efficiency, enhancing driver assistance systems, and expediting the response to emergencies [2, 3, 4, 5, 6, 7, 8]. Within this framework, vehicles act as mobile sensors, exchanging critical safety alerts and information to preemptively identify hazardous and irregular conditions. This capacity enables drivers to swiftly detect and respond to potential threats on the road. Key applications of V2V communication technology encompass a broad spectrum, including collision warning systems, enhanced traffic signal prioritization, navigational aids for route adjustments, alerts for obscured hazards, roadside assistance services, and coordination for vehicle platoons [9, 10, 11, 12, 13, 14]. Intelligent transportation systems (ITSs) integrate a diverse array of sensing technologies, including GPS, video cameras, radars, and advanced communication capabilities like software updates and speech recognition. These systems are capable of generatingsubstantial volumes of data, potentially overwhelming the current capabilities of V2V communication infrastructures. As a result, there is a critical emphasis on achieving minimal latency and maximal throughput in these networks. The primary technologies underpinning V2V communications, utilizing licensed spectrum, include Cellular Vehicle-to-Everything (C-V2X) based on the Long-Term Evolution (LTE) standards defined by the 3 rd Generation Partnership Project (3 GPP) LTE Release 14, and Dedicated Short-Range Communications (DSRC), which adhere to the IEEE 802.11p standards [15]. DSRC systems typically achieve data transmission speeds ranging from 2 to 6 Mbps, while C-V2X can reach speeds up to 100 Mbps. Despite their advancements, existing studies have highlighted limitations in DSRC and 4G cellular technologies regarding their ability to deliver high-speed data transmission, reduce latency, and facilitate extensive sharing of raw sensor data for V2V communication on a broad scale. The advent of next-generation radio interfaces, particularly standardized as new radio (NR) by the 3 rd Generation Partnership Project (3 GPP), including the use of millimeter wave (mmWave) bands, appears as a viable solution to meet the demanding requirements of connected vehicles. The mmWave technology, characterized by its large bandwidth, is capable of providing high data rates, low latency, and directional connections that enhance beam-forming gains. This is particularly advantageous in densely populated vehicular environments where the efficient handling of data traffic is crucial. Recent research highlights millimeter wave (mmWave) communication as a pivotal technology for enhancing throughput in 5G networks, addressing the burgeoning requirements of intelligent V2V systems. Despite its promise, the deployment of mmWave technology faces several challenges, chiefly its propagation difficulties. The high-frequency signals characteristic of mmWave communications suffer from limited penetration through solid objects, leading to significant signal attenuation and reflection. This issue becomes particularly acute over long distances and in environments with high vehicle densities. Moreover, leveraging the beam-forming capabilities of mmWave technology requires a precise directional alignment between transmitting and receiving devices to mitigate path loss and ensure a stable connection, a necessity that becomes even more critical under congested vehicular conditions.