Experimental Analysis of the Temporal Variability of the V2V Channel at 5.9 GHz

Vehicle-to-vehicle (V2V) wireless communication systems are crucial for intelligent transportation applications such as traffic load control, autonomous vehicles, and collision avoidance. Therefore, it is essential to thoroughly understand the realistic V2V channel propagation conditions to develop suitable V2V communication systems and standards. However, due to high costs, most existing V2V studies focus on characterizing the vehicular channel theoretically and comparing it with simulation data or studying the empirical V2V channel in a specific scenario. In this work, we investigate the time variability of the received signal based on experimental data collected in an extensive measurement campaign at 5.9 GHz in a large set of propagation environments: urban-high traffic density, urban-low traffic density, suburban, highway, and rural environments. The time-variability of the received signal is characterized by time and frequency. The relationship between coherence time and the terminal velocity, coherence time and transmitter-receiver separation distance, and the relationship between Doppler spread and both effective velocity and separation distance, have been investigated. Furthermore, the correlation between coherence time and separation distance and effective velocity was investigated, as well as the correlation between Doppler spread and separation distance and effective velocity. The results provide a deeper understanding of the temporal variability of the channel and how it is influenced by factors such as traffic density, unique/multiple driving directions, terminal speed, separation distance, characteristics of the propagation environment, and visibility conditions. This knowledge is crucial for developing vehicular communication systems and can be applied to design strategies that reduce temporal variability in received signals.